Add a new WebGLPointsLayer type using the shader builder utilities

This required adding a `a_index` attribute in the points layer renderer
to be able to make the precomputed shaders to work.

doc/errors/index.md

@@ -240,3 +240,7 @@ Support for the `OES_element_index_uint` WebGL extension is mandatory for WebGL
 ### 64
 
 Layer opacity must be a number.
+
+### 65
+
+A symbol literal representation must be defined on the style supplied to a `WebGLPointsLayer` instance.

src/ol/layer/WebGLPoints.js

@@ -0,0 +1,69 @@
+/**
+ * @module ol/layer/WebGLPoints
+ */
+import VectorLayer from './Vector.js';
+import {assign} from '../obj.js';
+import WebGLPointsLayerRenderer from '../renderer/webgl/PointsLayer.js';
+import {getSymbolFragmentShader, getSymbolVertexShader} from '../webgl/ShaderBuilder.js';
+import {assert} from '../asserts.js';
+
+
+/**
+ * @typedef {Object} Options
+ * @property {import('../style/LiteralStyle.js').LiteralStyle} literalStyle Literal style to apply to the layer features.
+ * @property {string} [className='ol-layer'] A CSS class name to set to the layer element.
+ * @property {number} [opacity=1] Opacity (0, 1).
+ * @property {boolean} [visible=true] Visibility.
+ * @property {import("../extent.js").Extent} [extent] The bounding extent for layer rendering.  The layer will not be
+ * rendered outside of this extent.
+ * @property {number} [zIndex] The z-index for layer rendering.  At rendering time, the layers
+ * will be ordered, first by Z-index and then by position. When `undefined`, a `zIndex` of 0 is assumed
+ * for layers that are added to the map's `layers` collection, or `Infinity` when the layer's `setMap()`
+ * method was used.
+ * @property {number} [minResolution] The minimum resolution (inclusive) at which this layer will be
+ * visible.
+ * @property {number} [maxResolution] The maximum resolution (exclusive) below which this layer will
+ * be visible.
+ * @property {import("../source/Vector.js").default} [source] Source.
+ */
+
+
+/**
+ * @classdesc
+ * Layer optimized for rendering large point datasets.
+ * Note that any property set in the options is set as a {@link module:ol/Object~BaseObject}
+ * property on the layer object; for example, setting `title: 'My Title'` in the
+ * options means that `title` is observable, and has get/set accessors.
+ *
+ * @fires import("../render/Event.js").RenderEvent
+ * @api
+ */
+class WebGLPointsLayer extends VectorLayer {
+  /**
+   * @param {Options} options Options.
+   */
+  constructor(options) {
+    const baseOptions = assign({}, options);
+
+    super(baseOptions);
+
+    /**
+     * @type {import('../style/LiteralStyle.js').LiteralStyle}
+     */
+    this.literalStyle = options.literalStyle;
+
+    assert(this.literalStyle.symbol !== undefined, 65);
+  }
+
+  /**
+   * @inheritDoc
+   */
+  createRenderer() {
+    return new WebGLPointsLayerRenderer(this, {
+      vertexShader: getSymbolVertexShader(this.literalStyle.symbol),
+      fragmentShader: getSymbolFragmentShader()
+    });
+  }
+}
+
+export default WebGLPointsLayer;

src/ol/renderer/webgl/Layer.js

@@ -123,9 +123,9 @@ const tmpArray_ = [];
 const bufferPositions_ = {vertexPosition: 0, indexPosition: 0};
 
 export const POINT_INSTRUCTIONS_COUNT = 13;
-export const POINT_VERTEX_STRIDE = 12;
+export const POINT_VERTEX_STRIDE = 13;
 
