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How would I go about making a global texture3d variable which I can modify in the geometry shader (HLSL)?

The size would be 64x64x64.

I would fill it up once in the first renderpass and use it in the second renderpass.

Any help appreciated. Preferably using D10.

EDIT:

I'm making a marching cube terrain shader by following this https://developer.nvidia.com/gpugems/GPUGems3/gpugems3_ch01.html guide (See paragraph 1.4). I got the geometry shader done it's just that I don't have normals and the guide suggests that I can create them by storing data in texture3D but I don't know how I can put data in a texture3D. (The guide is using DX10).

fospathi
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Achille Depla
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  • Maybe this would help, the GS version should work in DX10 as well http://stackoverflow.com/questions/29124668/rendering-to-a-full-3d-render-target-in-one-pass/29544276#29544276 – mrvux May 23 '15 at 13:48

2 Answers2

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You are probably thinking of a compute shader. In this case, you would declare your texture as an RWTexture3D in the compute shader, and then sample it in your render pass as a Texture3D. There are many resources/tutorials/examples on the internet about compute shaders to help you get started.

You cannot modify textures with a geometry shader in D3D11. The only thing that a geometry shader can do is generate primitives. However, as @Adam Miles answer states, it is possible to write the RWTexture3D in a geometry shader in D3D11.1. While this is feasible, unless you are also generating primitives with your geometry shader, it probably makes most sense to do it in a compute shader.

If you are working in D3D 10.x via the D3D11 API, you can still use compute shaders, although you cannot use an RWTexture3D type. You would have to view it as an RWByteAddressBuffer, and index it yourself which would be slightly awkward. You don't necessarily need to generate texture data within a shader, you can write into the texture with the CPU, by mapping it and writing the data directly. See ID3D10Texture3D::Map for more information.

MuertoExcobito
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  • Thanks for your answer but is there no way to do this in directx10? I'm making a marching cube terrain shader by following this http://http.developer.nvidia.com/GPUGems3/gpugems3_ch01.html guide (See paragraph 1.4). I got the geometry shader done it's just that I don't have normals and the guide suggests that I can create them by storing data in texture3D but I don't know how I can put data in a texture3D. (The guide is also using DX10). – Achille Depla May 21 '15 at 16:57
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If you're willing to support Direct3D 11.1 cards and above you can achieve what it is you're asking using an RWTexture3D, contrary to the other answer.

You're free to bind a 64x64x64 RWTexture3D to the Geometry Shader stage and write to it in the same way you would in a Compute Shader.

See Use UAVs at every pipeline stage for what's now possible.

Adam Miles
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  • Thanks for your answer but is there no way to do this in directx10? I'm making a marching cube terrain shader by following this http://http.developer.nvidia.com/GPUGems3/gpugems3_ch01.html guide (See paragraph 1.4). I got the geometry shader done it's just that I don't have normals and the guide suggests that I can create them by storing data in texture3D but I don't know how I can put data in a texture3D. (The guide is also using DX10). – Achille Depla May 21 '15 at 16:57