fix(heatmap): 解决颜色插值问题，优化渲染性能

demos/heatmap.html

@@ -34,11 +34,11 @@ scene.on('loaded', () => {
     .source(data)
     .size('mag', [ 0, 1 ]) // weight映射通道
     .style({
-      intensity: 1,
-      radius: 10,
+      intensity: 3,
+      radius: 20,
       rampColors: {
-        colors: [ 'rgba(33,102,172,0)', 'rgb(103,169,207)', 'rgb(209,229,240)', 'rgb(253,219,199)', 'rgb(239,138,98)', 'rgb(178,24,43)' ],
-        positions: [ 0.0, 0.2, 0.4, 0.6, 0.8, 1.0 ]
+        colors: [ 'rgba(33,102,172,0.0)', 'rgb(103,169,207)', 'rgb(209,229,240)', 'rgb(253,219,199)', 'rgb(239,138,98)', 'rgb(178,24,43,1.0)' ],
+        positions: [ 0, 0.2, 0.4, 0.6, 0.8, 1.0 ]
       }
     })
     .render();

src/core/engine/renderpass.js

@@ -8,21 +8,20 @@ export default class RenderPass {
     this.clearColor = cfg.clear.clearColor;
     this.clearAlpha = cfg.clear.clearAlpha;
     this.size = cfg.size ? cfg.size : cfg.renderer.getSize();
+    const defaultRenderCfg = {
+      minFilter: THREE.NearestFilter,
+      magFilter: THREE.NearestFilter,
+      format: THREE.RGBAFormat,
+      stencilBuffer: false,
+      depthBuffer: false
+    };
+    this.renderCfg = cfg.renderCfg ? cfg.renderCfg : defaultRenderCfg;
     this._init(cfg);
   }
 
   _init() {
     this.scene = new THREE.Scene();
-    const parameters = {
-      // minFilter: THREE.NearestFilter,
-      // magFilter: THREE.NearestFilter,
-      minFilter: THREE.LinearFilter,
-      magFilter: THREE.LinearFilter,
-      format: THREE.RGBAFormat,
-      stencilBuffer: false,
-      depthBuffer: false
-    };
-    this.pass = new THREE.WebGLRenderTarget(this.size.width, this.size.height, parameters);
+    this.pass = new THREE.WebGLRenderTarget(this.size.width, this.size.height, this.renderCfg);
     this.originClearColor = this.renderer.getClearColor();
     this.originClearAlpha = this.renderer.getClearAlpha();
     this.texture = this.pass.texture;
@@ -40,6 +39,5 @@ export default class RenderPass {
     this.renderer.setClearColor(this.clearColor, this.clearAlpha);
     this.renderer.render(this.scene, this.camera, this.pass, true);
     this.renderer.setClearColor(this.originClearColor, this.originClearAlpha);
-    this.texture = this.pass.texture;
   }
 }

src/geom/buffer/heatmap/heatmap.js

@@ -60,9 +60,9 @@ function getColorRamp(name) {
   const canvas = document.createElement('canvas');
   const ctx = canvas.getContext('2d');
 
-  canvas.width = 256;
-  canvas.height = 1;
-  const gradient = ctx.createLinearGradient(0, 0, 256, 0);
+  canvas.width = 1;
+  canvas.height = 256;
+  const gradient = ctx.createLinearGradient(0, 0, 0, 256);
   let data = null;
   if (typeof (colorscale) === 'string') {
     colorscale = colorScales[name];
@@ -76,21 +76,23 @@ function getColorRamp(name) {
       gradient.addColorStop(value, colorscale.colors[i]);
     }
     ctx.fillStyle = gradient;
-    ctx.fillRect(0, 0, 256, 1);
-    data = new Uint8ClampedArray(ctx.getImageData(0, 0, 256, 1).data);
+    ctx.fillRect(0, 0, 1, 256);
+    data = new Uint8ClampedArray(ctx.getImageData(0, 0, 1, 256).data);
   }
   if (Object.prototype.toString.call(colorscale) === '[object Uint8Array]') {
-    data = ctx.createImageData(256, 1);
+    data = ctx.createImageData(1, 256);
   }
 
-  return new ImageData(data, 16, 16);
+  return new ImageData(data, 1, 256);
 
