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							287 lines
						
					
					
						
							7.3 KiB
						
					
					
				
								<!-- Licensed under a BSD license. See license.html for license -->
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								<!DOCTYPE html>
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								<html>
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								  <head>
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								    <meta charset="utf-8">
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								    <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
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								    <title>Three.js - Voxel Geometry - Culled Faces</title>
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								    <style>
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								    html, body {
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								        height: 100%;
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								        margin: 0;
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								    }
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								    #c {
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								        width: 100%;
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								        height: 100%;
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								        display: block;
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								    }
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								    </style>
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								  </head>
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								  <body>
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								    <canvas id="c"></canvas>
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								  </body>
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								<!-- Import maps polyfill -->
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								<!-- Remove this when import maps will be widely supported -->
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								<script async src="https://unpkg.com/es-module-shims@1.3.6/dist/es-module-shims.js"></script>
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								<script type="importmap">
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								{
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								  "imports": {
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								    "three": "../../build/three.module.js",
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								    "three/addons/": "../../examples/jsm/"
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								  }
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								}
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								</script>
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								<script type="module">
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								import * as THREE from 'three';
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								import {OrbitControls} from 'three/addons/controls/OrbitControls.js';
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								class VoxelWorld {
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								  constructor(cellSize) {
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								    this.cellSize = cellSize;
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								    this.cellSliceSize = cellSize * cellSize;
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								    this.cell = new Uint8Array(cellSize * cellSize * cellSize);
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								  }
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								  computeVoxelOffset(x, y, z) {
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								    const {cellSize, cellSliceSize} = this;
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								    const voxelX = THREE.MathUtils.euclideanModulo(x, cellSize) | 0;
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								    const voxelY = THREE.MathUtils.euclideanModulo(y, cellSize) | 0;
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								    const voxelZ = THREE.MathUtils.euclideanModulo(z, cellSize) | 0;
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								    return voxelY * cellSliceSize +
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								           voxelZ * cellSize +
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								           voxelX;
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								  }
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								  getCellForVoxel(x, y, z) {
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								    const {cellSize} = this;
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								    const cellX = Math.floor(x / cellSize);
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								    const cellY = Math.floor(y / cellSize);
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								    const cellZ = Math.floor(z / cellSize);
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								    if (cellX !== 0 || cellY !== 0 || cellZ !== 0) {
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								      return null;
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								    }
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								    return this.cell;
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								  }
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								  setVoxel(x, y, z, v) {
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								    const cell = this.getCellForVoxel(x, y, z);
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								    if (!cell) {
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								      return;  // TODO: add a new cell?
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								    }
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								    const voxelOffset = this.computeVoxelOffset(x, y, z);
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								    cell[voxelOffset] = v;
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								  }
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								  getVoxel(x, y, z) {
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								    const cell = this.getCellForVoxel(x, y, z);
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								    if (!cell) {
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								      return 0;
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								    }
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								    const voxelOffset = this.computeVoxelOffset(x, y, z);
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								    return cell[voxelOffset];
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								  }
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								  generateGeometryDataForCell(cellX, cellY, cellZ) {
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								    const {cellSize} = this;
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								    const positions = [];
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								    const normals = [];
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								    const indices = [];
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								    const startX = cellX * cellSize;
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								    const startY = cellY * cellSize;
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								    const startZ = cellZ * cellSize;
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								    for (let y = 0; y < cellSize; ++y) {
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								      const voxelY = startY + y;
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								      for (let z = 0; z < cellSize; ++z) {
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								        const voxelZ = startZ + z;
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								        for (let x = 0; x < cellSize; ++x) {
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								          const voxelX = startX + x;
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								          const voxel = this.getVoxel(voxelX, voxelY, voxelZ);
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								          if (voxel) {
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								            // There is a voxel here but do we need faces for it?
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								            for (const {dir, corners} of VoxelWorld.faces) {
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								              const neighbor = this.getVoxel(
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								                  voxelX + dir[0],
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								                  voxelY + dir[1],
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								                  voxelZ + dir[2]);
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								              if (!neighbor) {
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								                // this voxel has no neighbor in this direction so we need a face.
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								                const ndx = positions.length / 3;
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								                for (const pos of corners) {
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								                  positions.push(pos[0] + x, pos[1] + y, pos[2] + z);
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								                  normals.push(...dir);
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								                }
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								                indices.push(
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								                  ndx, ndx + 1, ndx + 2,
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								                  ndx + 2, ndx + 1, ndx + 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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								    }
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								    return {
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								      positions,
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								      normals,
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								      indices,
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								    };
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								  }
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								}
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								VoxelWorld.faces = [
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								  { // left
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								    dir: [ -1,  0,  0, ],
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								    corners: [
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								      [ 0, 1, 0 ],
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								      [ 0, 0, 0 ],
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								      [ 0, 1, 1 ],
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								      [ 0, 0, 1 ],
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								    ],
