“Stencil routed A-Buffer” by Myers and Bavoil

  • ©Kevin Myers and Louis Bavoil




    Stencil routed A-Buffer



    We have developed a stencil routing algorithm for implementing a GPU accelerated A-Buffer, by using a multisample texture to store a vector of fragments per pixel. First, all the fragments are captured per pixel in rasterization order. Second, a fullscreen shader pass sorts the fragments using a bitonic sort. At this point, the sorted fragments can be blended arbitrarily to implement various types of algorithms such as order independent transparency or layered depth image generation. Since we handle only 8 fragments per pass, we developed a method for detecting overflow, so we can do additional passes to capture more fragments.


    1. Carpenter, L. 1984. The a -buffer, an antialiased hidden surface method. In SIGGRAPH ’84: Proceedings of the 11th annual conference on Computer graphics and interactive techniques.
    2. Everitt, C. 2001. Interactive order-independent transparency. Tech. rep., NVIDIA Corporation.
    3. Purcell, T. J., Donner, C., Cammarano, M., Jensen, H. W., and Hanrahan, P. 2003. Photon mapping on programmable graphics hardware.

ACM Digital Library Publication:

Overview Page: