Adjusts terrain elevation so plateau elevation is exactly what's requ…

…ested

README.md

@@ -23,7 +23,7 @@ Usage
 
 Include using 
 ```html
-<script src="https://unpkg.com/aframe-atoll-terrain@^0.7.0/dist/aframe-atoll-terrain.js"></script>
+<script src="https://unpkg.com/aframe-atoll-terrain@^1.0.0/dist/aframe-atoll-terrain.js"></script>
 ```
 
 
@@ -44,12 +44,6 @@ Parameters
 Typically, you'll leave the entity position and rotation as zero, but you don't have to.
 
 
-### mean-elevation
-* default: 10
-
-The average elevation of the high-resolution area, in meters (before the sea floods everything below 0).
-
-
 ### plateau-radius
 * default: 10
 * minimum: 0
@@ -59,10 +53,23 @@ Radius of the central plateau, in meters.
 If radius is 0, there is no plateau.
 
 
-### plateau-elevation-min
+### plateau-elevation
+* minimum: 0
 * default: 1
 
-Minimum elevation of the plateau.  Can be 0, in which case the "plateau" might be sea or land.
+Elevation of the plateau.  If zero, forces there to be water in the center of the island.
+
+If this is zero and `plateau-radius` is a large fraction of `middle-radius`, you'll have a ring-shaped island - an atoll!
+
+
+### elevation-bias
+* default: 0
+
+When there is no plateau, this is the elevation of the high-resolution area before noise is applied, in meters.
+
+When there is a plateau, the elevation of the high-resolution area is automatically adjusted so the plateau blends in.
+Leave this at zero, unless you want a volcano or an isolated plateau.
+
 
 ### plateau-yin-color, plateau-yang-color
 * default: land-yin-color, land-yang-color
@@ -111,7 +118,7 @@ The color of the sea smoothly varies between these two extremes.
 * default: {x:-1.0, y:1.0, z:-1.0}
 
 The direction from which the sun is shining.
-This primitive ignores directional lights, but others may use them.
+This primitive ignores directional lights.
 If you're using one of the *-sun-sky primitives, set its sun-position to the same value.
 
 
@@ -133,6 +140,17 @@ A number greater than zero and less than one, from which the terrain will be ran
 Whether to write diagnostic data to the console. 
 
 
+Extracting Elevation data
+-------------------------
+
+The geometry component has a `getElevation` method, which returns the approximate elevation of a point:
+
+```javascript
+const terrainGeometry = this.el.querySelector('a-atoll-terrain').getAttribute('geometry');
+const spherePosition = document.querySelector('a-sphere').getAttribute('position');
+spherePosition.y = terrainGeometry.getElevation(spherePosition.x, spherePosition.z) + 1.6;
+```
+
 
 Development
 ---

example.html

@@ -52,17 +52,17 @@
     <a-entity light="type: ambient; color: #888"></a-entity>
     <a-entity id="directional" light="type: directional; color: #FFF; intensity: 0.6" position="0.7 0.4 -1"></a-entity>
 
-    <a-sphere position="0 11.6 -5" radius="0.6" color="#EF2D5E" shadow></a-sphere>
+    <a-sphere position="0 11.6 -2" radius="0.6" color="#EF2D5E" shadow></a-sphere>
     <!-- terrain which is likely to have a good vista from the plateau, and runs ok on mobile -->
-    <a-atoll-terrain mean-elevation="3"
-                     plateau-radius="10"
+    <a-atoll-terrain plateau-radius="15" plateau-elevation="5"
+                     elevation-bias="0"
                      middle-radius="300" unit-size="2" far="1900"
                      sun-position="0.8 0.6 0"
                      log="true" flat-shading="false">
     </a-atoll-terrain>
 
-    <a-entity id="armature" position="0 10 0" movement-controls="fly:true; speed:0.5">
-        <a-entity camera="far:2500; near:0.05" position="0 1.6 0" look-controls="pointerLockEnabled: true"></a-entity>
+    <a-entity id="armature" position="0 10 2" movement-controls="fly:true; speed:0.5">
+        <a-entity camera="far:2500; near:0.05" position="0 1.6 0" look-controls="pointerLockEnabled: false"></a-entity>
         <a-entity hand-controls="hand:left"></a-entity>
         <a-entity hand-controls="hand:right"></a-entity>
     </a-entity>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "aframe-atoll-terrain",
-  "version": "0.7.3",
+  "version": "1.0.0",
   "description": "An A-Frame WebVR primitive that has a circle of high-resolution terrain near the origin, surrounded by a low-resolution plain that stretches to the horizon",
   "scripts": {
     "build": "webpack",

src/geometry-atoll-terrain.js

@@ -5,10 +5,9 @@ import ImprovedNoise from './ImprovedNoise';
 