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								  },
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								  { // right
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								    dir: [  1,  0,  0, ],
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								    corners: [
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								      [ 1, 1, 1 ],
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								      [ 1, 0, 1 ],
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								      [ 1, 1, 0 ],
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								      [ 1, 0, 0 ],
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								    ],
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								  },
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								  { // bottom
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								    dir: [  0, -1,  0, ],
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								    corners: [
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								      [ 1, 0, 1 ],
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								      [ 0, 0, 1 ],
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								      [ 1, 0, 0 ],
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								      [ 0, 0, 0 ],
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								    ],
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								  },
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								  { // top
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								    dir: [  0,  1,  0, ],
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								    corners: [
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								      [ 0, 1, 1 ],
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								      [ 1, 1, 1 ],
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								      [ 0, 1, 0 ],
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								      [ 1, 1, 0 ],
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								    ],
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								  },
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								  { // back
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								    dir: [  0,  0, -1, ],
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								    corners: [
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								      [ 1, 0, 0 ],
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								      [ 0, 0, 0 ],
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								      [ 1, 1, 0 ],
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								      [ 0, 1, 0 ],
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								    ],
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								  },
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								  { // front
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								    dir: [  0,  0,  1, ],
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								    corners: [
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								      [ 0, 0, 1 ],
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								      [ 1, 0, 1 ],
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								      [ 0, 1, 1 ],
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								      [ 1, 1, 1 ],
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								    ],
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								  },
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								];
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								function main() {
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								  const canvas = document.querySelector('#c');
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								  const renderer = new THREE.WebGLRenderer({canvas});
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								  const cellSize = 32;
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								  const fov = 75;
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								  const aspect = 2;  // the canvas default
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								  const near = 0.1;
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								  const far = 1000;
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								  const camera = new THREE.PerspectiveCamera(fov, aspect, near, far);
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								  camera.position.set(-cellSize * .3, cellSize * .8, -cellSize * .3);
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								  const controls = new OrbitControls(camera, canvas);
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								  controls.target.set(cellSize / 2, cellSize / 3, cellSize / 2);
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								  controls.update();
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								  const scene = new THREE.Scene();
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								  scene.background = new THREE.Color('lightblue');
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								  function addLight(x, y, z) {
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								    const color = 0xFFFFFF;
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								    const intensity = 1;
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								    const light = new THREE.DirectionalLight(color, intensity);
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								    light.position.set(x, y, z);
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								    scene.add(light);
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								  }
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								  addLight(-1,  2,  4);
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								  addLight( 1, -1, -2);
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								  const world = new VoxelWorld(cellSize);
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								  for (let y = 0; y < cellSize; ++y) {
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								    for (let z = 0; z < cellSize; ++z) {
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								      for (let x = 0; x < cellSize; ++x) {
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								        const height = (Math.sin(x / cellSize * Math.PI * 2) + Math.sin(z / cellSize * Math.PI * 3)) * (cellSize / 6) + (cellSize / 2);
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								        if (y < height) {
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								          world.setVoxel(x, y, z, 1);
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								        }
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								      }
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								    }
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								  }
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								  const {positions, normals, indices} = world.generateGeometryDataForCell(0, 0, 0);
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								  const geometry = new THREE.BufferGeometry();
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								  const material = new THREE.MeshLambertMaterial({color: 'green'});
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								  const positionNumComponents = 3;
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								  const normalNumComponents = 3;
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								  geometry.setAttribute(
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								      'position',
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								      new THREE.BufferAttribute(new Float32Array(positions), positionNumComponents));
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								  geometry.setAttribute(
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								      'normal',
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								      new THREE.BufferAttribute(new Float32Array(normals), normalNumComponents));
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								  geometry.setIndex(indices);
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								  const mesh = new THREE.Mesh(geometry, material);
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								  scene.add(mesh);
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								  function resizeRendererToDisplaySize(renderer) {
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								    const canvas = renderer.domElement;
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								    const width = canvas.clientWidth;
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								    const height = canvas.clientHeight;
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								    const needResize = canvas.width !== width || canvas.height !== height;
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								    if (needResize) {
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								      renderer.setSize(width, height, false);
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								    }
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								    return needResize;
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								  }
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								  let renderRequested = false;
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								  function render() {
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								    renderRequested = undefined;
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								    if (resizeRendererToDisplaySize(renderer)) {
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								      const canvas = renderer.domElement;
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								      camera.aspect = canvas.clientWidth / canvas.clientHeight;
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								      camera.updateProjectionMatrix();
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								    }
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								    controls.update();
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								    renderer.render(scene, camera);
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								  }
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								  render();
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								  function requestRenderIfNotRequested() {
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								    if (!renderRequested) {
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								      renderRequested = true;
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								      requestAnimationFrame(render);
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								    }
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								  }
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								  controls.addEventListener('change', requestRenderIfNotRequested);
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								  window.addEventListener('resize', requestRenderIfNotRequested);
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								}
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								main();
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								</script>
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								</html>
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