src/render/opengles2/SDL_render_gles2.c
changeset 5201 523409574510
child 5202 1f2b17f42fd0
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/render/opengles2/SDL_render_gles2.c	Sun Feb 06 00:00:13 2011 -0800
@@ -0,0 +1,1240 @@
+/*
+    SDL - Simple DirectMedia Layer
+    Copyright (C) 2010 itsnotabigtruck.
+
+    Permission is hereby granted, free of charge, to any person obtaining a
+    copy of this software and associated documentation files (the "Software"),
+    to deal in the Software without restriction, including without limitation
+    the rights to use, copy, modify, merge, publish, distribute, sublicense,
+    and/or sell copies of the Software, and to permit persons to whom the
+    Software is furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in
+    all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+    DEALINGS IN THE SOFTWARE.
+*/
+
+#include "SDL_config.h"
+
+#if SDL_VIDEO_RENDER_OGL_ES2
+
+#ifdef __IPHONEOS__
+#include <OpenGLES/ES2/gl.h>
+#include <OpenGLES/ES2/glext.h>
+#else
+#include <GLES2/gl2.h>
+#include <GLES2/gl2ext.h>
+#endif
+#include "../SDL_sysrender.h"
+#include "SDL_shaders_gles2.h"
+
+/*************************************************************************************************
+ * Bootstrap data                                                                                *
+ *************************************************************************************************/
+
+static SDL_Renderer *GLES2_CreateRenderer(SDL_Window *window, Uint32 flags);
+
+SDL_RenderDriver GLES2_RenderDriver = {
+    GLES2_CreateRenderer,
+    {
+        "opengles2",
+        (SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC),
+#if GLES2_ASSUME_BGRA
+        11,
+        {
+            SDL_PIXELFORMAT_ABGR8888,
+            SDL_PIXELFORMAT_ABGR4444,
+            SDL_PIXELFORMAT_ABGR1555,
+            SDL_PIXELFORMAT_BGR565,
+            SDL_PIXELFORMAT_BGR24,
+            SDL_PIXELFORMAT_ARGB8888,
+            SDL_PIXELFORMAT_ARGB4444,
+            SDL_PIXELFORMAT_ARGB1555,
+            SDL_PIXELFORMAT_RGB565,
+            SDL_PIXELFORMAT_RGB24
+        },
+#elif GLES2_ASSUME_BGRA8888
+        7,
+        {
+            SDL_PIXELFORMAT_ABGR8888,
+            SDL_PIXELFORMAT_ABGR4444,
+            SDL_PIXELFORMAT_ABGR1555,
+            SDL_PIXELFORMAT_BGR565,
+            SDL_PIXELFORMAT_BGR24,
+            SDL_PIXELFORMAT_ARGB8888
+        },
+#else
+        6,
+        {
+            SDL_PIXELFORMAT_ABGR8888,
+            SDL_PIXELFORMAT_ABGR4444,
+            SDL_PIXELFORMAT_ABGR1555,
+            SDL_PIXELFORMAT_BGR565,
+            SDL_PIXELFORMAT_BGR24
+        },
+#endif
+        0,
+        0
+    }
+};
+
+/*************************************************************************************************
+ * Context structures                                                                            *
+ *************************************************************************************************/
+
+typedef struct GLES2_TextureData
+{
+    GLenum texture;
+    GLenum texture_type;
+    GLenum pixel_format;
+    GLenum pixel_type;
+    void *pixel_data;
+    size_t pitch;
+} GLES2_TextureData;
+
+typedef struct GLES2_ShaderCacheEntry
+{
+    GLuint id;
+    GLES2_ShaderType type;
+    const GLES2_ShaderInstance *instance;
+    int references;
+    struct GLES2_ShaderCacheEntry *prev;
+    struct GLES2_ShaderCacheEntry *next;
+} GLES2_ShaderCacheEntry;
+
+typedef struct GLES2_ShaderCache
+{
+    int count;
+    GLES2_ShaderCacheEntry *head;
+} GLES2_ShaderCache;
+
+typedef struct GLES2_ProgramCacheEntry
+{
+    GLuint id;
+    SDL_BlendMode blend_mode;
+    GLES2_ShaderCacheEntry *vertex_shader;
+    GLES2_ShaderCacheEntry *fragment_shader;
+    GLuint uniform_locations[16];
+    struct GLES2_ProgramCacheEntry *prev;
+    struct GLES2_ProgramCacheEntry *next;
+} GLES2_ProgramCacheEntry;
+
+typedef struct GLES2_ProgramCache
+{
+    int count;
+    GLES2_ProgramCacheEntry *head;
+    GLES2_ProgramCacheEntry *tail;
+} GLES2_ProgramCache;
+
+typedef enum
+{
+    GLES2_ATTRIBUTE_POSITION = 0,
+    GLES2_ATTRIBUTE_TEXCOORD = 1
+} GLES2_Attribute;
+
+typedef enum
+{
+    GLES2_UNIFORM_PROJECTION,
+    GLES2_UNIFORM_TEXTURE,
+    GLES2_UNIFORM_MODULATION,
+    GLES2_UNIFORM_COLOR,
+    GLES2_UNIFORM_COLORTABLE
+} GLES2_Uniform;
+
+typedef enum
+{
+    GLES2_IMAGESOURCE_SOLID,
+    GLES2_IMAGESOURCE_TEXTURE
+} GLES2_ImageSource;
+
+typedef struct GLES2_DriverContext
+{
+    SDL_GLContext *context;
+    int shader_format_count;
+    GLenum *shader_formats;
+    GLES2_ShaderCache shader_cache;
+    GLES2_ProgramCache program_cache;
+    GLES2_ProgramCacheEntry *current_program;
+	SDL_bool updateSize;
+} GLES2_DriverContext;
+
+#define GLES2_MAX_CACHED_PROGRAMS 8
+
+/*************************************************************************************************
+ * Renderer state APIs                                                                           *
+ *************************************************************************************************/
+
+static void GLES2_WindowEvent(SDL_Renderer * renderer,
