Allow interpolation to be configured for data tile sources

src/ol/DataTile.js

@@ -16,6 +16,8 @@ import TileState from './TileState.js';
  * @property {function(): Promise<Data>} loader Data loader.
  * @property {number} [transition=250] A duration for tile opacity
  * transitions in milliseconds. A duration of 0 disables the opacity transition.
+ * @property {boolean} [interpolate=false] Use interpolated values when resampling.  By default,
+ * the nearest neighbor is used when resampling.
  * @api
  */
 
@@ -26,10 +28,27 @@ class DataTile extends Tile {
   constructor(options) {
     const state = TileState.IDLE;
 
-    super(options.tileCoord, state, {transition: options.transition});
+    super(options.tileCoord, state, {
+      transition: options.transition,
+      interpolate: options.interpolate,
+    });
 
+    /**
+     * @type {function(): Promise<Data>}
+     * @private
+     */
     this.loader_ = options.loader;
+
+    /**
+     * @type {Data}
+     * @private
+     */
     this.data_ = null;
+
+    /**
+     * @type {Error}
+     * @private
+     */
     this.error_ = null;
   }
 

src/ol/Tile.js

@@ -63,6 +63,8 @@ import {easeIn} from './easing.js';
  * @typedef {Object} Options
  * @property {number} [transition=250] A duration for tile opacity
  * transitions in milliseconds. A duration of 0 disables the opacity transition.
+ * @property {boolean} [interpolate=false] Use interpolated values when resampling.  By default,
+ * the nearest neighbor is used when resampling.
  * @api
  */
 
@@ -123,6 +125,11 @@ class Tile extends EventTarget {
      * @type {Object<string, number>}
      */
     this.transitionStarts_ = {};
+
+    /**
+     * @type {boolean}
+     */
+    this.interpolate = !!options.interpolate;
   }
 
   /**

src/ol/source/DataTile.js

@@ -34,6 +34,8 @@ import {toPromise} from '../functions.js';
  * @property {boolean} [wrapX=false] Render tiles beyond the antimeridian.
  * @property {number} [transition] Transition time when fading in new tiles (in miliseconds).
  * @property {number} [bandCount=4] Number of bands represented in the data.
+ * @property {boolean} [interpolate=false] Use interpolated values when resampling.  By default,
+ * the nearest neighbor is used when resampling.
  */
 
 /**
@@ -71,6 +73,7 @@ class DataTileSource extends TileSource {
       tilePixelRatio: options.tilePixelRatio,
       wrapX: options.wrapX,
       transition: options.transition,
+      interpolate: options.interpolate,
     });
 
     /**
@@ -90,6 +93,12 @@ class DataTileSource extends TileSource {
      * @type {number}
      */
     this.bandCount = options.bandCount === undefined ? 4 : options.bandCount; // assume RGBA if undefined
+
+    /**
+     * @type {boolean}
+     * @private
+     */
+    this.interpolate_ = !!options.interpolate;
   }
 
   /**

src/ol/source/GeoTIFF.js

@@ -315,6 +315,8 @@ function getMaxForDataType(array) {
  * @property {number} [transition=250] Duration of the opacity transition for rendering.
  * To disable the opacity transition, pass `transition: 0`.
  * @property {boolean} [wrapX=false] Render tiles beyond the tile grid extent.
+ * @property {boolean} [interpolate=true] Use interpolated values when resampling.  By default,
+ * the linear interpolation is used to resample the data.  If false, nearest neighbor is used.
  */
 
 /**
@@ -333,6 +335,7 @@ class GeoTIFFSource extends DataTile {
       projection: null,
       opaque: options.opaque,
       transition: options.transition,
+      interpolate: options.interpolate !== false,
       wrapX: options.wrapX,
     });
 

src/ol/source/Tile.js

@@ -38,6 +38,8 @@ import {scale as scaleSize, toSize} from '../size.js';
  * @property {number} [transition] Transition.
  * @property {string} [key] Key.
  * @property {number|import("../array.js").NearestDirectionFunction} [zDirection=0] ZDirection.
+ * @property {boolean} [interpolate=false] Use interpolated values when resampling.  By default,
+ * the nearest neighbor is used when resampling.
  */
 
 /**
@@ -122,7 +124,10 @@ class TileSource extends Source {
      * @protected
      * @type {import("../Tile.js").Options}
      */
-    this.tileOptions = {transition: options.transition};
+    this.tileOptions = {
+      transition: options.transition,
+      interpolate: options.interpolate,
+    };
 
     /**
      * zDirection hint, read by the renderer. Indicates which resolution should be used

src/ol/source/TileImage.js

@@ -86,6 +86,7 @@ class TileImage extends UrlTile {
       urls: options.urls,
       wrapX: options.wrapX,
       transition: options.transition,
+      interpolate: options.imageSmoothing !== false,
       key: options.key,
       attributionsCollapsible: options.attributionsCollapsible,
       zDirection: options.zDirection,

src/ol/source/UrlTile.js

@@ -26,6 +26,8 @@ import {getUid} from '../util.js';
  * @property {number} [transition] Transition.
  * @property {string} [key] Key.
  * @property {number|import("../array.js").NearestDirectionFunction} [zDirection=0] ZDirection.
+ * @property {boolean} [interpolate=false] Use interpolated values when resampling.  By default,
+ * the nearest neighbor is used when resampling.
  */
 
