dgl_common.c

/**\file dgl_common.c
 *\section License
 * License: GPL
 * Online License Link: http://www.gnu.org/licenses/gpl.html
 *
 *\author Copyright © 2004-2012 Jaakko Keränen <jaakko.keranen@iki.fi>
 *\author Copyright © 2007-2012 Daniel Swanson <danij@dengine.net>
 *
 * 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 2 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, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor,
 * Boston, MA  02110-1301  USA
 */

// HEADER FILES ------------------------------------------------------------

#include <stdlib.h>
#include <math.h>

#include "de_base.h"
#include "de_console.h"
#include "de_graphics.h"
#include "de_misc.h"
#include "de_filesys.h"

#include "sys_opengl.h"

// MACROS ------------------------------------------------------------------

// TYPES -------------------------------------------------------------------

// FUNCTION PROTOTYPES -----------------------------------------------------

// EXTERNAL DATA DECLARATIONS ----------------------------------------------

// PUBLIC DATA DEFINITIONS -------------------------------------------------

// PRIVATE DATA DEFINITIONS ------------------------------------------------

// CODE --------------------------------------------------------------------

/**
 * Requires a texture environment mode that can add and multiply.
 * Nvidia's and ATI's appropriate extensions are supported, other cards will
 * not be able to utilize multitextured lights.
 */
void envAddColoredAlpha(int activate, GLenum addFactor)
{
    LIBDENG_ASSERT_IN_MAIN_THREAD();
    LIBDENG_ASSERT_GL_CONTEXT_ACTIVE();

    if(activate)
    {
        glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE,
                  GL_state.extensions.texEnvCombNV ? GL_COMBINE4_NV : GL_COMBINE);
        glTexEnvi(GL_TEXTURE_ENV, GL_RGB_SCALE, 1);

        // Combine: texAlpha * constRGB + 1 * prevRGB.
        if(GL_state.extensions.texEnvCombNV)
        {
            glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_ADD);
            glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_TEXTURE);
            glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_RGB, addFactor);
            glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_RGB, GL_CONSTANT);
            glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND1_RGB, GL_SRC_COLOR);
            glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE2_RGB, GL_ZERO);
            glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND2_RGB, GL_ONE_MINUS_SRC_COLOR);
            glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE3_RGB_NV, GL_PREVIOUS);
            glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND3_RGB_NV, GL_SRC_COLOR);
        }
        else if(GL_state.extensions.texEnvCombATI)
        {   // MODULATE_ADD_ATI: Arg0 * Arg2 + Arg1.
            glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_MODULATE_ADD_ATI);
            glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_TEXTURE);
            glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_RGB, addFactor);
            glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE2_RGB, GL_CONSTANT);
            glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND2_RGB, GL_SRC_COLOR);
            glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_RGB, GL_PREVIOUS);
            glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND1_RGB, GL_SRC_COLOR);
        }
        else
        {   // This doesn't look right.
            glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_ADD);
            glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_TEXTURE);
            glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_RGB, addFactor);
            glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_RGB, GL_CONSTANT);
            glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND1_RGB, GL_SRC_COLOR);
        }
    }
    else
    {
        glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
    }
}

/**
 * Setup the texture environment for single-pass multiplicative lighting.
 * The last texture unit is always used for the texture modulation.
 * TUs 1...n-1 are used for dynamic lights.
 */
void envModMultiTex(int activate)
{
    LIBDENG_ASSERT_IN_MAIN_THREAD();
    LIBDENG_ASSERT_GL_CONTEXT_ACTIVE();

    // Setup TU 2: The modulated texture.
    glActiveTexture(GL_TEXTURE1);
    glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);

    // Setup TU 1: The dynamic light.
    glActiveTexture(GL_TEXTURE0);
    envAddColoredAlpha(activate, GL_SRC_ALPHA);

    // This is a single-pass mode. The alpha should remain unmodified
    // during the light stage.
    if(activate)
    {   // Replace: primAlpha.
        glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_ALPHA, GL_REPLACE);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_ALPHA, GL_PREVIOUS);
        glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_ALPHA, GL_SRC_ALPHA);
    }
}