-function writePointVertex(buffer, pos, x, y, offsetX, offsetY, u, v, opacity, rotateWithView, red, green, blue, alpha) {
+function writePointVertex(buffer, pos, x, y, offsetX, offsetY, u, v, opacity, rotateWithView, red, green, blue, alpha, index) {
   buffer[pos + 0] = x;
   buffer[pos + 1] = y;
   buffer[pos + 2] = offsetX;
@@ -138,6 +138,7 @@ function writePointVertex(buffer, pos, x, y, offsetX, offsetY, u, v, opacity, ro
   buffer[pos + 9] = green;
   buffer[pos + 10] = blue;
   buffer[pos + 11] = alpha;
+  buffer[pos + 12] = index;
 }
 
 function writeCustomAttrs(buffer, pos, customAttrs) {
@@ -202,19 +203,19 @@ export function writePointFeatureToBuffers(instructions, elementIndex, vertexBuf
   const baseIndex = vPos / stride;
 
   // push vertices for each of the four quad corners (first standard then custom attributes)
-  writePointVertex(vertexBuffer, vPos, x, y, -size / 2, -size / 2, u0, v0, opacity, rotateWithView, red, green, blue, alpha);
+  writePointVertex(vertexBuffer, vPos, x, y, -size / 2, -size / 2, u0, v0, opacity, rotateWithView, red, green, blue, alpha, 0);
   writeCustomAttrs(vertexBuffer, vPos + baseStride, customAttrs);
   vPos += stride;
 
-  writePointVertex(vertexBuffer, vPos, x, y, +size / 2, -size / 2, u1, v0, opacity, rotateWithView, red, green, blue, alpha);
+  writePointVertex(vertexBuffer, vPos, x, y, +size / 2, -size / 2, u1, v0, opacity, rotateWithView, red, green, blue, alpha, 1);
   writeCustomAttrs(vertexBuffer, vPos + baseStride, customAttrs);
   vPos += stride;
 
-  writePointVertex(vertexBuffer, vPos, x, y, +size / 2, +size / 2, u1, v1, opacity, rotateWithView, red, green, blue, alpha);
+  writePointVertex(vertexBuffer, vPos, x, y, +size / 2, +size / 2, u1, v1, opacity, rotateWithView, red, green, blue, alpha, 2);
   writeCustomAttrs(vertexBuffer, vPos + baseStride, customAttrs);
   vPos += stride;
 
-  writePointVertex(vertexBuffer, vPos, x, y, -size / 2, +size / 2, u0, v1, opacity, rotateWithView, red, green, blue, alpha);
+  writePointVertex(vertexBuffer, vPos, x, y, -size / 2, +size / 2, u0, v1, opacity, rotateWithView, red, green, blue, alpha, 3);
   writeCustomAttrs(vertexBuffer, vPos + baseStride, customAttrs);
   vPos += stride;
 

src/ol/renderer/webgl/PointsLayer.js

@@ -408,6 +408,7 @@ class WebGLPointsLayerRenderer extends WebGLLayerRenderer {
     this.helper.enableAttributeArray(DefaultAttrib.OPACITY, 1, FLOAT, bytesPerFloat * stride, bytesPerFloat * 6);
     this.helper.enableAttributeArray(DefaultAttrib.ROTATE_WITH_VIEW, 1, FLOAT, bytesPerFloat * stride, bytesPerFloat * 7);
     this.helper.enableAttributeArray(DefaultAttrib.COLOR, 4, FLOAT, bytesPerFloat * stride, bytesPerFloat * 8);
+    this.helper.enableAttributeArray('a_index', 1, FLOAT, bytesPerFloat * stride, bytesPerFloat * 12);
 
     return true;
   }
@@ -568,6 +569,7 @@ class WebGLPointsLayerRenderer extends WebGLLayerRenderer {
     this.helper.enableAttributeArray(DefaultAttrib.OPACITY, 1, FLOAT, bytesPerFloat * stride, bytesPerFloat * 6);
     this.helper.enableAttributeArray(DefaultAttrib.ROTATE_WITH_VIEW, 1, FLOAT, bytesPerFloat * stride, bytesPerFloat * 7);
     this.helper.enableAttributeArray(DefaultAttrib.COLOR, 4, FLOAT, bytesPerFloat * stride, bytesPerFloat * 8);
+    this.helper.enableAttributeArray('a_index', 1, FLOAT, bytesPerFloat * stride, bytesPerFloat * 12);
 
