From e3650baa3f2724f594f53bc85720bd0a5cbba866 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <slouken@libsdl.org>
Date: Tue, 8 Feb 2011 20:23:52 -0800
Subject: [PATCH] Fixed the shaders (needed to use texture2DRect) - thanks
 Ryan!

---
 src/render/opengl/SDL_render_gl.c  |  5 ----
 src/render/opengl/SDL_shaders_gl.c | 37 ++++++++++++++++++++++++------
 2 files changed, 30 insertions(+), 12 deletions(-)

diff --git a/src/render/opengl/SDL_render_gl.c b/src/render/opengl/SDL_render_gl.c
index 7765d24dd..3cd3df56a 100644
--- a/src/render/opengl/SDL_render_gl.c
+++ b/src/render/opengl/SDL_render_gl.c
@@ -297,11 +297,6 @@ GL_CreateRenderer(SDL_Window * window, Uint32 flags)
     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;
diff --git a/src/render/opengl/SDL_shaders_gl.c b/src/render/opengl/SDL_shaders_gl.c
index bc4cb655a..015851e3c 100644
--- a/src/render/opengl/SDL_shaders_gl.c
+++ b/src/render/opengl/SDL_shaders_gl.c
@@ -56,10 +56,16 @@ struct GL_ShaderContext
     PFNGLUNIFORM1FARBPROC glUniform1fARB;
     PFNGLUSEPROGRAMOBJECTARBPROC glUseProgramObjectARB;
 
+    SDL_bool GL_ARB_texture_rectangle_supported;
+
     GL_Shader current_shader;
     GL_ShaderData shaders[NUM_SHADERS];
 };
 
+/*
+ * NOTE: Always use sampler2D, etc here. We'll #define them to the
+ *  texture_rectangle versions if we choose to use that extension.
+ */
 static const char *shader_source[NUM_SHADERS][2] =
 {
     /* SHADER_NONE */
@@ -73,7 +79,7 @@ varying vec4 v_color; \
  \
 void main() \
 { \
-    gl_Position = ftransform(); \
+    gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex; \
     v_color = gl_Color; \
 } \
 ",
@@ -97,7 +103,7 @@ varying vec2 v_texCoord; \
  \
 void main() \
 { \
-    gl_Position = ftransform(); \
+    gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex; \
     v_color = gl_Color; \
     v_texCoord = vec2(gl_MultiTexCoord0); \
 } \
@@ -117,11 +123,15 @@ void main() \
 };
 
 static SDL_bool
-CompileShader(GL_ShaderContext *ctx, GLenum shader, const char *source)
+CompileShader(GL_ShaderContext *ctx, GLenum shader, const char *defines, const char *source)
 {
     GLint status;
+    const char *sources[2];
 
-    ctx->glShaderSourceARB(shader, 1, &source, NULL);
+    sources[0] = defines;
+    sources[1] = source;
+
+    ctx->glShaderSourceARB(shader, SDL_arraysize(sources), sources, NULL);
     ctx->glCompileShaderARB(shader);
     ctx->glGetObjectParameterivARB(shader, GL_OBJECT_COMPILE_STATUS_ARB, &status);
     if (status == 0) {
@@ -146,7 +156,8 @@ static SDL_bool
 CompileShaderProgram(GL_ShaderContext *ctx, int index, GL_ShaderData *data)
 {
     const int num_tmus_bound = 4;
-    GLint status;
+    const char *vert_defines = "";
+    const char *frag_defines = "";
     int i;
     GLint location;
 
@@ -156,18 +167,25 @@ CompileShaderProgram(GL_ShaderContext *ctx, int index, GL_ShaderData *data)
 
     ctx->glGetError();
 
+    /* Make sure we use the correct sampler type for our texture type */
+    if (ctx->GL_ARB_texture_rectangle_supported) {
+        frag_defines = 
+"#define sampler2D sampler2DRect\n"
+"#define texture2D texture2DRect\n";
+    }
+
     /* Create one program object to rule them all */
     data->program = ctx->glCreateProgramObjectARB();
 
     /* Create the vertex shader */
     data->vert_shader = ctx->glCreateShaderObjectARB(GL_VERTEX_SHADER_ARB);
-    if (!CompileShader(ctx, data->vert_shader, shader_source[index][0])) {
+    if (!CompileShader(ctx, data->vert_shader, vert_defines, shader_source[index][0])) {
         return SDL_FALSE;
     }
 
     /* Create the fragment shader */
     data->frag_shader = ctx->glCreateShaderObjectARB(GL_FRAGMENT_SHADER_ARB);
-    if (!CompileShader(ctx, data->frag_shader, shader_source[index][1])) {
+    if (!CompileShader(ctx, data->frag_shader, frag_defines, shader_source[index][1])) {
         return SDL_FALSE;
     }
 
@@ -215,6 +233,11 @@ GL_CreateShaderContext()
         return NULL;
     }
 
+    if (SDL_GL_ExtensionSupported("GL_ARB_texture_rectangle")
+        || SDL_GL_ExtensionSupported("GL_EXT_texture_rectangle")) {
+        ctx->GL_ARB_texture_rectangle_supported = SDL_TRUE;
+    }
+
     /* Check for shader support */
     shaders_supported = SDL_FALSE;
     if (SDL_GL_ExtensionSupported("GL_ARB_shader_objects") &&