README tweaks

extensions/2.0/Vendor/EXT_implicit_geometry/README.md

@@ -12,7 +12,7 @@ Written against the glTF 2.0 specification.
 
 ## Overview
 
-This extension allows mesh primitives to represent renderable implicit surfaces. Typically, a glTF mesh primitive requires `attributes` that supply mesh data, and uses `mode` to indicate the mesh topology. With `EXT_implicit_geometry`, the primitive may omit these properties. The extension's properties will be used instead to infer the implicit 3D volume.
+This extension allows mesh primitives to represent renderable implicit surfaces. Typically, a glTF mesh primitive requires `attributes` that supply mesh data, and uses `mode` to indicate the mesh topology. With `EXT_implicit_geometry`, the primitive may omit these properties and instead use the extension to infer the implicit 3D volume.
 
 The following example illustrates how a primitive with this extension may represent an implicit box.
 
@@ -43,7 +43,7 @@ Currently, this extension supports the following implicit geometries:
 - [`ellipsoid`](#ellipsoid)
 - [`region`](#region)
 
-Each shape is represented by its aptly named property in the extension. Only **one** shape may be defined at a time.
+Only **one** shape may be defined at a time.
 
 By default, the implicit 3D volume is assumed to fill the entire shape specified in the extension. However, each shape allows an optional `bounds` property to define the subsection of the shape in which the 3D volume is actually rendered. For instance, while the extension may define an implicit sphere, its `bounds` can limit the volume to be only half of the full sphere.
 
@@ -137,5 +137,25 @@ The implicit **sphere** is centered at the origin in local space. The unit spher
 
 The implicit **ellipsoid** is centered at the origin in local space. The unit ellipsoid has radii of `[1, 1, 1]` along the `x`, `y`, and `z` axes. The `radii` property is used to scale the ellipsoid along these axes in meters.
 
+**TODO** visual example
+
+```
+{
+  "primitives": [
+    {
+      "extensions": {
+        "EXT_implicit_geometry": {
+          "sphere": {
+            "radii": [2, 3, 4]
+          }
+        }
+      }
+    }
+  ]
+}
+```
+
+### Region
+
 ## Optional vs. Required
 This extension is required, meaning it should be placed in both the `extensionsUsed` list and `extensionsRequired` list.