src/video/SDL_renderer_gl.c
author Sam Lantinga <slouken@libsdl.org>
Sat, 21 Nov 2009 05:29:31 +0000
changeset 3468 789b97008d8a
parent 3458 0aed0755d1f1
child 3470 419f459f2f38
permissions -rw-r--r--
My first OpenGL shader! Momma will be so proud! This shader implements the software renderer mask semantics where the source pixel is multiplied by the color and alpha modulation values and then any pixel with non-zero alpha is fully opaque. The OpenGL renderer on Mac OS X now passes all the automated render tests! :)

/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2009 Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library 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
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    Sam Lantinga
    slouken@libsdl.org
*/
#include "SDL_config.h"

#if SDL_VIDEO_RENDER_OGL

#include "SDL_video.h"
#include "SDL_opengl.h"
#include "SDL_sysvideo.h"
#include "SDL_pixels_c.h"
#include "SDL_rect_c.h"
#include "SDL_yuv_sw_c.h"

#ifdef __MACOSX__
#include <OpenGL/OpenGL.h>
#endif


/* OpenGL renderer implementation */

/* Details on optimizing the texture path on Mac OS X:
   http://developer.apple.com/documentation/GraphicsImaging/Conceptual/OpenGL-MacProgGuide/opengl_texturedata/chapter_10_section_2.html
*/

/* !!! FIXME: this should go in a higher level than the GL renderer. */
static __inline__ int
bytes_per_pixel(const Uint32 format)
{
    if (!SDL_ISPIXELFORMAT_FOURCC(format)) {
        return SDL_BYTESPERPIXEL(format);
    }

    /* FOURCC format */
    switch (format) {
    case SDL_PIXELFORMAT_YV12:
    case SDL_PIXELFORMAT_IYUV:
    case SDL_PIXELFORMAT_YUY2:
    case SDL_PIXELFORMAT_UYVY:
    case SDL_PIXELFORMAT_YVYU:
        return 2;
    default:
        return 1;               /* shouldn't ever hit this. */
    }
}


static const float inv255f = 1.0f / 255.0f;

static SDL_Renderer *GL_CreateRenderer(SDL_Window * window, Uint32 flags);
static int GL_ActivateRenderer(SDL_Renderer * renderer);
static int GL_DisplayModeChanged(SDL_Renderer * renderer);
static int GL_CreateTexture(SDL_Renderer * renderer, SDL_Texture * texture);
static int GL_QueryTexturePixels(SDL_Renderer * renderer,
                                 SDL_Texture * texture, void **pixels,
                                 int *pitch);
static int GL_SetTexturePalette(SDL_Renderer * renderer,
                                SDL_Texture * texture,
                                const SDL_Color * colors, int firstcolor,
                                int ncolors);
static int GL_GetTexturePalette(SDL_Renderer * renderer,
                                SDL_Texture * texture, SDL_Color * colors,
                                int firstcolor, int ncolors);
static int GL_SetTextureColorMod(SDL_Renderer * renderer,
                                 SDL_Texture * texture);
static int GL_SetTextureAlphaMod(SDL_Renderer * renderer,
                                 SDL_Texture * texture);
static int GL_SetTextureBlendMode(SDL_Renderer * renderer,
                                  SDL_Texture * texture);
static int GL_SetTextureScaleMode(SDL_Renderer * renderer,
                                  SDL_Texture * texture);
static int GL_UpdateTexture(SDL_Renderer * renderer, SDL_Texture * texture,
                            const SDL_Rect * rect, const void *pixels,
                            int pitch);
static int GL_LockTexture(SDL_Renderer * renderer, SDL_Texture * texture,
                          const SDL_Rect * rect, int markDirty, void **pixels,
                          int *pitch);
static void GL_UnlockTexture(SDL_Renderer * renderer, SDL_Texture * texture);
static void GL_DirtyTexture(SDL_Renderer * renderer, SDL_Texture * texture,
                            int numrects, const SDL_Rect * rects);
static int GL_RenderPoint(SDL_Renderer * renderer, int x, int y);
static int GL_RenderLine(SDL_Renderer * renderer, int x1, int y1, int x2,
                         int y2);
static int GL_RenderFill(SDL_Renderer * renderer, const SDL_Rect * rect);
static int GL_RenderCopy(SDL_Renderer * renderer, SDL_Texture * texture,
                         const SDL_Rect * srcrect, const SDL_Rect * dstrect);
static int GL_RenderReadPixels(SDL_Renderer * renderer, const SDL_Rect * rect,
                               Uint32 pixel_format, void * pixels, int pitch);
static int GL_RenderWritePixels(SDL_Renderer * renderer, const SDL_Rect * rect,
                                Uint32 pixel_format, const void * pixels, int pitch);
static void GL_RenderPresent(SDL_Renderer * renderer);
static void GL_DestroyTexture(SDL_Renderer * renderer, SDL_Texture * texture);
static void GL_DestroyRenderer(SDL_Renderer * renderer);


SDL_RenderDriver GL_RenderDriver = {
    GL_CreateRenderer,
    {
     "opengl",
     (SDL_RENDERER_SINGLEBUFFER | SDL_RENDERER_PRESENTDISCARD |
      SDL_RENDERER_PRESENTVSYNC | SDL_RENDERER_ACCELERATED),
     (SDL_TEXTUREMODULATE_NONE | SDL_TEXTUREMODULATE_COLOR |
      SDL_TEXTUREMODULATE_ALPHA),
     (SDL_BLENDMODE_NONE | SDL_BLENDMODE_MASK |
      SDL_BLENDMODE_BLEND | SDL_BLENDMODE_ADD | SDL_BLENDMODE_MOD),
     (SDL_TEXTURESCALEMODE_NONE | SDL_TEXTURESCALEMODE_FAST |
      SDL_TEXTURESCALEMODE_SLOW),
     15,
     {
      SDL_PIXELFORMAT_INDEX1LSB,
      SDL_PIXELFORMAT_INDEX1MSB,
      SDL_PIXELFORMAT_INDEX8,
      SDL_PIXELFORMAT_RGB332,
      SDL_PIXELFORMAT_RGB444,
      SDL_PIXELFORMAT_RGB555,
      SDL_PIXELFORMAT_ARGB4444,
      SDL_PIXELFORMAT_ARGB1555,
      SDL_PIXELFORMAT_RGB565,
      SDL_PIXELFORMAT_RGB24,
      SDL_PIXELFORMAT_BGR24,
      SDL_PIXELFORMAT_RGB888,
      SDL_PIXELFORMAT_BGR888,
      SDL_PIXELFORMAT_ARGB8888,
      SDL_PIXELFORMAT_ABGR8888,
      SDL_PIXELFORMAT_ARGB2101010},
     0,
     0}
};

typedef struct
{
    SDL_GLContext context;
    SDL_bool updateSize;
    SDL_bool GL_ARB_texture_rectangle_supported;
    SDL_bool GL_EXT_paletted_texture_supported;
    SDL_bool GL_APPLE_ycbcr_422_supported;
    SDL_bool GL_MESA_ycbcr_texture_supported;
    SDL_bool GL_ARB_fragment_program_supported;
    int blendMode;
    int scaleMode;