+                              const SDL_WindowEvent *event);
+static int GLES2_ActivateRenderer(SDL_Renderer *renderer);
+static int GLES2_DisplayModeChanged(SDL_Renderer *renderer);
+static void GLES2_DestroyRenderer(SDL_Renderer *renderer);
+
+static SDL_GLContext SDL_CurrentContext = NULL;
+
+static int
+GLES2_ActivateRenderer(SDL_Renderer * renderer)
+{
+    GLES2_DriverContext *rdata = (GLES2_DriverContext *)renderer->driverdata;
+    SDL_Window *window = renderer->window;
+
+    if (SDL_CurrentContext != rdata->context) {
+        /* Null out the current program to ensure we set it again */
+        rdata->current_program = NULL;
+
+        if (SDL_GL_MakeCurrent(window, rdata->context) < 0) {
+            return -1;
+        }
+        SDL_CurrentContext = rdata->context;
+    }
+    if (rdata->updateSize) {
+        int w, h;
+
+        SDL_GetWindowSize(window, &w, &h);
+        glViewport(0, 0, w, h);
+        rdata->updateSize = SDL_FALSE;
+    }
+    return 0;
+}
+
+static void
+GLES2_WindowEvent(SDL_Renderer * renderer, const SDL_WindowEvent *event)
+{
+    GLES2_DriverContext *rdata = (GLES2_DriverContext *)renderer->driverdata;
+
+    if (event->event == SDL_WINDOWEVENT_RESIZED) {
+        /* Rebind the context to the window area */
+        SDL_CurrentContext = NULL;
+        rdata->updateSize = SDL_TRUE;
+    }
+}
+
+static void
+GLES2_DestroyRenderer(SDL_Renderer *renderer)
+{
+    GLES2_DriverContext *rdata = (GLES2_DriverContext *)renderer->driverdata;
+    GLES2_ProgramCacheEntry *entry;
+    GLES2_ProgramCacheEntry *next;
+
+    GLES2_ActivateRenderer(renderer);
+
+    /* Deallocate everything */
+    entry = rdata->program_cache.head;
+    while (entry)
+    {
+        glDeleteShader(entry->vertex_shader->id);
+        glDeleteShader(entry->fragment_shader->id);
+        SDL_free(entry->vertex_shader);
+        SDL_free(entry->fragment_shader);
+        glDeleteProgram(entry->id);
+        next = entry->next;
+        SDL_free(entry);
+        entry = next;
+    }
+    SDL_GL_DeleteContext(rdata->context);
+    SDL_free(rdata->shader_formats);
+    SDL_free(renderer->driverdata);
+    SDL_free(renderer);
+}
+
+/*************************************************************************************************
+ * Texture APIs                                                                                  *
+ *************************************************************************************************/
+
+#define GL_BGR_EXT  0x80E0
+#define GL_BGRA_EXT 0x80E1
+
+static int GLES2_CreateTexture(SDL_Renderer *renderer, SDL_Texture *texture);
+static void GLES2_DestroyTexture(SDL_Renderer *renderer, SDL_Texture *texture);
+static int GLES2_LockTexture(SDL_Renderer *renderer, SDL_Texture *texture, const SDL_Rect *rect,
+                             void **pixels, int *pitch);
+static void GLES2_UnlockTexture(SDL_Renderer *renderer, SDL_Texture *texture);
+static int GLES2_UpdateTexture(SDL_Renderer *renderer, SDL_Texture *texture, const SDL_Rect *rect,
+                               const void *pixels, int pitch);
+
+static int
+GLES2_CreateTexture(SDL_Renderer *renderer, SDL_Texture *texture)
+{
+    GLES2_DriverContext *rdata = (GLES2_DriverContext *)renderer->driverdata;
+    GLES2_TextureData *tdata;
+    GLenum format;
+    GLenum type;
+
+    GLES2_ActivateRenderer(renderer);
+
+    /* Determine the corresponding GLES texture format params */
+    switch (texture->format)
+    {
+    case SDL_PIXELFORMAT_BGR24:
+        format = GL_RGB;
+        type = GL_UNSIGNED_BYTE;
+        break;
+    case SDL_PIXELFORMAT_ABGR8888:
+        format = GL_RGBA;
+        type = GL_UNSIGNED_BYTE;
+        break;
+    case SDL_PIXELFORMAT_BGR565:
+        format = GL_RGB;
+        type = GL_UNSIGNED_SHORT_5_6_5;
+        break;
+    case SDL_PIXELFORMAT_ABGR1555:
+        format = GL_RGBA;
+        type = GL_UNSIGNED_SHORT_5_5_5_1;
+        break;
+    case SDL_PIXELFORMAT_ABGR4444:
+        format = GL_RGBA;
+        type = GL_UNSIGNED_SHORT_4_4_4_4;
+        break;
+#if GLES2_ASSUME_BGRA || GLES2_ASSUME_BGRA8888
+    case SDL_PIXELFORMAT_ARGB8888:
+        format = GL_BGRA_EXT;
+        type = GL_UNSIGNED_BYTE;
+        break;
+#endif /* GLES2_ASSUME_BGRA || GLES2_ASSUME_BGRA8888 */
+#if GLES2_ASSUME_BGRA
+    case SDL_PIXELFORMAT_RGB24:
+        format = GL_BGR_EXT;
+        type = GL_UNSIGNED_BYTE;
+        break;
+    case SDL_PIXELFORMAT_RGB565:
+        format = GL_BGR_EXT;
+        type = GL_UNSIGNED_SHORT_5_6_5;
+        break;
+    case SDL_PIXELFORMAT_ARGB1555:
+        format = GL_BGRA_EXT;
+        type = GL_UNSIGNED_SHORT_5_5_5_1;
+        break;
+    case SDL_PIXELFORMAT_ARGB4444:
+        format = GL_BGRA_EXT;
+        type = GL_UNSIGNED_SHORT_4_4_4_4;
+        break;
+#endif /* GLES2_ASSUME_BGRA */
+    default:
+        SDL_SetError("Texture format not supported");
+        return -1;
+    }
+
+    /* Allocate a texture struct */
+    tdata = (GLES2_TextureData *)SDL_calloc(1, sizeof(GLES2_TextureData));
+    if (!tdata)
+    {
+        SDL_OutOfMemory();
+        return -1;
+    }
+    tdata->texture = 0;
