MAXAR_collision_geometry

extensions/2.0/Vendor/MAXAR_collision_geometry/README.md

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+# MAXAR_collision_geometry
+
+## Contributors
+
+* Erik Dahlström, Maxar, [@erikdahlstrom](https://github.com/erikdahlstrom)
+* Sam Suhag, Cesium, [@sanjeetsuhag](https://github.com/sanjeetsuhag)
+
+## Status
+
+Draft
+
+## Dependencies
+
+Written against the glTF 2.0 spec.
+
+## Overview
+
+In gaming and simulation engines, high resolution 3D models are often paired with decimated versions of the model that are optimized for use in rigid-body physics. These collision volumes are the union of a set of convex polyhedra. This extension to glTF enables designating meshes as collision volumes for other meshes.
+
+## Adding Collision Meshes
+
+The following example illustrates how a mesh can designate another mesh as its collision volume:
+
+```json
+"meshes": [
+  {
+    "name": "Detailed Car Mesh",
+    "primitives": [
+      {
+        "attributes": {
+          "POSITION": 0,
+          "NORMAL": 1
+        },
+        "indices": 2
+      }
+    ],
+    "extensions": {
+      "MAXAR_collision_geometry": {
+        "mesh": 1
+      }
+    }
+  },
+  {
+    "name": "Box Collision Mesh",
+    "primitives": [
+      {
+        "attributes": {
+          "POSITION": 3,
+        },
+        "indices": 4
+      }
+    ]
+  },
+]
+```
+
+### Mesh Requirements
+
+This extension enforces the following rules on the relationships between meshes:
+
+1. Two or more meshes may use the same mesh as a collision mesh.
+2. A mesh may not designate itself as its collision mesh.
+3. A mesh with a collision mesh must not have morph targets.
+4. A collision mesh must not have morph targets.
+5. At runtime, the node transformation of a mesh must be applied to its collision mesh.
+
+### Primitive Requirements
+
+This extension enforces the following rules on the primitives inside a collision mesh:
+
+1. Primitives in a collision mesh must have the POSITION attribute.
+2. Primitives in a collision mesh must use the TRIANGLES primitive mode.
+3. Each primitive inside a collision mesh must represent a convex polyhedron.
+
+## Optional vs. Required
+
+This extension is considered optional, meaning it should be placed in the glTF root's `extensionsUsed` list, but not in the `extensionsRequired` list.
+
+## Schema Updates
+
+- **glTF mesh extension JSON schema**: [mesh.MAXAR_collision_geometry.schema.json](schema/mesh.MAXAR_collision_geometry.schema.json)

extensions/2.0/Vendor/MAXAR_collision_geometry/schema/mesh.MAXAR_collision_geometry.schema.json

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+{
+  "$schema": "http://json-schema.org/draft-04/schema",
+  "title": "MAXAR_collision_geometry mesh extension",
+  "type": "object",
+  "description": "Collision volumes for a mesh.",
+  "allOf": [
+    {
+      "$ref": "glTFProperty.schema.json"
+    }
+  ],
+  "properties": {
+    "mesh": {
+      "allOf": [
+        {
+          "$ref": "glTFid.schema.json"
+        }
+      ],
+      "description": "The index of the mesh to use as a collision volume."
+    },
+    "extensions": {},
+    "extras": {}
+  },
+  "required": [
+    "mesh"
+  ]
+}