    /* OpenGL functions */
#define SDL_PROC(ret,func,params) ret (APIENTRY *func) params;
#include "SDL_glfuncs.h"
#undef SDL_PROC

    PFNGLCOLORTABLEEXTPROC glColorTableEXT;
    void (*glTextureRangeAPPLE) (GLenum target, GLsizei length,
                                 const GLvoid * pointer);

    PFNGLGETPROGRAMIVARBPROC glGetProgramivARB;
    PFNGLGETPROGRAMSTRINGARBPROC glGetProgramStringARB;
    PFNGLPROGRAMLOCALPARAMETER4FVARBPROC glProgramLocalParameter4fvARB;
    PFNGLDELETEPROGRAMSARBPROC glDeleteProgramsARB;
    PFNGLGENPROGRAMSARBPROC glGenProgramsARB;
    PFNGLBINDPROGRAMARBPROC glBindProgramARB;
    PFNGLPROGRAMSTRINGARBPROC glProgramStringARB;

    /* (optional) fragment programs */
    GLuint fragment_program_mask;
    GLuint fragment_program_UYVY;
} GL_RenderData;

typedef struct
{
    GLuint texture;
    GLuint shader;
    GLenum type;
    GLfloat texw;
    GLfloat texh;
    GLenum format;
    GLenum formattype;
    Uint8 *palette;
    void *pixels;
    int pitch;
    SDL_DirtyRectList dirty;
    int HACK_RYAN_FIXME;
} GL_TextureData;


static void
GL_SetError(const char *prefix, GLenum result)
{
    const char *error;

    switch (result) {
    case GL_NO_ERROR:
        error = "GL_NO_ERROR";
        break;
    case GL_INVALID_ENUM:
        error = "GL_INVALID_ENUM";
        break;
    case GL_INVALID_VALUE:
        error = "GL_INVALID_VALUE";
        break;
    case GL_INVALID_OPERATION:
        error = "GL_INVALID_OPERATION";
        break;
    case GL_STACK_OVERFLOW:
        error = "GL_STACK_OVERFLOW";
        break;
    case GL_STACK_UNDERFLOW:
        error = "GL_STACK_UNDERFLOW";
        break;
    case GL_OUT_OF_MEMORY:
        error = "GL_OUT_OF_MEMORY";
        break;
    case GL_TABLE_TOO_LARGE:
        error = "GL_TABLE_TOO_LARGE";
        break;
    default:
        error = "UNKNOWN";
        break;
    }
    SDL_SetError("%s: %s", prefix, error);
}

static int
GL_LoadFunctions(GL_RenderData * data)
{
#if defined(__QNXNTO__) && (_NTO_VERSION < 630)
#define __SDL_NOGETPROCADDR__
#endif
#ifdef __SDL_NOGETPROCADDR__
#define SDL_PROC(ret,func,params) data->func=func;
#else
#define SDL_PROC(ret,func,params) \
    do { \
        data->func = SDL_GL_GetProcAddress(#func); \
        if ( ! data->func ) { \
            SDL_SetError("Couldn't load GL function %s: %s\n", #func, SDL_GetError()); \
            return -1; \
        } \
    } while ( 0 );
#endif /* __SDL_NOGETPROCADDR__ */

#include "SDL_glfuncs.h"
#undef SDL_PROC
    return 0;
}

void
GL_AddRenderDriver(_THIS)
{
    if (_this->GL_CreateContext) {
        SDL_AddRenderDriver(0, &GL_RenderDriver);
    }
}

SDL_Renderer *
GL_CreateRenderer(SDL_Window * window, Uint32 flags)
{
    SDL_Renderer *renderer;
    GL_RenderData *data;
    GLint value;
    int doublebuffer;

    /* Render directly to the window, unless we're compositing */
#ifndef __MACOSX__
    if (flags & SDL_RENDERER_SINGLEBUFFER) {
        SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 0);
    }
#endif
    if (!(window->flags & SDL_WINDOW_OPENGL)) {
        if (SDL_RecreateWindow(window, window->flags | SDL_WINDOW_OPENGL) < 0) {
            return NULL;
        }
    }

    renderer = (SDL_Renderer *) SDL_calloc(1, sizeof(*renderer));
    if (!renderer) {
        SDL_OutOfMemory();
        return NULL;
    }

    data = (GL_RenderData *) SDL_calloc(1, sizeof(*data));
    if (!data) {
        GL_DestroyRenderer(renderer);
        SDL_OutOfMemory();
        return NULL;
    }

    renderer->ActivateRenderer = GL_ActivateRenderer;
    renderer->DisplayModeChanged = GL_DisplayModeChanged;
    renderer->CreateTexture = GL_CreateTexture;
    renderer->QueryTexturePixels = GL_QueryTexturePixels;
    renderer->SetTexturePalette = GL_SetTexturePalette;
    renderer->GetTexturePalette = GL_GetTexturePalette;
    renderer->SetTextureColorMod = GL_SetTextureColorMod;
    renderer->SetTextureAlphaMod = GL_SetTextureAlphaMod;
    renderer->SetTextureBlendMode = GL_SetTextureBlendMode;
    renderer->SetTextureScaleMode = GL_SetTextureScaleMode;
    renderer->UpdateTexture = GL_UpdateTexture;
    renderer->LockTexture = GL_LockTexture;
    renderer->UnlockTexture = GL_UnlockTexture;
    renderer->DirtyTexture = GL_DirtyTexture;
    renderer->RenderPoint = GL_RenderPoint;
    renderer->RenderLine = GL_RenderLine;
    renderer->RenderFill = GL_RenderFill;
    renderer->RenderCopy = GL_RenderCopy;
    renderer->RenderReadPixels = GL_RenderReadPixels;
    renderer->RenderWritePixels = GL_RenderWritePixels;
    renderer->RenderPresent = GL_RenderPresent;
    renderer->DestroyTexture = GL_DestroyTexture;
    renderer->DestroyRenderer = GL_DestroyRenderer;
    renderer->info = GL_RenderDriver.info;
    renderer->window = window->id;
    renderer->driverdata = data;

    renderer->info.flags =
        (SDL_RENDERER_PRESENTDISCARD | SDL_RENDERER_ACCELERATED);

    if (GL_LoadFunctions(data) < 0) {
        GL_DestroyRenderer(renderer);
        return NULL;
    }

    data->context = SDL_GL_CreateContext(window->id);
    if (!data->context) {
        GL_DestroyRenderer(renderer);
        return NULL;
    }
    if (SDL_GL_MakeCurrent(window->id, data->context) < 0) {
        GL_DestroyRenderer(renderer);
        return NULL;
    }
#ifdef __MACOSX__
    /* Enable multi-threaded rendering */
    /* Disabled until Ryan finishes his VBO/PBO code...
       CGLEnable(CGLGetCurrentContext(), kCGLCEMPEngine);
     */
#endif

    if (flags & SDL_RENDERER_PRESENTVSYNC) {
        SDL_GL_SetSwapInterval(1);
    } else {
        SDL_GL_SetSwapInterval(0);
    }
    if (SDL_GL_GetSwapInterval() > 0) {
        renderer->info.flags |= SDL_RENDERER_PRESENTVSYNC;
    }