+    tdata->texture_type = GL_TEXTURE_2D;
+    tdata->pixel_format = format;
+    tdata->pixel_type = type;
+
+    /* Allocate a blob for image data */
+    if (texture->access == SDL_TEXTUREACCESS_STREAMING)
+    {
+        tdata->pitch = texture->w * SDL_BYTESPERPIXEL(texture->format);
+        tdata->pixel_data = SDL_malloc(tdata->pitch * texture->h);
+        if (!tdata->pixel_data)
+        {
+            SDL_OutOfMemory();
+            SDL_free(tdata);
+            return -1;
+        }
+    }
+
+    /* Allocate the texture */
+    glGetError();
+    glGenTextures(1, &tdata->texture);
+    glActiveTexture(GL_TEXTURE0);
+    glBindTexture(tdata->texture_type, tdata->texture);
+    glTexParameteri(tdata->texture_type, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+    glTexParameteri(tdata->texture_type, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+    glTexParameteri(tdata->texture_type, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+    glTexParameteri(tdata->texture_type, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+    glTexImage2D(tdata->texture_type, 0, format, texture->w, texture->h, 0, format, type, NULL);
+    if (glGetError() != GL_NO_ERROR)
+    {
+        SDL_SetError("Texture creation failed");
+        glDeleteTextures(1, &tdata->texture);
+        SDL_free(tdata);
+        return -1;
+    }
+    texture->driverdata = tdata;
+    return 0;
+}
+
+static void
+GLES2_DestroyTexture(SDL_Renderer *renderer, SDL_Texture *texture)
+{
+    GLES2_TextureData *tdata = (GLES2_TextureData *)texture->driverdata;
+
+    GLES2_ActivateRenderer(renderer);
+
+    /* Destroy the texture */
+    if (tdata)
+    {
+        glDeleteTextures(1, &tdata->texture);
+        SDL_free(tdata->pixel_data);
+        SDL_free(tdata);
+        texture->driverdata = NULL;
+    }
+}
+
+static int
+GLES2_LockTexture(SDL_Renderer *renderer, SDL_Texture *texture, const SDL_Rect *rect,
+                  void **pixels, int *pitch)
+{
+    GLES2_TextureData *tdata = (GLES2_TextureData *)texture->driverdata;
+
+    /* Retrieve the buffer/pitch for the specified region */
+    *pixels = (Uint8 *)tdata->pixel_data +
+              (tdata->pitch * rect->y) +
+              (rect->x * SDL_BYTESPERPIXEL(texture->format));
+    *pitch = tdata->pitch;
+
+    return 0;
+}
+
+static void
+GLES2_UnlockTexture(SDL_Renderer *renderer, SDL_Texture *texture)
+{
+    GLES2_TextureData *tdata = (GLES2_TextureData *)texture->driverdata;
+
+    GLES2_ActivateRenderer(renderer);
+
+    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
+    glActiveTexture(GL_TEXTURE0);
+    glBindTexture(tdata->texture_type, tdata->texture);
+    glTexSubImage2D(tdata->texture_type, 0, 0, 0, texture->w, texture->h,
+                    tdata->pixel_format, tdata->pixel_type, tdata->pixel_data);
+}
+
+static int
+GLES2_UpdateTexture(SDL_Renderer *renderer, SDL_Texture *texture, const SDL_Rect *rect,
+                    const void *pixels, int pitch)
+{
+    GLES2_TextureData *tdata = (GLES2_TextureData *)texture->driverdata;
+    Uint8 *blob = NULL;
+    Uint8 *src;
+    int srcPitch;
+    Uint8 *dest;
+    int y;
+
+    GLES2_ActivateRenderer(renderer);
+
+    /* Bail out if we're supposed to update an empty rectangle */
+    if (rect->w <= 0 || rect->h <= 0)
+        return 0;
+
+    /* Reformat the texture data into a tightly packed array */
+    srcPitch = rect->w * SDL_BYTESPERPIXEL(texture->format);
+    src = (Uint8 *)pixels;
+    if (pitch != srcPitch)
+    {
+        blob = (Uint8 *)SDL_malloc(srcPitch * rect->h);
+        if (!blob)
+        {
+            SDL_OutOfMemory();
+            return -1;
+        }
+        src = blob;
+        for (y = 0; y < rect->h; ++y)
+        {
+            SDL_memcpy(src, pixels, srcPitch);
+            src += srcPitch;
+            pixels = (Uint8 *)pixels + pitch;
+        }
+        src = blob;
+    }
+
+    /* Create a texture subimage with the supplied data */
+    glGetError();
+    glActiveTexture(GL_TEXTURE0);
+    glBindTexture(tdata->texture_type, tdata->texture);
+    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
+    glTexSubImage2D(tdata->texture_type,
+                    0,
+                    rect->x,
+                    rect->y,
+                    rect->w,
+                    rect->h,
+                    tdata->pixel_format,
+                    tdata->pixel_type,
+                    src);
+    if (glGetError() != GL_NO_ERROR)
+    {
+        SDL_SetError("Failed to update texture");
+        return -1;
+    }
+
+    /* Update the (streaming) texture buffer, in one pass if possible */
+    if (tdata->pixel_data)
+    {
+        dest = (Uint8 *)tdata->pixel_data +
+               (tdata->pitch * rect->y) +
+               (SDL_BYTESPERPIXEL(texture->format) * rect->x);
+        if (rect->w == texture->w)
+        {
+            SDL_memcpy(dest, src, srcPitch * rect->h);
+        }
+        else
+        {
+            for (y = 0; y < rect->h; ++y)
+            {
+                SDL_memcpy(dest, src, srcPitch);
+                src += srcPitch;
+                dest += tdata->pitch;
