From 71270efa75378b8aff862a5c80827fbc7b977080 Mon Sep 17 00:00:00 2001
From: Olivier Guyot <olivier.guyot@camptocamp.com>
Date: Tue, 13 Nov 2018 16:54:48 +0100
Subject: [PATCH] Added a new WebGLPointsRenderer

---
 src/ol/renderer/webgl-new/PointsLayer.js | 91 ++++++++++++++++++++++++
 1 file changed, 91 insertions(+)
 create mode 100644 src/ol/renderer/webgl-new/PointsLayer.js

diff --git a/src/ol/renderer/webgl-new/PointsLayer.js b/src/ol/renderer/webgl-new/PointsLayer.js
new file mode 100644
index 0000000000..32d7fafc50
--- /dev/null
+++ b/src/ol/renderer/webgl-new/PointsLayer.js
@@ -0,0 +1,91 @@
+/**
+ * @module ol/renderer/webgl-new/PointsLayer
+ */
+import LayerRenderer from '../Layer';
+import WebGLBuffer from '../../webgl/Buffer';
+import {DYNAMIC_DRAW, ARRAY_BUFFER, ELEMENT_ARRAY_BUFFER} from '../../webgl';
+import WebGLContext, {DefaultUniform} from '../../webgl/Context';
+
+/**
+ * @classdesc
+ * Webgl vector renderer optimized for points.
+ * All features will be rendered as points.
+ * @api
+ */
+class WebGLPointsLayerRenderer extends LayerRenderer {
+
+  /**
+   * @param {import("../../layer/Vector.js").default} vectorLayer Vector layer.
+   */
+  constructor(vectorLayer) {
+    super(vectorLayer);
+
+    this.element_ = document.createElement('canvas');
+
+    this.context_ = new WebGLContext(this.element_);
+
+    this.sourceRevision_ = -1;
+
+    this.primitiveCount_ = 0;
+
+    this.verticesBuffer_ = new WebGLBuffer();
+    this.indicesBuffer_ = new WebGLBuffer();
+  }
+
+  /**
+   * @inheritDoc
+   */
+  disposeInternal() {
+    super.disposeInternal();
+  }
+
+  /**
+   * @inheritDoc
+   */
+  composeFrame(frameState) {
+    this.context_.applyFrameState(frameState);
+    this.context_.setUniformFloatValue(DefaultUniform.OPACITY, this.getLayer().getOpacity());
+    this.context_.drawElements(0, this.primitiveCount_ * 3);
+  }
+
+  /**
+   * @inheritDoc
+   */
+  prepareFrame(frameState) {
+    const vectorLayer = this.getLayer();
+    const vectorSource = vectorLayer.getSource();
+
+    if (this.sourceRevision_ >= vectorSource.getRevision()) {
+      return false;
+    }
+    this.sourceRevision_ = vectorSource.getRevision();
+
+    // loop on features to fill the buffer
+    // vectorSource.loadFeatures(extent, resolution, projection);
+    vectorSource.forEachFeature((feature) => {
+      let x = 0, y = 0, size = 0;
+      let baseIndex = this.verticesBuffer_.getArray().length / 3;
+
+      // todo: put data in buffer
+      this.verticesBuffer_.getArray().push(
+        x - size / 2, y - size / 2,
+        x + size / 2, y - size / 2,
+        x + size / 2, y + size / 2,
+        x - size / 2, y + size / 2,
+      );
+      this.indicesBuffer_.getArray().push(
+        baseIndex, baseIndex + 1, baseIndex + 3,
+        baseIndex + 1, baseIndex + 2, baseIndex + 3
+      );
+      this.primitiveCount_++;
+    });
+
+    // write new data
+    this.context_.bindBuffer(ARRAY_BUFFER, this.verticesBuffer_);
+    this.context_.bindBuffer(ELEMENT_ARRAY_BUFFER, this.indicesBuffer_);
+
+    return true;
+  }
+}
+
+export default WebGLPointsLayerRenderer;