mikael-lovqvists-claude-agent
9600a2bc2a
Interactive WebGL Goldberg polyhedron viewer and painter with PBR shading, adjustable environment lighting, paint tools (pen, brush, circle, fill, line, pick), undo/redo, colour palettes, and mesh relaxation. Added to the standalone experiments index. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
69 lines
2.3 KiB
JavaScript
69 lines
2.3 KiB
JavaScript
// Placement via unfolding: each neighbor face is placed adjacent to its BFS
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// parent by a similarity transform, then shrunk toward its centroid by
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// DEPTH_SHRINK^depth so depth rings visually separate.
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//
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// Returns Map<face_index, { vertices_2d, centroid_2d, depth }>
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import {
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regular_polygon_2d,
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centroid_2d,
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similarity_transform_2d,
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apply_transform_2d,
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} from './geometry.mjs';
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const DEPTH_SHRINK = 0.82;
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export function place_unfold(poly, neighborhood, root_face_index, cx, cy, face_size) {
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const placements = new Map();
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for (const entry of neighborhood) {
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const fi = entry.face.index;
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const face = entry.face;
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const n = face.size;
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if (entry.parent_index === null) {
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// Root face: regular polygon centred on canvas.
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const pts = regular_polygon_2d(n, face_size).map(([x, y]) => [x + cx, y + cy]);
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placements.set(fi, { vertices_2d: pts, centroid_2d: [cx, cy], depth: 0 });
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} else {
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const parent_pl = placements.get(entry.parent_index);
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if (!parent_pl) { continue; }
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const parent_face = poly.faces[entry.parent_index];
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const pei = entry.parent_edge_index;
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const pa = parent_pl.vertices_2d[pei];
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const pb = parent_pl.vertices_2d[(pei + 1) % parent_face.size];
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// Find which edge of this face leads back to the parent.
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let nei = -1;
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for (let j = 0; j < face.edge_neighbors.length; j++) {
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if (face.edge_neighbors[j] === entry.parent_index) { nei = j; break; }
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}
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if (nei === -1) {
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console.warn(`place_unfold: face ${fi} has no reverse edge to parent ${entry.parent_index}`);
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continue;
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}
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// Winding is opposite: parent (a→b) ≡ neighbor (b→a).
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const local_pts = regular_polygon_2d(n, 1);
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const local_a = local_pts[nei];
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const local_b = local_pts[(nei + 1) % n];
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const transform = similarity_transform_2d(local_a, local_b, pb, pa);
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let vertices_2d = local_pts.map(pt => apply_transform_2d(transform, pt));
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const c = centroid_2d(vertices_2d);
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// Shrink toward centroid after transform (before would be cancelled by scaling).
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const shrink = Math.pow(DEPTH_SHRINK, entry.depth);
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vertices_2d = vertices_2d.map(([x, y]) => [
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c[0] + (x - c[0]) * shrink,
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c[1] + (y - c[1]) * shrink,
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]);
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placements.set(fi, { vertices_2d, centroid_2d: c, depth: entry.depth });
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}
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}
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return placements;
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}
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