AVCustomEditOSX/APLOpenGLRenderer.m

/*
     File: APLOpenGLRenderer.m
 Abstract:  OpenGL base class renderer setups a CGLContextObj for rendering, it also loads, compiles and links the vertex and fragment shaders. 
  Version: 1.1
 
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 */
 
#import "APLOpenGLRenderer.h"
 
static const char kSimpleVertexShader[] = {
    "attribute vec4 position; \n \
     attribute vec2 texCoord; \n \
     uniform mat4 renderTransform; \n \
     varying vec2 texCoordVarying; \n \
     void main() \n \
     { \n \
        gl_Position = position * renderTransform; \n \
        texCoordVarying = texCoord; \n \
     }"
};
 
static const char kSimpleFragmentShader[] = {
    "varying vec2 texCoordVarying; \n \
     uniform sampler2DRect Sampler; \n \
     void main() \n \
     { \n \
        gl_FragColor = texture2DRect(Sampler, texCoordVarying); \n \
     }"
};
 
@interface APLOpenGLRenderer ()
 
- (void)setupOffscreenRenderContext;
 
- (BOOL)loadShaders;
- (BOOL)compileShader:(GLuint *)shader type:(GLenum)type source:(NSString *)source;
- (BOOL)linkProgram:(GLuint)prog;
- (BOOL)validateProgram:(GLuint)prog;
 
@end
 
@implementation APLOpenGLRenderer
 
- (id)init
{
    self = [super init];
    if(self) {
        [self setupOffscreenRenderContext];
        [self loadShaders];
    }
    
    return self;
}
 
- (void)dealloc
{
    if (_videoTextureCache) {
        CFRelease(_videoTextureCache);
    }
    if (_offscreenBufferHandle) {
        glDeleteFramebuffers(1, &_offscreenBufferHandle);
        _offscreenBufferHandle = 0;
    }
}
 
- (void)renderPixelBuffer:(CVPixelBufferRef)destinationPixelBuffer usingForegroundSourceBuffer:(CVPixelBufferRef)foregroundPixelBuffer andBackgroundSourceBuffer:(CVPixelBufferRef)backgroundPixelBuffer forTweenFactor:(float)tween
{
    [self doesNotRecognizeSelector:_cmd];
}
 
- (void)setupOffscreenRenderContext
{
    CGDirectDisplayID display = CGMainDisplayID (); // 1
    CGOpenGLDisplayMask myDisplayMask = CGDisplayIDToOpenGLDisplayMask (display); // 2
    
    // Check capabilities of display represented by display mask
    CGLPixelFormatAttribute attribs[] = {kCGLPFADisplayMask,
        myDisplayMask,
        0}; // 3
    CGLPixelFormatObj pixelFormat = NULL;
    GLint numPixelFormats = 0;
    CGLContextObj myCGLContext = 0;
    
    CGLChoosePixelFormat (attribs, &pixelFormat, &numPixelFormats); // 5
    if (pixelFormat) {
        CGLCreateContext (pixelFormat, NULL, &myCGLContext); // 6
        CGLDestroyPixelFormat (pixelFormat); // 7
        _previousContext = CGLGetCurrentContext();
        CGLRetainContext(_previousContext);
        CGLSetCurrentContext (myCGLContext); // 8
        _currentContext = myCGLContext;
        CGLRetainContext(_currentContext);
    }
    
    //-- Create CVOpenGLESTextureCacheRef for optimal CVPixelBufferRef to GLES texture conversion.
    if (_videoTextureCache) {
        CFRelease(_videoTextureCache);
        _videoTextureCache = NULL;
    }
    CVReturn err = CVOpenGLTextureCacheCreate(kCFAllocatorDefault, NULL, myCGLContext, pixelFormat, NULL, &_videoTextureCache);
    if (err != noErr) {
        NSLog(@"Error at CVOpenGLESTextureCacheCreate %d", err);
    }
    
    glDisable(GL_DEPTH_TEST);
    glGenFramebuffers(1, &_offscreenBufferHandle);
    glBindFramebuffer(GL_FRAMEBUFFER, _offscreenBufferHandle);
}
 
- (CVOpenGLTextureRef)textureForPixelBuffer:(CVPixelBufferRef)pixelBuffer
{
    CVOpenGLTextureRef texture = NULL;
    CVReturn err;
    
    if (!_videoTextureCache) {
        NSLog(@"No video texture cache");
        goto bail;
    }
    
    // Periodic texture cache flush every frame
    CVOpenGLTextureCacheFlush(_videoTextureCache, 0);
    
    // CVOpenGLTextureCacheCreateTextureFromImage will create GL texture optimally from CVPixelBufferRef.
    
