Get average of vertex colours instead of interpolation

I have set up a vertex colouring system but ofcourse that creates a big blur as it interpolates between the three vertices colours. Yes the vertices are split so triangles don't share any vertices. So I wonder if it's possible to get an average, this way all vertices can have their own colour as well as the triangle being a flat colour. It feels like storing a colour per triangle would be much harder as the mesh is dynamicly created with the marching cubes algoritmen. Currently every point in the grid has a colour and the vertices of the mesh should get their colours from that. Atm every vertex takes it from the nearest point. Thanks.

 

Using only a vertex fragment shader, no, there's no way to get an average. Your options are the interpolated value, or to use something like a nointerpolation modifier on the value to get only the value on the first vertex of the triangle. If you move to adding a geometry shader stage, you can get all 3 vertices of a triangle and average the color value, then re-assign them.

But it seems odd to me that if your vertices are already split you don't have someplace in your code where you're dealing with a single triangle and it's 3 vertices where you could average the color, or perhaps get the color from the average of the 3 vertex positions (ie: the triangle center)?

 

Getting the average beforehand is defently a good way to go and then take in those values for all vertices or is it better to take it in once per triangle?

 

Presumably it'd cost less to only do one sample per triangle rather than 3 and interpolate?

 

Wonder how to give it to the shader tho. Mesh.setcolors results in vertex colours so how would I have one per triangle?

 

By setting it on all of the vertices of that triangle. Maybe additionally using nointerpolation as a minor optimization so the GPU doesn't try to interpolate between the same color.

Alternatively if you want to get fancy you could use the primitive id (SV_PrimitiveID) and an array or structured buffer with the color data.