    if (SDL_GL_GetAttribute(SDL_GL_DOUBLEBUFFER, &doublebuffer) == 0) {
        if (!doublebuffer) {
            renderer->info.flags |= SDL_RENDERER_SINGLEBUFFER;
        }
    }

    data->glGetIntegerv(GL_MAX_TEXTURE_SIZE, &value);
    renderer->info.max_texture_width = value;
    data->glGetIntegerv(GL_MAX_TEXTURE_SIZE, &value);
    renderer->info.max_texture_height = value;

    if (SDL_GL_ExtensionSupported("GL_ARB_texture_rectangle")
        || SDL_GL_ExtensionSupported("GL_EXT_texture_rectangle")) {
        data->GL_ARB_texture_rectangle_supported = SDL_TRUE;
    }
    if (SDL_GL_ExtensionSupported("GL_EXT_paletted_texture")) {
        data->GL_EXT_paletted_texture_supported = SDL_TRUE;
        data->glColorTableEXT =
            (PFNGLCOLORTABLEEXTPROC) SDL_GL_GetProcAddress("glColorTableEXT");
    } else {
        /* Don't advertise support for 8-bit indexed texture format */
        Uint32 i, j;
        SDL_RendererInfo *info = &renderer->info;
        for (i = 0, j = 0; i < info->num_texture_formats; ++i) {
            if (info->texture_formats[i] != SDL_PIXELFORMAT_INDEX8) {
                info->texture_formats[j++] = info->texture_formats[i];
            }
        }
        --info->num_texture_formats;
    }
    if (SDL_GL_ExtensionSupported("GL_APPLE_ycbcr_422")) {
        data->GL_APPLE_ycbcr_422_supported = SDL_TRUE;
    }
    if (SDL_GL_ExtensionSupported("GL_MESA_ycbcr_texture")) {
        data->GL_MESA_ycbcr_texture_supported = SDL_TRUE;
    }
    if (SDL_GL_ExtensionSupported("GL_APPLE_texture_range")) {
        data->glTextureRangeAPPLE =
            (void (*)(GLenum, GLsizei, const GLvoid *))
            SDL_GL_GetProcAddress("glTextureRangeAPPLE");
    }

    /* we might use fragment programs for YUV data, etc. */
    if (SDL_GL_ExtensionSupported("GL_ARB_fragment_program")) {
        /* !!! FIXME: this doesn't check for errors. */
        /* !!! FIXME: this should really reuse the glfuncs.h stuff. */
        data->glGetProgramivARB = (PFNGLGETPROGRAMIVARBPROC)
            SDL_GL_GetProcAddress("glGetProgramivARB");
        data->glGetProgramStringARB = (PFNGLGETPROGRAMSTRINGARBPROC)
            SDL_GL_GetProcAddress("glGetProgramStringARB");
        data->glProgramLocalParameter4fvARB =
            (PFNGLPROGRAMLOCALPARAMETER4FVARBPROC)
            SDL_GL_GetProcAddress("glProgramLocalParameter4fvARB");
        data->glDeleteProgramsARB = (PFNGLDELETEPROGRAMSARBPROC)
            SDL_GL_GetProcAddress("glDeleteProgramsARB");
        data->glGenProgramsARB = (PFNGLGENPROGRAMSARBPROC)
            SDL_GL_GetProcAddress("glGenProgramsARB");
        data->glBindProgramARB = (PFNGLBINDPROGRAMARBPROC)
            SDL_GL_GetProcAddress("glBindProgramARB");
        data->glProgramStringARB = (PFNGLPROGRAMSTRINGARBPROC)
            SDL_GL_GetProcAddress("glProgramStringARB");
        data->GL_ARB_fragment_program_supported = SDL_TRUE;
    }

    /* Set up parameters for rendering */
    data->blendMode = -1;
    data->scaleMode = -1;
    data->glDisable(GL_DEPTH_TEST);
    data->glDisable(GL_CULL_FACE);
    /* This ended up causing video discrepancies between OpenGL and Direct3D */
    /*data->glEnable(GL_LINE_SMOOTH);*/
    if (data->GL_ARB_texture_rectangle_supported) {
        data->glEnable(GL_TEXTURE_RECTANGLE_ARB);
    } else {
        data->glEnable(GL_TEXTURE_2D);
    }
    data->updateSize = SDL_TRUE;

    return renderer;
}

static int
GL_ActivateRenderer(SDL_Renderer * renderer)
{
    GL_RenderData *data = (GL_RenderData *) renderer->driverdata;
    SDL_Window *window = SDL_GetWindowFromID(renderer->window);

    if (SDL_GL_MakeCurrent(window->id, data->context) < 0) {
        return -1;
    }
    if (data->updateSize) {
        data->glMatrixMode(GL_PROJECTION);
        data->glLoadIdentity();
        data->glMatrixMode(GL_MODELVIEW);
        data->glLoadIdentity();
        data->glViewport(0, 0, window->w, window->h);
        data->glOrtho(0.0, (GLdouble) window->w,
                      (GLdouble) window->h, 0.0, 0.0, 1.0);
        data->updateSize = SDL_FALSE;
    }
    return 0;
}

static int
GL_DisplayModeChanged(SDL_Renderer * renderer)
{
    GL_RenderData *data = (GL_RenderData *) renderer->driverdata;

    /* Rebind the context to the window area and update matrices */
    data->updateSize = SDL_TRUE;
    return GL_ActivateRenderer(renderer);
}

static __inline__ int
power_of_2(int input)
{
    int value = 1;

    while (value < input) {
        value <<= 1;
    }
    return value;
}


//#define DEBUG_PROGRAM_COMPILE 1

static void
set_shader_error(GL_RenderData * data, const char *prefix)
{
    GLint pos = 0;
    const GLubyte *errstr;
    data->glGetIntegerv(GL_PROGRAM_ERROR_POSITION_ARB, &pos);
    errstr = data->glGetString(GL_PROGRAM_ERROR_STRING_ARB);
    printf("%s: shader compile error at position %d: %s",
           prefix, (int) pos, (const char *) errstr);
}

static GLuint
compile_shader(GL_RenderData * data, GLenum shader_type, const char *_code)
{
    const int have_texture_rects = data->GL_ARB_texture_rectangle_supported;
    const char *replacement = have_texture_rects ? "RECT" : "2D";
    const size_t replacementlen = SDL_strlen(replacement);
    const char *token = "%TEXTURETARGET%";
    const size_t tokenlen = SDL_strlen(token);
    char *code = NULL;
    char *ptr = NULL;
    GLuint program = 0;

    /*
     * The TEX instruction needs a different target depending on what we use.
     *  To handle this, we use "%TEXTURETARGET%" and replace the string before
     *  compiling the shader.
     */
    code = SDL_strdup(_code);
    if (code == NULL)
        return 0;

    for (ptr = SDL_strstr(code, token); ptr; ptr = SDL_strstr(ptr + 1, token)) {
        SDL_memcpy(ptr, replacement, replacementlen);
        SDL_memmove(ptr + replacementlen, ptr + tokenlen,
                    SDL_strlen(ptr + tokenlen) + 1);
    }

