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I'm working on terrain generation using marching cubes. As of now I'm able to generate the terrain vertices in a compute shader but I can't figure out how to draw the mesh without reading the vertices back to the cpu and assigning them to a new mesh object. the marching cubes compute shader output is an AppendStructuredBuffer where the vertices are set up so every 3 consecutive vertices in the buffer makes one triangle.

output is an append buffer of triangles:

struct Triangle { float3 a, b, c; };
AppendStructuredBuffer<Triangle> triangles;

I've looked at Graphics.DrawProcedural but it looks like I need to write a custom shader for that which would take in the compute buffers and draw from them but idk how to make that work since I only have access to shadergraph in urp. Mesh.SetVertexBufferData seemed promising but it won't take a pointer to a compute buffer on the gpu, only C# arrays and lists which it then sends over.

crfellows
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1 Answers1

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So I'm looking into doing the same thing as well, and my understanding is that yes, you do need a custom shader. However, you said "... I only have access to shadergraph in urp." but you can actually write custom shaders. It's called ShaderLab (I think?).

Here are some resources for other people looking to get started:

https://docs.unity3d.com/Packages/com.unity.render-pipelines.universal@8.2/manual/writing-custom-shaders-urp.html

https://www.cyanilux.com/tutorials/urp-shader-code/

And specifically, the latest unity docs give an example of a shader that reads from a graphics buffer (can be used in the same way as a compute buffer):

https://docs.unity3d.com/ScriptReference/Graphics.RenderPrimitives.html

I think you could start with a full working surface shader (that supports shadows or whatever you need) and then try adding in your compute buffer?

Oarc
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