/**
 * Configure the GL state for the specified texture modulation mode.
 *
 * @param mode          Modulation mode ident.
 */
void GL_ModulateTexture(int mode)
{
    LIBDENG_ASSERT_IN_MAIN_THREAD();
    LIBDENG_ASSERT_GL_CONTEXT_ACTIVE();

    switch(mode)
    {
    case 0:
        // No modulation: just replace with texture.
        glActiveTexture(GL_TEXTURE0);
        glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
        break;

    case 1:
        // Normal texture modulation with primary color.
        glActiveTexture(GL_TEXTURE0);
        glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
        break;

    case 12:
        // Normal texture modulation on both stages. TU 1 modulates with
        // primary color, TU 2 with TU 1.
        glActiveTexture(GL_TEXTURE1);
        glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
        glActiveTexture(GL_TEXTURE0);
        glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
        break;

    case 2:
    case 3:
        // Texture modulation and interpolation.
        glActiveTexture(GL_TEXTURE1);
        glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE);
        glTexEnvi(GL_TEXTURE_ENV, GL_RGB_SCALE, 1);
        if(mode == 2)
        {   // Used with surfaces that have a color.
            // TU 2: Modulate previous with primary color.
            glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_MODULATE);
            glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_PRIMARY_COLOR);
            glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_RGB, GL_SRC_COLOR);
            glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_RGB, GL_PREVIOUS);
            glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND1_RGB, GL_SRC_COLOR);

        }
        else
        {   // Mode 3: Used with surfaces with no primary color.
            // TU 2: Pass through.
            glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_REPLACE);
            glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_PREVIOUS);
            glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_RGB, GL_SRC_COLOR);
        }
        glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_ALPHA, GL_REPLACE);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_ALPHA, GL_PREVIOUS);
        glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_ALPHA, GL_SRC_ALPHA);

        // TU 1: Interpolate between texture 1 and 2, using the constant
        // alpha as the factor.
        glActiveTexture(GL_TEXTURE0);
        glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE);
        glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_INTERPOLATE);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_TEXTURE1);
        glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_RGB, GL_SRC_COLOR);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_RGB, GL_TEXTURE0);
        glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND1_RGB, GL_SRC_COLOR);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE2_RGB, GL_CONSTANT);
        glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND2_RGB, GL_SRC_ALPHA);
        glTexEnvi(GL_TEXTURE_ENV, GL_RGB_SCALE, 1);

        glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_ALPHA, GL_REPLACE);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_ALPHA, GL_PREVIOUS);
        glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_ALPHA, GL_SRC_ALPHA);
        break;

    case 4:
        // Apply sector light, dynamic light and texture.
        envModMultiTex(true);
        break;

    case 5:
    case 10:
        // Sector light * texture + dynamic light.
        glActiveTexture(GL_TEXTURE1);
        envAddColoredAlpha(true, mode == 5 ? GL_SRC_ALPHA : GL_SRC_COLOR);

        // Alpha remains unchanged.
        if(GL_state.extensions.texEnvCombNV)
        {
            glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_ALPHA, GL_ADD);
            glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_ALPHA, GL_ZERO);
            glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
            glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_ALPHA, GL_PREVIOUS);
            glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND1_ALPHA, GL_SRC_ALPHA);
            glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE2_ALPHA, GL_ZERO);
            glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND2_ALPHA, GL_SRC_ALPHA);
            glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE3_ALPHA_NV, GL_ZERO);
            glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND3_ALPHA_NV, GL_SRC_ALPHA);
        }
        else
        {
            glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_ALPHA, GL_REPLACE);
            glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_ALPHA, GL_PREVIOUS);
            glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_ALPHA, GL_SRC_ALPHA);
        }

        glActiveTexture(GL_TEXTURE0);
        glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
        break;

    case 6:
        // Simple dynlight addition (add to primary color).
        glActiveTexture(GL_TEXTURE0);
        envAddColoredAlpha(true, GL_SRC_ALPHA);
        break;

