import {
OrthographicCamera,
Scene,
WebGLRenderer,
WebGLRenderTarget,
} from "three";
const pixelBuffer = new Uint8Array(4);
export default function pickNodeIndex(
event: MouseEvent,
renderer: WebGLRenderer,
pickingScene: Scene,
camera: OrthographicCamera,
pickingRenderTarget: WebGLRenderTarget
) {
const rect = renderer.domElement.getBoundingClientRect();
// Convert from client coords to pixel coords in render target
const x =
((event.clientX - rect.left) / rect.width) * pickingRenderTarget.width;
const y =
pickingRenderTarget.height -
((event.clientY - rect.top) / rect.height) * pickingRenderTarget.height;
renderer.setRenderTarget(pickingRenderTarget);
renderer.clear();
renderer.render(pickingScene, camera);
renderer.readRenderTargetPixels(
pickingRenderTarget,
Math.floor(x),
Math.floor(y),
1,
1,
pixelBuffer
);
renderer.setRenderTarget(null);
const id = pixelBuffer[0] + pixelBuffer[1] * 256 + pixelBuffer[2] * 256 * 256;
return id || -1;
}
