OpenGL View shows only empty(pink) screen - ios

Question

I'm going to show pixel data on opengl view.
But I can't see anything, only can see the empty pink gl screen.
Please check my codes and let me know what it is wrong.
#implementation GLView
+ (Class) layerClass
{
return [CAEAGLLayer class];
}
- (id)initWithFrame:(CGRect)frame
{
if ((self = [super initWithFrame:frame]))
{
// Do OpenGL Core Animation layer setup
CAEAGLLayer *eaglLayer = (CAEAGLLayer *)self.layer;
eaglLayer.opaque = YES;
eaglLayer.drawableProperties = [NSDictionary dictionaryWithObjectsAndKeys:[NSNumber numberWithBool:NO], kEAGLDrawablePropertyRetainedBacking, kEAGLColorFormatRGBA8, kEAGLDrawablePropertyColorFormat, nil];
context = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2];
if (!context || ![EAGLContext setCurrentContext:context]
|| ![self createFramebuffers])
return nil;
}
return self;
}
- (BOOL)createFramebuffers
{
glEnable(GL_TEXTURE_2D);
glDisable(GL_DEPTH_TEST);
// Onscreen framebuffer object
glGenFramebuffers(1, &viewFramebuffer);
glBindFramebuffer(GL_FRAMEBUFFER, viewFramebuffer);
glGenRenderbuffers(1, &viewRenderbuffer);
glBindRenderbuffer(GL_RENDERBUFFER, viewRenderbuffer);
[context renderbufferStorage:GL_RENDERBUFFER fromDrawable:(CAEAGLLayer*)self.layer];
glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_WIDTH, &backingWidth);
glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_HEIGHT, &backingHeight);
NSLog(#"Backing width: %d, height: %d", backingWidth, backingHeight);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, viewRenderbuffer);
if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
{
NSLog(#"Failure with framebuffer generation");
return NO;
}
return YES;
}
- (void)setDisplayFramebuffer;
{
if (context)
{
// [EAGLContext setCurrentContext:context];
if (!viewFramebuffer)
[self createFramebuffers];
glBindFramebuffer(GL_FRAMEBUFFER, viewFramebuffer);
// glBindRenderbuffer(GL_RENDERBUFFER, viewRenderbuffer);
glViewport(0, 0, backingWidth, backingHeight);
}
}
- (BOOL)presentFramebuffer;
{
BOOL success = FALSE;
if (context)
{
// [EAGLContext setCurrentContext:context];
glBindRenderbuffer(GL_RENDERBUFFER, viewRenderbuffer);
success = [context presentRenderbuffer:GL_RENDERBUFFER];
}
return success;
}
and in viewcontroller
m_glView = [[GLView alloc] initWithFrame:CGRectMake(0, 0, m_viewPlayer.frame.size.width, m_viewPlayer.frame.size.height)];
[m_viewPlayer addSubview:m_glView];
[self loadVertexShader:#"DirectDisplayShader" fragmentShader:#"DirectDisplayShader" forProgram:&m_directDisplayProgram];
and in timer loop
CMSampleBufferRef buf = [m_trackOutput copyNextSampleBuffer];
if (buf == nil)
return;
[self processFrame:buf]; // draw frame to opengl view
CFRelease(buf);
- (void)processFrame:(CMSampleBufferRef)sampleBuffer
{
if (m_videoFrameTexture)
glDeleteTextures(1, &m_videoFrameTexture);
// Get a CMSampleBuffer's Core Video image buffer for the media data
CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
// Lock the base address of the pixel buffer
CVPixelBufferLockBaseAddress(imageBuffer, 0);
CGFloat width = CVPixelBufferGetWidth(imageBuffer);
CGFloat height = CVPixelBufferGetHeight(imageBuffer);
// Create a new texture from the camera frame data, display that using the shaders
glGenTextures(1, &m_videoFrameTexture);
glBindTexture(GL_TEXTURE_2D, m_videoFrameTexture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
// This is necessary for non-power-of-two textures
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
// Using BGRA extension to pull in video frame data directly
// glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_BGRA, GL_UNSIGNED_BYTE, CVPixelBufferGetBaseAddress(imageBuffer));
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, CVPixelBufferGetBaseAddress(imageBuffer));
[self drawFrame];
// glDeleteTextures(1, &videoFrameTexture);
CVPixelBufferUnlockBaseAddress(imageBuffer, 0);
}
- (void)drawFrame
{
[m_glView setDisplayFramebuffer];
[self drawCapturedScreen];
[m_glView presentFramebuffer];
}
- (void)drawCapturedScreen
{
glUseProgram(m_directDisplayProgram);
glBindTexture(GL_TEXTURE_2D, m_videoFrameTexture);
glUniform1i(uniforms[UNIFORM_VIDEOFRAME], 0);
// Update attribute values.
static const GLfloat squareVertices[] = {
-1.0f, -1.0f,
1.0f, -1.0f,
-1.0f, 1.0f,
1.0f, 1.0f,
};
glVertexAttribPointer(ATTRIB_VERTEX, 2, GL_FLOAT, 0, 0, squareVertices);
glEnableVertexAttribArray(ATTRIB_VERTEX);
float m_fScale = 1.0f; //
GLfloat kRate = 1.0f/m_fScale;
GLfloat kX = (1.0-kRate)/2;
GLfloat kY = (1.0-kRate)/2;
GLfloat kS = kX+kRate;
GLfloat kT = kY+kRate;
{
{
GLfloat textureVertices[] = {
kS, kT,
kS, kY,
kX, kT,
kX, kY,
};
glVertexAttribPointer(ATTRIB_TEXTUREPOSITON, 2, GL_FLOAT, 0, 0, textureVertices);
glEnableVertexAttribArray(ATTRIB_TEXTUREPOSITON);
}
}
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
}

Answer 1

Have you managed to render anything in OpenGL so far? I would suggest breaking what you're doing down into smaller steps and get those working first. First try rendering just using GL_POINTS and see if you can get anything and then build up from there. Make your shaders as simple as possible too to check for issues there. You should try to get the bare minimum rendering working and then build up the complexity (for example, after points try lines, then triangles, then textured triangles). By breaking down the rendering you can isolate what's causing the draw call to not show anything.