Collision Mask

Hello,

In blender game engine. We can use collision group and collision mask. But currently, blender only have collision collection. The combination of collision group and collision mask has better flexibility and hence is more powerful.

Without collision mask, the only way to avoid collision using collision collection is to stagger collections. But there are only 20 collections which is not enough.

When making a character animation, it's easy to have more than 100 rigid bodies. Especially when a character has very long hair. In this case, just the hair can have more than 50 rigid bodies. To manage the collision relationship between all the rigid bodies of a whole character required to consider the distance between them. Try to use 20 collections appropriately.

A "workaround" is to use a lot of empty as rigid body constrains and turn on "Disable collision between constrained rigid bodies." option. Use this workaround to simulate collision mask. This can lead to a performance issue.

I hope blender can add collision mask because the whole MMD community really need this. MMD is a program to make character dancing videos. And blender is going to replace it since blender is more powerful. However the key point is that MMD has collision mask and blender doesn't have collision mask. So the MMD community face a problem to handle rigid body physics for MMD models in blender.

Not only MMD but also other 3D software have collision mask will has compatibility issues when they want to do the same thing in Blender.