Add EXT_animation_map extension spec

extensions/Vendor/EXT_animation_map/README.md

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+# EXT_animation_map 
+
+## Contributors
+
+* Michael Feldstein, Facebook, [@msfeldstein](https://twitter.com/msfeldstein)
+* Ocean Quigley, Facebook, [@oceanquigley](https://twitter.com/oceanquigley)
+
+## Status
+
+Draft
+
+## Dependencies
+
+Written against the glTF draft 2.0 spec.
+
+## Overview
+
+This extensions maps optional semantic meaning to animations so that client applications can attach interactive and reactive behaviors to the 3d models and scenes. This can be useful to let a client know to play a certain animation when the model first enters a scene, or when a model is about to leave.
+
+Facebook uses it to play animations when a model enters/leaves the feed, or scrubs an animation as the user scrolls the model through the screen.
+It is also used to respond to user events, such as tapping, or horizontal panning
+
+It maps a semantic, which can be any string a client wishes to bind, to an array of animation indices, pointing to a list of gltf Animation.
+
+##### Example Semantics
+
+* **ENTER**: Trigger a single shot animation when the object first enters the scene or viewport
+* **LEAVE**: Trigger a single shot animation as the object is leaving the scene or viewport
+* **ALWAYS**: Constantly loop an animation
+* **TRIGGER**: A user triggering a single shot animation on Touch, Tap, Click, or any other way of activating
+* **GRAB**: Triggered when an object is picked up, for example grabbed in vr, or dragged in WebGL.
+* **HELD**: Looped during the entire duration an object is grabbed.
+* **RELEASED**: Triggered when an object is released from a grab.
+* **GAZE_ENTER**: Triggered when an object is first looked at
+* **GAZE**: Looped while an object is being looked at
+* **GAZE_LEAVE**: Triggered when an object stops being looked at
+* **PROXIMITY_ENTER**: Triggered when a viewer gets close to an object
+* **PROXIMITY**: Looped while a viewer is near to an object
+* **PROXIMITY_LEAVE**: Triggered when a viewer gets further from an object
+
+## glTF Schema Updates
+
+The new EXT_animation_map property is a root glTF level optional extension object. The **bindings** array is a list of objects with a semantic, and an array of animations mapped to that semantic.
+
+**Listing 1**: An animation map that binds animations 0 and 3 to the ENTER event, 1 to the LEAVE event, and 2 to loop continuously for the life of the object.
+
+```javascript
+{
+ "extensionsUsed": {
+ "EXT_animation_map"
+ },
+ "extensions" : {
+ "EXT_animation_map" : {
+ "bindings": [
+ {
+ "semantic": "ENTER",
+ "animations": [0, 3]
+ },
+ {
+ "semantic": "LEAVE",
+ "animations": [1]
+ },
+ {
+ "semantic": "ALWAYS",
+ "animations": [2]
+ }
+ ]
+ }
+ }
+}
+```
+
+### JSON Schema
+
+TODO: Links to the JSON schema for the new extension properties.
+
+## Known Implementations
+
+* None yet, will be implemented in Facebook 3d Posts
+
+## Resources
+
+* 

extensions/Vendor/EXT_animation_map/schema/EXT_animation_map.schema.json

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+{
+ "$schema" : "http://json-schema.org/draft-04/schema",
+ "title" : "EXT_animation_map extension",
+ "type" : "object",
+ "definitions": {
+ "semanticBinding": {
+ "type": "object",
+ "properties": {
+ "semantic": {
+ "type": "string"
+ },
+ "animations": {
+ "type": "array",
+ "items": {
+ "type": "number",
+ "minimum": 0
+ }
+ }
+ }
+ }
+ },
+ "properties" : {
+ "bindings" : {
+ "type" : "array",
+ "description" : "A list of bindings between event or state semantics and animation indexes",
+ "items": { "$ref": "#/definitions/semanticBinding" }
+ }
+ },
+ "required" : ["bindings"]
+}