    case 7:
        // Dynlight addition without primary color.
        glActiveTexture(GL_TEXTURE0);
        glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE);
        glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_MODULATE);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_TEXTURE);
        glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_RGB, GL_SRC_ALPHA);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_RGB, GL_CONSTANT);
        glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND1_RGB, GL_SRC_COLOR);
        glTexEnvi(GL_TEXTURE_ENV, GL_RGB_SCALE, 1);
        break;

    case 8:
    case 9:
        // Texture and Detail.
        glActiveTexture(GL_TEXTURE1);
        glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE);
        glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_MODULATE);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_PREVIOUS);
        glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_RGB, GL_SRC_COLOR);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_RGB, GL_TEXTURE);
        glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND1_RGB, GL_SRC_COLOR);
        glTexEnvi(GL_TEXTURE_ENV, GL_RGB_SCALE, 2);

        glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_ALPHA, GL_REPLACE);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_ALPHA, GL_PREVIOUS);
        glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_ALPHA, GL_SRC_ALPHA);

        glActiveTexture(GL_TEXTURE0);
        if(mode == 8)
        {
            glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
        }
        else
        {   // Mode 9: Ignore primary color.
            glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
        }
        break;

    case 11:
        // Normal modulation, alpha of 2nd stage.
        // Tex0: texture
        // Tex1: shiny texture
        glActiveTexture(GL_TEXTURE1);
        glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE);
        glTexEnvi(GL_TEXTURE_ENV, GL_RGB_SCALE, 1);
        glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_REPLACE);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_PREVIOUS);
        glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_RGB, GL_SRC_COLOR);
        glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_ALPHA, GL_REPLACE);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_ALPHA, GL_PREVIOUS);
        glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_ALPHA, GL_SRC_ALPHA);

        glActiveTexture(GL_TEXTURE0);
        glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE);
        glTexEnvi(GL_TEXTURE_ENV, GL_RGB_SCALE, 1);
        glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_MODULATE);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_PREVIOUS);
        glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_RGB, GL_SRC_COLOR);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_RGB, GL_TEXTURE1);
        glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND1_RGB, GL_SRC_COLOR);
        glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_ALPHA, GL_MODULATE);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_ALPHA, GL_PREVIOUS);
        glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_ALPHA, GL_SRC_ALPHA);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_ALPHA, GL_TEXTURE0);
        glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND1_ALPHA, GL_SRC_ALPHA);
        break;

    default:
        break;
    }
}

void GL_BlendOp(int op)
{
    if(!GL_state.features.blendSubtract)
        return;

    LIBDENG_ASSERT_IN_MAIN_THREAD();
    LIBDENG_ASSERT_GL_CONTEXT_ACTIVE();

    glBlendEquationEXT(op);
}

/*
boolean GL_Grab(int x, int y, int width, int height, dgltexformat_t format, void *buffer)
{
    if(format != DGL_RGB) return false;

    LIBDENG_ASSERT_IN_MAIN_THREAD();

    // y+height-1 is the bottom edge of the rectangle. It's
    // flipped to change the origin.
    glReadPixels(x, FLIP(y + height - 1), width, height, GL_RGB, GL_UNSIGNED_BYTE, buffer);
    return true;
}
*/

void GL_SetVSync(boolean on)
{
    Con_SetInteger("vid-vsync", on? 1 : 0);

    /*
    // Outside the main thread we'll need to defer the call.
    if(!Sys_InMainThread())
    {
        GL_DeferSetVSync(on);
        return;
    }

    if(!GL_state.features.vsync) return;

#ifdef WIN32
    wglSwapIntervalEXT(on? 1 : 0);
#endif

#ifdef MACOSX
    {
        // Tell CGL to wait for vertical refresh.
        CGLContextObj context = CGLGetCurrentContext();
        assert(context != 0);
        if(context)
        {
#ifdef MACOS_10_4
            long params[1] = { on? 1 : 0 };
#else
            GLint params[1] = { on? 1 : 0 };
#endif
            CGLSetParameter(context, kCGLCPSwapInterval, params);
        }
    }
#endif*/

}

void GL_SetMultisample(boolean on)
{
    if(!GL_state.features.multisample) return;

    LIBDENG_ASSERT_IN_MAIN_THREAD();

