Building a collision mesh for JanusWeb in Blender (timelapse)
Time lapse of building a simplified collision mesh for a Matterport scan in Blender. In this case we model the entire world using only cubes. We start with a cube with the _collider-box material, then we duplicate and scale it until we've blocked out the whole level.
At 3:30 for the stairs, the technique used is to model one step and then create an array modifier and set its count to the number of stairs we have. Then resize the stair horizontally and vertically until it fits perfectly.
At the end, select all collision mesh objects and apply their scale (ctrl+a, scale) before exporting as a .obj. Make sure you check "selection only", and you can uncheck "Write Normals" and "Include UVs" - they're not needed for our purposes.