#if DEBUG_PROGRAM_COMPILE
    printf("compiling shader:\n%s\n\n", code);
#endif

    data->glGetError();         /* flush any existing error state. */
    data->glGenProgramsARB(1, &program);
    data->glBindProgramARB(shader_type, program);
    data->glProgramStringARB(shader_type, GL_PROGRAM_FORMAT_ASCII_ARB,
                             (GLsizei)SDL_strlen(code), code);

    SDL_free(code);

    if (data->glGetError() == GL_INVALID_OPERATION) {
#if DEBUG_PROGRAM_COMPILE
        GLint pos = 0;
        const GLubyte *errstr;
        data->glGetIntegerv(GL_PROGRAM_ERROR_POSITION_ARB, &pos);
        errstr = data->glGetString(GL_PROGRAM_ERROR_STRING_ARB);
        printf("program compile error at position %d: %s\n\n",
               (int) pos, (const char *) errstr);
#endif
        data->glBindProgramARB(shader_type, 0);
        data->glDeleteProgramsARB(1, &program);
        return 0;
    }

    return program;
}


/*
 * Fragment program that implements mask semantics
 */
static const char *fragment_program_mask_source_code = "!!ARBfp1.0\n"
"OUTPUT output = result.color;\n"
"TEMP value;\n"
"TEX value, fragment.texcoord[0], texture[0], %TEXTURETARGET%;\n"
"MUL value, fragment.color, value;\n"
"SGE value.a, value.a, 0.001;\n"
"MOV output, value;\n"
"END";

/*
 * Fragment program that renders from UYVY textures.
 * The UYVY to RGB equasion is:
 *   R = 1.164(Y-16) + 1.596(Cr-128)
 *   G = 1.164(Y-16) - 0.813(Cr-128) - 0.391(Cb-128)
 *   B = 1.164(Y-16) + 2.018(Cb-128)
 * Byte layout is Cb, Y1, Cr, Y2, stored in the R, G, B, A channels.
 * 4 bytes == 2 pixels: Y1/Cb/Cr, Y2/Cb/Cr
 *
 * !!! FIXME: this ignores blendmodes, etc.
 * !!! FIXME: this could be more efficient...use a dot product for green, etc.
 */
static const char *fragment_program_UYVY_source_code = "!!ARBfp1.0\n"
    /* outputs... */
    "OUTPUT outcolor = result.color;\n"
    /* scratch registers... */
    "TEMP uyvy;\n" "TEMP luminance;\n" "TEMP work;\n"
    /* Halve the coordinates to grab the correct 32 bits for the fragment. */
    "MUL work, fragment.texcoord, { 0.5, 1.0, 1.0, 1.0 };\n"
    /* Sample the YUV texture. Cb, Y1, Cr, Y2, are stored in x, y, z, w. */
    "TEX uyvy, work, texture[0], %TEXTURETARGET%;\n"
    /* Do subtractions (128/255, 16/255, 128/255, 16/255) */
    "SUB uyvy, uyvy, { 0.501960784313726, 0.06274509803922, 0.501960784313726, 0.06274509803922 };\n"
    /* Choose the luminance component by texcoord. */
    /* !!! FIXME: laziness wins out for now... just average Y1 and Y2. */
    "ADD luminance, uyvy.yyyy, uyvy.wwww;\n"
    "MUL luminance, luminance, { 0.5, 0.5, 0.5, 0.5 };\n"
    /* Multiply luminance by its magic value. */
    "MUL luminance, luminance, { 1.164, 1.164, 1.164, 1.164 };\n"
    /* uyvy.xyzw becomes Cr/Cr/Cb/Cb, with multiplications. */
    "MUL uyvy, uyvy.zzxx, { 1.596, -0.813, 2.018, -0.391 };\n"
    /* Add luminance to Cr and Cb, store to RGB channels. */
    "ADD work.rgb, luminance, uyvy;\n"
    /* Do final addition for Green channel.  (!!! FIXME: this should be a DPH?) */
    "ADD work.g, work.g, uyvy.w;\n"
    /* Make sure alpha channel is fully opaque.  (!!! FIXME: blend modes!) */
    "MOV work.a, { 1.0 };\n"
    /* Store out the final fragment color... */
    "MOV outcolor, work;\n"
    /* ...and we're done! */
    "END\n";

