greedy meshing
This commit is contained in:
azykov@mail.ru
@@ -1,35 +1,23 @@
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import type { ObjectType, RuntimeGameObjectInstance, RuntimeObjectInstance } from "../types";
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import type { VoxelGroup } from "../types/runtime/voxelGroup";
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import { useEffect, useImperativeHandle, useLayoutEffect, useRef, type Ref, memo } from "react";
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import { Euler, Matrix4, Quaternion, type Group, type InstancedMesh } from "three";
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import { useEffect, useImperativeHandle, useRef, type Ref, memo, useMemo } from "react";
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import { Euler, Quaternion, type Group } from "three";
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import type { ThreeEvent } from "@react-three/fiber";
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import { ConvexHullCollider, RapierRigidBody } from "@react-three/rapier";
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import { SyncRigidBody } from "./SyncRigidBody";
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import { reaction, runInAction } from "mobx";
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import { v3toRapier } from "../utils";
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import { state } from "../state";
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const _m4 = new Matrix4();
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import { greedyMesh } from "../utils/graphics/greedyMesh";
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const VoxelGroupMesh = memo(function VoxelGroupMesh({ vg }: { vg: VoxelGroup }) {
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const ref = useRef<InstancedMesh>(null);
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useLayoutEffect(() => {
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const mesh = ref.current;
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if (!mesh)
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return;
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vg.positions.forEach(([x, y, z], i) => {
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mesh.setMatrixAt(i, _m4.makeTranslation(x, y, z));
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});
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mesh.instanceMatrix.needsUpdate = true;
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mesh.computeBoundingSphere();
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}, [vg]);
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const geo = useMemo(() => greedyMesh(vg.positions), [vg]);
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useEffect(() => () => { geo.dispose(); }, [geo]);
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return (
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<instancedMesh ref={ref} args={[undefined, undefined, vg.positions.length]}>
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<boxGeometry args={[1, 1, 1]} />
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<mesh geometry={geo}>
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<meshStandardMaterial color={vg.color} opacity={vg.opacity} transparent={vg.opacity < 1} />
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</instancedMesh>
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</mesh>
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);
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});
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@@ -0,0 +1,133 @@
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import { BufferGeometry, Float32BufferAttribute } from 'three';
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import type { V3 } from '../../types';
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// tangent axes for each main axis
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const U_OF = [1, 0, 0] as const;
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const V_OF = [2, 2, 1] as const;
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/**
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* Greedy meshing: merges face-adjacent same-material voxels into minimal quads.
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* A 50×1×50 flat layer produces 6 quads (12 triangles), not 50×50×6×2.
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*
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* Only face-adjacency counts — diagonal neighbours do not merge.
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*/
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export function greedyMesh(positions: V3[]): BufferGeometry {
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if (!positions.length)
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return new BufferGeometry();
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const occ = new Set<string>();
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let x0 = Infinity, y0 = Infinity, z0 = Infinity;
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let x1 = -Infinity, y1 = -Infinity, z1 = -Infinity;
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for (const [x, y, z] of positions) {
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occ.add(`${x},${y},${z}`);
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if (x < x0)
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x0 = x;
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if (x > x1)
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x1 = x;
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if (y < y0)
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y0 = y;
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if (y > y1)
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y1 = y;
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if (z < z0)
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z0 = z;
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if (z > z1)
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z1 = z;
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}
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const has = (x: number, y: number, z: number) => occ.has(`${x},${y},${z}`);
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const lo = [x0, y0, z0];
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const hi = [x1, y1, z1];
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const verts: number[] = [];
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const inds: number[] = [];
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for (let axis = 0; axis < 3; axis++) {
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const u = U_OF[axis];
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const v = V_OF[axis];
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const dLen = hi[axis] - lo[axis] + 1;
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const uLen = hi[u] - lo[u] + 1;
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const vLen = hi[v] - lo[v] + 1;
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const mask = new Uint8Array(uLen * vLen);
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const done = new Uint8Array(uLen * vLen);
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for (let dir = -1; dir <= 1; dir += 2) {
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// For corner order (u0,v0)(u1,v0)(u1,v1)(u0,v1),
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// cross product = +e_axis when axis≠Y, −e_Y when axis=Y.
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// flip reverses winding to point outward for the given dir.
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const flip = axis === 1 ? dir > 0 : dir < 0;
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for (let di = 0; di < dLen; di++) {
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const D = lo[axis] + di;
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mask.fill(0);
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done.fill(0);
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for (let vi = 0; vi < vLen; vi++) {
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for (let ui = 0; ui < uLen; ui++) {
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const p: [number, number, number] = [0, 0, 0];
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p[axis] = D;
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p[u] = lo[u] + ui;
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p[v] = lo[v] + vi;
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if (!has(p[0], p[1], p[2]))
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continue;
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const np: [number, number, number] = [p[0], p[1], p[2]];
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np[axis] += dir;
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if (!has(np[0], np[1], np[2]))
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mask[ui + vi * uLen] = 1;
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}
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}
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for (let vi = 0; vi < vLen; vi++) {
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for (let ui = 0; ui < uLen; ui++) {
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if (!mask[ui + vi * uLen] || done[ui + vi * uLen])
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continue;
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let wu = 1;
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while (ui + wu < uLen && mask[ui + wu + vi * uLen] && !done[ui + wu + vi * uLen])
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wu++;
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let wv = 1;
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expand: while (vi + wv < vLen) {
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for (let k = 0; k < wu; k++)
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if (!mask[ui + k + (vi + wv) * uLen] || done[ui + k + (vi + wv) * uLen])
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break expand;
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wv++;
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}
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for (let dv = 0; dv < wv; dv++)
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for (let du = 0; du < wu; du++)
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done[ui + du + (vi + dv) * uLen] = 1;
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const dp = D + (dir > 0 ? 0.5 : -0.5);
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const uA = lo[u] + ui - 0.5;
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const uB = uA + wu;
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const vA = lo[v] + vi - 0.5;
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const vB = vA + wv;
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const base = verts.length / 3;
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for (const [cu, cv] of [[uA, vA], [uB, vA], [uB, vB], [uA, vB]] as const) {
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const pt: [number, number, number] = [0, 0, 0];
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pt[axis] = dp;
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pt[u] = cu;
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pt[v] = cv;
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verts.push(pt[0], pt[1], pt[2]);
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}
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if (flip) {
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inds.push(base, base + 2, base + 1, base, base + 3, base + 2);
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} else {
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inds.push(base, base + 1, base + 2, base, base + 2, base + 3);
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}
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}
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}
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}
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}
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}
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const geo = new BufferGeometry();
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geo.setAttribute('position', new Float32BufferAttribute(verts, 3));
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geo.setIndex(inds);
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geo.computeVertexNormals();
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return geo;
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}
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