#if defined(WIN32)
    if(on) glEnable(GL_MULTISAMPLE_ARB);
    else  glDisable(GL_MULTISAMPLE_ARB);
#else
    if(on) glEnable(GL_MULTISAMPLE);
    else  glDisable(GL_MULTISAMPLE);
#endif
}

void DGL_SetScissor(const RectRaw* rect)
{
    if(!rect) return;

    LIBDENG_ASSERT_IN_MAIN_THREAD();
    LIBDENG_ASSERT_GL_CONTEXT_ACTIVE();

    glScissor(rect->origin.x, FLIP(rect->origin.y + rect->size.height - 1), rect->size.width, rect->size.height);
}

void DGL_SetScissor2(int x, int y, int width, int height)
{
    RectRaw rect;
    rect.origin.x = x;
    rect.origin.y = y;
    rect.size.width  = width;
    rect.size.height = height;
    DGL_SetScissor(&rect);
}

void DGL_Scissor(RectRaw* rect)
{
    GLint v[4];

    if(!rect) return;

    LIBDENG_ASSERT_IN_MAIN_THREAD();
    LIBDENG_ASSERT_GL_CONTEXT_ACTIVE();

    glGetIntegerv(GL_SCISSOR_BOX, (GLint*)v);
    // Y is flipped.
    v[1] = FLIP(v[1] + v[3] - 1);

    rect->origin.x = v[0];
    rect->origin.y = v[1];
    rect->size.width  = v[2];
    rect->size.height = v[3];
}

boolean DGL_GetIntegerv(int name, int* v)
{
    float color[4];
    int i;

    LIBDENG_ASSERT_IN_MAIN_THREAD();
    LIBDENG_ASSERT_GL_CONTEXT_ACTIVE();

    switch(name)
    {
    case DGL_MODULATE_ADD_COMBINE:
        *v = GL_state.extensions.texEnvCombNV || GL_state.extensions.texEnvCombATI;
        break;

    case DGL_SCISSOR_TEST:
        glGetIntegerv(GL_SCISSOR_TEST, (GLint*) v);
        break;

    case DGL_FOG:
        *v = GL_state.currentUseFog;
        break;

    case DGL_CURRENT_COLOR_R:
        glGetFloatv(GL_CURRENT_COLOR, color);
        *v = (int) (color[0] * 255);
        break;

    case DGL_CURRENT_COLOR_G:
        glGetFloatv(GL_CURRENT_COLOR, color);
        *v = (int) (color[1] * 255);
        break;

    case DGL_CURRENT_COLOR_B:
        glGetFloatv(GL_CURRENT_COLOR, color);
        *v = (int) (color[2] * 255);
        break;

    case DGL_CURRENT_COLOR_A:
        glGetFloatv(GL_CURRENT_COLOR, color);
        *v = (int) (color[3] * 255);
        break;

    case DGL_CURRENT_COLOR_RGBA:
        glGetFloatv(GL_CURRENT_COLOR, color);
        for(i = 0; i < 4; i++)
            v[i] = (int) (color[i] * 255);
        break;

    default:
        return false;
    }

    return true;
}

int DGL_GetInteger(int name)
{
    int         values[10];

    DGL_GetIntegerv(name, values);
    return values[0];
}

boolean DGL_SetInteger(int name, int value)
{
    LIBDENG_ASSERT_IN_MAIN_THREAD();
    LIBDENG_ASSERT_GL_CONTEXT_ACTIVE();

    switch(name)
    {
    case DGL_ACTIVE_TEXTURE:
        glActiveTexture(GL_TEXTURE0 + (byte)value);
        break;

    case DGL_MODULATE_TEXTURE:
        GL_ModulateTexture(value);
        break;

    default:
        return false;
    }

    return true;
}

boolean DGL_GetFloatv(int name, float* v)
{
    float color[4];

