visgl · Pessimistress · May 17, 2017 · May 12, 2017 · May 15, 2017 · May 15, 2017
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -17,6 +17,9 @@ Ref: http://keepachangelog.com/en/0.3.0/
 
 ## Beta Releases
 
+[TBD]
+- NEW: `pickingRadius` prop on the `DeckGL` component, enables more tolerant click and hover interaction.
+
 ### deck.gl v4.1.0-alpha.1
 
 - PERFORMANCE: Compiled are now cached for reuse so that same shaders are not recompiled for the same type of layers (#613)

diff --git a/docs/api-reference/deckgl.md b/docs/api-reference/deckgl.md
@@ -68,6 +68,13 @@ updated properties derived from the current application state.
 
 Css styles for the deckgl-canvas.
 
+##### `pickingRadius` (Number, optional)
+
+Extra pixels around the pointer to include while picking.
+This is helpful when rendered objects are difficult to target, for example
+irregularly shaped icons, small moving circles or interaction by touch.
+Default `0`.
+
 ##### `pixelRatio` (Number, optional)
 
 Will use device ratio by default.

diff --git a/examples/layer-browser/src/app.js b/examples/layer-browser/src/app.js
@@ -42,7 +42,8 @@ class App extends PureComponent {
         // immutable: false,
         // Effects are experimental for now. Will be enabled in the future
         // effects: false,
-        separation: 0
+        separation: 0,
+        pickingRadius: 0
         // the rotation controls works only for layers in
         // meter offset projection mode. They are commented out
         // here since layer browser currently only have one layer
@@ -175,7 +176,7 @@ class App extends PureComponent {
   }
 
   _renderMap() {
-    const {width, height, mapViewState, settings: {effects}} = this.state;
+    const {width, height, mapViewState, settings: {effects, pickingRadius}} = this.state;
     return (
       <MapboxGLMap
         mapboxApiAccessToken={MAPBOX_ACCESS_TOKEN || 'no_token'}
@@ -189,6 +190,7 @@ class App extends PureComponent {
           id="default-deckgl-overlay"
           width={width} height={height}
           {...mapViewState}
+          pickingRadius={pickingRadius}
           onWebGLInitialized={ this._onWebGLInitialized }
           onLayerHover={ this._onHover }
           onLayerClick={ this._onClick }

diff --git a/examples/layer-browser/src/components/layer-controls.js b/examples/layer-browser/src/components/layer-controls.js
@@ -46,7 +46,7 @@ export default class LayerControls extends PureComponent {
     if (propType && Number.isFinite(propType.max)) {
       max = propType.max;
 
-    } else if (/radiusScale|elevationScale|width|height|pixel|size|miter/i.test(settingName) &&
+    } else if (/radius|scale|width|height|pixel|size|miter/i.test(settingName) &&
 
       (/^((?!scale).)*$/).test(settingName)) {
       max = 100;

diff --git a/src/lib/draw-and-pick.js b/src/lib/draw-and-pick.js
@@ -59,9 +59,9 @@ export function drawLayers({layers, pass}) {
 export function pickLayers(gl, {
   layers,
   pickingFBO,
-  uniforms = {},
   x,
   y,
+  radius,
   viewport,
   mode,
   lastPickedInfo
@@ -71,8 +71,9 @@ export function pickLayers(gl, {
   // And compensate for pixelRatio
   const pixelRatio = typeof window !== 'undefined' ?
     window.devicePixelRatio : 1;
-  const deviceX = x * pixelRatio;
-  const deviceY = gl.canvas.height - y * pixelRatio;
+  const deviceX = Math.round(x * pixelRatio);
+  const deviceY = Math.round(gl.canvas.height - y * pixelRatio);
+  const deviceRadius = Math.round(radius * pixelRatio);
 
   let pickedColor;
   let pickedLayer;
@@ -99,12 +100,14 @@ export function pickLayers(gl, {
       layers,
       pickingFBO,
       deviceX,
-      deviceY
+      deviceY,
+      deviceRadius
     });
+
     pickedColor = pickInfo.pickedColor;
     pickedLayer = pickInfo.pickedLayer;
     pickedObjectIndex = pickInfo.pickedObjectIndex;
-    affectedLayers = pickInfo.affectedLayers;
+    affectedLayers = pickedLayer ? [pickedLayer] : [];
 
     if (mode === 'hover') {
       // only invoke onHover events if picked object has changed
@@ -152,21 +155,7 @@ export function pickLayers(gl, {
       info.picked = true;
     }
 
