Pixi layers: fallback to WebGL1, if WebGL2 isn't available

The PixiImageBlockLayer will now throw an error if it is initialized without WebGl2 being available. Fixes #1837
catmaid · Jan 29, 2019 · 2e400f5 · 2e400f5
1 parent 2fbd1aa
commit 2e400f5
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diff --git a/django/applications/catmaid/static/js/layers/pixi-image-block-layer.js b/django/applications/catmaid/static/js/layers/pixi-image-block-layer.js
@@ -6,6 +6,11 @@
     constructor(...args) {
       super(...args);
 
+      // This layer needs WebGL2, raise error if unavailable.
+      if (this._context.webglVersion < 2) {
+        throw new CATMAID.PreConditionError("PixiImageBlockLayer needs WebGL2, but it isn't available.");
+      }
+
       this._blockCache = CATMAID.ImageBlock.GlobalCacheManager.get(this.tileSource);
       this._blockCache.on(
           CATMAID.ImageBlock.Cache.EVENT_BLOCK_CHANGED,

diff --git a/django/applications/catmaid/static/js/layers/pixi-layer.js b/django/applications/catmaid/static/js/layers/pixi-layer.js
@@ -23,7 +23,15 @@
         antialias: true,
         stencil: true};
     let view = document.createElement('canvas');
+
+    // Try to get WebGL 2 context, if WebGL 2 is unavailable fall back to WebGl 1.
     let rawContext = view.getContext('webgl2', options);
+    if (rawContext) {
+      this.webglVersion = 2;
+    } else {
+      this.webglVersion = 1;
+      rawContext = view.getContext('webgl', options);
+    }
 
     options.context = rawContext;
     options.view = view;