/*

 Copyright (C) 2015 Apple Inc. All Rights Reserved.

 See LICENSE.txt for this sample’s licensing information

 Abstract:

 Includes the appropriate OpenGL headers (depending on whether this

  is built for iOS or OSX) and provides some API utility functions.

 */

#ifndef __GL_UTIL_H__

#define __GL_UTIL_H__

#if TARGET_IOS

#import <OpenGLES/ES2/gl.h>

#import <OpenGLES/ES2/glext.h>

#else 

#import <OpenGL/OpenGL.h>

// OpenGL 3.2 is only supported on MacOS X Lion and later

// CGL_VERSION_1_3 is defined as 1 on MacOS X Lion and later

#if CGL_VERSION_1_3

// Set to 0 to run on the Legacy OpenGL Profile

#define ESSENTIAL_GL_PRACTICES_SUPPORT_GL3 1

#else

#define ESSENTIAL_GL_PRACTICES_SUPPORT_GL3 0

#endif //!CGL_VERSION_1_3

#if ESSENTIAL_GL_PRACTICES_SUPPORT_GL3

#import <OpenGL/gl3.h>

#else

#import <OpenGL/gl.h>

#endif //!ESSENTIAL_GL_PRACTICES_SUPPORT_GL3

#endif // !TARGET_IOS

//The name of the VertexArrayObject are slightly different in

// OpenGLES, OpenGL Core Profile, and OpenGL Legacy

// The arguments are exactly the same across these APIs however

#if TARGET_IOS

#define glBindVertexArray glBindVertexArrayOES

#define glGenVertexArrays glGenVertexArraysOES

#define glDeleteVertexArrays glDeleteVertexArraysOES

#else

#if ESSENTIAL_GL_PRACTICES_SUPPORT_GL3

#define glBindVertexArray glBindVertexArray

#define glGenVertexArrays glGenVertexArrays

#define glGenerateMipmap glGenerateMipmap

#define glDeleteVertexArrays glDeleteVertexArrays

#else

#define glBindVertexArray glBindVertexArrayAPPLE 

#define glGenVertexArrays glGenVertexArraysAPPLE

#define glGenerateMipmap glGenerateMipmapEXT

#define glDeleteVertexArrays glDeleteVertexArraysAPPLE

#endif //!ESSENTIAL_GL_PRACTICES_SUPPORT_GL3

#endif //!TARGET_IOS

static inline const char * GetGLErrorString(GLenum error)

{

    const char *str;

    switch( error )

    {

        case GL_NO_ERROR:

            str = "GL_NO_ERROR";

            break;

        case GL_INVALID_ENUM:

            str = "GL_INVALID_ENUM";

            break;

        case GL_INVALID_VALUE:

            str = "GL_INVALID_VALUE";

            break;

        case GL_INVALID_OPERATION:

            str = "GL_INVALID_OPERATION";

            break;      

#if defined __gl_h_ || defined __gl3_h_

        case GL_OUT_OF_MEMORY:

            str = "GL_OUT_OF_MEMORY";

            break;

        case GL_INVALID_FRAMEBUFFER_OPERATION:

            str = "GL_INVALID_FRAMEBUFFER_OPERATION";

            break;

#endif

#if defined __gl_h_

        case GL_STACK_OVERFLOW:

            str = "GL_STACK_OVERFLOW";

            break;

        case GL_STACK_UNDERFLOW:

            str = "GL_STACK_UNDERFLOW";

            break;

        case GL_TABLE_TOO_LARGE:

            str = "GL_TABLE_TOO_LARGE";

            break;

#endif

        default:

            str = "(ERROR: Unknown Error Enum)";

            break;

    }

    return str;

}

#define GetGLError()                                    \

{                                                       \

    GLenum err = glGetError();                          \

    while (err != GL_NO_ERROR) {                        \

        NSLog(@"GLError %s set in File:%s Line:%d\n",   \

        GetGLErrorString(err), __FILE__, __LINE__);     \

        err = glGetError();                             \

    }                                                   \

}

#endif // __GL_UTIL_H__