-    // Walk up the composite chain and find the owner of the event
-    // sublayers are never directly exposed to the user
-    while (layer && info) {
-      // For a composite layer, sourceLayer will point to the sublayer
-      // where the event originates from.
-      // It provides additional context for the composite layer's
-      // getPickingInfo() method to populate the info object
-      const sourceLayer = info.layer || layer;
-      info.layer = layer;
-      // layer.pickLayer() function requires a non-null ```layer.state```
-      // object to funtion properly. So the layer refereced here
-      // must be the "current" layer, not an "out-dated" / "invalidated" layer
-      info = layer.pickLayer({info, mode, sourceLayer});
-      layer = layer.parentLayer;
-    }
+    info = getLayerPickingInfo({layer, info, mode});
 
     // This guarantees that there will be only one copy of info for
     // one composite layer
@@ -204,22 +193,33 @@ export function pickLayers(gl, {
 
   return unhandledPickInfos;
 }
-/* eslint-enable max-depth, max-statements */
 
+/**
+ * Pick at a specified pixel with a tolerance radius
+ * Returns the closest object to the pixel in shape `{pickedColor, pickedLayer, pickedObjectIndex}`
+ */
 function pickFromBuffer(gl, {
   layers,
   pickingFBO,
   deviceX,
-  deviceY
+  deviceY,
+  deviceRadius
 }) {
+
+  // Create a box of size `radius * 2 + 1` centered at [deviceX, deviceY]
+  const x = Math.max(0, deviceX - deviceRadius);
+  const y = Math.max(0, deviceY - deviceRadius);
+  const width = Math.min(pickingFBO.width, deviceX + deviceRadius) - x + 1;
+  const height = Math.min(pickingFBO.height, deviceY + deviceRadius) - y + 1;
+
   // TODO - just return glContextWithState once luma updates
   // Make sure we clear scissor test and fbo bindings in case of exceptions
   // We are only interested in one pixel, no need to render anything else
   // Note that the callback here is called synchronously.
   return glContextWithState(gl, {
     frameBuffer: pickingFBO,
     framebuffer: pickingFBO,
-    scissorTest: {x: deviceX, y: deviceY, w: 1, h: 1}
+    scissorTest: {x, y, w: width, h: height}
   }, () => {
 
     // Clear the frame buffer
@@ -251,23 +251,50 @@ function pickFromBuffer(gl, {
     });
 
     // Read color in the central pixel, to be mapped with picking colors
-    const pickedColor = new Uint8Array(4);
-    gl.readPixels(deviceX, deviceY, 1, 1, GL.RGBA, GL.UNSIGNED_BYTE, pickedColor);
+    const pickedColors = new Uint8Array(width * height * 4);
+    gl.readPixels(x, y, width, height, GL.RGBA, GL.UNSIGNED_BYTE, pickedColors);
 
     // restore blend mode
     setBlendMode(gl, oldBlendMode);
 
-    // Decode picked color
-    const pickedLayerIndex = pickedColor[3] - 1;
-    const pickedLayer = pickedLayerIndex >= 0 ? layers[pickedLayerIndex] : null;
-    return {
-      pickedColor,
-      pickedLayer,
-      pickedObjectIndex: pickedLayer ? pickedLayer.decodePickingColor(pickedColor) : -1,
-      affectedLayers: pickedLayer ? [pickedLayer] : []
+    // Traverse all pixels in picking results and find the one closest to the supplied
+    // [deviceX, deviceY]
+    let minSquareDistanceToCenter = deviceRadius * deviceRadius;
+    let closestResultToCenter = null;
+    let i = 0;
+
+    for (let row = 0; row < height; row++) {
+      for (let col = 0; col < width; col++) {
+        // Decode picked layer from color
+        const pickedLayerIndex = pickedColors[i + 3] - 1;
+
+        if (pickedLayerIndex >= 0) {
+          const dx = col + x - deviceX;
+          const dy = row + y - deviceY;
+          const d2 = dx * dx + dy * dy;
+
+          if (d2 <= minSquareDistanceToCenter) {
+            minSquareDistanceToCenter = d2;
+
+            // Decode picked object index from color
+            const pickedColor = pickedColors.slice(i, i + 4);
+            const pickedLayer = layers[pickedLayerIndex];
+            const pickedObjectIndex = pickedLayer.decodePickingColor(pickedColor);
+            closestResultToCenter = {pickedColor, pickedLayer, pickedObjectIndex};
+          }
+        }
+        i += 4;
+      }
+    }
+
+    return closestResultToCenter || {
+      pickedColor: EMPTY_PIXEL,
+      pickedLayer: null,
+      pickedObjectIndex: -1
     };
   });
 }
+/* eslint-enable max-depth, max-statements */
 
