Question by spiceboy9994 · Aug 20, 2013 at 03:24 PM · mesh vertices vertex color mesh color

Vertex Material add Burn Mark on Hit

Hi:

I am very new on the the UVs and meshes Vertices and colors topic. So I need to ac$$anonymous$$eve the following. I have a scene with a Single Model. The model has a Vertex Colored Shader Material with a single texture over it. I have a code that allows you to place a flame sprite over the model where you actually place the flame. I have the code that allows the player to drag the flame over the model and adds burn physics to the flame and the model, I have also placed some nice burning sound. However, Im not sure about how to ac$$anonymous$$eve the following: burn the material where the flame $$anonymous$$t occurred, by changing the vertex colors of the mesh only on the spot where the flame was burning. I know that I have to change the color Array of the mesh, but I dont know how to get the specific "polygons" or "area" where the $$anonymous$$t actually took place. Does anyone know a resource that I can refer to learn how to do t$$anonymous$$s?

Thanks a lot.

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spiceboy9994 · Aug 20, 2013 at 03:36 PM 0

Another important thing is that needs to be an "Area burn"... not just changing the color of specific pixel point. Thanks a lot again

$$anonymous$$ · Aug 20, 2013 at 03:51 PM 0

If your model isn't a SkinnedMesh you can try to apply a decal. If you download the free asset Bootcamp from the store there is a simple decal system, that build a decal mesh on the fly based on the collision of the object hit and apply a decal texture. But if your model is a SkinnedMesh you can't do that as the decal would need to be rigged within the bone hierarchy of the mesh.

Alternatively to paint the vertcies you can do with a raycast, fire a a raycast toward the mesh from the flame, and from the raycast try to find the nearest vertices of the hit point, then build an array from what can be found and color them.

Check this for further info on this second method:

http://answers.unity3d.com/questions/43415/finding-the-polygonface-youre-currently-looking-at.html

robertbu · Aug 21, 2013 at 04:39 AM 0

You do a Physics.Raycast() or a Collider.Raycast() to the point of the flame. The RaycastHit structure returns a RaycastHit.triangleindex. This index allows you to find the three vertices of the triangle hit by the raycast. There are sample source on the reference page for finding vertices from the RaycastHit.triangleindex. Since there is a one-to-one correspondence between vertices and vertex colors, the same logic finds the the colors in the color array:

     var c0 = colors[triangles[hit.triangleIndex * 3 + 0]];
     var c1 = colors[triangles[hit.triangleIndex * 3 + 1]];    
     var c2 = colors[triangles[hit.triangleIndex * 3 + 2]];

spiceboy9994 robertbu · Aug 29, 2013 at 08:51 PM 0

This answer implies that the mesh are components of the same game object right?, thanks so much, but it is not the case.

spiceboy9994 · Aug 29, 2013 at 08:51 PM 0

I have been struggling with this solution, but heres some important factor: the mesh and the colliders are different game objects. I have a gameobject that has the whole mesh of the model, and different colliders for each limb of my model (since it is a ragdoll). I have tried the second method, but the burning is not precise.