Question

I want to bump-map the cameras images with a fixed texture…

I found the following thread:
Bump Mapping on the iPhone

on general bump-mapping techniques. But they didn’t really have examples or tutorials on how to do it.

Now , just in case, does anyone know about good tutorials on how to bump-map on the iphone or on how to modify the iPhone Camera feed with openGL?

PS: Finally ended up doing something different, i.e. refracting my Image using the OpenGL ES 2.0 refract function.

Answer 1

Responding to your comment, to add OpenGL effects to camera outputs you need to use AVFoundation, which was introduced in iOS 4. That can be used to get a live feed of pixel data from the camera, which you can upload to OpenGL as a texture — allowing you to do whatever you want subsequently.

If you’ll forgive me referencing an answer I’ve supplied in the past, basic stuff to start receiving a suitable buffer is here.

You’ll receive CMSampleBuffers on a secondary thread in your delegate method:

- (void)captureOutput:(AVCaptureOutput *)captureOutput 
     didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer 
     fromConnection:(AVCaptureConnection *)connection

You can use CMSampleBufferGetImageBuffer to get a CVImageBuffer and from that use a combination of CVPixelBufferLockBaseAddress CVPixelBufferGetBaseAddress, CVPixelBufferGetBytesPerRow, and possibly CVPixelBufferGetWidth and CVPixelBufferGetHeight to get at a C array of the pixels. In my testing across an iPhone 4 and an iPhone 3GS, the buffer has only ever come back tightly packed (so, no padding between lines), meaning that it can be uploaded immediately as GL_BGRA, since the APPLE_texture_format_BGRA8888 extension is supported on all iPhones to date.

From there you obviously need to figure out what to do in terms of vertex and fragment shaders, depending on whether you have a normal map, a bump map that you actually want to affect visible shape (and, if so, whether by vertex perturbance or by ray casting) or something else.