Draw an IOSurface to an OpenGL context - opengl

Question

I have an OpenGL context on which I draw successfully using OpenGL.
I need to draw a specific rectangle of an IOSurface to this context.
What is the best way to do this on 10.8?
NOTE:
I know how to do this on 10.9 using CoreImage (by createing a CIImage from the IOSurface, and render it with [CIContext drawImage:inRect:fromRect]).
However, this does not work well for me on 10.8 (each raw of the image is displayed with a different offset, and the image is distorted diagonally).
Edit: Here is the code that works on 10.9 but not on 10.8:
CGColorSpaceRef colorSpace = CGColorSpaceCreateWithName(kCGColorSpaceSRGB);
CIImage* ciImage = [[CIImage alloc] initWithIOSurface:surface plane:0 format:kCVPixelFormatType_32BGRA options:#{kCIImageColorSpace : (__bridge id)colorSpace}];
NSRect flippedFromRect = fromRect;
// Flip rect before passing to CoreImage:
{
flippedFromRect.origin.y = IOSurfaceGetHeight(surface) - fromRect.origin.y - fromRect.size.height;
}
[ciContext drawImage:ciImage inRect:inRect fromRect:flippedFromRect];
CGColorSpaceRelease(colorSpace);

Answer 1

Here is the solution by wrapping the IOSurface with an OpenGL texture and draw the texture to the screen. This assumes a similar API to [CIContext render:toIOSurface:bounds:colorSpace:] but a vertically flipped OpenGL coordinate system.
// Draw surface on OpenGL context
{
// Enable the rectangle texture extenstion
glEnable(GL_TEXTURE_RECTANGLE_EXT);
// 1. Create a texture from the IOSurface
GLuint name;
{
CGLContextObj cgl_ctx = ...
glGenTextures(1, &name);
GLsizei surface_w = (GLsizei)IOSurfaceGetWidth(surface);
GLsizei surface_h = (GLsizei)IOSurfaceGetHeight(surface);
glBindTexture(GL_TEXTURE_RECTANGLE_EXT, name);
CGLError cglError =
CGLTexImageIOSurface2D(cgl_ctx, GL_TEXTURE_RECTANGLE_EXT, GL_RGBA, surface_w, surface_h, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, surface, 0);
glBindTexture(GL_TEXTURE_RECTANGLE_EXT, 0);
}
// 2. Draw the texture to the current OpenGL context
{
glBindTexture(GL_TEXTURE_RECTANGLE_EXT, name);
glTexParameteri(GL_TEXTURE_RECTANGLE_EXT, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_RECTANGLE_EXT, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
glBegin(GL_QUADS);
glColor4f(0.f, 0.f, 1.0f, 1.0f);
glTexCoord2f( (float)NSMinX(fromRect), (float)(NSMinY(fromRect)));
glVertex2f( (float)NSMinX(inRect), (float)(NSMinY(inRect)));
glTexCoord2f( (float)NSMaxX(fromRect), (float)NSMinY(fromRect));
glVertex2f( (float)NSMaxX(inRect), (float)NSMinY(inRect));
glTexCoord2f( (float)NSMaxX(fromRect), (float)NSMaxY(fromRect));
glVertex2f( (float)NSMaxX(inRect), (float)NSMaxY(inRect));
glTexCoord2f( (float)NSMinX(fromRect), (float)NSMaxY(fromRect));
glVertex2f( (float)NSMinX(inRect), (float)NSMaxY(inRect));
glEnd();
glBindTexture(GL_TEXTURE_RECTANGLE_EXT, 0);
}
glDeleteTextures(1, &name);
}
If you need to draw in the display's color profile, you can explicitly call ColorSync and pass it your source profile and destination profile. It will return to you a “recipe” to perform the color correction. That recipe actually has a linearization, a color conversion (a 3x3 conversion matrix) and a gamma.
FragmentInfo = ColorSyncTransformCopyProperty (transform, kColorSyncTransformFullConversionData, NULL);
If you like, you can combine all those operations into a 3D lookup table. That's actually what happens in the color management of many of the OS X frameworks and applications.
References:
Apple TextureUpload sample code
Draw IOSurfaces to another IOSurface
OpenGL Options for Advanced Color Management