+            }
+        }
+    }
+
+    /* Clean up and return */
+    SDL_free(blob);
+    return 0;
+}
+
+/*************************************************************************************************
+ * Shader management functions                                                                   *
+ *************************************************************************************************/
+
+static GLES2_ShaderCacheEntry *GLES2_CacheShader(SDL_Renderer *renderer, GLES2_ShaderType type,
+                                                 SDL_BlendMode blendMode);
+static void GLES2_EvictShader(SDL_Renderer *renderer, GLES2_ShaderCacheEntry *entry);
+static GLES2_ProgramCacheEntry *GLES2_CacheProgram(SDL_Renderer *renderer,
+                                                   GLES2_ShaderCacheEntry *vertex,
+                                                   GLES2_ShaderCacheEntry *fragment,
+                                                   SDL_BlendMode blendMode);
+static int GLES2_SelectProgram(SDL_Renderer *renderer, GLES2_ImageSource source,
+                               SDL_BlendMode blendMode);
+static int GLES2_SetOrthographicProjection(SDL_Renderer *renderer);
+
+static GLES2_ProgramCacheEntry *
+GLES2_CacheProgram(SDL_Renderer *renderer, GLES2_ShaderCacheEntry *vertex,
+                   GLES2_ShaderCacheEntry *fragment, SDL_BlendMode blendMode)
+{
+    GLES2_DriverContext *rdata = (GLES2_DriverContext *)renderer->driverdata;
+    GLES2_ProgramCacheEntry *entry;
+    GLES2_ShaderCacheEntry *shaderEntry;
+    GLint linkSuccessful;
+
+    /* Check if we've already cached this program */
+    entry = rdata->program_cache.head;
+    while (entry)
+    {
+        if (entry->vertex_shader == vertex && entry->fragment_shader == fragment)
+            break;
+        entry = entry->next;
+    }
+    if (entry)
+    {
+        if (rdata->program_cache.count > 1)
+        {
+            if (entry->next)
+                entry->next->prev = entry->prev;
+            if (entry->prev)
+                entry->prev->next = entry->next;
+            entry->prev = NULL;
+            entry->next = rdata->program_cache.head;
+            rdata->program_cache.head->prev = entry;
+            rdata->program_cache.head = entry;
+        }
+        return entry;
+    }
+
+    /* Create a program cache entry */
+    entry = (GLES2_ProgramCacheEntry *)SDL_calloc(1, sizeof(GLES2_ProgramCacheEntry));
+    if (!entry)
+    {
+        SDL_OutOfMemory();
+        return NULL;
+    }
+    entry->vertex_shader = vertex;
+    entry->fragment_shader = fragment;
+    entry->blend_mode = blendMode;
+    
+    /* Create the program and link it */
+    glGetError();
+    entry->id = glCreateProgram();
+    glAttachShader(entry->id, vertex->id);
+    glAttachShader(entry->id, fragment->id);
+    glBindAttribLocation(entry->id, GLES2_ATTRIBUTE_POSITION, "a_position");
+    glBindAttribLocation(entry->id, GLES2_ATTRIBUTE_TEXCOORD, "a_texCoord");
+    glLinkProgram(entry->id);
+    glGetProgramiv(entry->id, GL_LINK_STATUS, &linkSuccessful);
+    if (glGetError() != GL_NO_ERROR || !linkSuccessful)
+    {
+        SDL_SetError("Failed to link shader program");
+        glDeleteProgram(entry->id);
+        SDL_free(entry);
+        return NULL;
+    }
+    
+    /* Predetermine locations of uniform variables */
+    entry->uniform_locations[GLES2_UNIFORM_PROJECTION] =
+        glGetUniformLocation(entry->id, "u_projection");
+    entry->uniform_locations[GLES2_UNIFORM_TEXTURE] =
+        glGetUniformLocation(entry->id, "u_texture");
+    entry->uniform_locations[GLES2_UNIFORM_MODULATION] =
+        glGetUniformLocation(entry->id, "u_modulation");
+    entry->uniform_locations[GLES2_UNIFORM_COLOR] =
+        glGetUniformLocation(entry->id, "u_color");
+    entry->uniform_locations[GLES2_UNIFORM_COLORTABLE] =
+        glGetUniformLocation(entry->id, "u_colorTable");
+
+    /* Cache the linked program */
+    if (rdata->program_cache.head)
+    {
+        entry->next = rdata->program_cache.head;
+        rdata->program_cache.head->prev = entry;
+    }
+    else
+    {
+        rdata->program_cache.tail = entry;
+    }
+    rdata->program_cache.head = entry;
+    ++rdata->program_cache.count;
+
+    /* Increment the refcount of the shaders we're using */
+    ++vertex->references;
+    ++fragment->references;
+
+    /* Evict the last entry from the cache if we exceed the limit */
+    if (rdata->program_cache.count > GLES2_MAX_CACHED_PROGRAMS)
+    {
+        shaderEntry = rdata->program_cache.tail->vertex_shader;
+        if (--shaderEntry->references <= 0)
+            GLES2_EvictShader(renderer, shaderEntry);
+        shaderEntry = rdata->program_cache.tail->fragment_shader;
+        if (--shaderEntry->references <= 0)
+            GLES2_EvictShader(renderer, shaderEntry);
+        glDeleteProgram(rdata->program_cache.tail->id);
+        rdata->program_cache.tail = rdata->program_cache.tail->prev;
+        SDL_free(rdata->program_cache.tail->next);
+        rdata->program_cache.tail->next = NULL;
+        --rdata->program_cache.count;
+    }
+    return entry;
+}
+