 AFRAME.registerGeometry('atoll-terrain', {
     schema: {
-        buffer: {type: 'boolean', default: false},
-        meanElevation: {type: 'number', default: 10},
+        elevationBias: {type: 'number', default: 0},
         plateauRadius: {type: 'number', default: 10, min: 0},
-        plateauElevationMin: {type: 'number', default: 1, min: 0},
+        plateauElevation: {type: 'number', default: 1, min: 0},
         plateauYinColor: {type: 'color', default: undefined},
         plateauYangColor: {type: 'color', default: undefined},
         middleRadius: {type: 'number', default: 100, min: 10},
@@ -49,16 +48,21 @@ AFRAME.registerGeometry('atoll-terrain', {
         const BEACH_COLOR = new THREE.Color(0x71615b);   // brownish-gray beach
         const ROCK_COLOR = new THREE.Color(0x837E7C);   // granite
 
-        let plateauElevation = data.meanElevation;
-        // plateau has elevation of center
-        for (let quality = 25; quality <= 1500; quality *= 5) {
-            // The largest scale (625) is constrained to avoid all mountain or all sea.
-            plateauElevation += perlin.noise((0+data.middleRadius) / quality, (0+data.middleRadius) / quality, SEED) * Math.min(quality / 2, 62.5);
+        let elevationOffset;
+        if (data.plateauRadius > 0) {
+            let smoothNoise = 0;
+            // plateau has elevation of center
+            for (let quality = 25; quality <= 1500; quality *= 5) {
+                // The largest scale (625) is constrained to avoid all mountain or all sea.
+                smoothNoise += perlin.noise((0+data.middleRadius) / quality, (0+data.middleRadius) / quality, SEED) * Math.min(quality / 2, 62.5);
+            }
+            elevationOffset = data.plateauElevation - smoothNoise + data.elevationBias;
+        } else {
+            elevationOffset = data.elevationBias;
         }
-        plateauElevation = Math.max(plateauElevation, data.plateauElevationMin);
 
         if (data.log) {
-            console.log("atoll-terrain", "SEED="+SEED, "PLATEAU_EDGE="+PLATEAU_EDGE, "plateauElevation="+plateauElevation,
+            console.log("atoll-terrain", "SEED="+SEED, "PLATEAU_EDGE="+PLATEAU_EDGE, "elevationOffset="+elevationOffset,
                 "SIZE="+SIZE, "SCAN_SIZE="+SCAN_SIZE, "UNIT_SIZE="+UNIT_SIZE,
                 "middleRadius="+data.middleRadius, "FAR="+FAR);
         }
@@ -79,17 +83,17 @@ AFRAME.registerGeometry('atoll-terrain', {
                 if (r <= OUTER_RADIUS) {
                     let y;
                     if (data.plateauRadius > 0 && r <= PLATEAU_EDGE) {
-                        y = plateauElevation;
+                        y = data.plateauElevation;
                     } else if (r <= INNER_RADIUS) {
-                        y = data.meanElevation;
+                        y = elevationOffset;
                         // generates smooth noisy terrain
                         for (let quality = 25; quality <= 1500; quality *= 5) {
                             // The largest scale (625) is constrained to avoid all mountain or all sea.
                             y += perlin.noise((x+data.middleRadius) / quality, (z+data.middleRadius) / quality, SEED) * Math.min(quality / 2, 62.5);
                         }
 
                         if (data.plateauRadius > 0) {
-                            y = plateauElevation + (y - plateauElevation) * Math.min(r - PLATEAU_EDGE, MASK_EDGE) / MASK_EDGE;
+                            y = data.plateauElevation + (y - data.plateauElevation) * Math.min(r - PLATEAU_EDGE, MASK_EDGE) / MASK_EDGE;
                         }
                         y *= Math.min(INNER_RADIUS - r, MASK_EDGE) / MASK_EDGE;
 

src/index.js

@@ -21,9 +21,9 @@ AFRAME.registerPrimitive('a-atoll-terrain', {
     },
 
     mappings: {
-        'mean-elevation': 'geometry.meanElevation',
+        'elevation-bias': 'geometry.elevationBias',
         'plateau-radius': 'geometry.plateauRadius',
-        'plateau-elevation-min': 'geometry.plateauElevationMin',
+        'plateau-elevation': 'geometry.plateauElevation',
         'plateau-yin-color': 'geometry.plateauYinColor',
         'plateau-yang-color': 'geometry.plateauYangColor',
         'middle-radius': 'geometry.middleRadius',