    err = CVOpenGLTextureCacheCreateTextureFromImage(kCFAllocatorDefault,
                                                     _videoTextureCache,
                                                     pixelBuffer,
                                                     NULL,
                                                     &texture);
    
    if (!texture || err) {
        NSLog(@"Error at creating luma texture using CVOpenGLTextureCacheCreateTextureFromImage %d", err);
    }
    
bail:
    return texture;
}
 
#pragma mark -  OpenGL shader compilation
 
- (BOOL)loadShaders
{
    GLuint vertShader, fragShader;
    NSString *vertShaderSource, *fragShaderSource;
    
    // Create the shader program.
    _program = glCreateProgram();
    
    // Create and compile the vertex shader.
    vertShaderSource = [NSString stringWithCString:kSimpleVertexShader encoding:NSUTF8StringEncoding];
    if (![self compileShader:&vertShader type:GL_VERTEX_SHADER source:vertShaderSource]) {
        NSLog(@"Failed to compile vertex shader");
        return NO;
    }
    
    // Create and compile the fragment shader.
    fragShaderSource = [NSString stringWithCString:kSimpleFragmentShader encoding:NSUTF8StringEncoding];
    if (![self compileShader:&fragShader type:GL_FRAGMENT_SHADER source:fragShaderSource]) {
        NSLog(@"Failed to compile Y fragment shader");
        return NO;
    }
    
    // Attach vertex shader to programY.
    glAttachShader(_program, vertShader);
    
    // Attach fragment shader to programY.
    glAttachShader(_program, fragShader);
    
    // Bind attribute locations. This needs to be done prior to linking.
    glBindAttribLocation(_program, ATTRIB_VERTEX, "position");
    glBindAttribLocation(_program, ATTRIB_TEXCOORD, "texCoord");
 
    // Link the program.
    if (![self linkProgram:_program]) {
        NSLog(@"Failed to link program: %d", _program);
        
        if (vertShader) {
            glDeleteShader(vertShader);
            vertShader = 0;
        }
        if (fragShader) {
            glDeleteShader(fragShader);
            fragShader = 0;
        }
       
        if (_program) {
            glDeleteProgram(_program);
            _program = 0;
        }
        
        return NO;
    }
    
    // Get uniform locations.
    uniforms[UNIFORM_RGB] = glGetUniformLocation(_program, "Sampler");
    uniforms[UNIFORM_RENDER_TRANSFORM] = glGetUniformLocation(_program, "renderTransform");
    
    // Release vertex and fragment shaders.
    if (vertShader) {
        glDetachShader(_program, vertShader);
        glDeleteShader(vertShader);
    }
    if (fragShader) {
        glDetachShader(_program, fragShader);
        glDeleteShader(fragShader);
    }
    
    return YES;
}
 
- (BOOL)compileShader:(GLuint *)shader type:(GLenum)type source:(NSString *)sourceString
{
    if (sourceString == nil) {
        NSLog(@"Failed to load vertex shader: Empty source string");
        return NO;
    }
    
    GLint status;
    const GLchar *source;
    source = (GLchar *)[sourceString UTF8String];
    
    *shader = glCreateShader(type);
    glShaderSource(*shader, 1, &source, NULL);
    glCompileShader(*shader);
    
#if defined(DEBUG)
    GLint logLength;
    glGetShaderiv(*shader, GL_INFO_LOG_LENGTH, &logLength);
    if (logLength > 0) {
        GLchar *log = (GLchar *)malloc(logLength);
        glGetShaderInfoLog(*shader, logLength, &logLength, log);
        NSLog(@"Shader compile log:\n%s", log);
        free(log);
    }
#endif
    
    glGetShaderiv(*shader, GL_COMPILE_STATUS, &status);
    if (status == 0) {
        glDeleteShader(*shader);
        return NO;
    }
    
    return YES;
}
 
- (BOOL)linkProgram:(GLuint)prog
{
    GLint status;
    glLinkProgram(prog);
    
#if defined(DEBUG)
    GLint logLength;
    glGetProgramiv(prog, GL_INFO_LOG_LENGTH, &logLength);
    if (logLength > 0) {
        GLchar *log = (GLchar *)malloc(logLength);
        glGetProgramInfoLog(prog, logLength, &logLength, log);
        NSLog(@"Program link log:\n%s", log);
        free(log);
    }
#endif
    
    glGetProgramiv(prog, GL_LINK_STATUS, &status);
    if (status == 0) {
        return NO;
    }
    
    return YES;
}
 
- (BOOL)validateProgram:(GLuint)prog
{
    GLint logLength, status;
    
    glValidateProgram(prog);
    glGetProgramiv(prog, GL_INFO_LOG_LENGTH, &logLength);
    if (logLength > 0) {
        GLchar *log = (GLchar *)malloc(logLength);
        glGetProgramInfoLog(prog, logLength, &logLength, log);
        NSLog(@"Program validate log:\n%s", log);
        free(log);
    }
    
    glGetProgramiv(prog, GL_VALIDATE_STATUS, &status);
    if (status == 0) {
        return NO;
    }
    
    return YES;
}
 
@end


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