44 lines
1.1 KiB
JavaScript
44 lines
1.1 KiB
JavaScript
import { round } from './constants.js';
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export function computeHomography(state) {
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const w = state.widgetW, h = state.widgetH;
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if (w <= 0 || h <= 0) return null;
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const [p0, p1, p2, p3] = state.corners;
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const a11 = p2.x - p1.x, a12 = p2.x - p3.x;
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const b1 = p1.x + p3.x - p0.x - p2.x;
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const a21 = p2.y - p1.y, a22 = p2.y - p3.y;
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const b2 = p1.y + p3.y - p0.y - p2.y;
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const D = a11 * a22 - a12 * a21;
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if (Math.abs(D) < 1e-10) return null;
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const A = (b1 * a22 - b2 * a12) / D;
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const B = (a11 * b2 - a21 * b1) / D;
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return {
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h00: (p1.x * (A + 1) - p0.x) / w,
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h10: (p1.y * (A + 1) - p0.y) / w,
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h01: (p3.x * (B + 1) - p0.x) / h,
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h11: (p3.y * (B + 1) - p0.y) / h,
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h02: p0.x,
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h12: p0.y,
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h20: A / w,
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h21: B / h,
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h22: 1
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};
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}
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export function toMatrix3dCSS(H) {
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if (!H) return '/* degenerate configuration */';
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return [
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'transform-origin: 0 0;',
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'transform: matrix3d(',
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` ${round(H.h00)}, ${round(H.h10)}, 0, ${round(H.h20)},`,
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` ${round(H.h01)}, ${round(H.h11)}, 0, ${round(H.h21)},`,
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` 0, 0, 1, 0,`,
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` ${round(H.h02)}, ${round(H.h12)}, 0, ${round(H.h22)}`,
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');'
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].join('\n');
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}
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