 function createInfo(pixel, viewport) {
   // Assign a number of potentially useful props to the "info" object
@@ -281,3 +308,21 @@ function createInfo(pixel, viewport) {
     lngLat: viewport.unproject(pixel)
   };
 }
+
+// Walk up the layer composite chain to populate the info object
+function getLayerPickingInfo({layer, info, mode}) {
+  while (layer && info) {
+    // For a composite layer, sourceLayer will point to the sublayer
+    // where the event originates from.
+    // It provides additional context for the composite layer's
+    // getPickingInfo() method to populate the info object
+    const sourceLayer = info.layer || layer;
+    info.layer = layer;
+    // layer.pickLayer() function requires a non-null ```layer.state```
+    // object to funtion properly. So the layer refereced here
+    // must be the "current" layer, not an "out-dated" / "invalidated" layer
+    info = layer.pickLayer({info, mode, sourceLayer});
+    layer = layer.parentLayer;
+  }
+  return info;
+}
diff --git a/src/lib/layer-manager.js b/src/lib/layer-manager.js
@@ -146,7 +146,7 @@ export default class LayerManager {
     return this;
   }
 
-  pickLayer({x, y, mode}) {
+  pickLayer({x, y, mode, radius = 0}) {
     const {gl, uniforms} = this.context;
 
     // Set up a frame buffer if needed
@@ -161,10 +161,7 @@ export default class LayerManager {
     return pickLayers(gl, {
       x,
       y,
-      uniforms: {
-        renderPickingBuffer: true,
-        picking_uEnable: true
-      },
+      radius,
       layers: this.layers,
       mode,
       viewport: this.context.viewport,

diff --git a/src/react/deckgl.js b/src/react/deckgl.js
@@ -38,6 +38,7 @@ const propTypes = {
   effects: PropTypes.arrayOf(PropTypes.instanceOf(Effect)),
   gl: PropTypes.object,
   debug: PropTypes.bool,
+  pickingRadius: PropTypes.number,
   viewport: PropTypes.instanceOf(Viewport),
   onWebGLInitialized: PropTypes.func,
   onAfterRender: PropTypes.func,
@@ -52,6 +53,7 @@ const propTypes = {
 const defaultProps = {
   id: 'deckgl-overlay',
   debug: false,
+  pickingRadius: 0,
   gl: null,
   effects: [],
   onWebGLInitialized: noop,
@@ -146,7 +148,8 @@ export default class DeckGL extends React.Component {
       return;
     }
     const {event: {offsetX: x, offsetY: y}} = event;
-    const selectedInfos = this.layerManager.pickLayer({x, y, mode: 'click'});
+    const radius = this.props.pickingRadius;
+    const selectedInfos = this.layerManager.pickLayer({x, y, radius, mode: 'click'});
     if (selectedInfos.length) {
       const firstInfo = selectedInfos.find(info => info.index >= 0);
       // Event.event holds the original MouseEvent object
@@ -161,7 +164,8 @@ export default class DeckGL extends React.Component {
       return;
     }
     const {event: {offsetX: x, offsetY: y}} = event;
-    const selectedInfos = this.layerManager.pickLayer({x, y, mode: 'hover'});
+    const radius = this.props.pickingRadius;
+    const selectedInfos = this.layerManager.pickLayer({x, y, radius, mode: 'hover'});
     if (selectedInfos.length) {
       const firstInfo = selectedInfos.find(info => info.index >= 0);
       // Event.event holds the original MouseEvent object
@@ -201,7 +205,8 @@ export default class DeckGL extends React.Component {
     }
 
     if (mode) {
-      const selectedInfos = this.layerManager.pickLayer({x, y, mode});
+      const radius = this.props.pickingRadius;
+      const selectedInfos = this.layerManager.pickLayer({x, y, radius, mode});
       if (selectedInfos.length) {
         const firstInfo = selectedInfos.find(info => info.index >= 0);
         // Event.event holds the original MouseEvent object