/*
 * This file is part of the Colobot: Gold Edition source code
 * Copyright (C) 2001-2014, Daniel Roux, EPSITEC SA & TerranovaTeam
 * http://epsitec.ch; http://colobot.info; http://github.com/colobot
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see http://gnu.org/licenses
 */


#include "graphics/opengl/gl21device.h"
#include "graphics/engine/engine.h"

#include "common/config.h"
#include "common/image.h"
#include "common/logger.h"
#include "common/profile.h"

#include "math/geometry.h"


#include <SDL.h>
#include <physfs.h>

#include <cassert>


// Graphics module namespace
namespace Gfx {

CGL21Device::CGL21Device(const GLDeviceConfig &config)
{
    m_config = config;
    m_lighting = false;
    m_lastVboId = 0;
    m_anisotropyAvailable = false;
    m_maxAnisotropy = 1;
    m_glMajor = 1;
    m_glMinor = 1;

    m_framebuffer = 0;
    m_colorBuffer = 0;
    m_depthBuffer = 0;
    m_offscreenRenderingEnabled = false;

    m_perPixelLighting = false;
}


CGL21Device::~CGL21Device()
{
}

void CGL21Device::DebugHook()
{
    /* This function is only called here, so it can be used
     * as a breakpoint when debugging using gDEBugger */
    glColor3i(0, 0, 0);
}

void CGL21Device::DebugLights()
{
    Gfx::ColorHSV color(0.0, 1.0, 1.0);

    glLineWidth(3.0f);
    glDisable(GL_LIGHTING);
    glDepthMask(GL_FALSE);
    glDisable(GL_BLEND);

    Math::Matrix saveWorldMat = m_worldMat;
    m_worldMat.LoadIdentity();
    SetTransform(TRANSFORM_WORLD, m_worldMat);

    for (int i = 0; i < static_cast<int>( m_lights.size() ); ++i)
    {
        color.h = static_cast<float>(i) / static_cast<float>(m_lights.size());
        if (m_lightsEnabled[i])
        {
            const Light& l = m_lights[i];
            if (l.type == LIGHT_DIRECTIONAL)
            {
                Gfx::VertexCol v[2];
                v[0].coord = -Math::Normalize(l.direction) * 100.0f + Math::Vector(0.0f, 0.0f, 1.0f) * i;
                v[0].color = HSV2RGB(color);
                v[1].coord =  Math::Normalize(l.direction) * 100.0f + Math::Vector(0.0f, 0.0f, 1.0f) * i;
                v[1].color = HSV2RGB(color);
                while (v[0].coord.y < 60.0f && v[0].coord.y < 60.0f)
                {
                    v[0].coord.y += 10.0f;
                    v[1].coord.y += 10.0f;
                }
                DrawPrimitive(PRIMITIVE_LINES, v, 2);

                v[0].coord = v[1].coord + Math::Normalize(v[0].coord - v[1].coord) * 50.0f;

                glLineWidth(10.0f);
                DrawPrimitive(PRIMITIVE_LINES, v, 2);
                glLineWidth(3.0f);
            }
            else  if (l.type == LIGHT_POINT)
            {
                Gfx::VertexCol v[8];
                for (int i = 0; i < 8; ++i)
                    v[i].color = HSV2RGB(color);

                v[0].coord = l.position + Math::Vector(-1.0f, -1.0f, -1.0f) * 4.0f;
                v[1].coord = l.position + Math::Vector( 1.0f, -1.0f, -1.0f) * 4.0f;
                v[2].coord = l.position + Math::Vector( 1.0f,  1.0f, -1.0f) * 4.0f;
                v[3].coord = l.position + Math::Vector(-1.0f,  1.0f, -1.0f) * 4.0f;
                v[4].coord = l.position + Math::Vector(-1.0f, -1.0f, -1.0f) * 4.0f;
                DrawPrimitive(PRIMITIVE_LINE_STRIP, v, 5);

                v[0].coord = l.position + Math::Vector(-1.0f, -1.0f,  1.0f) * 4.0f;
                v[1].coord = l.position + Math::Vector( 1.0f, -1.0f,  1.0f) * 4.0f;
                v[2].coord = l.position + Math::Vector( 1.0f,  1.0f,  1.0f) * 4.0f;
                v[3].coord = l.position + Math::Vector(-1.0f,  1.0f,  1.0f) * 4.0f;
                v[4].coord = l.position + Math::Vector(-1.0f, -1.0f,  1.0f) * 4.0f;
                DrawPrimitive(PRIMITIVE_LINE_STRIP, v, 5);

                v[0].coord = l.position + Math::Vector(-1.0f, -1.0f, -1.0f) * 4.0f;
                v[1].coord = l.position + Math::Vector(-1.0f, -1.0f,  1.0f) * 4.0f;
                v[2].coord = l.position + Math::Vector( 1.0f, -1.0f, -1.0f) * 4.0f;
                v[3].coord = l.position + Math::Vector( 1.0f, -1.0f,  1.0f) * 4.0f;
                v[4].coord = l.position + Math::Vector( 1.0f,  1.0f, -1.0f) * 4.0f;
                v[5].coord = l.position + Math::Vector( 1.0f,  1.0f,  1.0f) * 4.0f;
                v[6].coord = l.position + Math::Vector(-1.0f,  1.0f, -1.0f) * 4.0f;
                v[7].coord = l.position + Math::Vector(-1.0f,  1.0f,  1.0f) * 4.0f;
                DrawPrimitive(PRIMITIVE_LINES, v, 8);
            }
            else if (l.type == LIGHT_SPOT)
            {
                Gfx::VertexCol v[5];
                for (int i = 0; i < 5; ++i)
                    v[i].color = HSV2RGB(color);

                v[0].coord = l.position + Math::Vector(-1.0f,  0.0f, -1.0f) * 4.0f;
                v[1].coord = l.position + Math::Vector( 1.0f,  0.0f, -1.0f) * 4.0f;
                v[2].coord = l.position + Math::Vector( 1.0f,  0.0f,  1.0f) * 4.0f;
                v[3].coord = l.position + Math::Vector(-1.0f,  0.0f,  1.0f) * 4.0f;
                v[4].coord = l.position + Math::Vector(-1.0f,  0.0f, -1.0f) * 4.0f;
                DrawPrimitive(PRIMITIVE_LINE_STRIP, v, 5);

                v[0].coord = l.position;
                v[1].coord = l.position + Math::Normalize(l.direction) * 100.0f;
                glEnable(GL_LINE_STIPPLE);
                glLineStipple(3.0, 0xFF);
                DrawPrimitive(PRIMITIVE_LINES, v, 2);
                glDisable(GL_LINE_STIPPLE);
            }
        }
    }

    glLineWidth(1.0f);
    glEnable(GL_LIGHTING);
    glDepthMask(GL_TRUE);
    glEnable(GL_BLEND);

    SetTransform(TRANSFORM_WORLD, saveWorldMat);
    m_worldMat = saveWorldMat;
}

bool CGL21Device::Create()
{
    GetLogger()->Info("Creating CDevice - OpenGL 2.1\n");

    /*static*/ bool glewInited = false;

    if (!glewInited)
    {
        glewInited = true;

        glewExperimental = GL_TRUE;

        if (glewInit() != GLEW_OK)
        {
            GetLogger()->Error("GLEW initialization failed\n");
            return false;
        }

        // Extract OpenGL version
        const char *version = reinterpret_cast<const char*>(glGetString(GL_VERSION));
        sscanf(version, "%d.%d", &m_glMajor, &m_glMinor);

        if (m_glMajor < 2)
        {
            GetLogger()->Error("Your hardware does not support OpenGL 2.0 or 2.1.");
            return false;
        }

        GetLogger()->Info("OpenGL %d.%d\n", m_glMajor, m_glMinor);

        m_framebufferObject = glewIsSupported("GL_EXT_framebuffer_object");
        if (m_framebufferObject)
        {
            glGetIntegerv(GL_MAX_RENDERBUFFER_SIZE_EXT, &m_maxRenderbufferSize);

            GetLogger()->Info("Offscreen rendering available\n");
            GetLogger()->Info("Maximum renderbuffer size: %d\n", m_maxRenderbufferSize);
        }

        // Detect support of anisotropic filtering
        m_anisotropyAvailable = glewIsSupported("GL_EXT_texture_filter_anisotropic");
        if(m_anisotropyAvailable)
        {
            // Obtain maximum anisotropy level available
            float level;
            glGetFloatv(GL_MAX_TEXTURE_MAX_ANISOTROPY_EXT, &level);
            m_maxAnisotropy = static_cast<int>(level);
            