    LIBDENG_ASSERT_IN_MAIN_THREAD();
    LIBDENG_ASSERT_GL_CONTEXT_ACTIVE();

    switch(name)
    {
    case DGL_CURRENT_COLOR_R:
        glGetFloatv(GL_CURRENT_COLOR, color);
        *v = color[0];
        break;

    case DGL_CURRENT_COLOR_G:
        glGetFloatv(GL_CURRENT_COLOR, color);
        *v = color[1];
        break;

    case DGL_CURRENT_COLOR_B:
        glGetFloatv(GL_CURRENT_COLOR, color);
        *v = color[2];
        break;

    case DGL_CURRENT_COLOR_A:
        glGetFloatv(GL_CURRENT_COLOR, color);
        *v = color[3];
        break;

    case DGL_CURRENT_COLOR_RGBA:
        {
        int i;
        glGetFloatv(GL_CURRENT_COLOR, color);
        for(i = 0; i < 4; ++i)
            v[i] = color[i];
        break;
        }
    default:
        return false;
    }

    return true;
}

float DGL_GetFloat(int name)
{
    switch(name)
    {
    case DGL_LINE_WIDTH:
        return GL_state.currentLineWidth;

    case DGL_POINT_SIZE:
        return GL_state.currentPointSize;

    default:
        return 0;
    }
}

boolean DGL_SetFloat(int name, float value)
{
    LIBDENG_ASSERT_IN_MAIN_THREAD();
    LIBDENG_ASSERT_GL_CONTEXT_ACTIVE();

    switch(name)
    {
    case DGL_LINE_WIDTH:
        GL_state.currentLineWidth = value;
        glLineWidth(value);
        break;

    case DGL_POINT_SIZE:
        GL_state.currentPointSize = value;
        glPointSize(value);
        break;

    default:
        return false;
    }

    return true;
}

int DGL_Enable(int cap)
{
    LIBDENG_ASSERT_IN_MAIN_THREAD();
    LIBDENG_ASSERT_GL_CONTEXT_ACTIVE();

    switch(cap)
    {
    case DGL_TEXTURE_2D:
#ifndef DRMESA
        glEnable(GL_TEXTURE_2D);
#endif
        break;

    case DGL_FOG:
        glEnable(GL_FOG);
        GL_state.currentUseFog = true;
        break;

    case DGL_SCISSOR_TEST:
        glEnable(GL_SCISSOR_TEST);
        break;

    case DGL_LINE_SMOOTH:
        glEnable(GL_LINE_SMOOTH);
        break;

    case DGL_POINT_SMOOTH:
        glEnable(GL_POINT_SMOOTH);
        break;

    default:
        return 0;
    }

    return 1;
}

void DGL_Disable(int cap)
{
    LIBDENG_ASSERT_IN_MAIN_THREAD();
    LIBDENG_ASSERT_GL_CONTEXT_ACTIVE();

    switch(cap)
    {
    case DGL_TEXTURE_2D:
        glDisable(GL_TEXTURE_2D);
        break;

    case DGL_FOG:
        glDisable(GL_FOG);
        GL_state.currentUseFog = false;
        break;

    case DGL_SCISSOR_TEST:
        glDisable(GL_SCISSOR_TEST);
        break;

    case DGL_LINE_SMOOTH:
        glDisable(GL_LINE_SMOOTH);
        break;

    case DGL_POINT_SMOOTH:
        glDisable(GL_POINT_SMOOTH);
        break;

    default:
        break;
    }
}

void DGL_BlendOp(int op)
{
    GL_BlendOp(op == DGL_SUBTRACT ? GL_FUNC_SUBTRACT : op ==
               DGL_REVERSE_SUBTRACT ? GL_FUNC_REVERSE_SUBTRACT :
               GL_FUNC_ADD);
}

void DGL_BlendFunc(int param1, int param2)
{
    LIBDENG_ASSERT_IN_MAIN_THREAD();
    LIBDENG_ASSERT_GL_CONTEXT_ACTIVE();

