Avoid clipping when rendering to tiles that don't exceed the clip extent

src/ol/render/canvas/Executor.js

@@ -55,27 +55,19 @@ const p4 = [];
 
 class Executor extends Disposable {
   /**
-   * @param {import("../../extent.js").Extent} maxExtent Maximum extent.
    * @param {number} resolution Resolution.
    * @param {number} pixelRatio Pixel ratio.
    * @param {boolean} overlaps The replay can have overlapping geometries.
    * @param {?} declutterTree Declutter tree.
    * @param {SerializableInstructions} instructions The serializable instructions
    */
-  constructor(maxExtent, resolution, pixelRatio, overlaps, declutterTree, instructions) {
+  constructor(resolution, pixelRatio, overlaps, declutterTree, instructions) {
     super();
     /**
      * @type {?}
      */
     this.declutterTree = declutterTree;
 
-    /**
-     * @protected
-     * @const
-     * @type {import("../../extent.js").Extent}
-     */
-    this.maxExtent = maxExtent;
-
     /**
      * @protected
      * @type {boolean}

src/ol/render/canvas/ExecutorGroup.js

@@ -28,7 +28,10 @@ const ORDER = [
 
 class ExecutorGroup extends Disposable {
   /**
-   * @param {import("../../extent.js").Extent} maxExtent Max extent.
+   * @param {import("../../extent.js").Extent} maxExtent Max extent for clipping. When a
+   * `maxExtent` was set on the Buillder for this executor group, the same `maxExtent`
+   * should be set here, unless the target context does not exceet that extent (which
+   * can be the case when rendering to tiles).
    * @param {number} resolution Resolution.
    * @param {number} pixelRatio Pixel ratio.
    * @param {boolean} overlaps The executor group can have overlapping geometries.
@@ -124,7 +127,7 @@ class ExecutorGroup extends Disposable {
       const instructionByZindex = allInstructions[zIndex];
       for (const builderType in instructionByZindex) {
         const instructions = instructionByZindex[builderType];
-        executors[builderType] = new Executor(this.maxExtent_,
+        executors[builderType] = new Executor(
           this.resolution_, this.pixelRatio_, this.overlaps_, this.declutterTree_, instructions);
       }
     }
@@ -283,6 +286,9 @@ class ExecutorGroup extends Disposable {
    */
   getClipCoords(transform) {
     const maxExtent = this.maxExtent_;
+    if (!maxExtent) {
+      return null;
+    }
     const minX = maxExtent[0];
     const minY = maxExtent[1];
     const maxX = maxExtent[2];
@@ -308,7 +314,7 @@ class ExecutorGroup extends Disposable {
     let executor = executors[builderType];
     if (executor === undefined) {
       // FIXME: it should not be possible to ask for an executor that does not exist
-      executor = new Executor(this.maxExtent_,
+      executor = new Executor(
         this.resolution_, this.pixelRatio_, this.overlaps_, {
           instructions: [],
           hitDetectionInstructions: [],
@@ -353,8 +359,10 @@ class ExecutorGroup extends Disposable {
 
     // setup clipping so that the parts of over-simplified geometries are not
     // visible outside the current extent when panning
-    context.save();
-    this.clip(context, transform);
+    if (this.maxExtent_) {
+      context.save();
+      this.clip(context, transform);
+    }
 
     const builderTypes = opt_builderTypes ? opt_builderTypes : ORDER;
     let i, ii, j, jj, replays, replay;
@@ -380,7 +388,9 @@ class ExecutorGroup extends Disposable {
       }
     }
 
-    context.restore();
+    if (this.maxExtent_) {
+      context.restore();
+    }
   }
 }
 

src/ol/renderer/canvas/VectorTileLayer.js

@@ -313,7 +313,11 @@ class CanvasVectorTileLayerRenderer extends CanvasTileLayerRenderer {
         }
       }
       const executorGroupInstructions = builderGroup.finish();
-      const renderingReplayGroup = new CanvasExecutorGroup(sharedExtent, resolution,
+      // no need to clip when the render tile is covered by a single source tile
+      const replayExtent = layer.getDeclutter() && sourceTiles.length === 1 ?
+        null :
+        sharedExtent;
+      const renderingReplayGroup = new CanvasExecutorGroup(replayExtent, resolution,
         pixelRatio, source.getOverlaps(), this.declutterTree_, executorGroupInstructions, layer.getRenderBuffer());
       tile.executorGroups[layerUid].push(renderingReplayGroup);
     }
@@ -462,7 +466,6 @@ class CanvasVectorTileLayerRenderer extends CanvasTileLayerRenderer {
     const tiles = this.renderedTiles;
     const tileGrid = source.getTileGridForProjection(frameState.viewState.projection);
     const clips = [];
-    const zs = [];
     for (let i = tiles.length - 1; i >= 0; --i) {
       const tile = /** @type {import("../../VectorRenderTile.js").default} */ (tiles[i]);
       if (tile.getState() == TileState.ABORT) {
@@ -481,32 +484,38 @@ class CanvasVectorTileLayerRenderer extends CanvasTileLayerRenderer {
           continue;
         }
         const currentZ = tile.tileCoord[0];
-        const currentClip = executorGroup.getClipCoords(transform);
-        context.save();
+        let zs, currentClip;
+        if (!declutterReplays) {
+          zs = [];
+          currentClip = executorGroup.getClipCoords(transform);
+          context.save();
 
-        // Create a clip mask for regions in this low resolution tile that are
-        // already filled by a higher resolution tile
-        for (let j = 0, jj = clips.length; j < jj; ++j) {
-          const clip = clips[j];
-          if (currentZ < zs[j]) {
-            context.beginPath();
-            // counter-clockwise (outer ring) for current tile
-            context.moveTo(currentClip[0], currentClip[1]);
-            context.lineTo(currentClip[2], currentClip[3]);
-            context.lineTo(currentClip[4], currentClip[5]);
-            context.lineTo(currentClip[6], currentClip[7]);
-            // clockwise (inner ring) for higher resolution tile
-            context.moveTo(clip[6], clip[7]);
-            context.lineTo(clip[4], clip[5]);
-            context.lineTo(clip[2], clip[3]);
-            context.lineTo(clip[0], clip[1]);
-            context.clip();
+          // Create a clip mask for regions in this low resolution tile that are
+          // already filled by a higher resolution tile
+          for (let j = 0, jj = clips.length; j < jj; ++j) {
+            const clip = clips[j];
+            if (currentZ < zs[j]) {
+              context.beginPath();
+              // counter-clockwise (outer ring) for current tile
+              context.moveTo(currentClip[0], currentClip[1]);
+              context.lineTo(currentClip[2], currentClip[3]);
+              context.lineTo(currentClip[4], currentClip[5]);
+              context.lineTo(currentClip[6], currentClip[7]);
+              // clockwise (inner ring) for higher resolution tile
+              context.moveTo(clip[6], clip[7]);
+              context.lineTo(clip[4], clip[5]);
+              context.lineTo(clip[2], clip[3]);
+              context.lineTo(clip[0], clip[1]);
+              context.clip();
+            }
           }
         }
         executorGroup.execute(context, transform, rotation, {}, hifi, replayTypes, declutterReplays);
-        context.restore();
-        clips.push(currentClip);
-        zs.push(currentZ);
+        if (!declutterReplays) {
+          context.restore();
+          clips.push(currentClip);
+          zs.push(currentZ);
+        }
       }
     }
     if (declutterReplays) {