+static GLES2_ShaderCacheEntry *
+GLES2_CacheShader(SDL_Renderer *renderer, GLES2_ShaderType type, SDL_BlendMode blendMode)
+{
+    GLES2_DriverContext *rdata = (GLES2_DriverContext *)renderer->driverdata;
+    const GLES2_Shader *shader;
+    const GLES2_ShaderInstance *instance = NULL;
+    GLES2_ShaderCacheEntry *entry = NULL;
+    GLint compileSuccessful = GL_FALSE;
+    int i, j;
+
+    /* Find the corresponding shader */
+    shader = GLES2_GetShader(type, blendMode);
+    if (!shader)
+    {
+        SDL_SetError("No shader matching the requested characteristics was found");
+        return NULL;
+    }
+    
+    /* Find a matching shader instance that's supported on this hardware */
+    for (i = 0; i < shader->instance_count; ++i)
+    {
+        for (j = 0; j < rdata->shader_format_count; ++j)
+        {
+            if (!shader->instances)
+                continue;
+            if (shader->instances[i]->format != rdata->shader_formats[j])
+                continue;
+            instance = shader->instances[i];
+            break;
+        }
+    }
+    if (!instance)
+    {
+        SDL_SetError("The specified shader cannot be loaded on the current platform");
+        return NULL;
+    }
+
+    /* Check if we've already cached this shader */
+    entry = rdata->shader_cache.head;
+    while (entry)
+    {
+        if (entry->instance == instance)
+            break;
+        entry = entry->next;
+    }
+    if (entry)
+        return entry;
+
+    /* Create a shader cache entry */
+    entry = (GLES2_ShaderCacheEntry *)SDL_calloc(1, sizeof(GLES2_ShaderCacheEntry));
+    if (!entry)
+    {
+        SDL_OutOfMemory();
+        return NULL;
+    }
+    entry->type = type;
+    entry->instance = instance;
+
+    /* Compile or load the selected shader instance */
+    glGetError();
+    entry->id = glCreateShader(instance->type);
+    if (instance->format == (GLenum)-1)
+    {
+        glShaderSource(entry->id, 1, (const char **)&instance->data, &instance->length);
+        glCompileShader(entry->id);
+        glGetShaderiv(entry->id, GL_COMPILE_STATUS, &compileSuccessful);
+    }
+    else
+    {
+        glShaderBinary(1, &entry->id, instance->format, instance->data, instance->length);
+        compileSuccessful = GL_TRUE;
+    }
+    if (glGetError() != GL_NO_ERROR || !compileSuccessful)
+    {
+        SDL_SetError("Failed to load the specified shader");
+        glDeleteShader(entry->id);
+        SDL_free(entry);
+        return NULL;
+    }
+
+    /* Link the shader entry in at the front of the cache */
+    if (rdata->shader_cache.head)
+    {
+        entry->next = rdata->shader_cache.head;
+        rdata->shader_cache.head->prev = entry;
+    }
+    rdata->shader_cache.head = entry;
+    ++rdata->shader_cache.count;
+    return entry;
+}
+
+static void
+GLES2_EvictShader(SDL_Renderer *renderer, GLES2_ShaderCacheEntry *entry)
+{
+    GLES2_DriverContext *rdata = (GLES2_DriverContext *)renderer->driverdata;
+
+    /* Unlink the shader from the cache */
+    if (entry->next)
+        entry->next->prev = entry->prev;
+    if (entry->prev)
+        entry->prev->next = entry->next;
+    if (rdata->shader_cache.head == entry)
+        rdata->shader_cache.head = entry->next;
+    --rdata->shader_cache.count;
+
+    /* Deallocate the shader */
+    glDeleteShader(entry->id);
+    SDL_free(entry);
+}
+
+static int
+GLES2_SelectProgram(SDL_Renderer *renderer, GLES2_ImageSource source, SDL_BlendMode blendMode)
+{
+    GLES2_DriverContext *rdata = (GLES2_DriverContext *)renderer->driverdata;
+    GLES2_ShaderCacheEntry *vertex = NULL;
+    GLES2_ShaderCacheEntry *fragment = NULL;
+    GLES2_ShaderType vtype, ftype;
+    GLES2_ProgramCacheEntry *program;
+
+    /* Select an appropriate shader pair for the specified modes */
+    vtype = GLES2_SHADER_VERTEX_DEFAULT;
+    switch (source)
+    {
+    case GLES2_IMAGESOURCE_SOLID:
+        ftype = GLES2_SHADER_FRAGMENT_SOLID_SRC;
+        break;
+    case GLES2_IMAGESOURCE_TEXTURE:
+        ftype = GLES2_SHADER_FRAGMENT_TEXTURE_SRC;
+        break;
+    }
+
+    /* Load the requested shaders */
+    vertex = GLES2_CacheShader(renderer, vtype, blendMode);
+    if (!vertex)
+        goto fault;
+    fragment = GLES2_CacheShader(renderer, ftype, blendMode);
+    if (!fragment)
+        goto fault;
+
+    /* Check if we need to change programs at all */
+    if (rdata->current_program &&
+        rdata->current_program->vertex_shader == vertex &&
+        rdata->current_program->fragment_shader == fragment)
+        return 0;
+
+    /* Generate a matching program */
+    program = GLES2_CacheProgram(renderer, vertex, fragment, blendMode);
+    if (!program)
+        goto fault;
+
+    /* Select that program in OpenGL */
+    glGetError();
+    glUseProgram(program->id);
+    if (glGetError() != GL_NO_ERROR)
+    {
+        SDL_SetError("Failed to select program");
+        goto fault;
+    }
+
+    /* Set the current program */
+    rdata->current_program = program;
+
+    /* Activate an orthographic projection */
+    if (GLES2_SetOrthographicProjection(renderer) < 0)
+        goto fault;
+
