From e63bb45e6f9af550fb90643a6fd30f33d4cb16f4 Mon Sep 17 00:00:00 2001
From: Olivier Guyot <olivier.guyot@camptocamp.com>
Date: Fri, 25 Oct 2019 15:11:29 +0200
Subject: [PATCH] Webgl points layer / allow disabling hit detection

Having hit detection enabled has an overhead as it means
continously generating additional render instructions and rendering
to an offscreen canvas
---
 examples/filter-points-webgl.js |  3 ++-
 examples/webgl-points-layer.js  |  3 ++-
 src/ol/layer/WebGLPoints.js     | 14 ++++++++++++--
 3 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/examples/filter-points-webgl.js b/examples/filter-points-webgl.js
index 3c36fc973a..fa09676c8b 100644
--- a/examples/filter-points-webgl.js
+++ b/examples/filter-points-webgl.js
@@ -122,7 +122,8 @@ const map = new Map({
     }),
     new WebGLPointsLayer({
       style: style,
-      source: vectorSource
+      source: vectorSource,
+      disableHitDetection: true
     })
   ],
   target: document.getElementById('map'),
diff --git a/examples/webgl-points-layer.js b/examples/webgl-points-layer.js
index 73b023f469..ae04790a71 100644
--- a/examples/webgl-points-layer.js
+++ b/examples/webgl-points-layer.js
@@ -117,7 +117,8 @@ function refreshLayer(newStyle) {
   const previousLayer = pointsLayer;
   pointsLayer = new WebGLPointsLayer({
     source: vectorSource,
-    style: newStyle
+    style: newStyle,
+    disableHitDetection: true
   });
   map.addLayer(pointsLayer);
 
diff --git a/src/ol/layer/WebGLPoints.js b/src/ol/layer/WebGLPoints.js
index 7c9327e234..c3bdb80b10 100644
--- a/src/ol/layer/WebGLPoints.js
+++ b/src/ol/layer/WebGLPoints.js
@@ -24,6 +24,8 @@ import Layer from './Layer.js';
  * @property {number} [maxResolution] The maximum resolution (exclusive) below which this layer will
  * be visible.
  * @property {import("../source/Vector.js").default} [source] Source.
+ * @property {boolean} [disableHitDetection] Setting this to true will provide a slight performance boost, but will
+ * prevent all hit detection on the layer.
  */
 
 
@@ -75,6 +77,12 @@ class WebGLPointsLayer extends Layer {
      * @type {import('../webgl/ShaderBuilder.js').StyleParseResult}
      */
     this.parseResult_ = parseLiteralStyle(options.style);
+
+    /**
+     * @private
+     * @type {boolean}
+     */
+    this.hitDetectionDisabled_ = !!options.disableHitDetection;
   }
 
   /**
@@ -84,8 +92,10 @@ class WebGLPointsLayer extends Layer {
     return new WebGLPointsLayerRenderer(this, {
       vertexShader: this.parseResult_.builder.getSymbolVertexShader(),
       fragmentShader: this.parseResult_.builder.getSymbolFragmentShader(),
-      hitVertexShader: this.parseResult_.builder.getSymbolVertexShader(true),
-      hitFragmentShader: this.parseResult_.builder.getSymbolFragmentShader(true),
+      hitVertexShader: !this.hitDetectionDisabled_ &&
+        this.parseResult_.builder.getSymbolVertexShader(true),
+      hitFragmentShader: !this.hitDetectionDisabled_ &&
+        this.parseResult_.builder.getSymbolFragmentShader(true),
       uniforms: this.parseResult_.uniforms,
       attributes: this.parseResult_.attributes
     });