GPU Pro 6

536 VII 3D Engine Design

output, as we described in Section 3.4.3, to capture texture data into a buffer

using a vertex shader. Direct3D’s constraints on stream output notably lack

support for some data types, making this quite challenging. Compute shaders

also offer a promising and elegant solution. Since we are limited to supporting

Shader Model 4 as a minimum, we unfortunately couldn’t rely on compute shaders

in all cases.

More problems arise from the different requirements GL and Direct3D 11

both enforce on the data packing after the asynchronous copy step. GL gives a

set of fine-grained pack parameters, which control how the pixel data packs into

the ...