            GetLogger()->Info("Anisotropic filtering available\n");
            GetLogger()->Info("Maximum anisotropy: %d\n", m_maxAnisotropy);
        }
        else
        {
            GetLogger()->Info("Anisotropic filtering not available\n");
        }
    }

    // This is mostly done in all modern hardware by default
    // DirectX doesn't even allow the option to turn off perspective correction anymore
    // So turn it on permanently
    glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);

    // Set just to be sure
    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);

    glViewport(0, 0, m_config.size.x, m_config.size.y);

    int numLights = 0;
    glGetIntegerv(GL_MAX_LIGHTS, &numLights);

    m_lights        = std::vector<Light>(numLights, Light());
    m_lightsEnabled = std::vector<bool> (numLights, false);

    int maxTextures = 0;
    glGetIntegerv(GL_MAX_TEXTURE_IMAGE_UNITS, &maxTextures);
    GetLogger()->Info("Maximum texture image units: %d\n", maxTextures);

    m_currentTextures    = std::vector<Texture>           (maxTextures, Texture());
    m_texturesEnabled    = std::vector<bool>              (maxTextures, false);
    m_textureStageParams = std::vector<TextureStageParams>(maxTextures, TextureStageParams());

    int value;
    if (CProfile::GetInstance().GetIntProperty("Setup", "PerPixelLighting", value))
    {
        m_perPixelLighting = value > 0;
    }

    if (m_perPixelLighting)
        CLogger::GetInstance().Info("Using per-pixel lighting\n");
    else
        CLogger::GetInstance().Info("Using per-vertex lighting\n");

    // Create shader program
    GLchar source[65536];
    const GLchar *sources[] = { source };

    char filename[128];

    if (m_perPixelLighting)
        sprintf(filename, "shaders/vertex_shader_21_perpixel.glsl");
    else
        sprintf(filename, "shaders/vertex_shader_21_pervertex.glsl");

    PHYSFS_file *file = PHYSFS_openRead(filename);
    if (file == nullptr)
    {
        CLogger::GetInstance().Error("Cannot read vertex shader code file!\n");
        CLogger::GetInstance().Error("Missing file \"%s\"\n", filename);
        return false;
    }

    int length = PHYSFS_read(file, source, 1, 65536);
    source[length] = '\0';

    PHYSFS_close(file);

    GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertexShader, 1, sources, nullptr);
    glCompileShader(vertexShader);

    GLint status;
    glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &status);

    if (status != GL_TRUE)
    {
        GLint len;
        glGetShaderiv(vertexShader, GL_INFO_LOG_LENGTH, &len);

        GLchar *message = new GLchar[len + 1];
        glGetShaderInfoLog(vertexShader, len + 1, nullptr, message);

        GetLogger()->Error("Vertex shader compilation error occured!\n%s\n", message);

        delete[] message;
        return false;
    }

    if (m_perPixelLighting)
        sprintf(filename, "shaders/fragment_shader_21_perpixel.glsl");
    else
        sprintf(filename, "shaders/fragment_shader_21_pervertex.glsl");

    file = PHYSFS_openRead(filename);
    if (file == nullptr)
    {
        CLogger::GetInstance().Error("Cannot read fragment shader code file!\n");
        CLogger::GetInstance().Error("Missing file \"%s\"\n", filename);
        return false;
    }

    length = PHYSFS_read(file, source, 1, 65536);
    source[length] = '\0';

    PHYSFS_close(file);

    GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragmentShader, 1, sources, nullptr);
    glCompileShader(fragmentShader);

    glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &status);

    if (status != GL_TRUE)
    {
        GLint len;
        glGetShaderiv(fragmentShader, GL_INFO_LOG_LENGTH, &len);

        GLchar *message = new GLchar[len + 1];
        glGetShaderInfoLog(fragmentShader, len + 1, nullptr, message);

        GetLogger()->Error("Fragment shader compilation error occured!\n%s\n", message);

        delete[] message;
        return false;
    }

    m_shaderProgram = glCreateProgram();
    glAttachShader(m_shaderProgram, vertexShader);
    glAttachShader(m_shaderProgram, fragmentShader);

    glLinkProgram(m_shaderProgram);

    glDetachShader(m_shaderProgram, vertexShader);
    glDetachShader(m_shaderProgram, fragmentShader);

    glGetProgramiv(m_shaderProgram, GL_LINK_STATUS, &status);

    if (status != GL_TRUE)
    {
        GLint len;
        glGetProgramiv(m_shaderProgram, GL_INFO_LOG_LENGTH, &len);

        GLchar *message = new GLchar[len + 1];
        glGetProgramInfoLog(m_shaderProgram, len + 1, nullptr, message);

        GetLogger()->Error("Shader program linking error occured!\n%s\n", message);

        delete[] message;
        return false;
    }

    glDeleteShader(vertexShader);
    glDeleteShader(fragmentShader);

    glUseProgram(m_shaderProgram);

    // Obtain uniform locations
    uni_ProjectionMatrix = glGetUniformLocation(m_shaderProgram, "uni_ProjectionMatrix");
    uni_ViewMatrix = glGetUniformLocation(m_shaderProgram, "uni_ViewMatrix");
    uni_ModelMatrix = glGetUniformLocation(m_shaderProgram, "uni_ModelMatrix");
    uni_NormalMatrix = glGetUniformLocation(m_shaderProgram, "uni_NormalMatrix");
    uni_ShadowMatrix = glGetUniformLocation(m_shaderProgram, "uni_ShadowMatrix");

    uni_PrimaryTexture = glGetUniformLocation(m_shaderProgram, "uni_PrimaryTexture");
    uni_SecondaryTexture = glGetUniformLocation(m_shaderProgram, "uni_SecondaryTexture");
    uni_ShadowTexture = glGetUniformLocation(m_shaderProgram, "uni_ShadowTexture");

    for (int i = 0; i < 3; i++)
    {
        char name[64];
        sprintf(name, "uni_TextureEnabled[%d]", i);
        uni_TextureEnabled[i] = glGetUniformLocation(m_shaderProgram, name);
    }

    uni_AlphaTestEnabled = glGetUniformLocation(m_shaderProgram, "uni_AlphaTestEnabled");
    uni_AlphaReference = glGetUniformLocation(m_shaderProgram, "uni_AlphaReference");

    uni_FogEnabled = glGetUniformLocation(m_shaderProgram, "uni_FogEnabled");
    uni_FogRange = glGetUniformLocation(m_shaderProgram, "uni_FogRange");
    uni_FogColor = glGetUniformLocation(m_shaderProgram, "uni_FogColor");

    uni_ShadowColor =  glGetUniformLocation(m_shaderProgram, "uni_ShadowColor");
    uni_LightingEnabled = glGetUniformLocation(m_shaderProgram, "uni_LightingEnabled");

    for (int i = 0; i < 8; i++)
    {
        char name[64];
        sprintf(name, "uni_LightEnabled[%d]", i);
        uni_LightEnabled[i] = glGetUniformLocation(m_shaderProgram, name);
    }

    // Set default uniform values
    Math::Matrix matrix;
    matrix.LoadIdentity();

    glUniformMatrix4fv(uni_ProjectionMatrix, 1, GL_FALSE, matrix.Array());
    glUniformMatrix4fv(uni_ViewMatrix, 1, GL_FALSE, matrix.Array());
    glUniformMatrix4fv(uni_ModelMatrix, 1, GL_FALSE, matrix.Array());
    glUniformMatrix4fv(uni_NormalMatrix, 1, GL_FALSE, matrix.Array());
    glUniformMatrix4fv(uni_ShadowMatrix, 1, GL_FALSE, matrix.Array());

    glUniform1i(uni_PrimaryTexture, 0);
    glUniform1i(uni_SecondaryTexture, 1);
    glUniform1i(uni_ShadowTexture, 2);

    for (int i = 0; i < 3; i++)
        glUniform1i(uni_TextureEnabled[i], 0);

    glUniform1i(uni_AlphaTestEnabled, 0);
    glUniform1f(uni_AlphaReference, 0.5f);

    glUniform1i(uni_FogEnabled, 0);
    glUniform2f(uni_FogRange, 100.0f, 200.0f);
    glUniform4f(uni_FogColor, 0.8f, 0.8f, 0.8f, 1.0f);

    glUniform1i(uni_LightingEnabled, 0);
    for (int i = 0; i < 8; i++)
        glUniform1i(uni_LightEnabled[i], 0);

    GetLogger()->Info("CDevice created successfully\n");

    return true;
}

void CGL21Device::Destroy()
{
    // Delete the remaining textures
    // Should not be strictly necessary, but just in case
    glUseProgram(0);
    glDeleteProgram(m_shaderProgram);