static __inline__ SDL_bool
convert_format(GL_RenderData *renderdata, Uint32 pixel_format,
               GLint* internalFormat, GLenum* format, GLenum* type)
{
    switch (pixel_format) {
    case SDL_PIXELFORMAT_INDEX1LSB:
    case SDL_PIXELFORMAT_INDEX1MSB:
        *internalFormat = GL_RGB;
        *format = GL_COLOR_INDEX;
        *type = GL_BITMAP;
        break;
    case SDL_PIXELFORMAT_INDEX8:
        if (!renderdata->GL_EXT_paletted_texture_supported) {
            return SDL_FALSE;
        }
        *internalFormat = GL_COLOR_INDEX8_EXT;
        *format = GL_COLOR_INDEX;
        *type = GL_UNSIGNED_BYTE;
        break;
    case SDL_PIXELFORMAT_RGB332:
        *internalFormat = GL_R3_G3_B2;
        *format = GL_RGB;
        *type = GL_UNSIGNED_BYTE_3_3_2;
        break;
    case SDL_PIXELFORMAT_RGB444:
        *internalFormat = GL_RGB4;
        *format = GL_RGB;
        *type = GL_UNSIGNED_SHORT_4_4_4_4;
        break;
    case SDL_PIXELFORMAT_RGB555:
        *internalFormat = GL_RGB5;
        *format = GL_RGB;
        *type = GL_UNSIGNED_SHORT_5_5_5_1;
        break;
    case SDL_PIXELFORMAT_ARGB4444:
        *internalFormat = GL_RGBA4;
        *format = GL_BGRA;
        *type = GL_UNSIGNED_SHORT_4_4_4_4_REV;
        break;
    case SDL_PIXELFORMAT_ARGB1555:
        *internalFormat = GL_RGB5_A1;
        *format = GL_BGRA;
        *type = GL_UNSIGNED_SHORT_1_5_5_5_REV;
        break;
    case SDL_PIXELFORMAT_RGB565:
        *internalFormat = GL_RGB8;
        *format = GL_RGB;
        *type = GL_UNSIGNED_SHORT_5_6_5;
        break;
    case SDL_PIXELFORMAT_RGB24:
        *internalFormat = GL_RGB8;
        *format = GL_RGB;
        *type = GL_UNSIGNED_BYTE;
        break;
    case SDL_PIXELFORMAT_RGB888:
        *internalFormat = GL_RGB8;
        *format = GL_BGRA;
        *type = GL_UNSIGNED_BYTE;
        break;
    case SDL_PIXELFORMAT_BGR24:
        *internalFormat = GL_RGB8;
        *format = GL_BGR;
        *type = GL_UNSIGNED_BYTE;
        break;
    case SDL_PIXELFORMAT_BGR888:
        *internalFormat = GL_RGB8;
        *format = GL_RGBA;
        *type = GL_UNSIGNED_BYTE;
        break;
    case SDL_PIXELFORMAT_ARGB8888:
#ifdef __MACOSX__
        *internalFormat = GL_RGBA;
        *format = GL_BGRA;
        *type = GL_UNSIGNED_INT_8_8_8_8_REV;
#else
        *internalFormat = GL_RGBA8;
        *format = GL_BGRA;
        *type = GL_UNSIGNED_BYTE;
#endif
        break;
    case SDL_PIXELFORMAT_ABGR8888:
        *internalFormat = GL_RGBA8;
        *format = GL_RGBA;
        *type = GL_UNSIGNED_BYTE;
        break;
    case SDL_PIXELFORMAT_ARGB2101010:
        *internalFormat = GL_RGB10_A2;
        *format = GL_BGRA;
        *type = GL_UNSIGNED_INT_2_10_10_10_REV;
        break;
    case SDL_PIXELFORMAT_UYVY:
        if (renderdata->GL_APPLE_ycbcr_422_supported) {
            *internalFormat = GL_RGB;
            *format = GL_YCBCR_422_APPLE;
#if SDL_BYTEORDER == SDL_LIL_ENDIAN
            *type = GL_UNSIGNED_SHORT_8_8_APPLE;
#else
            *type = GL_UNSIGNED_SHORT_8_8_REV_APPLE;
#endif
        } else if (renderdata->GL_MESA_ycbcr_texture_supported) {
            *internalFormat = GL_RGB;
            *format = GL_YCBCR_MESA;
#if SDL_BYTEORDER == SDL_LIL_ENDIAN
            *type = GL_UNSIGNED_SHORT_8_8_MESA;
#else
            *type = GL_UNSIGNED_SHORT_8_8_REV_MESA;
#endif
        } else if (renderdata->GL_ARB_fragment_program_supported) {
            *internalFormat = GL_RGBA;
            *format = GL_RGBA;
            *type = GL_UNSIGNED_BYTE;
        } else {
            return SDL_FALSE;
        }
        break;
    case SDL_PIXELFORMAT_YUY2:
        if (renderdata->GL_APPLE_ycbcr_422_supported) {
            *internalFormat = GL_RGB;
            *format = GL_YCBCR_422_APPLE;
#if SDL_BYTEORDER == SDL_LIL_ENDIAN
            *type = GL_UNSIGNED_SHORT_8_8_REV_APPLE;
#else
            *type = GL_UNSIGNED_SHORT_8_8_APPLE;
#endif
        } else if (renderdata->GL_MESA_ycbcr_texture_supported) {
            *internalFormat = GL_RGB;
            *format = GL_YCBCR_MESA;
#if SDL_BYTEORDER == SDL_LIL_ENDIAN
            *type = GL_UNSIGNED_SHORT_8_8_REV_MESA;
#else
            *type = GL_UNSIGNED_SHORT_8_8_MESA;
#endif
        } else {
            return SDL_FALSE;
        }
        break;
    default:
        return SDL_FALSE;
    }
    return SDL_TRUE;
}

static int
GL_CreateTexture(SDL_Renderer * renderer, SDL_Texture * texture)
{
    GL_RenderData *renderdata = (GL_RenderData *) renderer->driverdata;
    SDL_Window *window = SDL_GetWindowFromID(renderer->window);
    GL_TextureData *data;
    GLint internalFormat;
    GLenum format, type;
    int texture_w, texture_h;
    GLuint shader = 0;
    GLenum result;

    if (!convert_format(renderdata, texture->format, &internalFormat,
                        &format, &type)) {
        SDL_SetError("Unsupported texture format");
        return -1;
    }
    if (texture->format == SDL_PIXELFORMAT_UYVY &&
        !renderdata->GL_APPLE_ycbcr_422_supported &&
        !renderdata->GL_MESA_ycbcr_texture_supported &&
        renderdata->GL_ARB_fragment_program_supported) {
        if (renderdata->fragment_program_UYVY == 0) {
            renderdata->fragment_program_UYVY =
                compile_shader(renderdata, GL_FRAGMENT_PROGRAM_ARB,
                               fragment_program_UYVY_source_code);
            if (renderdata->fragment_program_UYVY == 0) {
                set_shader_error(renderdata, "UYVY");
                return -1;
            }
        }
        shader = renderdata->fragment_program_UYVY;
    }

    data = (GL_TextureData *) SDL_calloc(1, sizeof(*data));
    if (!data) {
        SDL_OutOfMemory();
        return -1;
    }

    data->shader = shader;

    if (texture->format == SDL_PIXELFORMAT_INDEX8) {
        data->palette = (Uint8 *) SDL_malloc(3 * 256 * sizeof(Uint8));
        if (!data->palette) {
            SDL_OutOfMemory();
            SDL_free(data);
            return -1;
        }
        SDL_memset(data->palette, 0xFF, 3 * 256 * sizeof(Uint8));
    }

    if (texture->access == SDL_TEXTUREACCESS_STREAMING) {
        data->pitch = texture->w * bytes_per_pixel(texture->format);
        data->pixels = SDL_malloc(texture->h * data->pitch);
        if (!data->pixels) {
            SDL_OutOfMemory();
            SDL_free(data);
            return -1;
        }
    }

    texture->driverdata = data;

    renderdata->glGetError();
    renderdata->glGenTextures(1, &data->texture);
    if (renderdata->GL_ARB_texture_rectangle_supported) {
        data->type = GL_TEXTURE_RECTANGLE_ARB;
        texture_w = texture->w;
        texture_h = texture->h;
        data->texw = (GLfloat) texture_w;
        data->texh = (GLfloat) texture_h;
    } else {
        data->type = GL_TEXTURE_2D;
        texture_w = power_of_2(texture->w);
        texture_h = power_of_2(texture->h);
        data->texw = (GLfloat) (texture->w) / texture_w;
        data->texh = (GLfloat) texture->h / texture_h;
    }

    /* YUV formats use RGBA but are really two bytes per pixel */
    if (internalFormat == GL_RGBA && bytes_per_pixel(texture->format) < 4) {
        data->HACK_RYAN_FIXME = 2;
    } else {
        data->HACK_RYAN_FIXME = 1;
    }
    texture_w /= data->HACK_RYAN_FIXME;