+    /* Clean up and return */
+    return 0;
+fault:
+    if (vertex && vertex->references <= 0)
+        GLES2_EvictShader(renderer, vertex);
+    if (fragment && fragment->references <= 0)
+        GLES2_EvictShader(renderer, fragment);
+    rdata->current_program = NULL;
+    return -1;
+}
+
+static int
+GLES2_SetOrthographicProjection(SDL_Renderer *renderer)
+{
+    GLES2_DriverContext *rdata = (GLES2_DriverContext *)renderer->driverdata;
+    SDL_Window *window = renderer->window;
+    int w, h;
+    GLfloat projection[4][4];
+    GLuint locProjection;
+
+    /* Get the window width and height */
+    SDL_GetWindowSize(window, &w, &h);
+
+    /* Prepare an orthographic projection */
+    projection[0][0] = 2.0f / w;
+    projection[0][1] = 0.0f;
+    projection[0][2] = 0.0f;
+    projection[0][3] = 0.0f;
+    projection[1][0] = 0.0f;
+    projection[1][1] = -2.0f / h;
+    projection[1][2] = 0.0f;
+    projection[1][3] = 0.0f;
+    projection[2][0] = 0.0f;
+    projection[2][1] = 0.0f;
+    projection[2][2] = 1.0f;
+    projection[2][3] = 0.0f;
+    projection[3][0] = -1.0f;
+    projection[3][1] = 1.0f;
+    projection[3][2] = 0.0f;
+    projection[3][3] = 1.0f;
+
+    /* Set the projection matrix */
+    locProjection = rdata->current_program->uniform_locations[GLES2_UNIFORM_PROJECTION];
+    glGetError();
+    glUniformMatrix4fv(locProjection, 1, GL_FALSE, (GLfloat *)projection);
+    if (glGetError() != GL_NO_ERROR)
+    {
+        SDL_SetError("Failed to set orthographic projection");
+        return -1;
+    }
+    return 0;
+}
+
+/*************************************************************************************************
+ * Rendering functions                                                                           *
+ *************************************************************************************************/
+
+static int GLES2_RenderClear(SDL_Renderer *renderer);
+static int GLES2_RenderDrawPoints(SDL_Renderer *renderer, const SDL_Point *points, int count);
+static int GLES2_RenderDrawLines(SDL_Renderer *renderer, const SDL_Point *points, int count);
+static int GLES2_RenderDrawRects(SDL_Renderer *renderer, const SDL_Rect **rects, int count);
+static int GLES2_RenderFillRects(SDL_Renderer *renderer, const SDL_Rect **rects, int count);
+static int GLES2_RenderCopy(SDL_Renderer *renderer, SDL_Texture *texture, const SDL_Rect *srcrect,
+                            const SDL_Rect *dstrect);
+static void GLES2_RenderPresent(SDL_Renderer *renderer);
+
+static int
+GLES2_RenderClear(SDL_Renderer *renderer)
+{
+    float r = (float)renderer->r / 255.0f;
+    float g = (float)renderer->g / 255.0f;
+    float b = (float)renderer->b / 255.0f;
+    float a = (float)renderer->a / 255.0f;
+
+    GLES2_ActivateRenderer(renderer);
+
+    /* Clear the backbuffer with the selected color */
+    glClearColor(r, g, b, a);
+    glClear(GL_COLOR_BUFFER_BIT);
+    return 0;
+}
+
+static void
+GLES2_SetBlendMode(int blendMode)
+{
+    switch (blendMode)
+    {
+    case SDL_BLENDMODE_NONE:
+    default:
+        glDisable(GL_BLEND);
+        break;
+    case SDL_BLENDMODE_BLEND:
+        glEnable(GL_BLEND);
+        glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+        break;
+    case SDL_BLENDMODE_ADD:
+        glEnable(GL_BLEND);
+        glBlendFunc(GL_SRC_ALPHA, GL_ONE);
+        break;
+    case SDL_BLENDMODE_MOD:
+        glEnable(GL_BLEND);
+        glBlendFunc(GL_ZERO, GL_SRC_COLOR);
+        break;
+    }
+}
+
+static int
+GLES2_RenderDrawPoints(SDL_Renderer *renderer, const SDL_Point *points, int count)
+{
+    GLES2_DriverContext *rdata = (GLES2_DriverContext *)renderer->driverdata;
+    GLfloat *vertices;
+    SDL_BlendMode blendMode;
+    int alpha;
+    GLuint locColor;
+    int idx;
+
+    GLES2_ActivateRenderer(renderer);
+
+    blendMode = renderer->blendMode;
+    alpha = renderer->a;
+
+    /* Activate an appropriate shader and set the projection matrix */
+    if (GLES2_SelectProgram(renderer, GLES2_IMAGESOURCE_SOLID, blendMode) < 0)
+        return -1;
+
+    /* Select the color to draw with */
+    locColor = rdata->current_program->uniform_locations[GLES2_UNIFORM_COLOR];
+    glGetError();
+    glUniform4f(locColor,
+                renderer->r / 255.0f,
+                renderer->g / 255.0f,
+                renderer->b / 255.0f,
+                alpha / 255.0f);
+
+    /* Configure the correct blend mode */
+    GLES2_SetBlendMode(blendMode);
+
+    /* Emit the specified vertices as points */
+    vertices = SDL_stack_alloc(GLfloat, count * 2);
+    for (idx = 0; idx < count; ++idx)
+    {
+        GLfloat x = (GLfloat)points[idx].x + 0.5f;
+        GLfloat y = (GLfloat)points[idx].y + 0.5f;
+
+        vertices[idx * 2] = x;
+        vertices[(idx * 2) + 1] = y;
+    }
+    glEnableVertexAttribArray(GLES2_ATTRIBUTE_POSITION);
+    glVertexAttribPointer(GLES2_ATTRIBUTE_POSITION, 2, GL_FLOAT, GL_FALSE, 0, vertices);
+    glDrawArrays(GL_POINTS, 0, count);
+    glDisableVertexAttribArray(GLES2_ATTRIBUTE_POSITION);
+    SDL_stack_free(vertices);
+    if (glGetError() != GL_NO_ERROR)
+    {
+        SDL_SetError("Failed to render lines");