    DestroyAllTextures();

    m_lights.clear();
    m_lightsEnabled.clear();

    m_currentTextures.clear();
    m_texturesEnabled.clear();
    m_textureStageParams.clear();
}

void CGL21Device::ConfigChanged(const GLDeviceConfig& newConfig)
{
    m_config = newConfig;

    // Reset state
    m_lighting = false;
    Destroy();
    Create();
}

void CGL21Device::BeginScene()
{
    Clear();
}

void CGL21Device::EndScene()
{
}

void CGL21Device::Clear()
{
    glDepthMask(GL_TRUE);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
}

void CGL21Device::SetTransform(TransformType type, const Math::Matrix &matrix)
{
    if (type == TRANSFORM_WORLD)
    {
        m_worldMat = matrix;
        glUniformMatrix4fv(uni_ModelMatrix, 1, GL_FALSE, m_worldMat.Array());

        // normal transform
        Math::Matrix normalMat = matrix;
        normalMat = normalMat.Inverse();

        glUniformMatrix4fv(uni_NormalMatrix, 1, GL_TRUE, normalMat.Array());
    }
    else if (type == TRANSFORM_VIEW)
    {
        m_viewMat = matrix;
        Math::Matrix scale;
        Math::LoadScaleMatrix(scale, Math::Vector(1.0f, 1.0f, -1.0f));
        Math::Matrix temp = Math::MultiplyMatrices(scale, matrix);
        glUniformMatrix4fv(uni_ViewMatrix, 1, GL_FALSE, temp.Array());
    }
    else if (type == TRANSFORM_PROJECTION)
    {
        m_projectionMat = matrix;
        glUniformMatrix4fv(uni_ProjectionMatrix, 1, GL_FALSE, m_projectionMat.Array());
    }
    else if (type == TRANSFORM_SHADOW)
    {
        Math::Matrix temp = matrix;
        glUniformMatrix4fv(uni_ShadowMatrix, 1, GL_FALSE, temp.Array());
    }
    else
    {
        assert(false);
    }
}

void CGL21Device::SetMaterial(const Material &material)
{
    m_material = material;

    glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT,  m_material.ambient.Array());
    glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, m_material.diffuse.Array());
    glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, m_material.specular.Array());
}

int CGL21Device::GetMaxLightCount()
{
    return m_lights.size();
}

void CGL21Device::SetLight(int index, const Light &light)
{
    assert(index >= 0);
    assert(index < static_cast<int>( m_lights.size() ));

    m_lights[index] = light;

    // Indexing from GL_LIGHT0 should always work
    glLightfv(GL_LIGHT0 + index, GL_AMBIENT,  const_cast<GLfloat*>(light.ambient.Array()));
    glLightfv(GL_LIGHT0 + index, GL_DIFFUSE,  const_cast<GLfloat*>(light.diffuse.Array()));
    glLightfv(GL_LIGHT0 + index, GL_SPECULAR, const_cast<GLfloat*>(light.specular.Array()));

    glLightf(GL_LIGHT0 + index, GL_CONSTANT_ATTENUATION,  light.attenuation0);
    glLightf(GL_LIGHT0 + index, GL_LINEAR_ATTENUATION,    light.attenuation1);
    glLightf(GL_LIGHT0 + index, GL_QUADRATIC_ATTENUATION, light.attenuation2);

    if (light.type == LIGHT_SPOT)
    {
        glLightf(GL_LIGHT0 + index, GL_SPOT_CUTOFF, light.spotAngle * Math::RAD_TO_DEG);
        glLightf(GL_LIGHT0 + index, GL_SPOT_EXPONENT, light.spotIntensity);
    }
    else
    {
        glLightf(GL_LIGHT0 + index, GL_SPOT_CUTOFF, 180.0f);
    }

    UpdateLightPosition(index);
}

void CGL21Device::UpdateLightPosition(int index)
{
    assert(index >= 0);
    assert(index < static_cast<int>( m_lights.size() ));

    glMatrixMode(GL_MODELVIEW);

    glPushMatrix();

    glLoadIdentity();
    //glScalef(1.0f, 1.0f, -1.0f);

    if (m_lights[index].type == LIGHT_SPOT)
    {
        GLfloat direction[4] = { -m_lights[index].direction.x, -m_lights[index].direction.y, -m_lights[index].direction.z, 1.0f };
        glLightfv(GL_LIGHT0 + index, GL_SPOT_DIRECTION, direction);
    }

    if (m_lights[index].type == LIGHT_DIRECTIONAL)
    {
        GLfloat position[4] = { -m_lights[index].direction.x, -m_lights[index].direction.y, -m_lights[index].direction.z, 0.0f };
        glLightfv(GL_LIGHT0 + index, GL_POSITION, position);
    }
    else
    {
        GLfloat position[4] = { m_lights[index].position.x, m_lights[index].position.y, m_lights[index].position.z, 1.0f };
        glLightfv(GL_LIGHT0 + index, GL_POSITION, position);
    }

    glPopMatrix();
}

void CGL21Device::SetLightEnabled(int index, bool enabled)
{
    assert(index >= 0);
    assert(index < static_cast<int>( m_lights.size() ));

    m_lightsEnabled[index] = enabled;

    glUniform1i(uni_LightEnabled[index], enabled ? 1 : 0);
}

/** If image is invalid, returns invalid texture.
    Otherwise, returns pointer to new Texture struct.
    This struct must not be deleted in other way than through DeleteTexture() */
Texture CGL21Device::CreateTexture(CImage *image, const TextureCreateParams &params)
{
    ImageData *data = image->GetData();
    if (data == nullptr)
    {
        GetLogger()->Error("Invalid texture data\n");
        return Texture(); // invalid texture
    }

    Math::IntPoint originalSize = image->GetSize();

    if (params.padToNearestPowerOfTwo)
        image->PadToNearestPowerOfTwo();

    Texture tex = CreateTexture(data, params);
    tex.originalSize = originalSize;

    return tex;
}

Texture CGL21Device::CreateTexture(ImageData *data, const TextureCreateParams &params)
{
    Texture result;

    result.size.x = data->surface->w;
    result.size.y = data->surface->h;

    if (!Math::IsPowerOfTwo(result.size.x) || !Math::IsPowerOfTwo(result.size.y))
        GetLogger()->Warn("Creating non-power-of-2 texture (%dx%d)!\n", result.size.x, result.size.y);
    
    result.originalSize = result.size;

    glActiveTexture(GL_TEXTURE0);
    glEnable(GL_TEXTURE_2D);

    glGenTextures(1, &result.id);
    glBindTexture(GL_TEXTURE_2D, result.id);

    // Set texture parameters
    GLint minF = GL_NEAREST, magF = GL_NEAREST;
    int mipmapLevel = 1;

    switch (params.filter)
    {
    case TEX_FILTER_NEAREST:
        minF = GL_NEAREST;
        magF = GL_NEAREST;
        break;
    case TEX_FILTER_BILINEAR:
        minF = GL_LINEAR;
        magF = GL_LINEAR;
        break;
    case TEX_FILTER_TRILINEAR:
        minF = GL_LINEAR_MIPMAP_LINEAR;
        magF = GL_LINEAR;
        mipmapLevel = CEngine::GetInstance().GetTextureMipmapLevel();
        break;
    }

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, minF);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, magF);

    // Set mipmap level and automatic mipmap generation if neccesary
    if (params.mipmap)
    {
	    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, 0);
	    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, mipmapLevel - 1);
	    glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP, GL_TRUE);
    }
    else
    {
	    // Has to be set to 0 because no mipmaps are generated
	    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, 0);
	    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 0);
	    glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP, GL_FALSE);
    }

    // Set anisotropy level if available
    if (m_anisotropyAvailable)
    {
	    float level = Math::Min(m_maxAnisotropy, CEngine::GetInstance().GetTextureAnisotropyLevel());

