This article will use 3DS Max, so if you don't use that you'll have to wait until we get a blender equivalent up and running.
Overview:
Basic Concepts and Explanations:
Rules a Collision Model must follow:
- A collision model must be made entirely out of convex elements.
- A collision model must not have any open edges or faces.
- A collision model must be smoothed in a very specific fashion. All smoothing must be cleared off of the model, and then each element gets it's own unique smoothing group. You may reuse smoothing groups, but only on the condition that no two elements that come into contact with each other share a group. [1][2][1] would be valid, [1][1][2] would not be valid.
- A collision model must have a texture applied to it, or it will not export or compile. It does not matter what the texture is, and it does not matter if it has UV maps or not.
Differentiation of Convex and Concave elements and shapes
- You can define "convex" as a mesh where you can draw a direct line in 3D space from any two points on the model's surface and *not* leave the surface or interior volume of the mesh at any point.
- The shapes on the left of the below image are Convex, and thus are valid as elements of a collision model. The shapes on the right are Concave, and thus will throw errors when compiling and in general screw up your collision. You can, however, re-build the shapes on the right out of convex objects and you will have a valid collision model.
Below, we can see a concave object being recreated out of convex elements.
Top left: detailed model
Top right: all detail cleaned from model
Bottom left: concave elements separated into individual convex elements, which are then reassembled into the...
Bottom right: final collision model with smoothing applied.
Process In-Depth
Step 1
Basic Detail model, no modifications.
Step 2
Step 3
Text Explanation/Process Followed
Step 4
Text Explanation/Process Followed
Image
Step 5
Text Explanation/Process Followed
Image
Step 6
Text Explanation/Process Followed
Image
Step 7
Text Explanation/Process Followed
Image