    data->format = format;
    data->formattype = type;
    renderdata->glEnable(data->type);
    renderdata->glBindTexture(data->type, data->texture);
    renderdata->glTexParameteri(data->type, GL_TEXTURE_MIN_FILTER,
                                GL_NEAREST);
    renderdata->glTexParameteri(data->type, GL_TEXTURE_MAG_FILTER,
                                GL_NEAREST);
    renderdata->glTexParameteri(data->type, GL_TEXTURE_WRAP_S,
                                GL_CLAMP_TO_EDGE);
    renderdata->glTexParameteri(data->type, GL_TEXTURE_WRAP_T,
                                GL_CLAMP_TO_EDGE);
#ifdef __MACOSX__
#ifndef GL_TEXTURE_STORAGE_HINT_APPLE
#define GL_TEXTURE_STORAGE_HINT_APPLE       0x85BC
#endif
#ifndef STORAGE_CACHED_APPLE
#define STORAGE_CACHED_APPLE                0x85BE
#endif
#ifndef STORAGE_SHARED_APPLE
#define STORAGE_SHARED_APPLE                0x85BF
#endif
    if (texture->access == SDL_TEXTUREACCESS_STREAMING) {
        renderdata->glTexParameteri(data->type, GL_TEXTURE_STORAGE_HINT_APPLE,
                                    GL_STORAGE_SHARED_APPLE);
    } else {
        renderdata->glTexParameteri(data->type, GL_TEXTURE_STORAGE_HINT_APPLE,
                                    GL_STORAGE_CACHED_APPLE);
    }
/* This causes a crash in testoverlay for some reason.  Apple bug? */
#if 0
    if (texture->access == SDL_TEXTUREACCESS_STREAMING
        && texture->format == SDL_PIXELFORMAT_ARGB8888) {
        /*
           if (renderdata->glTextureRangeAPPLE) {
           renderdata->glTextureRangeAPPLE(data->type,
           texture->h * data->pitch,
           data->pixels);
           }
         */
        renderdata->glPixelStorei(GL_UNPACK_CLIENT_STORAGE_APPLE, GL_TRUE);
        renderdata->glTexImage2D(data->type, 0, internalFormat, texture_w,
                                 texture_h, 0, format, type, data->pixels);
    } else
#endif
#endif
    {
        renderdata->glTexImage2D(data->type, 0, internalFormat, texture_w,
                                 texture_h, 0, format, type, NULL);
    }
    renderdata->glDisable(data->type);
    result = renderdata->glGetError();
    if (result != GL_NO_ERROR) {
        GL_SetError("glTexImage2D()", result);
        return -1;
    }
    return 0;
}

static int
GL_QueryTexturePixels(SDL_Renderer * renderer, SDL_Texture * texture,
                      void **pixels, int *pitch)
{
    GL_TextureData *data = (GL_TextureData *) texture->driverdata;

    *pixels = data->pixels;
    *pitch = data->pitch;
    return 0;
}

static int
GL_SetTexturePalette(SDL_Renderer * renderer, SDL_Texture * texture,
                     const SDL_Color * colors, int firstcolor, int ncolors)
{
    GL_RenderData *renderdata = (GL_RenderData *) renderer->driverdata;
    GL_TextureData *data = (GL_TextureData *) texture->driverdata;
    Uint8 *palette;

    if (!data->palette) {
        SDL_SetError("Texture doesn't have a palette");
        return -1;
    }
    palette = data->palette + firstcolor * 3;
    while (ncolors--) {
        *palette++ = colors->r;
        *palette++ = colors->g;
        *palette++ = colors->b;
        ++colors;
    }
    renderdata->glEnable(data->type);
    renderdata->glBindTexture(data->type, data->texture);
    renderdata->glColorTableEXT(data->type, GL_RGB8, 256, GL_RGB,
                                GL_UNSIGNED_BYTE, data->palette);
    return 0;
}

static int
GL_GetTexturePalette(SDL_Renderer * renderer, SDL_Texture * texture,
                     SDL_Color * colors, int firstcolor, int ncolors)
{
    GL_RenderData *renderdata = (GL_RenderData *) renderer->driverdata;
    GL_TextureData *data = (GL_TextureData *) texture->driverdata;
    Uint8 *palette;

    if (!data->palette) {
        SDL_SetError("Texture doesn't have a palette");
        return -1;
    }
    palette = data->palette + firstcolor * 3;
    while (ncolors--) {
        colors->r = *palette++;
        colors->g = *palette++;
        colors->b = *palette++;
        colors->unused = SDL_ALPHA_OPAQUE;
        ++colors;
    }
    return 0;
}

static void
SetupTextureUpdate(GL_RenderData * renderdata, SDL_Texture * texture,
                   int pitch)
{
    if (texture->format == SDL_PIXELFORMAT_INDEX1LSB) {
        renderdata->glPixelStorei(GL_UNPACK_LSB_FIRST, 1);
    } else if (texture->format == SDL_PIXELFORMAT_INDEX1MSB) {
        renderdata->glPixelStorei(GL_UNPACK_LSB_FIRST, 0);
    }
    renderdata->glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
    renderdata->glPixelStorei(GL_UNPACK_ROW_LENGTH,
                              (pitch / bytes_per_pixel(texture->format)) /
                              ((GL_TextureData *) texture->driverdata)->
                              HACK_RYAN_FIXME);
}

static int
GL_SetTextureColorMod(SDL_Renderer * renderer, SDL_Texture * texture)
{
    return 0;
}

static int
GL_SetTextureAlphaMod(SDL_Renderer * renderer, SDL_Texture * texture)
{
    return 0;
}

static int
GL_SetTextureBlendMode(SDL_Renderer * renderer, SDL_Texture * texture)
{
    switch (texture->blendMode) {
    case SDL_BLENDMODE_NONE:
    case SDL_BLENDMODE_MASK:
    case SDL_BLENDMODE_BLEND:
    case SDL_BLENDMODE_ADD:
    case SDL_BLENDMODE_MOD:
        return 0;
    default:
        SDL_Unsupported();
        texture->blendMode = SDL_BLENDMODE_NONE;
        return -1;
    }
}

static int
GL_SetTextureScaleMode(SDL_Renderer * renderer, SDL_Texture * texture)
{
    switch (texture->scaleMode) {
    case SDL_TEXTURESCALEMODE_NONE:
    case SDL_TEXTURESCALEMODE_FAST:
    case SDL_TEXTURESCALEMODE_SLOW:
        return 0;
    case SDL_TEXTURESCALEMODE_BEST:
        SDL_Unsupported();
        texture->scaleMode = SDL_TEXTURESCALEMODE_SLOW;
        return -1;
    default:
        SDL_Unsupported();
        texture->scaleMode = SDL_TEXTURESCALEMODE_NONE;
        return -1;
    }
}

static int
GL_UpdateTexture(SDL_Renderer * renderer, SDL_Texture * texture,
                 const SDL_Rect * rect, const void *pixels, int pitch)
{
    GL_RenderData *renderdata = (GL_RenderData *) renderer->driverdata;
    GL_TextureData *data = (GL_TextureData *) texture->driverdata;
    GLenum result;

    renderdata->glGetError();
    SetupTextureUpdate(renderdata, texture, pitch);
    renderdata->glEnable(data->type);
    renderdata->glBindTexture(data->type, data->texture);
    renderdata->glTexSubImage2D(data->type, 0, rect->x, rect->y, rect->w,
                                rect->h, data->format, data->formattype,
                                pixels);
    renderdata->glDisable(data->type);
    result = renderdata->glGetError();
    if (result != GL_NO_ERROR) {
        GL_SetError("glTexSubImage2D()", result);
        return -1;
    }
    return 0;
}