	    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAX_ANISOTROPY_EXT, level);
    }

    bool convert = false;
    GLenum sourceFormat = 0;

    if (params.format == TEX_IMG_RGB)
    {
        sourceFormat = GL_RGB;
        result.alpha = false;
    }
    else if (params.format == TEX_IMG_BGR)
    {
        sourceFormat = GL_BGR;
        result.alpha = false;
    }
    else if (params.format == TEX_IMG_RGBA)
    {
        sourceFormat = GL_RGBA;
        result.alpha = true;
    }
    else if (params.format == TEX_IMG_BGRA)
    {
        sourceFormat = GL_BGRA;
        result.alpha = true;
    }
    else if (params.format == TEX_IMG_AUTO)
    {
        if (data->surface->format->BytesPerPixel == 4)
        {
            if ((data->surface->format->Amask == 0xFF000000) &&
                (data->surface->format->Rmask == 0x00FF0000) &&
                (data->surface->format->Gmask == 0x0000FF00) &&
                (data->surface->format->Bmask == 0x000000FF))
            {
                sourceFormat = GL_BGRA;
                result.alpha = true;
            }
            else if ((data->surface->format->Amask == 0xFF000000) &&
                     (data->surface->format->Bmask == 0x00FF0000) &&
                     (data->surface->format->Gmask == 0x0000FF00) &&
                     (data->surface->format->Rmask == 0x000000FF))
            {
                sourceFormat = GL_RGBA;
                result.alpha = true;
            }
            else
            {
                sourceFormat = GL_RGBA;
                convert = true;
            }
        }
        else if (data->surface->format->BytesPerPixel == 3)
        {
            if ((data->surface->format->Rmask == 0xFF0000) &&
                (data->surface->format->Gmask == 0x00FF00) &&
                (data->surface->format->Bmask == 0x0000FF))
            {
                sourceFormat = GL_BGR;
                result.alpha = false;
            }
            else if ((data->surface->format->Bmask == 0xFF0000) &&
                     (data->surface->format->Gmask == 0x00FF00) &&
                     (data->surface->format->Rmask == 0x0000FF))
            {
                sourceFormat = GL_RGB;
                result.alpha = false;
            }
            else
            {
                sourceFormat = GL_RGBA;
                convert = true;
            }
        }
        else {
            GetLogger()->Error("Unknown data surface format");
            assert(false);
        }
    }
    else
        assert(false);

    SDL_Surface* actualSurface = data->surface;
    SDL_Surface* convertedSurface = nullptr;

    if (convert)
    {
        SDL_PixelFormat format;
        format.BytesPerPixel = 4;
        format.BitsPerPixel = 32;
        format.alpha = 0;
        format.colorkey = 0;
        format.Aloss = format.Bloss = format.Gloss = format.Rloss = 0;
        format.Amask = 0xFF000000;
        format.Ashift = 24;
        format.Bmask = 0x00FF0000;
        format.Bshift = 16;
        format.Gmask = 0x0000FF00;
        format.Gshift = 8;
        format.Rmask = 0x000000FF;
        format.Rshift = 0;
        format.palette = nullptr;
        convertedSurface = SDL_ConvertSurface(data->surface, &format, SDL_SWSURFACE);
        if (convertedSurface != nullptr)
            actualSurface = convertedSurface;
    }

    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, actualSurface->w, actualSurface->h,
                 0, sourceFormat, GL_UNSIGNED_BYTE, actualSurface->pixels);

    SDL_FreeSurface(convertedSurface);

    // Restore the previous state of 1st stage
    glBindTexture(GL_TEXTURE_2D, m_currentTextures[0].id);

    if (! m_texturesEnabled[0])
        glDisable(GL_TEXTURE_2D);

    return result;
}

Texture CGL21Device::CreateDepthTexture(int width, int height, int depth)
{
    Texture result;
    
    result.alpha = false;
    result.size.x = width;
    result.size.y = height;

    // Use & enable 1st texture stage
    glActiveTexture(GL_TEXTURE0);

    glGenTextures(1, &result.id);
    glBindTexture(GL_TEXTURE_2D, result.id);

    GLuint format = GL_DEPTH_COMPONENT;

    switch (depth)
    {
    case 16:
        format = GL_DEPTH_COMPONENT16;
        break;
    case 24:
        format = GL_DEPTH_COMPONENT24;
        break;
    case 32:
        format = GL_DEPTH_COMPONENT32;
        break;
    }

    glTexImage2D(GL_TEXTURE_2D, 0, format, width, height, 0, GL_DEPTH_COMPONENT, GL_INT, nullptr);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_MODE, GL_COMPARE_R_TO_TEXTURE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_FUNC, GL_LEQUAL);

    float color[] = { 1.0f, 1.0f, 1.0f, 1.0f };

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);
    glTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_BORDER_COLOR, color);

    glBindTexture(GL_TEXTURE_2D, m_currentTextures[0].id);

    return result;
}

void CGL21Device::DestroyTexture(const Texture &texture)
{
    // Unbind the texture if in use anywhere
    for (int index = 0; index < static_cast<int>( m_currentTextures.size() ); ++index)
    {
        if (m_currentTextures[index] == texture)
            SetTexture(index, Texture()); // set to invalid texture
    }

    glDeleteTextures(1, &texture.id);

    auto it = m_allTextures.find(texture);
    if (it != m_allTextures.end())
        m_allTextures.erase(it);
}

void CGL21Device::DestroyAllTextures()
{
    // Unbind all texture stages
    for (int index = 0; index < static_cast<int>( m_currentTextures.size() ); ++index)
        SetTexture(index, Texture());

    for (auto it = m_allTextures.begin(); it != m_allTextures.end(); ++it)
        glDeleteTextures(1, &(*it).id);

    m_allTextures.clear();
}

int CGL21Device::GetMaxTextureStageCount()
{
    return m_currentTextures.size();
}

/**
  If \a texture is invalid, unbinds the given texture.
  If valid, binds the texture and enables the given texture stage.
  The setting is remembered, even if texturing is disabled at the moment. */
void CGL21Device::SetTexture(int index, const Texture &texture)
{
    assert(index >= 0 && index < static_cast<int>( m_currentTextures.size() ));

    bool same = m_currentTextures[index].id == texture.id;

    m_currentTextures[index] = texture; // remember the new value

    if (same)
        return; // nothing to do

    glActiveTexture(GL_TEXTURE0 + index);

    glBindTexture(GL_TEXTURE_2D, texture.id);

    // Params need to be updated for the new bound texture
    UpdateTextureParams(index);

    UpdateTextureStatus();
}

void CGL21Device::SetTexture(int index, unsigned int textureId)
{
    assert(index >= 0 && index < static_cast<int>( m_currentTextures.size() ));

    if (m_currentTextures[index].id == textureId)
        return; // nothing to do

    m_currentTextures[index].id = textureId;

    glActiveTexture(GL_TEXTURE0 + index);

    glBindTexture(GL_TEXTURE_2D, textureId);

    // Params need to be updated for the new bound texture
    UpdateTextureParams(index);

    UpdateTextureStatus();
}

void CGL21Device::SetTextureEnabled(int index, bool enabled)
{
    assert(index >= 0 && index < static_cast<int>( m_currentTextures.size() ));

    bool same = m_texturesEnabled[index] == enabled;

    m_texturesEnabled[index] = enabled;

    if (same)
        return; // nothing to do

    glUniform1i(uni_TextureEnabled[index], enabled ? 1 : 0);

    //UpdateTextureStatus();
}

void CGL21Device::UpdateTextureStatus()
{
    glUniform1i(uni_TextureEnabled[0], m_currentTextures[0].id != 0 ? 1 : 0);

    /*
    bool enabled = m_texturesEnabled[0] && m_currentTextures[0].id != 0;
    glUniform1i(uni_PrimaryTextureEnabled, enabled ? 1 : 0);

    enabled = m_texturesEnabled[1] && m_currentTextures[1].id != 0;
    glUniform1i(uni_SecondaryTextureEnabled, enabled ? 1 : 0);

    enabled = m_texturesEnabled[2] && m_currentTextures[2].id != 0;
    glUniform1i(uni_ShadowTextureEnabled, enabled ? 1 : 0);
    */
}

/**
  Sets the texture parameters for the given texture stage.
  If the given texture was not set (bound) yet, nothing happens.
  The settings are remembered, even if texturing is disabled at the moment. */
void CGL21Device::SetTextureStageParams(int index, const TextureStageParams &params)
{
    assert(index >= 0 && index < static_cast<int>( m_currentTextures.size() ));

    // Remember the settings
    m_textureStageParams[index] = params;

    UpdateTextureParams(index);
}

void CGL21Device::SetTextureCoordGeneration(int index, TextureGenerationParams &params)
{
    /*
    glActiveTexture(GL_TEXTURE0 + index);

    for (int i = 0; i < 4; i++)
    {
        GLuint texCoordGen = TranslateTextureCoordinateGen(i);
        GLuint texCoord = TranslateTextureCoordinate(i);

        switch (params.coords[i].mode)
        {
        case TEX_GEN_NONE:
            glDisable(texCoordGen);
            break;
        case TEX_GEN_OBJECT_LINEAR:
            glEnable(texCoordGen);
            glTexGeni(texCoord, GL_TEXTURE_GEN_MODE, GL_OBJECT_LINEAR);
            glTexGenfv(texCoord, GL_OBJECT_PLANE, params.coords[i].plane);
            break;
        case TEX_GEN_EYE_LINEAR:
            glEnable(texCoordGen);
            glTexGeni(texCoord, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR);
            glTexGenfv(texCoord, GL_EYE_PLANE, params.coords[i].plane);
            break;
        case TEX_GEN_SPHERE_MAP:
            glEnable(texCoordGen);
            glTexGeni(texCoord, GL_TEXTURE_GEN_MODE, GL_SPHERE_MAP);
            break;
        case TEX_GEN_NORMAL_MAP:
            glEnable(texCoordGen);
            glTexGeni(texCoord, GL_TEXTURE_GEN_MODE, GL_NORMAL_MAP);
            break;
        case TEX_GEN_REFLECTION_MAP:
            glEnable(texCoordGen);
            glTexGeni(texCoord, GL_TEXTURE_GEN_MODE, GL_REFLECTION_MAP);
            break;
        }
    }
    // */
}

void CGL21Device::UpdateTextureParams(int index)
{
    assert(index >= 0 && index < static_cast<int>( m_currentTextures.size() ));

