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perf: optimize displacement export falloff — SoA layout, flat grid, merged passes #34

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perf: optimize displacement export falloff — SoA layout, flat grid, merged passes #34

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49d68d8
perf: integrate position lookup into dedup pass, eliminate redundant …
Avatarsia Apr 7, 2026
21d0d7b
perf: replace array-of-arrays with flat SoA layout for boundary posit…
Avatarsia Apr 7, 2026
198c2ff
perf: replace Map with flat array for spatial grid in boundary falloff
Avatarsia Apr 7, 2026
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77 changes: 40 additions & 37 deletions js/displacement.js
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Original file line number Diff line number Diff line change
Expand Up @@ -66,11 +66,20 @@ export function applyDisplacement(geometry, imageData, imgWidth, imgHeight, sett
const _dedupMap = new Map();
let _nextId = 0;
const vertexId = new Uint32Array(count);
const _idPosX = [];
const _idPosY = [];
const _idPosZ = [];
for (let i = 0; i < count; i++) {
const x = posAttr.getX(i), y = posAttr.getY(i), z = posAttr.getZ(i);
const key = `${Math.round(x * QUANT)}_${Math.round(y * QUANT)}_${Math.round(z * QUANT)}`;
let id = _dedupMap.get(key);
if (id === undefined) { id = _nextId++; _dedupMap.set(key, id); }
if (id === undefined) {
id = _nextId++;
_dedupMap.set(key, id);
_idPosX.push(x);
_idPosY.push(y);
_idPosZ.push(z);
}
vertexId[i] = id;
}
const uniqueCount = _nextId;
Expand Down Expand Up @@ -191,61 +200,55 @@ export function applyDisplacement(geometry, imageData, imgWidth, imgHeight, sett
let falloffArr = null;

if (boundaryFalloff > 0) {
// Build position lookup per unique vertex ID (first occurrence)
const idPosX = new Float64Array(uniqueCount);
const idPosY = new Float64Array(uniqueCount);
const idPosZ = new Float64Array(uniqueCount);
const idPosSeen = new Uint8Array(uniqueCount);
for (let i = 0; i < count; i++) {
const vid = vertexId[i];
if (!idPosSeen[vid]) {
idPosSeen[vid] = 1;
idPosX[vid] = posAttr.getX(i);
idPosY[vid] = posAttr.getY(i);
idPosZ[vid] = posAttr.getZ(i);
}
// Count boundary positions first, then allocate flat SoA arrays
let bpCount = 0;
for (let id = 0; id < uniqueCount; id++) {
const mfTotal = maskedFracTotal[id];
const maskedFrac = mfTotal > 0 ? maskedFracMasked[id] / mfTotal : 0;
const isOnExclBoundary = excludedPos && excludedPos[id] === 1;
if (isOnExclBoundary || (maskedFrac > 0 && maskedFrac < 1)) bpCount++;
}

const boundaryPositions = []; // [[x, y, z], ...]

// Collect boundary positions: vertices where maskedFrac is between 0 and 1,
// or that sit on the user-exclusion seam.
const bpX = new Float64Array(bpCount);
const bpY = new Float64Array(bpCount);
const bpZ = new Float64Array(bpCount);
let bpIdx = 0;
for (let id = 0; id < uniqueCount; id++) {
const mfTotal = maskedFracTotal[id];
const maskedFrac = mfTotal > 0 ? maskedFracMasked[id] / mfTotal : 0;
const isOnExclBoundary = excludedPos && excludedPos[id] === 1;
if (isOnExclBoundary || (maskedFrac > 0 && maskedFrac < 1)) {
boundaryPositions.push([idPosX[id], idPosY[id], idPosZ[id]]);
bpX[bpIdx] = _idPosX[id]; bpY[bpIdx] = _idPosY[id]; bpZ[bpIdx] = _idPosZ[id];
bpIdx++;
}
}

