Revert 35500 - Added an application framework for demos. Ported hellotriangle...

third_party/gles_book_examples/Chapter_2/Hello_Triangle/Hello_Triangle.c

 //
 // Book:      OpenGL(R) ES 2.0 Programming Guide
 // Authors:   Aaftab Munshi, Dan Ginsburg, Dave Shreiner
 // ISBN-10:   0321502795
 // ISBN-13:   9780321502797
 // Publisher: Addison-Wesley Professional
 // URLs:      http://safari.informit.com/9780321563835
 //            http://www.opengles-book.com
 //
 
 // Hello_Triangle.c
 //
 //    This is a simple example that draws a single triangle with
 //    a minimal vertex/fragment shader.  The purpose of this 
 //    example is to demonstrate the basic concepts of 
 //    OpenGL ES 2.0 rendering.
+#include <stdlib.h>
+#include "esUtil.h"
 
-#include "Hello_Triangle.h"
+typedef struct
+{
+   // Handle to a program object
+   GLuint programObject;
 
-#include <stdlib.h>
+} UserData;
+
+///
+// Create a shader object, load the shader source, and
+// compile the shader.
+//
+GLuint LoadShader ( GLenum type, const char *shaderSrc )
+{
+   GLuint shader;
+   GLint compiled;
+   
+   // Create the shader object
+   shader = glCreateShader ( type );
+
+   if ( shader == 0 )
+        return 0;
+
+   // Load the shader source
+   glShaderSource ( shader, 1, &shaderSrc, NULL );
+   
+   // Compile the shader
+   glCompileShader ( shader );
+
+   // Check the compile status
+   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 );
+         esLogMessage ( "Error compiling shader:\n%s\n", infoLog );            
+         
+         free ( infoLog );
+      }
+
+      glDeleteShader ( shader );
+      return 0;
+   }
+
+   return shader;
+
+}
 
 ///
 // Initialize the shader and program object
 //
-int htInit ( ESContext *esContext )
+int Init ( ESContext *esContext )
 {
-   HTUserData *userData = esContext->userData;
-
+   UserData *userData = esContext->userData;
    GLbyte vShaderStr[] =  
       "attribute vec4 vPosition;    \n"
       "void main()                  \n"
       "{                            \n"
       "   gl_Position = vPosition;  \n"
       "}                            \n";
    
-   // TODO(alokp): Shaders containing "precision" do not compile.
    GLbyte fShaderStr[] =  
+      "precision mediump float;\n"\
       "void main()                                  \n"
       "{                                            \n"
       "  gl_FragColor = vec4 ( 1.0, 0.0, 0.0, 1.0 );\n"
       "}                                            \n";
 
-   // TODO(alokp): Client-side vertex arrays do not work.
-   GLfloat vVertices[] = {  0.0f,  0.5f, 0.0f, 
-                           -0.5f, -0.5f, 0.0f,
-                            0.5f, -0.5f, 0.0f };
+   GLuint vertexShader;
+   GLuint fragmentShader;
+   GLuint programObject;
+   GLint linked;
 
-   userData->programObject = esLoadProgram ( vShaderStr, fShaderStr );
-   if ( userData->programObject == 0 ) return FALSE;
+   // Load the vertex/fragment shaders
+   vertexShader = LoadShader ( GL_VERTEX_SHADER, vShaderStr );
+   fragmentShader = LoadShader ( GL_FRAGMENT_SHADER, fShaderStr );
+
+   // Create the program object
+   programObject = glCreateProgram ( );
+   
+   if ( programObject == 0 )
+      return 0;
+
+   glAttachShader ( programObject, vertexShader );
+   glAttachShader ( programObject, fragmentShader );
 
    // Bind vPosition to attribute 0   
-   glBindAttribLocation ( userData->programObject, 0, "vPosition" );
+   glBindAttribLocation ( programObject, 0, "vPosition" );
 
-   glGenBuffers ( 1, &userData->vbo );
-   glBindBuffer ( GL_ARRAY_BUFFER, userData->vbo );
-   glBufferData ( GL_ARRAY_BUFFER, sizeof(vVertices), NULL, GL_STATIC_DRAW );
-   glBufferSubData ( GL_ARRAY_BUFFER, 0, sizeof(vVertices), vVertices );
+   // Link the program
+   glLinkProgram ( programObject );
+
+   // Check the link status
+   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 );
+         esLogMessage ( "Error linking program:\n%s\n", infoLog );            
+         
+         free ( infoLog );
+      }
+
+      glDeleteProgram ( programObject );
+      return FALSE;
+   }
+
+   // Store the program object
+   userData->programObject = programObject;
 
    glClearColor ( 0.0f, 0.0f, 0.0f, 0.0f );
    return TRUE;
 }
 
 ///
 // Draw a triangle using the shader pair created in Init()
 //
-void htDraw ( ESContext *esContext )
+void Draw ( ESContext *esContext )
 {
-   HTUserData *userData = esContext->userData;
-
+   UserData *userData = esContext->userData;
+   GLfloat vVertices[] = {  0.0f,  0.5f, 0.0f, 
+                           -0.5f, -0.5f, 0.0f,
+                            0.5f, -0.5f, 0.0f };
+      
    // Set the viewport
    glViewport ( 0, 0, esContext->width, esContext->height );
    
    // Clear the color buffer
    glClear ( GL_COLOR_BUFFER_BIT );
 
    // Use the program object
    glUseProgram ( userData->programObject );
 
    // Load the vertex data
-   glBindBuffer ( GL_ARRAY_BUFFER, userData->vbo );
+   glVertexAttribPointer ( 0, 3, GL_FLOAT, GL_FALSE, 0, vVertices );
    glEnableVertexAttribArray ( 0 );
-   glVertexAttribPointer ( 0, 3, GL_FLOAT, GL_FALSE, 0, 0 );
 
    glDrawArrays ( GL_TRIANGLES, 0, 3 );
 
-   // Nothing is drawn or application crashes without glFlush.
-   // TODO(alokp): glFlush should not be necessary with SwapBuffers().
-   glFlush();
+   eglSwapBuffers ( esContext->eglDisplay, esContext->eglSurface );
 }
 
-///
-// Cleanup
-//
-void htShutDown ( ESContext *esContext )
+
+int main ( int argc, char *argv[] )
 {
-   HTUserData *userData = esContext->userData;
+   ESContext esContext;
+   UserData  userData;
 
-   // Delete program object
-   if ( userData->programObject != 0 )
-   {
-      glDeleteProgram ( userData->programObject );
-      userData->programObject = 0;
-   }
-   if ( userData->vbo != 0 )
-   {
-      glDeleteBuffers ( 1, &userData->vbo );
-      userData->vbo = 0;
-   }
+   esInitContext ( &esContext );
+   esContext.userData = &userData;
+
+   esCreateWindow ( &esContext, "Hello Triangle", 320, 240, ES_WINDOW_RGB );
+   
+   if ( !Init ( &esContext ) )
+      return 0;
+
+   esRegisterDrawFunc ( &esContext, Draw );
+   
+   esMainLoop ( &esContext );
 }