WasmGPU.pickLasso¶
Summary¶
WasmGPU.pickLasso performs polygon-region picking using a lasso path in canvas space. The lasso is rasterized to a bounded query region, then sampled against the pick buffers. Use it for free-form selection where a rectangle is too coarse.
Syntax¶
WasmGPU.pickLasso(scene: Scene, camera: Camera, points: PickLassoPoint[], opts?: PickRegionQuery): Promise<PickRegionResult>
const result = await wgpu.pickLasso(scene, camera, points, opts);
Parameters¶
| Name | Type | Required | Description |
|---|---|---|---|
scene |
Scene |
Yes | Scene to query for pickable mesh, point cloud, glyph field, and nodelink elements. |
camera |
Camera |
Yes | Camera used to project the lasso query. |
points |
PickLassoPoint[] |
Yes | Ordered polygon points in canvas CSS pixels; at least 3 points are needed for non-empty selection. |
opts |
PickRegionQuery |
No | Optional limits and payload flags for lasso queries. |
Returns¶
Promise<PickRegionResult> - Resolves to lasso mode metadata and the selected hit set.
Type Details¶
type PickLassoPoint = {
x: number;
y: number;
};
type PickRegionQuery = {
includeAttributes?: boolean; // default: true
maxHits?: number; // default: 10000
};
type PickRegionResult = {
mode: "rect" | "lasso";
hits: PickHit[];
truncated: boolean;
bounds: { x: number; y: number; width: number; height: number };
sampledPixels: number;
};
Each hit in result.hits uses the same PickHit contract as WasmGPU.pick, so nodelink region picks can report node-or-edge payloads when attributes are included.
Example¶
const canvas = document.querySelector("canvas");
const wgpu = await WasmGPU.create(canvas);
const scene = wgpu.createScene();
const camera = wgpu.createCamera.perspective({ fov: 50, aspect: canvas.clientWidth / canvas.clientHeight, near: 0.1, far: 1000 });
const controls = wgpu.createControls.trackball(camera, canvas, { target: [0, 0, 0], enableDamping: true });
const lassoPoints = [
{ x: 40, y: 80 }, { x: 150, y: 40 }, { x: 280, y: 100 },
{ x: 260, y: 220 }, { x: 110, y: 240 }
];
const lassoResult = await wgpu.pickLasso(scene, camera, lassoPoints, { includeAttributes: true, maxHits: 3000 });
console.log(lassoResult.mode, lassoResult.hits.length, lassoResult.truncated);
wgpu.run((dt) => {
controls.update(dt);
wgpu.render(scene, camera);
});