Godot Version
4.3 dev and 4.2 stable
Question
I would like to give an example of application: Imagine that you want to build a child’s room, and inside it you want to place a row of domino pieces. The room can be a few meters in size and the pieces can be a few centimeters in size.
MY PROBLEM: Small rigid bodies (whose dimensions are a few centimeters). To properly identify the problem I made a simple test scene. In my scene (root node) I do the following constructions…
I create a “floor”: A StaticBody3D node with position (0,0,0), which has a child MeshInstance3d, wich uses a PlaneMesh resource (by default 2m x 2m). Having chosen the MeshInstance3d node, I click on the Mesh button in the toolbar (above the scene display area) and choose “Create Single Convex Collision Sibling” (it creates a CollisionShape3D)
I create a “Big” block: A RigidBody3D node with position (0.5,0.51,0.5), which has a child MeshInstance3d, and uses a BoxMesh resource (by default 1mx1mx1m). Having chosen the MeshInstance3d node, I click on the Mesh button the toolbar (above the scene display area) and choose “Create Single Convex Collision Sibling” (it creates a CollisionShape3D)
I create a “Small” block: A RigidBody3D node with position (-0.5,0.01,-0.5), which has a child MeshInstance3d, and uses a BoxMesh resource. I make it unique and set its Size property to 0.01 in all three directions. Having chosen the MeshInstance3d node, I click on the Mesh button in the toolbar (above the scene display area) and choose “Create Single Convex Collision Sibling” (it creates a CollisionShape3D)
Additionally I added a camera and light to the scene…
When I play the scene, the Big block rests on the floor as expected. But the small block crosses the floor and falls to the unknow. I have repeated this test placing that block higher but the result is the same. Then I also created a floor using a BoxMesh (that is, it has a certain thickness). But for a thickness of 0.01 the small block also passes through it and for a thickness of 0.02 or greater the small block remains vibrating erratically, partially penetrated into the box (the floor).
Additionally, the orange boxes (I think they are called “bounding boxes”) look too big for small MeshInstance3D nodes. Also when the body is not a cube the orange box of CollisionShape3D nodes can protrude in some direction.
I would like to know if there is a way to make physics work better at the 0.01 size scale or if the only alternative is to make everything larger. I feel that the coexistence of objects with a size ratio of 1 to 100 is perfectly expected, but perhaps I am wrong.
Thank you very much in advance