    // Don't actually do anything if texture not set
    if (! m_currentTextures[index].Valid())
        return;

    const TextureStageParams &params = m_textureStageParams[index];

    glActiveTexture(GL_TEXTURE0 + index);

    if      (params.wrapS == TEX_WRAP_CLAMP)
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    else if (params.wrapS == TEX_WRAP_CLAMP_TO_BORDER)
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
    else if (params.wrapS == TEX_WRAP_REPEAT)
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    else  assert(false);

    if      (params.wrapT == TEX_WRAP_CLAMP)
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    else if (params.wrapT == TEX_WRAP_CLAMP_TO_BORDER)
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);
    else if (params.wrapT == TEX_WRAP_REPEAT)
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    else  assert(false);

    glTexEnvfv(GL_TEXTURE_ENV, GL_TEXTURE_ENV_COLOR, params.factor.Array());

    // To save some trouble
    if ( (params.colorOperation == TEX_MIX_OPER_DEFAULT) &&
         (params.alphaOperation == TEX_MIX_OPER_DEFAULT) )
    {
        glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
        goto after_tex_operations;
    }

    glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE);

    // Only these modes of getting color & alpha are used
    glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_RGB, GL_SRC_COLOR);
    glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND1_RGB, GL_SRC_COLOR);
    glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_ALPHA, GL_SRC_ALPHA);
    glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND1_ALPHA, GL_SRC_ALPHA);

    // Color operation

    if (params.colorOperation == TEX_MIX_OPER_DEFAULT)
    {
        glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_MODULATE);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_PREVIOUS);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_RGB, GL_TEXTURE);
        goto after_tex_color;
    }
    else if (params.colorOperation == TEX_MIX_OPER_REPLACE)
        glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_REPLACE);
    else if (params.colorOperation == TEX_MIX_OPER_MODULATE)
        glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_MODULATE);
    else if (params.colorOperation == TEX_MIX_OPER_ADD)
        glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_ADD);
    else if (params.colorOperation == TEX_MIX_OPER_SUBTRACT)
        glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_SUBTRACT);
    else  assert(false);

    // Color arg1
    if (params.colorArg1 == TEX_MIX_ARG_TEXTURE)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_TEXTURE);
    else if (params.colorArg1 == TEX_MIX_ARG_TEXTURE_0)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_TEXTURE0);
    else if (params.colorArg1 == TEX_MIX_ARG_TEXTURE_1)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_TEXTURE1);
    else if (params.colorArg1 == TEX_MIX_ARG_TEXTURE_2)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_TEXTURE2);
    else if (params.colorArg1 == TEX_MIX_ARG_TEXTURE_3)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_TEXTURE3);
    else if (params.colorArg1 == TEX_MIX_ARG_COMPUTED_COLOR)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_PREVIOUS);
    else if (params.colorArg1 == TEX_MIX_ARG_SRC_COLOR)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_PRIMARY_COLOR);
    else if (params.colorArg1 == TEX_MIX_ARG_FACTOR)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_CONSTANT);
    else  assert(false);

    // Color arg2
    if (params.colorArg2 == TEX_MIX_ARG_TEXTURE)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_RGB, GL_TEXTURE);
    else if (params.colorArg2 == TEX_MIX_ARG_TEXTURE_0)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_RGB, GL_TEXTURE0);
    else if (params.colorArg2 == TEX_MIX_ARG_TEXTURE_1)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_RGB, GL_TEXTURE1);
    else if (params.colorArg2 == TEX_MIX_ARG_TEXTURE_2)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_RGB, GL_TEXTURE2);
    else if (params.colorArg2 == TEX_MIX_ARG_TEXTURE_3)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_RGB, GL_TEXTURE3);
    else if (params.colorArg2 == TEX_MIX_ARG_COMPUTED_COLOR)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_RGB, GL_PREVIOUS);
    else if (params.colorArg2 == TEX_MIX_ARG_SRC_COLOR)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_RGB, GL_PRIMARY_COLOR);
    else if (params.colorArg2 == TEX_MIX_ARG_FACTOR)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_RGB, GL_CONSTANT);
    else  assert(false);


after_tex_color:

    // Alpha operation
    if (params.alphaOperation == TEX_MIX_OPER_DEFAULT)
    {
        glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_ALPHA, GL_MODULATE);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_ALPHA, GL_PREVIOUS);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_ALPHA, GL_TEXTURE);
        goto after_tex_operations;
    }
    else if (params.alphaOperation == TEX_MIX_OPER_REPLACE)
        glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_ALPHA, GL_REPLACE);
    else if (params.alphaOperation == TEX_MIX_OPER_MODULATE)
        glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_ALPHA, GL_MODULATE);
    else if (params.alphaOperation == TEX_MIX_OPER_ADD)
        glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_ALPHA, GL_ADD);
    else if (params.alphaOperation == TEX_MIX_OPER_SUBTRACT)
        glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_ALPHA, GL_SUBTRACT);
    else  assert(false);

    // Alpha arg1
    if (params.alphaArg1 == TEX_MIX_ARG_TEXTURE)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_ALPHA, GL_TEXTURE);
    else if (params.alphaArg1 == TEX_MIX_ARG_TEXTURE_0)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_ALPHA, GL_TEXTURE0);
    else if (params.alphaArg1 == TEX_MIX_ARG_TEXTURE_1)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_ALPHA, GL_TEXTURE1);
    else if (params.alphaArg1 == TEX_MIX_ARG_TEXTURE_2)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_ALPHA, GL_TEXTURE2);
    else if (params.alphaArg1 == TEX_MIX_ARG_TEXTURE_3)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_ALPHA, GL_TEXTURE3);
    else if (params.alphaArg1 == TEX_MIX_ARG_COMPUTED_COLOR)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_ALPHA, GL_PREVIOUS);
    else if (params.alphaArg1 == TEX_MIX_ARG_SRC_COLOR)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_ALPHA, GL_PRIMARY_COLOR);
    else if (params.alphaArg1 == TEX_MIX_ARG_FACTOR)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_ALPHA, GL_CONSTANT);
    else  assert(false);

    // Alpha arg2
    if (params.alphaArg2 == TEX_MIX_ARG_TEXTURE)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_ALPHA, GL_TEXTURE);
    else if (params.alphaArg2 == TEX_MIX_ARG_TEXTURE_0)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_ALPHA, GL_TEXTURE0);
    else if (params.alphaArg2 == TEX_MIX_ARG_TEXTURE_1)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_ALPHA, GL_TEXTURE1);
    else if (params.alphaArg2 == TEX_MIX_ARG_TEXTURE_2)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_ALPHA, GL_TEXTURE2);
    else if (params.alphaArg2 == TEX_MIX_ARG_TEXTURE_3)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_ALPHA, GL_TEXTURE3);
    else if (params.alphaArg2 == TEX_MIX_ARG_COMPUTED_COLOR)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_ALPHA, GL_PREVIOUS);
    else if (params.alphaArg2 == TEX_MIX_ARG_SRC_COLOR)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_ALPHA, GL_PRIMARY_COLOR);
    else if (params.alphaArg2 == TEX_MIX_ARG_FACTOR)
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_ALPHA, GL_CONSTANT);
    else  assert(false);

after_tex_operations: ;
}

void CGL21Device::SetTextureStageWrap(int index, TexWrapMode wrapS, TexWrapMode wrapT)
{
    assert(index >= 0 && index < static_cast<int>( m_currentTextures.size() ));

    // Remember the settings
    m_textureStageParams[index].wrapS = wrapS;
    m_textureStageParams[index].wrapT = wrapT;

