src/video/SDL_renderer_gl.c
author Sam Lantinga <slouken@libsdl.org>
Sat, 21 Nov 2009 07:26:52 +0000
changeset 3475 3bd01435287f
parent 3474 1edb86163d62
child 3479 6f887204fa7a
permissions -rw-r--r--
Added comment for pixel-perfect line workaround.

/*
    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();

    /* The line is half open, so we need one more point to complete the line.
     * http://www.opengl.org/documentation/specs/version1.1/glspec1.1/node47.html
     * If we have to, we can use vertical line and horizontal line textures
     * for vertical and horizontal lines, and then create custom textures
     * for diagonal lines and software render those.  It's terrible, but at
     * least it would be pixel perfect.
     */
    data->glBegin(GL_POINTS);
#ifdef __APPLE__
    /* Mac OS X seems to always leave the second point open */
    data->glVertex2f(0.5f + x2, 0.5f + y2);
#else
    /* Linux seems to leave the right-most or bottom-most point open */
    if (x1 > x2) {
        data->glVertex2f(0.5f + x1, 0.5f + y1);
    } else if (x2 > x1) {
        data->glVertex2f(0.5f + x2, 0.5f + y2);
    } else if (y1 > y2) {
        data->glVertex2f(0.5f + x1, 0.5f + y1);
    } else if (y2 > y1) {
        data->glVertex2f(0.5f + x2, 0.5f + y2);
    }
#endif
    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((GLfloat) minx, (GLfloat) miny);
    data->glTexCoord2f(maxu, minv);
    data->glVertex2f((GLfloat) maxx, (GLfloat) miny);
    data->glTexCoord2f(minu, maxv);
    data->glVertex2f((GLfloat) minx, (GLfloat) maxy);
    data->glTexCoord2f(maxu, maxv);
    data->glVertex2f((GLfloat) maxx, (GLfloat) 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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