First Compute Shader

This week I am still very much in pre-production.  I am still setting up my system for profiling cpu and shader resources so I thought I would make a couple of hello world shaders and see what I need to do in order to collect the performance data I want.  I am focusing on DirectCompute's impact on render techniques (even though the compute shader can be used for many other things like physics) so my first shader reads in a texture, manipulates the data and then displays the output texture.

Input Texture

 

The compute shader take the input texture and multiplies it with the a horizontally and vertically flipped version of the input and then passes the resulting data out as a texture which is then rendered to the screen as:

Output from Compute Shader

The CS ends up creating a "thread" (term used by DC, even though it is not exactly a true thread) for each pixel on the screen.  The breakdown is as follows:

32, 24, 1 Thread groups (so a 2D grid 32 x 24)

20, 20, 1 Threads per group (so another 2D grid this time of 20x20)

The result is 640 x 480 total threads, and as the input image is 640 x 480 this relates to one thread per pixel

                                   

While this is not exactly exciting output, it has given me an initial program that I can use with my performance analyser tools, and it has the basics of the applications I will be writing in the production phase.  It has a DirectX Render context, and it uses the compute shader to produce a final texture that is rendered to the screen.

This test is also the start of my DirectX 11 framework, that will no doubt grow and improve as the project progresses, and hopefully these tests will help me determine what to include in my Renderer.