+        return -1;
+    }
+    return 0;
+}
+
+static int
+GLES2_RenderDrawLines(SDL_Renderer *renderer, const SDL_Point *points, int count)
+{
+    GLES2_DriverContext *rdata = (GLES2_DriverContext *)renderer->driverdata;
+    GLfloat *vertices;
+    SDL_BlendMode blendMode;
+    int alpha;
+    GLuint locColor;
+    int idx;
+
+    GLES2_ActivateRenderer(renderer);
+
+    blendMode = renderer->blendMode;
+    alpha = renderer->a;
+
+    /* Activate an appropriate shader and set the projection matrix */
+    if (GLES2_SelectProgram(renderer, GLES2_IMAGESOURCE_SOLID, blendMode) < 0)
+        return -1;
+
+    /* Select the color to draw with */
+    locColor = rdata->current_program->uniform_locations[GLES2_UNIFORM_COLOR];
+    glGetError();
+    glUniform4f(locColor,
+                renderer->r / 255.0f,
+                renderer->g / 255.0f,
+                renderer->b / 255.0f,
+                alpha / 255.0f);
+
+    /* Configure the correct blend mode */
+    GLES2_SetBlendMode(blendMode);
+
+    /* Emit a line strip including the specified vertices */
+    vertices = SDL_stack_alloc(GLfloat, count * 2);
+    for (idx = 0; idx < count; ++idx)
+    {
+        GLfloat x = (GLfloat)points[idx].x + 0.5f;
+        GLfloat y = (GLfloat)points[idx].y + 0.5f;
+
+        vertices[idx * 2] = x;
+        vertices[(idx * 2) + 1] = y;
+    }
+    glEnableVertexAttribArray(GLES2_ATTRIBUTE_POSITION);
+    glVertexAttribPointer(GLES2_ATTRIBUTE_POSITION, 2, GL_FLOAT, GL_FALSE, 0, vertices);
+    glDrawArrays(GL_LINE_STRIP, 0, count);
+    glDisableVertexAttribArray(GLES2_ATTRIBUTE_POSITION);
+    SDL_stack_free(vertices);
+    if (glGetError() != GL_NO_ERROR)
+    {
+        SDL_SetError("Failed to render lines");
+        return -1;
+    }
+    return 0;
+}
+
+static int
+GLES2_RenderFillRects(SDL_Renderer *renderer, const SDL_Rect **rects, int count)
+{
+    GLES2_DriverContext *rdata = (GLES2_DriverContext *)renderer->driverdata;
+    GLfloat vertices[8];
+    SDL_BlendMode blendMode;
+    int alpha;
+    GLuint locColor;
+    int idx;
+
+    GLES2_ActivateRenderer(renderer);
+
+    blendMode = renderer->blendMode;
+    alpha = renderer->a;
+
+    /* Activate an appropriate shader and set the projection matrix */
+    if (GLES2_SelectProgram(renderer, GLES2_IMAGESOURCE_SOLID, blendMode) < 0)
+        return -1;
+
+    /* Select the color to draw with */
+    locColor = rdata->current_program->uniform_locations[GLES2_UNIFORM_COLOR];
+    glGetError();
+    glUniform4f(locColor,
+                renderer->r / 255.0f,
+                renderer->g / 255.0f,
+                renderer->b / 255.0f,
+                alpha / 255.0f);
+
+    /* Configure the correct blend mode */
+    GLES2_SetBlendMode(blendMode);
+
+    /* Emit a line loop for each rectangle */
+    glEnableVertexAttribArray(GLES2_ATTRIBUTE_POSITION);
+    for (idx = 0; idx < count; ++idx)
+    {
+        GLfloat xMin = (GLfloat)rects[idx]->x;
+        GLfloat xMax = (GLfloat)(rects[idx]->x + rects[idx]->w);
+        GLfloat yMin = (GLfloat)rects[idx]->y;
+        GLfloat yMax = (GLfloat)(rects[idx]->y + rects[idx]->h);
+
+        vertices[0] = xMin;
+        vertices[1] = yMin;
+        vertices[2] = xMax;
+        vertices[3] = yMin;
+        vertices[4] = xMin;
+        vertices[5] = yMax;
+        vertices[6] = xMax;
+        vertices[7] = yMax;
+        glVertexAttribPointer(GLES2_ATTRIBUTE_POSITION, 2, GL_FLOAT, GL_FALSE, 0, vertices);
+        glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+    }
+    glDisableVertexAttribArray(GLES2_ATTRIBUTE_POSITION);
+    if (glGetError() != GL_NO_ERROR)
+    {
+        SDL_SetError("Failed to render lines");
+        return -1;
+    }
+    return 0;
+}
+
+static int
+GLES2_RenderCopy(SDL_Renderer *renderer, SDL_Texture *texture, const SDL_Rect *srcrect,
+                 const SDL_Rect *dstrect)
+{
+    GLES2_DriverContext *rdata = (GLES2_DriverContext *)renderer->driverdata;
+    GLES2_TextureData *tdata = (GLES2_TextureData *)texture->driverdata;
+    GLES2_ImageSource sourceType;
+    SDL_BlendMode blendMode;
+    int alpha;
+    GLfloat vertices[8];
+    GLfloat texCoords[8];
+    GLuint locTexture;
+    GLuint locModulation;
+    GLuint locColorTable;
+
+    GLES2_ActivateRenderer(renderer);
+
+    /* Activate an appropriate shader and set the projection matrix */
+    blendMode = texture->blendMode;
+    alpha = texture->a;
+    sourceType = GLES2_IMAGESOURCE_TEXTURE;
+    if (GLES2_SelectProgram(renderer, sourceType, blendMode) < 0)
+        return -1;
+
+    /* Select the target texture */
+    locTexture = rdata->current_program->uniform_locations[GLES2_UNIFORM_TEXTURE];
+    glGetError();
+    glActiveTexture(GL_TEXTURE0);
+    glBindTexture(tdata->texture_type, tdata->texture);
+    glUniform1i(locTexture, 0);
+
+    /* Configure texture blending */
+    GLES2_SetBlendMode(blendMode);
+
+    /* Configure color modulation */
+    locModulation = rdata->current_program->uniform_locations[GLES2_UNIFORM_MODULATION];
+    glUniform4f(locModulation,
+                texture->r / 255.0f,
+                texture->g / 255.0f,