 /**
@@ -49,6 +51,7 @@ class UrlTile extends TileSource {
       tilePixelRatio: options.tilePixelRatio,
       wrapX: options.wrapX,
       transition: options.transition,
+      interpolate: options.interpolate,
       key: options.key,
       attributionsCollapsible: options.attributionsCollapsible,
       zDirection: options.zDirection,

src/ol/webgl/TileTexture.js

@@ -11,21 +11,28 @@ import WebGLArrayBuffer from './Buffer.js';
 import {ARRAY_BUFFER, STATIC_DRAW} from '../webgl.js';
 import {toSize} from '../size.js';
 
-function bindAndConfigure(gl, texture) {
+/**
+ * @param {WebGLRenderingContext} gl The WebGL context.
+ * @param {WebGLTexture} texture The texture.
+ * @param {boolean} interpolate Interpolate when resampling.
+ */
+function bindAndConfigure(gl, texture, interpolate) {
+  const resampleFilter = interpolate ? gl.LINEAR : gl.NEAREST;
   gl.bindTexture(gl.TEXTURE_2D, texture);
   gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
   gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
-  gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
+  gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, resampleFilter);
-  gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
+  gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, resampleFilter);
 }
 
 /**
  * @param {WebGLRenderingContext} gl The WebGL context.
  * @param {WebGLTexture} texture The texture.
  * @param {HTMLImageElement|HTMLCanvasElement|HTMLVideoElement} image The image.
+ * @param {boolean} interpolate Interpolate when resampling.
  */
-function uploadImageTexture(gl, texture, image) {
+function uploadImageTexture(gl, texture, image, interpolate) {
-  bindAndConfigure(gl, texture);
+  bindAndConfigure(gl, texture, interpolate);
 
   gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, image);
 }
@@ -36,10 +43,18 @@ function uploadImageTexture(gl, texture, image) {
  * @param {import("../DataTile.js").Data} data The pixel data.
  * @param {import("../size.js").Size} size The pixel size.
  * @param {number} bandCount The band count.
+ * @param {boolean} interpolate Interpolate when resampling.
  */
-function uploadDataTexture(helper, texture, data, size, bandCount) {
+function uploadDataTexture(
+  helper,
+  texture,
+  data,
+  size,
+  bandCount,
+  interpolate
+) {
   const gl = helper.getGL();
-  bindAndConfigure(gl, texture);
+  bindAndConfigure(gl, texture, interpolate);
 
   const bytesPerRow = data.byteLength / size[1];
   let unpackAlignment = 1;
@@ -174,7 +189,7 @@ class TileTexture extends EventTarget {
       const texture = gl.createTexture();
       this.textures.push(texture);
       this.bandCount = 4;
-      uploadImageTexture(gl, texture, tile.getImage());
+      uploadImageTexture(gl, texture, tile.getImage(), tile.interpolate);
       return;
     }
 
@@ -191,7 +206,14 @@ class TileTexture extends EventTarget {
     if (textureCount === 1) {
       const texture = gl.createTexture();
       this.textures.push(texture);
-      uploadDataTexture(helper, texture, data, this.size, this.bandCount);
+      uploadDataTexture(
+        helper,
+        texture,
+        data,
+        this.size,
+        this.bandCount,
+        tile.interpolate
+      );
       return;
     }
 
@@ -229,7 +251,14 @@ class TileTexture extends EventTarget {
       const texture = this.textures[textureIndex];
       const textureData = textureDataArrays[textureIndex];
       const bandCount = textureData.length / pixelCount;
-      uploadDataTexture(helper, texture, textureData, this.size, bandCount);
+      uploadDataTexture(
+        helper,
+        texture,
+        textureData,
+        this.size,
+        bandCount,
+        tile.interpolate
+      );
     }
   }
 

test/rendering/cases/webgl-data-tile-interpolate-false/main.js

@@ -0,0 +1,31 @@
+import DataTile from '../../../../src/ol/source/DataTile.js';
+import Map from '../../../../src/ol/Map.js';
+import TileLayer from '../../../../src/ol/layer/WebGLTile.js';
+import View from '../../../../src/ol/View.js';
+
+const size = 256;
+
+const data = new Uint8Array(size * size);
+for (let row = 0; row < size; ++row) {
+  for (let col = 0; col < size; ++col) {
+    data[row * size + col] = (row + col) % 2 === 0 ? 255 : 0;
+  }
+}
+
+new Map({
+  target: 'map',
+  layers: [
+    new TileLayer({
+      source: new DataTile({
+        maxZoom: 0,
+        loader: () => data,
+      }),
+    }),
+  ],
+  view: new View({
+    center: [0, 0],
+    zoom: 4,
+  }),
+});
+
+render();

test/rendering/cases/webgl-data-tile-interpolate-true/main.js

@@ -0,0 +1,32 @@
+import DataTile from '../../../../src/ol/source/DataTile.js';
+import Map from '../../../../src/ol/Map.js';
+import TileLayer from '../../../../src/ol/layer/WebGLTile.js';
+import View from '../../../../src/ol/View.js';
+
+const size = 256;
+
+const data = new Uint8Array(size * size);
+for (let row = 0; row < size; ++row) {
+  for (let col = 0; col < size; ++col) {
+    data[row * size + col] = (row + col) % 2 === 0 ? 255 : 0;
+  }
+}
+
+new Map({
+  target: 'map',
+  layers: [
+    new TileLayer({
+      source: new DataTile({
+        maxZoom: 0,
+        interpolate: true,
+        loader: () => data,
+      }),
+    }),
+  ],
+  view: new View({
+    center: [0, 0],
+    zoom: 4,
+  }),
+});
+
+render();