Pro OpenGL ES for iOS

314 CHAPTER 10: OpenGL ES 2, Shaders, and...^

Listing 10-4. Loading the Shaders and Resolving Parameters

• (BOOL)loadShaders
  {
  GLuint vertShader, fragShader;
  NSString vertShaderPathname, fragShaderPathname;

_program = glCreateProgram(); //1

vertShaderPathname = [[NSBundle mainBundle]

pathForResource:@"Shader" ofType:@"vsh"];

if (![self compileShader:&vertShader //2

type:GL_VERTEX_SHADER file:vertShaderPathname])

{

NSLog(@"Failed to compile vertex shader");

return NO;

}

fragShaderPathname = [[NSBundle mainBundle] pathForResource:@"Shader"

ofType:@"fsh"];

if (![self compileShader:&fragShader

type:GL_FRAGMENT_SHADER file:fragShaderPathname])

{

NSLog(@"Failed to compile fragment shader");

return NO;

}

glAttachShader(_program, vertShader); //3

glAttachShader(_program, fragShader);

glBindAttribLocation(_program, ATTRIB_VERTEX, "position"); //4

glBindAttribLocation(_program, ATTRIB_NORMAL, "normal");

if (![self linkProgram:_program]) //5

{

NSLog(@"Failed to link program: %d", _program);

if (vertShader)

{

glDeleteShader(vertShader);

vertShader = 0;

}

if (fragShader)

{

glDeleteShader(fragShader);

fragShader = 0;

}