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import type { ElementWithBounds } from "./element-bounds";
function pointInRotatedRect({
px,
py,
cx,
cy,
width,
height,
rotation,
}: {
px: number;
py: number;
cx: number;
cy: number;
width: number;
height: number;
rotation: number;
}): boolean {
const angleRad = (rotation * Math.PI) / 180;
const cos = Math.cos(-angleRad);
const sin = Math.sin(-angleRad);
const dx = px - cx;
const dy = py - cy;
const localX = dx * cos - dy * sin;
const localY = dx * sin + dy * cos;
const halfW = width / 2;
const halfH = height / 2;
return (
localX >= -halfW && localX <= halfW && localY >= -halfH && localY <= halfH
);
}
export function hitTest({
canvasX,
canvasY,
elementsWithBounds,
}: {
canvasX: number;
canvasY: number;
elementsWithBounds: ElementWithBounds[];
}): ElementWithBounds | null {
for (let i = elementsWithBounds.length - 1; i >= 0; i--) {
const { bounds } = elementsWithBounds[i];
if (
pointInRotatedRect({
px: canvasX,
py: canvasY,
cx: bounds.cx,
cy: bounds.cy,
width: bounds.width,
height: bounds.height,
rotation: bounds.rotation,
})
) {
return elementsWithBounds[i];
}
}
return null;
}
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