From 792e15124d7503a7d212c58911dd99d776dbcdc5 Mon Sep 17 00:00:00 2001
From: Andreas Hocevar <andreas.hocevar@gmail.com>
Date: Sun, 23 Aug 2020 12:37:52 +0200
Subject: [PATCH] VectorTile source projection has to match the view projection

---
 doc/errors/index.md                       |  6 +++++-
 src/ol/renderer/canvas/VectorTileLayer.js | 12 +++++++++++-
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/doc/errors/index.md b/doc/errors/index.md
index e45f47bd3b..58c85f79ff 100644
--- a/doc/errors/index.md
+++ b/doc/errors/index.md
@@ -248,4 +248,8 @@ This is done by providing adequate shaders using the `hitVertexShader` and `hitF
 
 ### 67
 
-A layer can only be added to the map once. Use either `layer.setMap()` or `map.addLayer()`, not both.
\ No newline at end of file
+A layer can only be added to the map once. Use either `layer.setMap()` or `map.addLayer()`, not both.
+
+### 68
+
+A VectorTile source can only be rendered if it has a projection compatible with the view projection.
\ No newline at end of file
diff --git a/src/ol/renderer/canvas/VectorTileLayer.js b/src/ol/renderer/canvas/VectorTileLayer.js
index 80d88dfc0c..ab53ca17c5 100644
--- a/src/ol/renderer/canvas/VectorTileLayer.js
+++ b/src/ol/renderer/canvas/VectorTileLayer.js
@@ -20,6 +20,7 @@ import {
   scale as scaleTransform,
   translate as translateTransform,
 } from '../../transform.js';
+import {assert} from '../../asserts.js';
 import {
   buffer,
   containsCoordinate,
@@ -34,6 +35,7 @@ import {
   createHitDetectionImageData,
   hitDetect,
 } from '../../render/canvas/hitdetect.js';
+import {equivalent} from '../../proj.js';
 import {
   getSquaredTolerance as getSquaredRenderTolerance,
   renderFeature,
@@ -230,7 +232,15 @@ class CanvasVectorTileLayerRenderer extends CanvasTileLayerRenderer {
    * @return {boolean} Layer is ready to be rendered.
    */
   prepareFrame(frameState) {
-    const layerRevision = this.getLayer().getRevision();
+    const layer = this.getLayer();
+    assert(
+      equivalent(
+        layer.getSource().getProjection(),
+        frameState.viewState.projection
+      ),
+      68 // A VectorTile source can only be rendered if it has a projection compatible with the view projection.
+    );
+    const layerRevision = layer.getRevision();
     if (this.renderedLayerRevision_ != layerRevision) {
       this.renderedTiles.length = 0;
     }