    glBlendFunc(param1 == DGL_ZERO ? GL_ZERO : param1 ==
                DGL_ONE ? GL_ONE : param1 ==
                DGL_DST_COLOR ? GL_DST_COLOR : param1 ==
                DGL_ONE_MINUS_DST_COLOR ? GL_ONE_MINUS_DST_COLOR : param1
                == DGL_SRC_ALPHA ? GL_SRC_ALPHA : param1 ==
                DGL_ONE_MINUS_SRC_ALPHA ? GL_ONE_MINUS_SRC_ALPHA : param1
                == DGL_DST_ALPHA ? GL_DST_ALPHA : param1 ==
                DGL_ONE_MINUS_DST_ALPHA ? GL_ONE_MINUS_DST_ALPHA : param1
                ==
                DGL_SRC_ALPHA_SATURATE ? GL_SRC_ALPHA_SATURATE : GL_ZERO,
                param2 == DGL_ZERO ? GL_ZERO : param2 ==
                DGL_ONE ? GL_ONE : param2 ==
                DGL_SRC_COLOR ? GL_SRC_COLOR : param2 ==
                DGL_ONE_MINUS_SRC_COLOR ? GL_ONE_MINUS_SRC_COLOR : param2
                == DGL_SRC_ALPHA ? GL_SRC_ALPHA : param2 ==
                DGL_ONE_MINUS_SRC_ALPHA ? GL_ONE_MINUS_SRC_ALPHA : param2
                == DGL_DST_ALPHA ? GL_DST_ALPHA : param2 ==
                DGL_ONE_MINUS_DST_ALPHA ? GL_ONE_MINUS_DST_ALPHA :
                GL_ZERO);
}

void DGL_BlendMode(blendmode_t mode)
{
    GL_BlendMode(mode);
}

void DGL_MatrixMode(int mode)
{
    LIBDENG_ASSERT_IN_MAIN_THREAD();
    LIBDENG_ASSERT_GL_CONTEXT_ACTIVE();

    glMatrixMode(mode == DGL_PROJECTION ? GL_PROJECTION :
                 mode == DGL_TEXTURE ? GL_TEXTURE :
                 GL_MODELVIEW);
}

void DGL_PushMatrix(void)
{
    LIBDENG_ASSERT_IN_MAIN_THREAD();
    LIBDENG_ASSERT_GL_CONTEXT_ACTIVE();

    glPushMatrix();

#if _DEBUG
if(glGetError() == GL_STACK_OVERFLOW)
    Con_Error("DG_PushMatrix: Stack overflow.\n");
#endif
}

void DGL_SetNoMaterial(void)
{
    GL_SetNoTexture();
}

static int DGL_ToGLWrapCap(DGLint cap)
{
    switch(cap)
    {
    case DGL_CLAMP:         return GL_CLAMP;
    case DGL_CLAMP_TO_EDGE: return GL_CLAMP_TO_EDGE;
    case DGL_REPEAT:        return GL_REPEAT;
    default:
        Con_Error("DGL_ToGLWrapCap: Unknown cap value %i.", (int)cap);
        exit(1); // Unreachable.
    }
}

void DGL_SetMaterialUI(material_t* mat, DGLint wrapS, DGLint wrapT)
{
    GL_SetMaterialUI2(mat, DGL_ToGLWrapCap(wrapS), DGL_ToGLWrapCap(wrapT));
}

void DGL_SetPatch(patchid_t id, DGLint wrapS, DGLint wrapT)
{
    Texture* tex = Textures_ToTexture(Textures_TextureForUniqueId(TN_PATCHES, id));
    if(!tex) return;
    GL_BindTexture(GL_PreparePatchTexture2(tex, DGL_ToGLWrapCap(wrapS), DGL_ToGLWrapCap(wrapT)));
}

void DGL_SetPSprite(material_t* mat)
{
    GL_SetPSprite(mat, 0, 0);
}

void DGL_SetPSprite2(material_t* mat, int tclass, int tmap)
{
    GL_SetPSprite(mat, tclass, tmap);
}

void DGL_SetRawImage(lumpnum_t lumpNum, DGLint wrapS, DGLint wrapT)
{
    GL_SetRawImage(lumpNum, DGL_ToGLWrapCap(wrapS), DGL_ToGLWrapCap(wrapT));
}

void DGL_PopMatrix(void)
{
    LIBDENG_ASSERT_IN_MAIN_THREAD();
    LIBDENG_ASSERT_GL_CONTEXT_ACTIVE();

    glPopMatrix();