static int
GL_LockTexture(SDL_Renderer * renderer, SDL_Texture * texture,
               const SDL_Rect * rect, int markDirty, void **pixels,
               int *pitch)
{
    GL_TextureData *data = (GL_TextureData *) texture->driverdata;

    if (markDirty) {
        SDL_AddDirtyRect(&data->dirty, rect);
    }

    *pixels =
        (void *) ((Uint8 *) data->pixels + rect->y * data->pitch +
                  rect->x * bytes_per_pixel(texture->format));
    *pitch = data->pitch;
    return 0;
}

static void
GL_UnlockTexture(SDL_Renderer * renderer, SDL_Texture * texture)
{
}

static void
GL_DirtyTexture(SDL_Renderer * renderer, SDL_Texture * texture, int numrects,
                const SDL_Rect * rects)
{
    GL_TextureData *data = (GL_TextureData *) texture->driverdata;
    int i;

    for (i = 0; i < numrects; ++i) {
        SDL_AddDirtyRect(&data->dirty, &rects[i]);
    }
}

static void
GL_SetBlendMode(GL_RenderData * data, int blendMode, int isprimitive)
{
    if (blendMode != data->blendMode) {
        switch (blendMode) {
        case SDL_BLENDMODE_NONE:
            data->glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
            data->glDisable(GL_BLEND);
            break;
        case SDL_BLENDMODE_MASK:
            if (isprimitive) {
                /* The same as SDL_BLENDMODE_NONE */
                blendMode = SDL_BLENDMODE_NONE;
                data->glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
                data->glDisable(GL_BLEND);
            } else {
                data->glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
                data->glEnable(GL_BLEND);
                data->glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
            }
            break;
        case SDL_BLENDMODE_BLEND:
            data->glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
            data->glEnable(GL_BLEND);
            data->glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
            break;
        case SDL_BLENDMODE_ADD:
            data->glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
            data->glEnable(GL_BLEND);
            data->glBlendFunc(GL_SRC_ALPHA, GL_ONE);
            break;
        case SDL_BLENDMODE_MOD:
            data->glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
            data->glEnable(GL_BLEND);
            data->glBlendFunc(GL_ZERO, GL_SRC_COLOR);
            break;
        }
        data->blendMode = blendMode;
    }
}

static int
GL_RenderPoint(SDL_Renderer * renderer, int x, int y)
{
    GL_RenderData *data = (GL_RenderData *) renderer->driverdata;

    GL_SetBlendMode(data, renderer->blendMode, 1);

    data->glColor4f((GLfloat) renderer->r * inv255f,
                    (GLfloat) renderer->g * inv255f,
                    (GLfloat) renderer->b * inv255f,
                    (GLfloat) renderer->a * inv255f);

    data->glBegin(GL_POINTS);
    data->glVertex2f(0.5f + x, 0.5f + y);
    data->glEnd();

    return 0;
}

static int
GL_RenderLine(SDL_Renderer * renderer, int x1, int y1, int x2, int y2)
{
    GL_RenderData *data = (GL_RenderData *) renderer->driverdata;

    GL_SetBlendMode(data, renderer->blendMode, 1);

    data->glColor4f((GLfloat) renderer->r * inv255f,
                    (GLfloat) renderer->g * inv255f,
                    (GLfloat) renderer->b * inv255f,
                    (GLfloat) renderer->a * inv255f);

    data->glBegin(GL_LINES);
    data->glVertex2f(0.5f + x1, 0.5f + y1);
    data->glVertex2f(0.5f + x2, 0.5f + y2);
    data->glEnd();

    /* For some reason the second endpoint is skipped */
    data->glBegin(GL_POINTS);
    data->glVertex2f(0.5f + x2, 0.5f + y2);
    data->glEnd();

    return 0;
}

static int
GL_RenderFill(SDL_Renderer * renderer, const SDL_Rect * rect)
{
    GL_RenderData *data = (GL_RenderData *) renderer->driverdata;

    GL_SetBlendMode(data, renderer->blendMode, 1);

    data->glColor4f((GLfloat) renderer->r * inv255f,
                    (GLfloat) renderer->g * inv255f,
                    (GLfloat) renderer->b * inv255f,
                    (GLfloat) renderer->a * inv255f);

    data->glRecti(rect->x, rect->y, rect->x + rect->w, rect->y + rect->h);

    return 0;
}

static int
GL_RenderCopy(SDL_Renderer * renderer, SDL_Texture * texture,
              const SDL_Rect * srcrect, const SDL_Rect * dstrect)
{
    GL_RenderData *data = (GL_RenderData *) renderer->driverdata;
    GL_TextureData *texturedata = (GL_TextureData *) texture->driverdata;
    GLuint shader = 0;
    int minx, miny, maxx, maxy;
    GLfloat minu, maxu, minv, maxv;

    if (texturedata->dirty.list) {
        SDL_DirtyRect *dirty;
        void *pixels;
        int bpp = bytes_per_pixel(texture->format);
        int pitch = texturedata->pitch;

        SetupTextureUpdate(data, texture, pitch);
        data->glEnable(texturedata->type);
        data->glBindTexture(texturedata->type, texturedata->texture);
        for (dirty = texturedata->dirty.list; dirty; dirty = dirty->next) {
            SDL_Rect *rect = &dirty->rect;
            pixels =
                (void *) ((Uint8 *) texturedata->pixels + rect->y * pitch +
                          rect->x * bpp);
            data->glTexSubImage2D(texturedata->type, 0, rect->x, rect->y,
                                  rect->w / texturedata->HACK_RYAN_FIXME,
                                  rect->h, texturedata->format,
                                  texturedata->formattype, pixels);
        }
        SDL_ClearDirtyRects(&texturedata->dirty);
    }

    minx = dstrect->x;
    miny = dstrect->y;
    maxx = dstrect->x + dstrect->w;
    maxy = dstrect->y + dstrect->h;

    minu = (GLfloat) srcrect->x / texture->w;
    minu *= texturedata->texw;
    maxu = (GLfloat) (srcrect->x + srcrect->w) / texture->w;
    maxu *= texturedata->texw;
    minv = (GLfloat) srcrect->y / texture->h;
    minv *= texturedata->texh;
    maxv = (GLfloat) (srcrect->y + srcrect->h) / texture->h;
    maxv *= texturedata->texh;

    data->glEnable(texturedata->type);
    data->glBindTexture(texturedata->type, texturedata->texture);

    if (texture->modMode) {
        data->glColor4f((GLfloat) texture->r * inv255f,
                        (GLfloat) texture->g * inv255f,
                        (GLfloat) texture->b * inv255f,
                        (GLfloat) texture->a * inv255f);
    } else {
        data->glColor4f(1.0f, 1.0f, 1.0f, 1.0f);
    }

    GL_SetBlendMode(data, texture->blendMode, 0);