if (boundaryPositions.length > 0) {
if (bpCount > 0) {
// Build a spatial grid of boundary positions for fast nearest-neighbor lookup
let gMinX = Infinity, gMinY = Infinity, gMinZ = Infinity;
let gMaxX = -Infinity, gMaxY = -Infinity, gMaxZ = -Infinity;
for (const bp of boundaryPositions) {
if (bp[0] < gMinX) gMinX = bp[0]; if (bp[0] > gMaxX) gMaxX = bp[0];
if (bp[1] < gMinY) gMinY = bp[1]; if (bp[1] > gMaxY) gMaxY = bp[1];
if (bp[2] < gMinZ) gMinZ = bp[2]; if (bp[2] > gMaxZ) gMaxZ = bp[2];
for (let i = 0; i < bpCount; i++) {
if (bpX[i] < gMinX) gMinX = bpX[i]; if (bpX[i] > gMaxX) gMaxX = bpX[i];
if (bpY[i] < gMinY) gMinY = bpY[i]; if (bpY[i] > gMaxY) gMaxY = bpY[i];
if (bpZ[i] < gMinZ) gMinZ = bpZ[i]; if (bpZ[i] > gMaxZ) gMaxZ = bpZ[i];
}
const gPad = boundaryFalloff + 1e-3;
gMinX -= gPad; gMinY -= gPad; gMinZ -= gPad;
gMaxX += gPad; gMaxY += gPad; gMaxZ += gPad;

const gRes = Math.max(4, Math.min(128, Math.ceil(Math.cbrt(boundaryPositions.length) * 2)));
const gRes = Math.max(4, Math.min(128, Math.ceil(Math.cbrt(bpCount) * 2)));
const gDx = (gMaxX - gMinX) / gRes || 1;
const gDy = (gMaxY - gMinY) / gRes || 1;
const gDz = (gMaxZ - gMinZ) / gRes || 1;
const bGrid = new Map();
const gridSize = gRes * gRes * gRes;
const bGrid = new Array(gridSize);
const bCellKey = (ix, iy, iz) => (ix * gRes + iy) * gRes + iz;

for (const bp of boundaryPositions) {
const ix = Math.max(0, Math.min(gRes - 1, Math.floor((bp[0] - gMinX) / gDx)));
const iy = Math.max(0, Math.min(gRes - 1, Math.floor((bp[1] - gMinY) / gDy)));
const iz = Math.max(0, Math.min(gRes - 1, Math.floor((bp[2] - gMinZ) / gDz)));
for (let i = 0; i < bpCount; i++) {
const ix = Math.max(0, Math.min(gRes - 1, Math.floor((bpX[i] - gMinX) / gDx)));
const iy = Math.max(0, Math.min(gRes - 1, Math.floor((bpY[i] - gMinY) / gDy)));
const iz = Math.max(0, Math.min(gRes - 1, Math.floor((bpZ[i] - gMinZ) / gDz)));
const ck = bCellKey(ix, iy, iz);
const cell = bGrid.get(ck);
if (cell) cell.push(bp); else bGrid.set(ck, [bp]);
if (bGrid[ck]) bGrid[ck].push(i); else bGrid[ck] = [i];
}

// How many grid cells to search in each direction to cover boundaryFalloff distance
Expand All @@ -262,7 +265,7 @@ export function applyDisplacement(geometry, imageData, imgWidth, imgHeight, sett
// Only compute falloff for fully-textured, non-boundary positions
if (maskedFrac > 0 || isOnExclBoundary) continue;

const px = idPosX[id], py = idPosY[id], pz = idPosZ[id];
const px = _idPosX[id], py = _idPosY[id], pz = _idPosZ[id];
const cix = Math.max(0, Math.min(gRes - 1, Math.floor((px - gMinX) / gDx)));
const ciy = Math.max(0, Math.min(gRes - 1, Math.floor((py - gMinY) / gDy)));
const ciz = Math.max(0, Math.min(gRes - 1, Math.floor((pz - gMinZ) / gDz)));
Expand All @@ -277,10 +280,10 @@ export function applyDisplacement(geometry, imageData, imgWidth, imgHeight, sett
for (let diz = -searchZ; diz <= searchZ; diz++) {
const niz = ciz + diz;
if (niz < 0 || niz >= gRes) continue;
const cell = bGrid.get(bCellKey(nix, niy, niz));
const cell = bGrid[bCellKey(nix, niy, niz)];
if (!cell) continue;
for (const bp of cell) {
const dx = px - bp[0], dy = py - bp[1], dz = pz - bp[2];
for (const idx of cell) {
const dx = px - bpX[idx], dy = py - bpY[idx], dz = pz - bpZ[idx];
const d2 = dx * dx + dy * dy + dz * dz;
if (d2 < minDist2) minDist2 = d2;
}
Expand Down