I was trying to achieve an effect like this: I have a mesh with multiple faces, and I want to animate each face appearing sequentially (to show a quickhull being constructed). To this pupose, I tried creating a mesh with one material for each face, but I’m having a problem with the transparencies.
In this example, I have the red face as the first one, and the blue face as the second one. If I set the alpha of both faces to the same value, let’s say 0.5, the effect is as expected:
If I increase the alpha of the second face and decrease the first, it also makes sense (0.2 to red, 1.0 to blue):
However, if I increase the alpha of the first face and decrease the second, I can’t see anything behind the second face anymore:
Here’s the playground link for the example above: https://playground.babylonjs.com/#Y8HRP3#9
I also tried a slightly more complex 3D object and got the same result. Setting the alpha of the first face material to 1.0 makes the whole object opaque:
However, if I try the same with the MultiMaterials demo, I can achieve the desired effect with no problems, so I assume there is a way to achieve this effect and I’m doing something wrong: https://playground.babylonjs.com/#2Q4S2S#529