CODEWITHSUNDEEP
iosshadermetal
aledalgrande
aledalgrande

Reputation: 5227

Dynamic output from compute shader

If I am generating 0-12 triangles in a compute shader, is there a way I can stream them to a buffer that will then be used for rendering to screen?

My current strategy is:

If I want to render from this though, I would need to skip the empty memory. It sounds ugly, but probably there is no other way currently. I know CUDA geometry shaders can have variable length output, but I wonder if/how games on iOS can generate variable-length data on GPU.

UPDATE 1:

As soon as I wrote the question, I thought about the possibility of using a second buffer that would point out how many triangles are available for each block. The vertex shader would then process all vertices of all triangles of that block.

This will not solve the problem of the unused memory though and as I have a big number of threads, the total memory wasted would be considerable.

Upvotes: 4

Views: 1898

Answers (1)

Adam Miles
Adam Miles

Reputation: 3584

What you're looking for is the Metal equivalent of D3D's "AppendStructuredBuffer". You want a type that can have structures added to it atomically.

I'm not familiar with Metal, but it does support Atomic operations such as 'Add' which is all you really need to roll your own Append Buffer. Initialise the counter to 0 and have each thread add '1' to the counter and use the original value as the index to write to in your buffer.

Upvotes: 4

Related Questions