 }
 
 function getTexture(image) {
   const texture = new THREE.Texture(image);
-  texture.magFilter = THREE.LinearFilter;
-  texture.minFilter = THREE.LinearFilter;
+  texture.wrapS = THREE.ClampToEdgeWrapping;
+  texture.wrapT = THREE.ClampToEdgeWrapping;
+  texture.magFilter = THREE.NearestFilter;
+  texture.minFilter = THREE.NearestFilter;
   texture.format = THREE.RGBAFormat;
   texture.type = THREE.UnsignedByteType;
   texture.needsUpdate = true;

src/geom/material/heatmapMateial.js

@@ -27,7 +27,8 @@ export function HeatmapColorizeMaterial(opt) {
       u_colorRamp: { value: opt.colorRamp }
     },
     vertexShader: heatmap_colorize_vert,
-    fragmentShader: heatmap_colorize_frag
+    fragmentShader: heatmap_colorize_frag,
+    transparent: true
   });
   return material;
 }

src/geom/shader/heatmap_colorize_frag.glsl

@@ -5,5 +5,5 @@ varying vec2 v_uv;
 void main(){
     float intensity = texture2D(u_texture,v_uv).r;
     vec4 color = texture2D(u_colorRamp,vec2(0.5,1.0-intensity));
-    gl_FragColor = color * intensity;
+    gl_FragColor = color;
 }

src/geom/shader/heatmap_intensity_frag.glsl

@@ -1,4 +1,5 @@
 precision highp float;
+uniform float u_intensity;
 varying float v_weight;
 varying vec2 v_extrude;
 
@@ -6,6 +7,6 @@ varying vec2 v_extrude;
 void main(){
     float GAUSS_COEF = 0.3989422804014327;
     float d = -0.5 * 3.0 * 3.0 * dot(v_extrude, v_extrude);
-    float val = v_weight * 10.0 * GAUSS_COEF * exp(d);
-    gl_FragColor = vec4(val, val, val, 1.0);
+    float val = v_weight * u_intensity * GAUSS_COEF * exp(d);
+    gl_FragColor = vec4(val, val, val, val);
 }

src/geom/shader/heatmap_intensity_vert.glsl

@@ -16,7 +16,7 @@ void main(){
     vec2 extrude_dir = normalize(vec2(extrude_x,extrude_y));
     float S = sqrt(-2.0 * log(ZERO / a_weight / u_intensity / GAUSS_COEF)) / 3.0;
     v_extrude = extrude_dir * S;
-    vec2 extrude =  v_extrude * u_radius * pow(2.0,20.0-min(u_zoom,9.0)); 
+    vec2 extrude =  v_extrude * u_radius * pow(2.0,20.0-u_zoom); 
     vec4 pos = vec4( position.xy+ extrude, 0.0, 1.0);
     gl_Position = projectionMatrix * modelViewMatrix * pos;
 }

src/layer/render/heatmap/heatmap.js

@@ -37,16 +37,30 @@ function createIntensityPass(layer, bbox) {
   const passOrth = new THREE.OrthographicCamera(bbox.width / -2, bbox.width / 2, bbox.height / 2, bbox.height / -2, 1, 10000);
   passOrth.position.set(bbox.minX + bbox.width / 2, bbox.minY + bbox.height / 2, 1000);
     // renderpass
+  const renderer = layer.scene._engine._renderer;
+  // get extension for bilinear texture interpolation:https://threejs.org/docs/#api/en/textures/DataTexture
+  const gl = renderer.domElement.getContext('webgl') ||
+    renderer.domElement.getContext('experimental-webgl');
+  gl.getExtension('OES_texture_float_linear');
   const renderpass = new Renderpass({
-    renderer: layer.scene._engine._renderer,
+    renderer,
     camera: passOrth,
     size: {
-      width: 10000,
-      height: 10000 * (bbox.height / bbox.width)
+      width: 2000,
+      height: 2000 * (bbox.height / bbox.width)
     },
     clear: {
       clearColor: 0x000000,
-      clearAlpha: 1.0
+      clearAlpha: 0.0
+    },
+    renderCfg: {
+      wrapS: THREE.ClampToEdgeWrapping,
+      wrapT: THREE.ClampToEdgeWrapping,
+      minFilter: THREE.LinearFilter,
+      magFilter: THREE.LinearFilter,
+      format: THREE.RGBAFormat,
+      stencilBuffer: false,
+      depthBuffer: false
     }
   });
   renderpass.add(mesh);
@@ -56,8 +70,12 @@ function createIntensityPass(layer, bbox) {
   render();
   function render() {
     requestAnimationFrame(render);
+    const zoom = scene.getZoom();
+    mesh.material.uniforms.u_zoom.value = zoom;
+    const passWidth = Math.min(10000, Math.pow(zoom, 2.0) * 200);
+    const passHeight = passWidth * (bbox.height / bbox.width);
+    renderpass.pass.setSize(passWidth, passHeight);
     renderpass.render();
-    mesh.material.uniforms.u_zoom.value = scene.getZoom();
   }
 }
 function createColorizePass(layer, bbox) {