    // Don't actually do anything if texture not set
    if (! m_currentTextures[index].Valid())
        return;

    glActiveTexture(GL_TEXTURE0 + index);
    
    if      (wrapS == TEX_WRAP_CLAMP)
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    else if (wrapS == TEX_WRAP_CLAMP_TO_BORDER)
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
    else if (wrapS == TEX_WRAP_REPEAT)
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    else  assert(false);

    if      (wrapT == TEX_WRAP_CLAMP)
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    else if (wrapT == TEX_WRAP_CLAMP_TO_BORDER)
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);
    else if (wrapT == TEX_WRAP_REPEAT)
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    else  assert(false);
}

void CGL21Device::DrawPrimitive(PrimitiveType type, const Vertex *vertices, int vertexCount,
                              Color color)
{
    Vertex* vs = const_cast<Vertex*>(vertices);

    glEnableClientState(GL_VERTEX_ARRAY);
    glVertexPointer(3, GL_FLOAT, sizeof(Vertex), reinterpret_cast<GLfloat*>(&vs[0].coord));

    glEnableClientState(GL_NORMAL_ARRAY);
    glNormalPointer(GL_FLOAT, sizeof(Vertex), reinterpret_cast<GLfloat*>(&vs[0].normal));

    glClientActiveTexture(GL_TEXTURE0);

    glEnableClientState(GL_TEXTURE_COORD_ARRAY);
    glTexCoordPointer(2, GL_FLOAT, sizeof(Vertex), reinterpret_cast<GLfloat*>(&vs[0].texCoord));

    glColor4fv(color.Array());

    glDrawArrays(TranslateGfxPrimitive(type), 0, vertexCount);

    glDisableClientState(GL_VERTEX_ARRAY);
    glDisableClientState(GL_NORMAL_ARRAY);
    glDisableClientState(GL_TEXTURE_COORD_ARRAY); // GL_TEXTURE0
}

void CGL21Device::DrawPrimitive(PrimitiveType type, const VertexTex2 *vertices, int vertexCount,
                              Color color)
{
    VertexTex2* vs = const_cast<VertexTex2*>(vertices);

    glEnableClientState(GL_VERTEX_ARRAY);
    glVertexPointer(3, GL_FLOAT, sizeof(VertexTex2), reinterpret_cast<GLfloat*>(&vs[0].coord));

    glEnableClientState(GL_NORMAL_ARRAY);
    glNormalPointer(GL_FLOAT, sizeof(VertexTex2), reinterpret_cast<GLfloat*>(&vs[0].normal));

    glClientActiveTexture(GL_TEXTURE0);

    glEnableClientState(GL_TEXTURE_COORD_ARRAY);
    glTexCoordPointer(2, GL_FLOAT, sizeof(VertexTex2), reinterpret_cast<GLfloat*>(&vs[0].texCoord));

    glClientActiveTexture(GL_TEXTURE1);
    glEnableClientState(GL_TEXTURE_COORD_ARRAY);
    glTexCoordPointer(2, GL_FLOAT, sizeof(VertexTex2), reinterpret_cast<GLfloat*>(&vs[0].texCoord2));
    
    glColor4fv(color.Array());

    glDrawArrays(TranslateGfxPrimitive(type), 0, vertexCount);

    glDisableClientState(GL_VERTEX_ARRAY);
    glDisableClientState(GL_NORMAL_ARRAY);
    glDisableClientState(GL_TEXTURE_COORD_ARRAY); // GL_TEXTURE1

    glClientActiveTexture(GL_TEXTURE0);
    glDisableClientState(GL_TEXTURE_COORD_ARRAY);
}

void CGL21Device::DrawPrimitive(PrimitiveType type, const VertexCol *vertices, int vertexCount)
{
    VertexCol* vs = const_cast<VertexCol*>(vertices);

    glEnableClientState(GL_VERTEX_ARRAY);
    glVertexPointer(3, GL_FLOAT, sizeof(VertexCol), reinterpret_cast<GLfloat*>(&vs[0].coord));

    glEnableClientState(GL_COLOR_ARRAY);
    glColorPointer(4, GL_FLOAT, sizeof(VertexCol), reinterpret_cast<GLfloat*>(&vs[0].color));

    glDrawArrays(TranslateGfxPrimitive(type), 0, vertexCount);

    glDisableClientState(GL_VERTEX_ARRAY);
    glDisableClientState(GL_COLOR_ARRAY);
}

unsigned int CGL21Device::CreateStaticBuffer(PrimitiveType primitiveType, const Vertex* vertices, int vertexCount)
{
    unsigned int id = ++m_lastVboId;

    VboObjectInfo info;
    info.primitiveType = primitiveType;
    info.vertexType = VERTEX_TYPE_NORMAL;
    info.vertexCount = vertexCount;
    info.bufferId = 0;
    info.size = vertexCount * sizeof(Vertex);

    glGenBuffers(1, &info.bufferId);
    glBindBuffer(GL_ARRAY_BUFFER, info.bufferId);
    glBufferData(GL_ARRAY_BUFFER, info.size, vertices, GL_STATIC_DRAW);
    glBindBuffer(GL_ARRAY_BUFFER, 0);

    m_vboObjects[id] = info;

    return id;
}

unsigned int CGL21Device::CreateStaticBuffer(PrimitiveType primitiveType, const VertexTex2* vertices, int vertexCount)
{
    unsigned int id = ++m_lastVboId;

    VboObjectInfo info;
    info.primitiveType = primitiveType;
    info.vertexType = VERTEX_TYPE_TEX2;
    info.vertexCount = vertexCount;
    info.bufferId = 0;
    info.size = vertexCount * sizeof(VertexTex2);

    glGenBuffers(1, &info.bufferId);
    glBindBuffer(GL_ARRAY_BUFFER, info.bufferId);
    glBufferData(GL_ARRAY_BUFFER, info.size, vertices, GL_STATIC_DRAW);
    glBindBuffer(GL_ARRAY_BUFFER, 0);

    m_vboObjects[id] = info;

    return id;
}

unsigned int CGL21Device::CreateStaticBuffer(PrimitiveType primitiveType, const VertexCol* vertices, int vertexCount)
{
    unsigned int id = ++m_lastVboId;

    VboObjectInfo info;
    info.primitiveType = primitiveType;
    info.vertexType = VERTEX_TYPE_COL;
    info.vertexCount = vertexCount;
    info.bufferId = 0;
    info.size = vertexCount * sizeof(VertexCol);

    glGenBuffers(1, &info.bufferId);
    glBindBuffer(GL_ARRAY_BUFFER, info.bufferId);
    glBufferData(GL_ARRAY_BUFFER, info.size, vertices, GL_STATIC_DRAW);
    glBindBuffer(GL_ARRAY_BUFFER, 0);

    m_vboObjects[id] = info;

    return id;
}

void CGL21Device::UpdateStaticBuffer(unsigned int bufferId, PrimitiveType primitiveType, const Vertex* vertices, int vertexCount)
{
    auto it = m_vboObjects.find(bufferId);
    if (it == m_vboObjects.end())
        return;

    int newSize = vertexCount * sizeof(Vertex);

    VboObjectInfo& info = (*it).second;
    info.primitiveType = primitiveType;
    info.vertexType = VERTEX_TYPE_NORMAL;
    info.vertexCount = vertexCount;

    glBindBuffer(GL_ARRAY_BUFFER, info.bufferId);

    if (info.size < newSize)
    {
        glBufferData(GL_ARRAY_BUFFER, newSize, vertices, GL_STATIC_DRAW);
        info.size = newSize;
    }
    else
    {
        glBufferSubData(GL_ARRAY_BUFFER, 0, newSize, vertices);
    }
    
    glBindBuffer(GL_ARRAY_BUFFER, 0);
}

void CGL21Device::UpdateStaticBuffer(unsigned int bufferId, PrimitiveType primitiveType, const VertexTex2* vertices, int vertexCount)
{
    auto it = m_vboObjects.find(bufferId);
    if (it == m_vboObjects.end())
        return;

    VboObjectInfo& info = (*it).second;
    info.primitiveType = primitiveType;
    info.vertexType = VERTEX_TYPE_TEX2;
    info.vertexCount = vertexCount;

    int newSize = vertexCount * sizeof(VertexTex2);
    
    glBindBuffer(GL_ARRAY_BUFFER, info.bufferId);

    if (info.size < newSize)
    {
        glBufferData(GL_ARRAY_BUFFER, newSize, vertices, GL_STATIC_DRAW);
        info.size = newSize;
    }
    else
    {
        glBufferSubData(GL_ARRAY_BUFFER, 0, newSize, vertices);
    }

    glBindBuffer(GL_ARRAY_BUFFER, 0);
}

void CGL21Device::UpdateStaticBuffer(unsigned int bufferId, PrimitiveType primitiveType, const VertexCol* vertices, int vertexCount)
{
    auto it = m_vboObjects.find(bufferId);
    if (it == m_vboObjects.end())
        return;

