feat: LOD 网格分级——meshopt 解析期简化 + 按距离/级联选级

vendored meshoptimizer 1.2（submodule 环境故障改直接 vendor）。Mesh 多 LOD：各级索引连续拼进同一 index buffer（共享顶点，LodRange 区间选择），解析期 meshopt_simplify 生成链（LOD0=原始，每级目标减半，相对误差 1e-2，小网格复用上级）；都在 worker 线程，加载零额外卡顿。 SceneRenderer 按 (mesh, LOD) 聚合 batch（lookup key = 指针<<8|lod）：主视图按屏占比近似 radius/dist 选级（阈值 10/20 倍半径）；阴影级联按级联序降级（越远越简）。Draw 按 batch.lod 选索引区间。 A/B 对比（100 背包 10×10，RTX 5060 Laptop，vsync off）： - 纯背包：LOD 开 93-95 fps / 关 90-107 fps —— 无显著差异 - 加 SunTemple：LOD 开 52-56 / 关 51-55 —— 无显著差异结论：当前场景瓶颈不在顶点数（5060 顶点吞吐富余），LOD 基础设施保留（几何复杂资产/低端 GPU/更大场景生效），帧率问题转向 Tracy GPU 时间线定位真实瓶颈。坑：LodRange 记录"LOD 不足复用最后一级"时 first 不得继续累加（buffer 无重复数据，累加必越界——VUID-08798 抓的）。
2026-09-24 20:53:19 +08:00
parent 34b593f734
commit 5bdfb53566
125 changed files with 67608 additions and 29 deletions
@@ -0,0 +1,124 @@
+import assert from 'assert/strict';
+import { MeshoptTangents as tangents } from './meshopt_tangents.js';
+
+process.on('unhandledRejection', (error) => {
+	console.log('unhandledRejection', error);
+	process.exit(1);
+});
+
+var tests = {
+	tangentsBasic: function () {
+		// unindexed quad with matching corner data for shared diagonal
+		var positions = new Float32Array([0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0]);
+		var normals = new Float32Array([-0.28, 0, 0.96, 0.28, 0, 0.96, 0.28, 0, 0.96, -0.28, 0, 0.96, 0.28, 0, 0.96, -0.28, 0, 0.96]);
+		var uvs = new Float32Array([0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1]);
+
+		// (1, 0, 0) reprojected onto tilted normals
+		var left = [0.96, 0, 0.28, 1];
+		var right = [0.96, 0, -0.28, 1];
+		var expected = [left, right, right, left, right, left].flat();
+
+		// unindexed input: indices = null
+		var result = tangents.generateTangents(null, positions, 3, normals, 3, uvs, 2, []);
+
+		assert.equal(result.length, expected.length);
+
+		for (var i = 0; i < result.length; ++i) {
+			assert(Math.abs(result[i] - expected[i]) < 1e-3);
+		}
+
+		// shared vertices get the same tangent vector
+		for (var k = 0; k < 4; ++k) {
+			assert(result[0 * 4 + k] === result[3 * 4 + k]); // diag 1
+			assert(result[2 * 4 + k] === result[4 * 4 + k]); // diag 2
+		}
+	},
+
+	tangentDegenerate: function () {
+		var positions = new Float32Array([0, 0, 0, 1, 1, 0, 2, 2, 0, -1, -2, 1, 0, 1, 1, -1, 0, 0]);
+		var normals = new Float32Array([0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1]);
+		var uvs = new Float32Array([0, 0, 1, 1, 2, 2, 0, -2, 1, 0, 1, 0]);
+
+		var indices = new Uint32Array([
+			// outer, positive
+			0, 3, 1,
+			// inner, degenerate UVs
+			0, 1, 2,
+			// outer, positive
+			1, 4, 2,
+			// outer, negative
+			2, 5, 0,
+		]);
+
+		var vx = 0.0836;
+		var vy = 0.9965;
+		var expected = [
+			// outer, positive
+			[1, 0, 0, 1],
+			[1, 0, 0, 1],
+			[vx, vy, 0, 1],
+			// inner, degenerate UVs
+			[1, 0, 0, 1],
+			[vx, vy, 0, 1],
+			[0, 1, 0, 1],
+			// outer, positive
+			[vx, vy, 0, 1],
+			[0, 1, 0, 1],
+			[0, 1, 0, 1],
+			// outer, negative
+			[-1, 0, 0, -1],
+			[-1, 0, 0, -1],
+			[-1, 0, 0, -1],
+		].flat();
+
+		var result = tangents.generateTangents(indices, positions, 3, normals, 3, uvs, 2, ['Compatible']);
+
+		assert.equal(result.length, expected.length);
+
+		for (var i = 0; i < result.length; ++i) {
+			assert(Math.abs(result[i] - expected[i]) < 1e-3);
+		}
+	},
+
+	normalsBasic: function () {
+		var positions = new Float32Array([-1, -0.57735, 0, 1, -0.57735, 0, 0, 1.1547, 0, 0, 0, 0.38]);
+
+		// flattened tetrahedron (apex is closer to the base so that we can get soft side edges)
+		var indices = new Uint32Array([0, 2, 1, 0, 1, 3, 1, 2, 3, 2, 0, 3]);
+
+		var base = [0, 0, -1];
+		var side0 = [-0.2707, -0.1563, 0.9499];
+		var side1 = [0.2707, -0.1563, 0.9499];
+		var side2 = [0, 0.3126, 0.9499];
+		var apex = [0, 0, 1];
+		var expected = [base, base, base, side0, side1, apex, side1, side2, apex, side2, side0, apex].flat();
+
+		var result = tangents.generateNormals(indices, positions, 3, Math.PI / 3);
+
+		assert.equal(result.length, expected.length);
+
+		for (var i = 0; i < result.length; ++i) {
+			assert(Math.abs(result[i] - expected[i]) < 1e-3);
+		}
+
+		// shared vertices around soft side edges get the same normal vector
+		for (var k = 0; k < 3; ++k) {
+			assert(result[3 * 3 + k] === result[10 * 3 + k]); // side0
+			assert(result[4 * 3 + k] === result[6 * 3 + k]); // side1
+			assert(result[7 * 3 + k] === result[9 * 3 + k]); // side2
+			assert(result[5 * 3 + k] === result[8 * 3 + k]); // apex
+			assert(result[5 * 3 + k] === result[11 * 3 + k]); // apex
+		}
+	},
+};
+
+tangents.ready.then(() => {
+	var count = 0;
+
+	for (var key in tests) {
+		tests[key]();
+		count++;
+	}
+
+	console.log(count, 'tests passed');
+});