Move Drawable.NONE into new RenderConstants

This constant will soon be shared with another class.

src/Drawable.js

@@ -2,6 +2,7 @@ const twgl = require('twgl.js');
 const xhr = require('xhr');
 
 const Rectangle = require('./Rectangle');
+const RenderConstants = require('./RenderConstants');
 const SvgRenderer = require('./svg-quirks-mode/svg-renderer');
 const ShaderManager = require('./ShaderManager');
 
@@ -86,14 +87,6 @@ class Drawable {
         this.setSkin(Drawable._DEFAULT_SKIN);
     }
 
-    /**
-     * An invalid Drawable ID which can be used to signify absence, etc.
-     * @type {int}
-     */
-    static get NONE () {
-        return -1;
-    }
-
     /**
      * Fetch a Drawable by its ID number.
      * @param {int} drawableID The ID of the Drawable to fetch.
@@ -496,12 +489,12 @@ class Drawable {
 
     /**
      * Calculate a color to represent the given ID number. At least one component of
-     * the resulting color will be non-zero if the ID is not Drawable.NONE.
+     * the resulting color will be non-zero if the ID is not RenderConstants.ID_NONE.
      * @param {int} id The ID to convert.
      * @returns {number[]} An array of [r,g,b,a], each component in the range [0,1].
      */
     static color4fFromID (id) {
-        id -= Drawable.NONE;
+        id -= RenderConstants.ID_NONE;
         const r = ((id >> 0) & 255) / 255.0;
         const g = ((id >> 8) & 255) / 255.0;
         const b = ((id >> 16) & 255) / 255.0;
@@ -510,7 +503,7 @@ class Drawable {
 
     /**
      * Calculate the ID number represented by the given color. If all components of
-     * the color are zero, the result will be Drawable.NONE; otherwise the result
+     * the color are zero, the result will be RenderConstants.ID_NONE; otherwise the result
      * will be a valid ID.
      * @param {int} r The red value of the color, in the range [0,255].
      * @param {int} g The green value of the color, in the range [0,255].
@@ -522,7 +515,7 @@ class Drawable {
         id = (r & 255) << 0;
         id |= (g & 255) << 8;
         id |= (b & 255) << 16;
-        return id + Drawable.NONE;
+        return id + RenderConstants.ID_NONE;
     }
 }
 

src/RenderConstants.js

@@ -0,0 +1,11 @@
+/**
+ * Various constants meant for use throughout the renderer.
+ * @type {object}
+ */
+module.exports = {
+    /**
+     * The ID value to use for "no item" or when an object has been disposed.
+     * @type {int}
+     */
+    ID_NONE: -1
+};

src/RenderWebGL.js

@@ -2,6 +2,7 @@ const hull = require('hull.js');
 const twgl = require('twgl.js');
 
 const Drawable = require('./Drawable');
+const RenderConstants = require('./RenderConstants');
 const ShaderManager = require('./ShaderManager');
 
 /**
@@ -341,7 +342,7 @@ class RenderWebGL {
         gl.viewport(0, 0, bounds.width, bounds.height);
         const projection = twgl.m4.ortho(bounds.left, bounds.right, bounds.bottom, bounds.top, -1, 1);
 
-        const noneColor = Drawable.color4fFromID(Drawable.NONE);
+        const noneColor = Drawable.color4fFromID(RenderConstants.ID_NONE);
         gl.clearColor.apply(gl, noneColor);
         gl.clear(gl.COLOR_BUFFER_BIT | gl.STENCIL_BUFFER_BIT);
 
@@ -383,7 +384,7 @@ class RenderWebGL {
                 pixels[pixelBase],
                 pixels[pixelBase + 1],
                 pixels[pixelBase + 2]);
-            if (pixelID > Drawable.NONE) {
+            if (pixelID > RenderConstants.ID_NONE) {
                 return true;
             }
         }
@@ -399,7 +400,7 @@ class RenderWebGL {
      * @param {int} touchHeight The client height of the touch event (optional).
      * @param {int[]} candidateIDs The Drawable IDs to pick from, otherwise all.
      * @returns {int} The ID of the topmost Drawable under the picking location, or
-     * Drawable.NONE if there is no Drawable at that location.
+     * RenderConstants.ID_NONE if there is no Drawable at that location.
      */
     pick (centerX, centerY, touchWidth, touchHeight, candidateIDs) {
         const gl = this._gl;
@@ -427,7 +428,7 @@ class RenderWebGL {
         twgl.bindFramebufferInfo(gl, this._pickBufferInfo);
         gl.viewport(0, 0, touchWidth, touchHeight);
 
-        const noneColor = Drawable.color4fFromID(Drawable.NONE);
+        const noneColor = Drawable.color4fFromID(RenderConstants.ID_NONE);
         gl.clearColor.apply(gl, noneColor);
         gl.clear(gl.COLOR_BUFFER_BIT);
 
@@ -467,9 +468,9 @@ class RenderWebGL {
         }
 
         // Bias toward selecting anything over nothing
-        hits[Drawable.NONE] = 0;
+        hits[RenderConstants.ID_NONE] = 0;
 
-        let hit = Drawable.NONE;
+        let hit = RenderConstants.ID_NONE;
         for (const hitID in hits) {
             if (hits.hasOwnProperty(hitID) && (hits[hitID] > hits[hit])) {
                 hit = hitID;
@@ -663,8 +664,8 @@ class RenderWebGL {
         twgl.bindFramebufferInfo(gl, this._queryBufferInfo);
         gl.viewport(0, 0, width, height);
 
-        // Clear the canvas with Drawable.NONE.
+        // Clear the canvas with RenderConstants.ID_NONE.
-        const noneColor = Drawable.color4fFromID(Drawable.NONE);
+        const noneColor = Drawable.color4fFromID(RenderConstants.ID_NONE);
         gl.clearColor.apply(gl, noneColor);
         gl.clear(gl.COLOR_BUFFER_BIT);
 
@@ -692,7 +693,7 @@ class RenderWebGL {
          * Helper method to look up a pixel.
          * @param {int} x X coordinate of the pixel in `pixels`.
          * @param {int} y Y coordinate of the pixel in `pixels`.
-         * @return {int} Known ID at that pixel, or Drawable.NONE.
+         * @return {int} Known ID at that pixel, or RenderConstants.ID_NONE.
          */
         const _getPixel = (x, y) => {
             const pixelBase = ((width * y) + x) * 4;
@@ -704,14 +705,14 @@ class RenderWebGL {
         for (let y = 0; y <= height; y++) {
             // Scan from left.
             for (let x = 0; x < width; x++) {
-                if (_getPixel(x, y) > Drawable.NONE) {
+                if (_getPixel(x, y) > RenderConstants.ID_NONE) {
                     boundaryPoints.push([x, y]);
                     break;
                 }
             }
             // Scan from right.
             for (let x = width - 1; x >= 0; x--) {
-                if (_getPixel(x, y) > Drawable.NONE) {
+                if (_getPixel(x, y) > RenderConstants.ID_NONE) {
                     boundaryPoints.push([x, y]);
                     break;
                 }