1 files changed, 155 insertions, 0 deletions
diff --git a/tests/sdl_gl_read.c b/tests/sdl_gl_read.c
new file mode 100644
index 00000000..552eb8c0
--- /dev/null
+++ b/tests/sdl_gl_read.c
@@ -0,0 +1,155 @@
+// Built from glbook/hello triange and sdl_ogl, see details there
+
+#include "SDL/SDL.h"
+#include "SDL/SDL_image.h"
+#include "SDL/SDL_opengl.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+
+GLuint programObject;
+int width = 512;
+int height = 256;
+
+GLuint LoadShader ( GLenum type, const char *shaderSrc )
+{
+   GLuint shader;
+   GLint compiled;
+   
+   shader = glCreateShader ( type );
+   if ( shader == 0 )
+   	return 0;
+
+   glShaderSource ( shader, 1, &shaderSrc, NULL );
+   glCompileShader ( shader );
+   glGetShaderiv ( shader, GL_COMPILE_STATUS, &compiled );
+   if ( !compiled ) 
+   {
+      GLint infoLen = 0;
+      glGetShaderiv ( shader, GL_INFO_LOG_LENGTH, &infoLen );
+      if ( infoLen > 1 )
+      {
+         char* infoLog = malloc (sizeof(char) * infoLen );
+         glGetShaderInfoLog ( shader, infoLen, NULL, infoLog );
+         printf ( "Error compiling shader:\n%s\n", infoLog );            
+         free ( infoLog );
+      }
+      glDeleteShader ( shader );
+      return 0;
+   }
+   return shader;
+}
+
+int Init ()
+{
+   GLbyte vShaderStr[] =  
+      "attribute vec4 vPosition;    \n"
+      "void main()                  \n"
+      "{                            \n"
+      "   gl_Position = vPosition;  \n"
+      "}                            \n";
+   
+   GLbyte fShaderStr[] =  
+      "precision mediump float;\n"\
+      "void main()                                  \n"
+      "{                                            \n"
+      "  gl_FragColor = vec4 ( 0.0, 0.0, 1.0, 1.0 );\n"
+      "}                                            \n";
+
+   GLuint vertexShader;
+   GLuint fragmentShader;
+   GLint linked;
+
+   vertexShader = LoadShader ( GL_VERTEX_SHADER, vShaderStr );
+   fragmentShader = LoadShader ( GL_FRAGMENT_SHADER, fShaderStr );
+
+   programObject = glCreateProgram ( );
+   if ( programObject == 0 )
+      return 0;
+
+   glAttachShader ( programObject, vertexShader );
+   glAttachShader ( programObject, fragmentShader );
+   glBindAttribLocation ( programObject, 0, "vPosition" );
+   glLinkProgram ( programObject );
+   glGetProgramiv ( programObject, GL_LINK_STATUS, &linked );
+   if ( !linked ) 
+   {
+      GLint infoLen = 0;
+      glGetProgramiv ( programObject, GL_INFO_LOG_LENGTH, &infoLen );
+      if ( infoLen > 1 )
+      {
+         char* infoLog = malloc (sizeof(char) * infoLen );
+         glGetProgramInfoLog ( programObject, infoLen, NULL, infoLog );
+         printf ( "Error linking program:\n%s\n", infoLog );            
+         free ( infoLog );
+      }
+      glDeleteProgram ( programObject );
+      return GL_FALSE;
+   }
+
+   glClearColor ( 0.0f, 0.0f, 0.0f, 0.0f );
+   return GL_TRUE;
+}
+
+///
+// Draw a triangle using the shader pair created in Init()
+//
+void Draw ()
+{
+   GLfloat vVertices[] = {  0.0f,  0.5f, 0.0f, 
+                           -0.5f, -0.5f, 0.0f,
+                            0.5f, -0.5f, 0.0f };
+
+   // No clientside arrays, so do this in a webgl-friendly manner
+   GLuint vertexPosObject;
+   glGenBuffers(1, &vertexPosObject);
+   glBindBuffer(GL_ARRAY_BUFFER, vertexPosObject);
+   glBufferData(GL_ARRAY_BUFFER, 9*4, vVertices, GL_STATIC_DRAW);
+   
+   glViewport ( 0, 0, width, height );
+   glClear ( GL_COLOR_BUFFER_BIT );
+   glUseProgram ( programObject );
+
+   glBindBuffer(GL_ARRAY_BUFFER, vertexPosObject);
+   glVertexAttribPointer(0 /* ? */, 3, GL_FLOAT, 0, 0, 0);
+   glEnableVertexAttribArray(0);
+
+   glDrawArrays ( GL_TRIANGLES, 0, 3 );
+}
+
+void Verify() {
+  unsigned char *data = malloc(width*height*4);
+  glReadPixels(0, 0, width, height, GL_RGBA, GL_UNSIGNED_BYTE, data);
+  // Should see some blue, and nothing else
+  int seen = 0;
+  int ok = 1;
+  for (int x = 0; x < width*height; x++) {
+    seen = seen || data[x*4+2] != 0;
+    ok = ok && (data[x*4+0] == 0);
+    ok = ok && (data[x*4+1] == 0);
+  }
+  int result = seen && ok;
+  REPORT_RESULT();
+}
+
+int main(int argc, char *argv[])
+{
+  SDL_Surface *screen;
+  if ( SDL_Init(SDL_INIT_VIDEO) != 0 ) {
+    printf("Unable to initialize SDL: %s\n", SDL_GetError());
+    return 1;
+  }
+
+  screen = SDL_SetVideoMode(width, height, 32, SDL_OPENGL);
+  if (!screen) {
+    printf("Unable to set video mode: %s\n", SDL_GetError());
+    return 1;
+  }
+
+  Init();
+  Draw();
+  Verify();
+
+  return 0;
+}
+