     const renderCount = this.indicesBuffer_.getSize();
     this.helper.drawElements(0, renderCount);

src/ol/style/LiteralStyle.js

@@ -0,0 +1,56 @@
+/**
+ * Literal Style objects differ from standard styles in that they cannot
+ * be functions and are made up of simple objects instead of classes.
+ * @module ol/style/LiteralStyle
+ */
+
+/**
+ * Here are a few samples of literal style objects:
+ * ```js
+ * const style = {
+ *   symbol: {
+ *     symbolType: 'circle',
+ *     size: 8,
+ *     color: '#33AAFF',
+ *     opacity: 0.9
+ *   }
+ * }
+ * ```
+ *
+ * ```js
+ * const style = {
+ *   symbol: {
+ *     symbolType: 'image',
+ *     offset: [0, 12],
+ *     size: [4, 8],
+ *     src: '../static/exclamation-mark.png'
+ *   }
+ * }
+ * ```
+ *
+ * @typedef {Object} LiteralStyle
+ * @property {LiteralSymbolStyle} [symbol] Symbol representation.
+ */
+
+/**
+ * @enum {string}
+ */
+export const SymbolType = {
+  CIRCLE: 'circle',
+  SQUARE: 'square',
+  TRIANGLE: 'triangle',
+  IMAGE: 'image'
+};
+
+
+/**
+ * @typedef {Object} LiteralSymbolStyle
+ * @property {number|Array.<number, number>} size Size, mandatory.
+ * @property {SymbolType} symbolType Symbol type to use, either a regular shape or an image.
+ * @property {string} [src] Path to the image to be used for the symbol. Only required with `symbolType: 'image'`.
+ * @property {import("../color.js").Color|string} [color='#FFFFFF'] Color used for the representation (either fill, line or symbol).
+ * @property {number} [opacity=0] Opacity.
+ * @property {Array.<number, number>} [offset] Offset on X and Y axis for symbols. If not specified, the symbol will be centered.
+ * @property {Array.<number, number, number, number>} [textureCoord] Texture coordinates. If not specified, the whole texture will be used (range for 0 to 1 on both axes).
+ * @property {boolean} [rotateWithView=false] Specify whether the symbol must rotate with the view or stay upwards.
+ */

src/ol/webgl/ShaderBuilder.js

@@ -16,17 +16,8 @@ export function formatNumber(v) {
 }
 
 /**
- * @typedef {Object} SymbolShaderParameters
- * @property {number|Array.<number, number>} size Size.
- * @property {boolean} [rotateWithView] Rotate with view.
- * @property {Array.<number, number>} [offset] Offset.
- * @property {Array.<number, number, number, number>} [textureCoord] Texture coordinates: u0, v0, u1, v1.
- * @property {number} [opacity] Opacity.
- * @property {import("../color.js").Color|string} [color] Color.
- */
-
-/**
- * Generates a symbol vertex shader, i.e. a shader intended to be used on point geometries.
+ * Generates a symbol vertex shader from a literal style,
+ * intended to be used on point geometries.
  *
  * Expected the following attributes to be present in the attribute array:
  * `vec2 a_position`, `float a_index` (being the index of the vertex in the quad, 0 to 3).
@@ -34,7 +25,7 @@ export function formatNumber(v) {
  * Transmits the following varyings to the fragment shader:
  * `vec2 v_texCoord`, `float v_opacity`, `vec4 v_color`
  *
- * @param {SymbolShaderParameters} parameters Parameters for the shader.
+ * @param {import('../style/LiteralStyle.js').LiteralSymbolStyle} parameters Parameters for the shader.
  * @returns {string} The full shader as a string.
  */
 export function getSymbolVertexShader(parameters) {
@@ -82,7 +73,7 @@ void main(void) {
 }
 
 /**
- * Generates a symbol fragment shader, i.e. a shader intended to be used on point geometries.
+ * Generates a symbol fragment shader intended to be used on point geometries.
  *
  * Expected the following varyings to be transmitted by the vertex shader:
  * `vec2 v_texCoord`, `float v_opacity`, `vec4 v_color`