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fix: Hit tests

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Signed-off-by: Mark Tolmacs <mark@lazycat.hu>
This commit is contained in:
Mark Tolmacs
2026-03-24 19:18:04 +00:00
parent cc1f502a0f
commit 3e69b33a28
6 changed files with 76 additions and 47 deletions
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packages/element/src/shape.ts
+38 -4
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@@ -44,7 +44,7 @@ import type {
} from "@excalidraw/excalidraw/scene/types";
import { elementWithCanvasCache } from "./renderElement";
import { debugDrawLine, debugDrawPoint, debugDrawPolygon } from "./visualdebug";
import { debugDrawLine, debugDrawPolygon } from "./visualdebug";
import {
canBecomePolygon,
@@ -90,7 +90,7 @@ const CP_CHORD_POWER = 1;
// This factor [0, 1] controls how far the tangent direction is pulled toward
// the bisector (the chord-bisector normal) linearly with turn sharpness.
// 0 = pure C2 spline; 1 = tangent fully aligned with the bisector.
const CP_ANGLE_CORRECTION = 0.5;
const CP_ANGLE_CORRECTION = 1;
export class ShapeCache {
private static rg = new RoughGenerator();
@@ -665,8 +665,8 @@ export const generateLinearCollisionShape = (
data: rotateLocal(points[1][0], points[1][1]),
});
} else {
// Chord-length C2 spline – mirrors generateRoundedSimpleArrowShape exactly
// so hit-testing matches rendering.
// Chord-length C2 spline. Mirrors generateRoundedSimpleArrowShape
// exactly so hit-testing matches rendering.
const n = points.length - 1;
const h = new Float64Array(n);
for (let i = 0; i < n; i++) {
@@ -725,6 +725,40 @@ export const generateLinearCollisionShape = (
mlen[i] = Math.max(1e-10, Math.hypot(mx[i], my[i]));
}
// At interior knots, blend the C2 tangent direction toward the
// bisector direction by a factor proportional to turn sharpness *
// CP_ANGLE_CORRECTION
for (let k = 1; k < n; k++) {
const d1x = (points[k][0] - points[k - 1][0]) / h[k - 1];
const d1y = (points[k][1] - points[k - 1][1]) / h[k - 1];
const d2x = (points[k + 1][0] - points[k][0]) / h[k];
const d2y = (points[k + 1][1] - points[k][1]) / h[k];
const dot = d1x * d2x + d1y * d2y;
const t = ((1 - dot) / 2) * CP_ANGLE_CORRECTION;
if (t < 1e-6) {
continue;
}
const bx = d1x + d2x;
const by = d1y + d2y;
const blen = Math.hypot(bx, by);
if (blen < 1e-10) {
continue;
}
let px = bx / blen;
let py = by / blen;
const tx = mx[k] / mlen[k];
const ty = my[k] / mlen[k];
if (tx * px + ty * py < 0) {
px = -px;
py = -py;
}
const blendX = tx + t * (px - tx);
const blendY = ty + t * (py - ty);
const blendLen = Math.max(1e-10, Math.hypot(blendX, blendY));
mx[k] = (blendX / blendLen) * mlen[k];
my[k] = (blendY / blendLen) * mlen[k];
}
for (let i = 0; i < n; i++) {
const cpDist = Math.pow(h[i], CP_CHORD_POWER) / 3;
const cp1x = points[i][0] + (mx[i] / mlen[i]) * cpDist;