    VboObjectInfo& info = (*it).second;
    info.primitiveType = primitiveType;
    info.vertexType = VERTEX_TYPE_COL;
    info.vertexCount = vertexCount;

    int newSize = vertexCount * sizeof(VertexCol);

    glBindBuffer(GL_ARRAY_BUFFER, info.bufferId);

    if (info.size < newSize)
    {
        glBufferData(GL_ARRAY_BUFFER, newSize, vertices, GL_STATIC_DRAW);
        info.size = newSize;
    }
    else
    {
        glBufferSubData(GL_ARRAY_BUFFER, 0, newSize, vertices);
    }

    glBindBuffer(GL_ARRAY_BUFFER, 0);
}

void CGL21Device::DrawStaticBuffer(unsigned int bufferId)
{
    auto it = m_vboObjects.find(bufferId);
    if (it == m_vboObjects.end())
        return;

    glEnable(GL_VERTEX_ARRAY);
    glBindBuffer(GL_ARRAY_BUFFER, (*it).second.bufferId);

    if ((*it).second.vertexType == VERTEX_TYPE_NORMAL)
    {
        glEnableClientState(GL_VERTEX_ARRAY);
        glVertexPointer(3, GL_FLOAT, sizeof(Vertex), static_cast<char*>(nullptr) + offsetof(Vertex, coord));

        glEnableClientState(GL_NORMAL_ARRAY);
        glNormalPointer(GL_FLOAT, sizeof(Vertex), static_cast<char*>(nullptr) + offsetof(Vertex, normal));

        glClientActiveTexture(GL_TEXTURE0);

        glEnableClientState(GL_TEXTURE_COORD_ARRAY);
        glTexCoordPointer(2, GL_FLOAT, sizeof(Vertex), static_cast<char*>(nullptr) + offsetof(Vertex, texCoord));
    }
    else if ((*it).second.vertexType == VERTEX_TYPE_TEX2)
    {
        glEnableClientState(GL_VERTEX_ARRAY);
        glVertexPointer(3, GL_FLOAT, sizeof(VertexTex2), static_cast<char*>(nullptr) + offsetof(VertexTex2, coord));

        glEnableClientState(GL_NORMAL_ARRAY);
        glNormalPointer(GL_FLOAT, sizeof(VertexTex2), static_cast<char*>(nullptr) + offsetof(VertexTex2, normal));

        glClientActiveTexture(GL_TEXTURE0);

        glEnableClientState(GL_TEXTURE_COORD_ARRAY);
        glTexCoordPointer(2, GL_FLOAT, sizeof(VertexTex2), static_cast<char*>(nullptr) + offsetof(VertexTex2, texCoord));

        glClientActiveTexture(GL_TEXTURE1);
        glEnableClientState(GL_TEXTURE_COORD_ARRAY);
        glTexCoordPointer(2, GL_FLOAT, sizeof(VertexTex2), static_cast<char*>(nullptr) + offsetof(VertexTex2, texCoord2));
    }
    else if ((*it).second.vertexType == VERTEX_TYPE_COL)
    {
        glEnableClientState(GL_VERTEX_ARRAY);
        glVertexPointer(3, GL_FLOAT, sizeof(VertexCol), static_cast<char*>(nullptr) + offsetof(VertexCol, coord));

        glEnableClientState(GL_COLOR_ARRAY);
        glColorPointer(4, GL_FLOAT, sizeof(VertexCol), static_cast<char*>(nullptr) + offsetof(VertexCol, color));
    }

    GLenum mode = TranslateGfxPrimitive((*it).second.primitiveType);
    glDrawArrays(mode, 0, (*it).second.vertexCount);

    if ((*it).second.vertexType == VERTEX_TYPE_NORMAL)
    {
        glDisableClientState(GL_VERTEX_ARRAY);
        glDisableClientState(GL_NORMAL_ARRAY);
        glDisableClientState(GL_TEXTURE_COORD_ARRAY); // GL_TEXTURE0
    }
    else if ((*it).second.vertexType == VERTEX_TYPE_TEX2)
    {
        glDisableClientState(GL_VERTEX_ARRAY);
        glDisableClientState(GL_NORMAL_ARRAY);
        glDisableClientState(GL_TEXTURE_COORD_ARRAY); // GL_TEXTURE1
        glClientActiveTexture(GL_TEXTURE0);
        glDisableClientState(GL_TEXTURE_COORD_ARRAY);
    }
    else if ((*it).second.vertexType == VERTEX_TYPE_COL)
    {
        glDisableClientState(GL_VERTEX_ARRAY);
        glDisableClientState(GL_COLOR_ARRAY);
    }

    glBindBuffer(GL_ARRAY_BUFFER, 0);
    glDisable(GL_VERTEX_ARRAY);
}

void CGL21Device::DestroyStaticBuffer(unsigned int bufferId)
{
    auto it = m_vboObjects.find(bufferId);
    if (it == m_vboObjects.end())
        return;

    glDeleteBuffers(1, &(*it).second.bufferId);

    m_vboObjects.erase(it);
}

/* Based on libwine's implementation */

int CGL21Device::ComputeSphereVisibility(const Math::Vector &center, float radius)
{
    Math::Matrix m;
    m = Math::MultiplyMatrices(m_worldMat, m);
    m = Math::MultiplyMatrices(m_viewMat, m);
    Math::Matrix sc;
    Math::LoadScaleMatrix(sc, Math::Vector(1.0f, 1.0f, -1.0f));
    m = Math::MultiplyMatrices(sc, m);
    m = Math::MultiplyMatrices(m_projectionMat, m);

    Math::Vector vec[6];
    float originPlane[6];

    // Left plane
    vec[0].x = m.Get(4, 1) + m.Get(1, 1);
    vec[0].y = m.Get(4, 2) + m.Get(1, 2);
    vec[0].z = m.Get(4, 3) + m.Get(1, 3);
    float l1 = vec[0].Length();
    vec[0].Normalize();
    originPlane[0] = (m.Get(4, 4) + m.Get(1, 4)) / l1;

    // Right plane
    vec[1].x = m.Get(4, 1) - m.Get(1, 1);
    vec[1].y = m.Get(4, 2) - m.Get(1, 2);
    vec[1].z = m.Get(4, 3) - m.Get(1, 3);
    float l2 = vec[1].Length();
    vec[1].Normalize();
    originPlane[1] = (m.Get(4, 4) - m.Get(1, 4)) / l2;

    // Bottom plane
    vec[2].x = m.Get(4, 1) + m.Get(2, 1);
    vec[2].y = m.Get(4, 2) + m.Get(2, 2);
    vec[2].z = m.Get(4, 3) + m.Get(2, 3);
    float l3 = vec[2].Length();
    vec[2].Normalize();
    originPlane[2] = (m.Get(4, 4) + m.Get(2, 4)) / l3;

    // Top plane
    vec[3].x = m.Get(4, 1) - m.Get(2, 1);
    vec[3].y = m.Get(4, 2) - m.Get(2, 2);
    vec[3].z = m.Get(4, 3) - m.Get(2, 3);
    float l4 = vec[3].Length();
    vec[3].Normalize();
    originPlane[3] = (m.Get(4, 4) - m.Get(2, 4)) / l4;

    // Front plane
    vec[4].x = m.Get(4, 1) + m.Get(3, 1);
    vec[4].y = m.Get(4, 2) + m.Get(3, 2);
    vec[4].z = m.Get(4, 3) + m.Get(3, 3);
    float l5 = vec[4].Length();
    vec[4].Normalize();
    originPlane[4] = (m.Get(4, 4) + m.Get(3, 4)) / l5;

