//-----------------------------------------------------------------------------

// Purpose: Compiles a GL shader program and returns the handle. Returns 0 if

//            the shader couldn't be compiled for some reason.

//-----------------------------------------------------------------------------

GLuint CMainApplication::CompileGLShader( const char *pchShaderName, const char *pchVertexShader, const char *pchFragmentShader )

{

    GLuint unProgramID = glCreateProgram();

    GLuint nSceneVertexShader = glCreateShader(GL_VERTEX_SHADER);

    glShaderSource( nSceneVertexShader, 1, &pchVertexShader, NULL);

    glCompileShader( nSceneVertexShader );

    GLint vShaderCompiled = GL_FALSE;

    glGetShaderiv( nSceneVertexShader, GL_COMPILE_STATUS, &vShaderCompiled);

    if ( vShaderCompiled != GL_TRUE)

    {

        dprintf("%s - Unable to compile vertex shader %d!\n", pchShaderName, nSceneVertexShader);

        glDeleteProgram( unProgramID );

        glDeleteShader( nSceneVertexShader );

        return 0;

    }

    glAttachShader( unProgramID, nSceneVertexShader);

    glDeleteShader( nSceneVertexShader ); // the program hangs onto this once it's attached

    GLuint  nSceneFragmentShader = glCreateShader(GL_FRAGMENT_SHADER);

    glShaderSource( nSceneFragmentShader, 1, &pchFragmentShader, NULL);

    glCompileShader( nSceneFragmentShader );

    GLint fShaderCompiled = GL_FALSE;

    glGetShaderiv( nSceneFragmentShader, GL_COMPILE_STATUS, &fShaderCompiled);

    if (fShaderCompiled != GL_TRUE)

    {

        dprintf("%s - Unable to compile fragment shader %d!\n", pchShaderName, nSceneFragmentShader );

        glDeleteProgram( unProgramID );

        glDeleteShader( nSceneFragmentShader );

        return 0;    

    }

    glAttachShader( unProgramID, nSceneFragmentShader );

    glDeleteShader( nSceneFragmentShader ); // the program hangs onto this once it's attached

    glLinkProgram( unProgramID );

    GLint programSuccess = GL_TRUE;

    glGetProgramiv( unProgramID, GL_LINK_STATUS, &programSuccess);

    if ( programSuccess != GL_TRUE )

    {

        dprintf("%s - Error linking program %d!\n", pchShaderName, unProgramID);

        glDeleteProgram( unProgramID );

        return 0;

    }

    glUseProgram( unProgramID );

    glUseProgram( 0 );

    return unProgramID;

}