    /* Set up the shader for the copy, we have a special one for MASK */
    shader = texturedata->shader;
    if (texture->blendMode == SDL_BLENDMODE_MASK && !shader) {
        if (data->fragment_program_mask == 0) {
            data->fragment_program_mask =
                compile_shader(data, GL_FRAGMENT_PROGRAM_ARB,
                               fragment_program_mask_source_code);
            if (data->fragment_program_mask == 0) {
                /* That's okay, we'll just miss some of the blend semantics */
                data->fragment_program_mask = ~0;
            }
        }
        if (data->fragment_program_mask != ~0) {
            shader = data->fragment_program_mask;
        }
    }

    if (texture->scaleMode != data->scaleMode) {
        switch (texture->scaleMode) {
        case SDL_TEXTURESCALEMODE_NONE:
        case SDL_TEXTURESCALEMODE_FAST:
            data->glTexParameteri(texturedata->type, GL_TEXTURE_MIN_FILTER,
                                  GL_NEAREST);
            data->glTexParameteri(texturedata->type, GL_TEXTURE_MAG_FILTER,
                                  GL_NEAREST);
            break;
        case SDL_TEXTURESCALEMODE_SLOW:
        case SDL_TEXTURESCALEMODE_BEST:
            data->glTexParameteri(texturedata->type, GL_TEXTURE_MIN_FILTER,
                                  GL_LINEAR);
            data->glTexParameteri(texturedata->type, GL_TEXTURE_MAG_FILTER,
                                  GL_LINEAR);
            break;
        }
        data->scaleMode = texture->scaleMode;
    }

    if (shader) {
        data->glEnable(GL_FRAGMENT_PROGRAM_ARB);
        data->glBindProgramARB(GL_FRAGMENT_PROGRAM_ARB, shader);
    }

    data->glBegin(GL_TRIANGLE_STRIP);
    data->glTexCoord2f(minu, minv);
    data->glVertex2f(0.5f + minx, 0.5f + miny);
    data->glTexCoord2f(maxu, minv);
    data->glVertex2f(0.5f + maxx, 0.5f + miny);
    data->glTexCoord2f(minu, maxv);
    data->glVertex2f(0.5f + minx, 0.5f + maxy);
    data->glTexCoord2f(maxu, maxv);
    data->glVertex2f(0.5f + maxx, 0.5f + maxy);
    data->glEnd();

    if (shader) {
        data->glDisable(GL_FRAGMENT_PROGRAM_ARB);
    }

    data->glDisable(texturedata->type);

    return 0;
}

static int
GL_RenderReadPixels(SDL_Renderer * renderer, const SDL_Rect * rect,
                    Uint32 pixel_format, void * pixels, int pitch)
{
    GL_RenderData *data = (GL_RenderData *) renderer->driverdata;
    SDL_Window *window = SDL_GetWindowFromID(renderer->window);
    GLint internalFormat;
    GLenum format, type;
    Uint8 *src, *dst, *tmp;
    int length, rows;

    if (!convert_format(data, pixel_format, &internalFormat, &format, &type)) {
        /* FIXME: Do a temp copy to a format that is supported */
        SDL_SetError("Unsupported pixel format");
        return -1;
    }

    if (pixel_format == SDL_PIXELFORMAT_INDEX1LSB) {
        data->glPixelStorei(GL_PACK_LSB_FIRST, 1);
    } else if (pixel_format == SDL_PIXELFORMAT_INDEX1MSB) {
        data->glPixelStorei(GL_PACK_LSB_FIRST, 0);
    }
    data->glPixelStorei(GL_PACK_ALIGNMENT, 1);
    data->glPixelStorei(GL_PACK_ROW_LENGTH,
                        (pitch / bytes_per_pixel(pixel_format)));

    data->glReadPixels(rect->x, (window->h-rect->y)-rect->h, rect->w, rect->h,
                       format, type, pixels);

    /* Flip the rows to be top-down */
    length = rect->w * bytes_per_pixel(pixel_format);
    src = (Uint8*)pixels + (rect->h-1)*pitch;
    dst = (Uint8*)pixels;
    tmp = SDL_stack_alloc(Uint8, length);
    rows = rect->h / 2;
    while (rows--) {
        SDL_memcpy(tmp, dst, length);
        SDL_memcpy(dst, src, length);
        SDL_memcpy(src, tmp, length);
        dst += pitch;
        src -= pitch;
    }
    SDL_stack_free(tmp);

    return 0;
}

static int
GL_RenderWritePixels(SDL_Renderer * renderer, const SDL_Rect * rect,
                     Uint32 pixel_format, const void * pixels, int pitch)
{
    GL_RenderData *data = (GL_RenderData *) renderer->driverdata;
    GLint internalFormat;
    GLenum format, type;

    if (!convert_format(data, pixel_format, &internalFormat, &format, &type)) {
        /* FIXME: Do a temp copy to a format that is supported */
        SDL_SetError("Unsupported pixel format");
        return -1;
    }

    /* FIXME: We need to copy the data and flip it */

    if (pixel_format == SDL_PIXELFORMAT_INDEX1LSB) {
        data->glPixelStorei(GL_UNPACK_LSB_FIRST, 1);
    } else if (pixel_format == SDL_PIXELFORMAT_INDEX1MSB) {
        data->glPixelStorei(GL_UNPACK_LSB_FIRST, 0);
    }
    data->glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
    data->glPixelStorei(GL_UNPACK_ROW_LENGTH,
                        (pitch / bytes_per_pixel(pixel_format)));

    data->glRasterPos2i(rect->x, rect->y);
    data->glDrawPixels(rect->w, rect->h, format, type, pixels);

    return 0;
}

static void
GL_RenderPresent(SDL_Renderer * renderer)
{
    SDL_GL_SwapWindow(renderer->window);
}

static void
GL_DestroyTexture(SDL_Renderer * renderer, SDL_Texture * texture)
{
    GL_RenderData *renderdata = (GL_RenderData *) renderer->driverdata;
    GL_TextureData *data = (GL_TextureData *) texture->driverdata;

    if (!data) {
        return;
    }
    if (data->texture) {
        renderdata->glDeleteTextures(1, &data->texture);
    }
    if (data->palette) {
        SDL_free(data->palette);
    }
    if (data->pixels) {
        SDL_free(data->pixels);
    }
    SDL_FreeDirtyRects(&data->dirty);
    SDL_free(data);
    texture->driverdata = NULL;
}

static void
GL_DestroyRenderer(SDL_Renderer * renderer)
{
    GL_RenderData *data = (GL_RenderData *) renderer->driverdata;

    if (data) {
        if (data->context) {
            if (data->GL_ARB_fragment_program_supported) {
                data->glDisable(GL_FRAGMENT_PROGRAM_ARB);
                data->glBindProgramARB(GL_FRAGMENT_PROGRAM_ARB, 0);
                if (data->fragment_program_mask &&
                    data->fragment_program_mask != ~0) {
                    data->glDeleteProgramsARB(1,
                                              &data->fragment_program_mask);
                }
                if (data->fragment_program_UYVY &&
                    data->fragment_program_UYVY != ~0) {
                    data->glDeleteProgramsARB(1,
                                              &data->fragment_program_UYVY);
                }
            }

            /* SDL_GL_MakeCurrent(0, NULL); *//* doesn't do anything */
            SDL_GL_DeleteContext(data->context);
        }
        SDL_free(data);
    }
    SDL_free(renderer);
}

#endif /* SDL_VIDEO_RENDER_OGL */

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