    // Back plane
    vec[5].x = m.Get(4, 1) - m.Get(3, 1);
    vec[5].y = m.Get(4, 2) - m.Get(3, 2);
    vec[5].z = m.Get(4, 3) - m.Get(3, 3);
    float l6 = vec[5].Length();
    vec[5].Normalize();
    originPlane[5] = (m.Get(4, 4) - m.Get(3, 4)) / l6;

    int result = 0;

    if (InPlane(vec[0], originPlane[0], center, radius))
        result |= FRUSTUM_PLANE_LEFT;
    if (InPlane(vec[1], originPlane[1], center, radius))
        result |= FRUSTUM_PLANE_RIGHT;
    if (InPlane(vec[2], originPlane[2], center, radius))
        result |= FRUSTUM_PLANE_BOTTOM;
    if (InPlane(vec[3], originPlane[3], center, radius))
        result |= FRUSTUM_PLANE_TOP;
    if (InPlane(vec[4], originPlane[4], center, radius))
        result |= FRUSTUM_PLANE_FRONT;
    if (InPlane(vec[5], originPlane[5], center, radius))
        result |= FRUSTUM_PLANE_BACK;

    return result;
}

void CGL21Device::SetViewport(int x, int y, int width, int height)
{
    glViewport(x, y, width, height);
}

void CGL21Device::SetRenderState(RenderState state, bool enabled)
{
    if (state == RENDER_STATE_DEPTH_WRITE)
    {
        glDepthMask(enabled ? GL_TRUE : GL_FALSE);
        return;
    }
    else if (state == RENDER_STATE_LIGHTING)
    {
        m_lighting = enabled;

        glUniform1i(uni_LightingEnabled, enabled ? 1 : 0);

        if (enabled)
        {
            for (int index = 0; index < static_cast<int>( m_lights.size() ); ++index)
                UpdateLightPosition(index);
        }

        return;
    }
    else if (state == RENDER_STATE_OFFSCREEN_RENDERING)
    {
        if (!m_framebufferObject)
        {
            GetLogger()->Error("Cannot enable offscreen rendering without framebuffer object!\n");
            return;
        }

        m_offscreenRenderingEnabled = enabled;

        if (m_framebuffer == 0)
            InitOffscreenBuffer(2048, 2048);

        GLuint toBind = (enabled ? m_framebuffer : 0);

        glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, toBind);

        return;
    }
    else if (state == RENDER_STATE_ALPHA_TEST)
    {
        glUniform1i(uni_AlphaTestEnabled, enabled ? 1 : 0);

        return;
    }
    else if (state == RENDER_STATE_FOG)
    {
        glUniform1i(uni_FogEnabled, enabled ? 1 : 0);

        return;
    }

    GLenum flag = 0;

    switch (state)
    {
        case RENDER_STATE_BLENDING:    flag = GL_BLEND; break;
        case RENDER_STATE_DEPTH_TEST:  flag = GL_DEPTH_TEST; break;
        case RENDER_STATE_ALPHA_TEST:  flag = GL_ALPHA_TEST; break;
        case RENDER_STATE_CULLING:     flag = GL_CULL_FACE; break;
        case RENDER_STATE_DEPTH_BIAS:  flag = GL_POLYGON_OFFSET_FILL; break;
        default: assert(false); break;
    }

    if (enabled)
        glEnable(flag);
    else
        glDisable(flag);
}

void CGL21Device::SetColorMask(bool red, bool green, bool blue, bool alpha)
{
    glColorMask(red, green, blue, alpha);
}

void CGL21Device::SetDepthTestFunc(CompFunc func)
{
    glDepthFunc(TranslateGfxCompFunc(func));
}

void CGL21Device::SetDepthBias(float factor, float units)
{
    glPolygonOffset(factor, units);
}

void CGL21Device::SetAlphaTestFunc(CompFunc func, float refValue)
{
    glUniform1i(uni_AlphaReference, refValue);
}

void CGL21Device::SetBlendFunc(BlendFunc srcBlend, BlendFunc dstBlend)
{
    glBlendFunc(TranslateGfxBlendFunc(srcBlend), TranslateGfxBlendFunc(dstBlend));
}

void CGL21Device::SetClearColor(const Color &color)
{
    glClearColor(color.r, color.g, color.b, color.a);
}

void CGL21Device::SetGlobalAmbient(const Color &color)
{
    glLightModelfv(GL_LIGHT_MODEL_AMBIENT, color.Array());
}

void CGL21Device::SetFogParams(FogMode mode, const Color &color, float start, float end, float density)
{
    glUniform2f(uni_FogRange, start, end);
    glUniform4f(uni_FogColor, color.r, color.g, color.b, color.a);

    /*
    if      (mode == FOG_LINEAR) glFogi(GL_FOG_MODE, GL_LINEAR);
    else if (mode == FOG_EXP)    glFogi(GL_FOG_MODE, GL_EXP);
    else if (mode == FOG_EXP2)   glFogi(GL_FOG_MODE, GL_EXP2);
    else assert(false);

    glFogf(GL_FOG_START,   start);
    glFogf(GL_FOG_END,     end);
    glFogf(GL_FOG_DENSITY, density);
    glFogfv(GL_FOG_COLOR,  color.Array());
    // */
}

void CGL21Device::SetCullMode(CullMode mode)
{
    // Cull clockwise back faces, so front face is the opposite
    // (assuming GL_CULL_FACE is GL_BACK)
    if      (mode == CULL_CW ) glFrontFace(GL_CCW);
    else if (mode == CULL_CCW) glFrontFace(GL_CW);
    else assert(false);
}

void CGL21Device::SetShadeModel(ShadeModel model)
{
    if      (model == SHADE_FLAT)   glShadeModel(GL_FLAT);
    else if (model == SHADE_SMOOTH) glShadeModel(GL_SMOOTH);
    else  assert(false);
}

void CGL21Device::SetShadowColor(float value)
{
    glUniform1f(uni_ShadowColor, value);
}

void CGL21Device::SetFillMode(FillMode mode)
{
    if      (mode == FILL_POINT) glPolygonMode(GL_FRONT_AND_BACK, GL_POINT);
    else if (mode == FILL_LINES) glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
    else if (mode == FILL_POLY)  glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
    else assert(false);
}

void CGL21Device::InitOffscreenBuffer(int width, int height)
{
    if (!m_framebufferObject) return;

    width = Math::Min(width, m_maxRenderbufferSize);
    height = Math::Min(height, m_maxRenderbufferSize);

    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);

    if (m_colorBuffer != 0)
        glDeleteRenderbuffersEXT(1, &m_colorBuffer);

    glGenRenderbuffersEXT(1, &m_colorBuffer);
    glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, m_colorBuffer);
    glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_RGBA8, width, height);
    glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, 0);

    if (m_depthBuffer != 0)
        glDeleteRenderbuffersEXT(1, &m_depthBuffer);

    glGenRenderbuffersEXT(1, &m_depthBuffer);
    glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, m_depthBuffer);
    glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_DEPTH_COMPONENT24, width, height);
    glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, 0);

    if (m_framebuffer == 0)
        glGenFramebuffersEXT(1, &m_framebuffer);

    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, m_framebuffer);
    glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_RENDERBUFFER_EXT, m_colorBuffer);
    glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT, GL_RENDERBUFFER_EXT, m_depthBuffer);
    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);

    GetLogger()->Info("Initialized offscreen buffer %dx%d\n", width, height);
}

void CGL21Device::SetRenderTexture(RenderTarget target, int texture)
{
    if (!m_framebufferObject) return;
    if (!m_offscreenRenderingEnabled) return;

    GLenum attachment;
    GLuint defaultBuffer;

    switch (target)
    {
    case RENDER_TARGET_COLOR:
        attachment = GL_COLOR_ATTACHMENT0_EXT;
        defaultBuffer = m_colorBuffer;
        break;
    case RENDER_TARGET_DEPTH:
        attachment = GL_DEPTH_ATTACHMENT_EXT;
        defaultBuffer = m_depthBuffer;
        break;
    case RENDER_TARGET_STENCIL:
        attachment = GL_STENCIL_ATTACHMENT_EXT;
        defaultBuffer = 0;
        break;
    default: assert(false); break;
    }

    if (texture == 0)       // unbind texture and bind default buffer
    {
        glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, attachment, GL_TEXTURE_2D, 0, 0);
        glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, attachment, GL_RENDERBUFFER_EXT, defaultBuffer);
    }
    else            // unbind default buffer and bind texture
    {
        glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, attachment, GL_RENDERBUFFER_EXT, 0);
        glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, attachment, GL_TEXTURE_2D, texture, 0);
    }
}

void CGL21Device::CopyFramebufferToTexture(Texture& texture, int xOffset, int yOffset, int x, int y, int width, int height)
{
    if (texture.id == 0) return;

    // Use & enable 1st texture stage
    glActiveTexture(GL_TEXTURE0);

    glBindTexture(GL_TEXTURE_2D, texture.id);
    glCopyTexSubImage2D(GL_TEXTURE_2D, 0, xOffset, yOffset, x, y, width, height);

    // Restore previous texture
    glBindTexture(GL_TEXTURE_2D, m_currentTextures[0].id);
}

void* CGL21Device::GetFrameBufferPixels()const{

    GLubyte* pixels = new GLubyte[4 * m_config.size.x * m_config.size.y];

    glReadPixels(0, 0, m_config.size.x, m_config.size.y, GL_RGBA, GL_UNSIGNED_BYTE, pixels);

    unsigned int* p = static_cast<unsigned int*> ( static_cast<void*>(pixels) );

    for (int i = 0; i < m_config.size.x * m_config.size.y; ++i)
        p[i] |= 0xFF000000;

    return static_cast<void*>(p);
}

} // namespace Gfx