#if _DEBUG
if(glGetError() == GL_STACK_UNDERFLOW)
    Con_Error("DG_PopMatrix: Stack underflow.\n");
#endif
}

void DGL_LoadIdentity(void)
{
    LIBDENG_ASSERT_IN_MAIN_THREAD();
    LIBDENG_ASSERT_GL_CONTEXT_ACTIVE();

    glLoadIdentity();
}

void DGL_Translatef(float x, float y, float z)
{
    LIBDENG_ASSERT_IN_MAIN_THREAD();
    LIBDENG_ASSERT_GL_CONTEXT_ACTIVE();

    glTranslatef(x, y, z);
}

void DGL_Rotatef(float angle, float x, float y, float z)
{
    LIBDENG_ASSERT_IN_MAIN_THREAD();
    LIBDENG_ASSERT_GL_CONTEXT_ACTIVE();

    glRotatef(angle, x, y, z);
}

void DGL_Scalef(float x, float y, float z)
{
    LIBDENG_ASSERT_IN_MAIN_THREAD();
    LIBDENG_ASSERT_GL_CONTEXT_ACTIVE();

    glScalef(x, y, z);
}

void DGL_Ortho(float left, float top, float right, float bottom, float znear,
               float zfar)
{
    LIBDENG_ASSERT_IN_MAIN_THREAD();
    LIBDENG_ASSERT_GL_CONTEXT_ACTIVE();

    glOrtho(left, right, bottom, top, znear, zfar);
}

void DGL_DeleteTextures(int num, const DGLuint *names)
{
    if(!num || !names)
        return;

    glDeleteTextures(num, (const GLuint*) names);
}

int DGL_Bind(DGLuint texture)
{
    GL_BindTextureUnmanaged(texture, GL_LINEAR);
    assert(!Sys_GLCheckError());
    return 0;
}

#if 0 // Currently unused.
int DGL_Project(int num, dgl_fc3vertex_t *inVertices,
               dgl_fc3vertex_t *outVertices)
{
    GLdouble    modelMatrix[16], projMatrix[16];
    GLint       viewport[4];
    GLdouble    x, y, z;
    int         i, numOut;
    dgl_fc3vertex_t *in = inVertices, *out = outVertices;

    if(num == 0)
        return 0;

    // Get the data we'll need in the operation.
    glGetDoublev(GL_MODELVIEW_MATRIX, modelMatrix);
    glGetDoublev(GL_PROJECTION_MATRIX, projMatrix);
    glGetIntegerv(GL_VIEWPORT, viewport);
    for(i = numOut = 0; i < num; ++i, in++)
    {
        if(gluProject
           (in->pos[VX], in->pos[VY], in->pos[VZ], modelMatrix, projMatrix,
            viewport, &x, &y, &z) == GL_TRUE)
        {
            // A success: add to the out vertices.
            out->pos[VX] = (float) x;
            out->pos[VY] = (float) FLIP(y);
            out->pos[VZ] = (float) z;

            // Check that it's truly visible.
            if(out->pos[VX] < 0 || out->pos[VY] < 0 ||
               out->pos[VX] >= theWindow->width ||
               out->pos[VY] >= theWindow->height)
                continue;

            memcpy(out->color, in->color, sizeof(in->color));
            numOut++;
            out++;
        }
    }
    return numOut;
}
#endif

DGLuint DGL_NewTextureWithParams(dgltexformat_t format, int width, int height,
    const uint8_t* pixels, int flags, int minFilter, int magFilter,
    int anisoFilter, int wrapS, int wrapT)
{
    return GL_NewTextureWithParams2(format, width, height, (uint8_t*)pixels,
        flags, 0,
        (minFilter == DGL_LINEAR? GL_LINEAR :
         minFilter == DGL_NEAREST? GL_NEAREST :
         minFilter == DGL_NEAREST_MIPMAP_NEAREST? GL_NEAREST_MIPMAP_NEAREST :
         minFilter == DGL_LINEAR_MIPMAP_NEAREST? GL_LINEAR_MIPMAP_NEAREST :
         minFilter == DGL_NEAREST_MIPMAP_LINEAR? GL_NEAREST_MIPMAP_LINEAR :
         GL_LINEAR_MIPMAP_LINEAR),
        (magFilter == DGL_LINEAR? GL_LINEAR : GL_NEAREST), anisoFilter,
        (wrapS == DGL_CLAMP? GL_CLAMP :
         wrapS == DGL_CLAMP_TO_EDGE? GL_CLAMP_TO_EDGE : GL_REPEAT),
        (wrapT == DGL_CLAMP? GL_CLAMP :
         wrapT == DGL_CLAMP_TO_EDGE? GL_CLAMP_TO_EDGE : GL_REPEAT));
}