+                texture->b / 255.0f,
+                alpha / 255.0f);
+
+    /* Emit the textured quad */
+    glEnableVertexAttribArray(GLES2_ATTRIBUTE_TEXCOORD);
+    glEnableVertexAttribArray(GLES2_ATTRIBUTE_POSITION);
+    vertices[0] = (GLfloat)dstrect->x;
+    vertices[1] = (GLfloat)dstrect->y;
+    vertices[2] = (GLfloat)(dstrect->x + dstrect->w);
+    vertices[3] = (GLfloat)dstrect->y;
+    vertices[4] = (GLfloat)dstrect->x;
+    vertices[5] = (GLfloat)(dstrect->y + dstrect->h);
+    vertices[6] = (GLfloat)(dstrect->x + dstrect->w);
+    vertices[7] = (GLfloat)(dstrect->y + dstrect->h);
+    glVertexAttribPointer(GLES2_ATTRIBUTE_POSITION, 2, GL_FLOAT, GL_FALSE, 0, vertices);
+    texCoords[0] = srcrect->x / (GLfloat)texture->w;
+    texCoords[1] = srcrect->y / (GLfloat)texture->h;
+    texCoords[2] = (srcrect->x + srcrect->w) / (GLfloat)texture->w;
+    texCoords[3] = srcrect->y / (GLfloat)texture->h;
+    texCoords[4] = srcrect->x / (GLfloat)texture->w;
+    texCoords[5] = (srcrect->y + srcrect->h) / (GLfloat)texture->h;
+    texCoords[6] = (srcrect->x + srcrect->w) / (GLfloat)texture->w;
+    texCoords[7] = (srcrect->y + srcrect->h) / (GLfloat)texture->h;
+    glVertexAttribPointer(GLES2_ATTRIBUTE_TEXCOORD, 2, GL_FLOAT, GL_FALSE, 0, texCoords);
+    glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+    glDisableVertexAttribArray(GLES2_ATTRIBUTE_POSITION);
+    glDisableVertexAttribArray(GLES2_ATTRIBUTE_TEXCOORD);
+    if (glGetError() != GL_NO_ERROR)
+    {
+        SDL_SetError("Failed to render texture");
+        return -1;
+    }
+    return 0;
+}
+
+static void
+GLES2_RenderPresent(SDL_Renderer *renderer)
+{
+    GLES2_ActivateRenderer(renderer);
+
+    /* Tell the video driver to swap buffers */
+    SDL_GL_SwapWindow(renderer->window);
+}
+
+/*************************************************************************************************
+ * Renderer instantiation                                                                        *
+ *************************************************************************************************/
+
+#define GL_NVIDIA_PLATFORM_BINARY_NV 0x890B
+
+static SDL_Renderer *
+GLES2_CreateRenderer(SDL_Window *window, Uint32 flags)
+{
+    SDL_Renderer *renderer;
+    GLES2_DriverContext *rdata;
+    GLint nFormats;
+#ifndef ZUNE_HD
+    GLboolean hasCompiler;
+#endif
+
+    /* Create the renderer struct */
+    renderer = (SDL_Renderer *)SDL_calloc(1, sizeof(SDL_Renderer));
+    rdata = (GLES2_DriverContext *)SDL_calloc(1, sizeof(GLES2_DriverContext));
+    if (!renderer)
+    {
+        SDL_OutOfMemory();
+        SDL_free(renderer);
+        SDL_free(rdata);
+        return NULL;
+    }
+    renderer->info = GLES2_RenderDriver.info;
+    renderer->window = window;
+    renderer->driverdata = rdata;
+
+    /* Create the GL context */
+    rdata->context = SDL_GL_CreateContext(window);
+    if (!rdata->context)
+    {
+        SDL_free(renderer);
+        SDL_free(rdata);
+        return NULL;
+    }
+
+    /* Determine supported shader formats */
+    /* HACK: glGetInteger is broken on the Zune HD's compositor, so we just hardcode this */
+    glGetError();
+#ifdef ZUNE_HD
+    nFormats = 1;
+#else /* !ZUNE_HD */
+    glGetIntegerv(GL_NUM_SHADER_BINARY_FORMATS, &nFormats);
+    glGetBooleanv(GL_SHADER_COMPILER, &hasCompiler);
+    if (hasCompiler)
+        ++nFormats;
+#endif /* ZUNE_HD */
+    rdata->shader_formats = (GLenum *)SDL_calloc(nFormats, sizeof(GLenum));
+    if (!rdata->shader_formats)
+    {
+        SDL_OutOfMemory();
+        SDL_free(renderer);
+        SDL_free(rdata);
+        return NULL;
+    }
+    rdata->shader_format_count = nFormats;
+#ifdef ZUNE_HD
+    rdata->shader_formats[0] = GL_NVIDIA_PLATFORM_BINARY_NV;
+#else /* !ZUNE_HD */
+    glGetIntegerv(GL_SHADER_BINARY_FORMATS, (GLint *)rdata->shader_formats);
+    if (glGetError() != GL_NO_ERROR)
+    {
+        SDL_SetError("Failed to query supported shader formats");
+        SDL_free(renderer);
+        SDL_free(rdata->shader_formats);
+        SDL_free(rdata);
+        return NULL;
+    }
+    if (hasCompiler)
+        rdata->shader_formats[nFormats - 1] = (GLenum)-1;
+#endif /* ZUNE_HD */
+
+    /* Populate the function pointers for the module */
+    renderer->WindowEvent         = &GLES2_WindowEvent;
+    renderer->CreateTexture       = &GLES2_CreateTexture;
+    renderer->UpdateTexture       = &GLES2_UpdateTexture;
+    renderer->LockTexture         = &GLES2_LockTexture;
+    renderer->UnlockTexture       = &GLES2_UnlockTexture;
+    renderer->RenderClear         = &GLES2_RenderClear;
+    renderer->RenderDrawPoints    = &GLES2_RenderDrawPoints;
+    renderer->RenderDrawLines     = &GLES2_RenderDrawLines;
+    renderer->RenderFillRects     = &GLES2_RenderFillRects;
+    renderer->RenderCopy          = &GLES2_RenderCopy;
+    renderer->RenderPresent       = &GLES2_RenderPresent;
+    renderer->DestroyTexture      = &GLES2_DestroyTexture;
+    renderer->DestroyRenderer     = &GLES2_DestroyRenderer;
+    return renderer;
+}
+
+#endif /* SDL_VIDEO_RENDER_OGL_ES2 */
+
+/* vi: set ts=4 sw=4 expandtab: */