Tests for and adjustments to unpack alignment handling

test/rendering/cases/webgl-data-tile-3-band/main.js

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+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 = [81, 99];
+
+const canvas = document.createElement('canvas');
+canvas.width = size[0];
+canvas.height = size[1];
+
+const context = canvas.getContext('2d');
+context.strokeStyle = 'white';
+context.textAlign = 'center';
+const lineHeight = 16;
+context.font = `${lineHeight}px sans-serif`;
+
+new Map({
+  target: 'map',
+  layers: [
+    new TileLayer({
+      source: new DataTile({
+        loader: function (z, x, y) {
+          const halfWidth = size[0] / 2;
+          const halfHeight = size[1] / 2;
+          context.fillStyle = '#00AAFF';
+          context.fillRect(0, 0, size[0], size[1]);
+          context.fillStyle = 'white';
+          context.fillText(`z: ${z}`, halfWidth, halfHeight - lineHeight);
+          context.fillText(`x: ${x}`, halfWidth, halfHeight);
+          context.fillText(`y: ${y}`, halfWidth, halfHeight + lineHeight);
+          context.strokeRect(0, 0, size[0], size[1]);
+          const data = context.getImageData(0, 0, size[0], size[1]).data;
+
+          const bandCount = 3;
+          const result = data.filter((_, index) => index % 4 < bandCount);
+          return Promise.resolve(result);
+        },
+        tileSize: size,
+      }),
+    }),
+  ],
+  view: new View({
+    center: [0, 0],
+    zoom: 4,
+  }),
+});
+
+render({tolerance: 0.03});

test/rendering/cases/webgl-data-tile-loosely-packed/main.js

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+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 = [81, 99];
+
+const canvas = document.createElement('canvas');
+canvas.width = size[0];
+canvas.height = size[1];
+
+const context = canvas.getContext('2d');
+context.strokeStyle = 'white';
+context.textAlign = 'center';
+const lineHeight = 16;
+context.font = `${lineHeight}px sans-serif`;
+
+new Map({
+  target: 'map',
+  layers: [
+    new TileLayer({
+      source: new DataTile({
+        tileSize: size,
+        loader: function (z, x, y) {
+          const halfW = size[0] / 2;
+          const halfH = size[1] / 2;
+          context.fillStyle = '#00AAFF';
+          context.fillRect(0, 0, size[0], size[1]);
+          context.fillStyle = 'white';
+          context.fillText(`z: ${z}`, halfW, halfH - lineHeight);
+          context.fillText(`x: ${x}`, halfW, halfH);
+          context.fillText(`y: ${y}`, halfW, halfH + lineHeight);
+          context.strokeRect(0, 0, size[0], size[1]);
+
+          const input = context.getImageData(0, 0, size[0], size[1]).data;
+          const bandCount = input.length / (size[0] * size[1]);
+          const inputColCount = bandCount * size[0];
+
+          const packAlignment = 8;
+          const outputColCount =
+            Math.ceil((bandCount * size[0]) / packAlignment) * packAlignment;
+          const output = new Uint8Array(outputColCount * size[1]);
+
+          for (let row = 0; row < size[1]; ++row) {
+            let inputOffset = row * inputColCount;
+            let outputOffset = row * outputColCount;
+            for (let col = 0; col < inputColCount; col += bandCount) {
+              for (let band = 0; band < bandCount; ++band) {
+                output[outputOffset] = input[inputOffset];
+                inputOffset += 1;
+                outputOffset += 1;
+              }
+            }
+          }
+
+          return Promise.resolve(output);
+        },
+      }),
+    }),
+  ],
+  view: new View({
+    center: [0, 0],
+    zoom: 4,
+  }),
+});
+
+render({tolerance: 0.03});