Compositing

Compositing with Alpha



• Porter-Duff compositing
• OpenGL does not premultiply color by alpha
• Use glCopyPixels or color matrix imaging extension
  • over: glBlendFunc(GL_ONE_MINUS_SRC_ALPHA, GL_ONE)
  • under: glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA)
  • in: glBlendFunc(GL_DST_ALPHA, GL_ZERO)
  • out: glBlendFunc(GL_ONE_MINUS_DST_ALPHA, GL_ZERO)

Previous slide

Next slide

Back to first slide

View graphic version