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196 lines
5.6 KiB
196 lines
5.6 KiB
2 years ago
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<!-- 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 - Custom Geometry - Heightmap</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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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 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 = 200;
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const camera = new THREE.PerspectiveCamera(fov, aspect, near, far);
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camera.position.set(20, 20, 20);
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const controls = new OrbitControls(camera, canvas);
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controls.target.set(0, 0, 0);
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controls.update();
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const scene = new THREE.Scene();
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function addLight(...pos) {
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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(...pos);
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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, 2, -2);
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const imgLoader = new THREE.ImageLoader();
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imgLoader.load('resources/images/heightmap-96x64.png', createHeightmap);
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function createHeightmap(image) {
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// extract the data from the image by drawing it to a canvas
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// and calling getImageData
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const ctx = document.createElement('canvas').getContext('2d');
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const {width, height} = image;
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ctx.canvas.width = width;
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ctx.canvas.height = height;
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ctx.drawImage(image, 0, 0);
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const {data} = ctx.getImageData(0, 0, width, height);
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const geometry = new THREE.Geometry();
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const cellsAcross = width - 1;
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const cellsDeep = height - 1;
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for (let z = 0; z < cellsDeep; ++z) {
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for (let x = 0; x < cellsAcross; ++x) {
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// compute row offsets into the height data
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// we multiply by 4 because the data is R,G,B,A but we
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// only care about R
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const base0 = (z * width + x) * 4;
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const base1 = base0 + (width * 4);
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// look up the height for the for points
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// around this cell
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const h00 = data[base0] / 32;
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const h01 = data[base0 + 4] / 32;
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const h10 = data[base1] / 32;
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const h11 = data[base1 + 4] / 32;
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// compute the average height
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const hm = (h00 + h01 + h10 + h11) / 4;
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// the corner positions
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const x0 = x;
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const x1 = x + 1;
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const z0 = z;
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const z1 = z + 1;
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// remember the first index of these 5 vertices
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const ndx = geometry.vertices.length;
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// add the 4 corners for this cell and the midpoint
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geometry.vertices.push(
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new THREE.Vector3(x0, h00, z0),
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new THREE.Vector3(x1, h01, z0),
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new THREE.Vector3(x0, h10, z1),
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new THREE.Vector3(x1, h11, z1),
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new THREE.Vector3((x0 + x1) / 2, hm, (z0 + z1) / 2),
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);
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// 2----3
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// |\ /|
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// | \/4|
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// | /\ |
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// |/ \|
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// 0----1
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// create 4 triangles
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geometry.faces.push(
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new THREE.Face3(ndx , ndx + 4, ndx + 1),
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new THREE.Face3(ndx + 1, ndx + 4, ndx + 3),
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new THREE.Face3(ndx + 3, ndx + 4, ndx + 2),
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new THREE.Face3(ndx + 2, ndx + 4, ndx + 0),
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);
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// add the texture coordinates for each vertex of each face.
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const u0 = x / cellsAcross;
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const v0 = z / cellsDeep;
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const u1 = (x + 1) / cellsAcross;
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const v1 = (z + 1) / cellsDeep;
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const um = (u0 + u1) / 2;
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const vm = (v0 + v1) / 2;
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geometry.faceVertexUvs[0].push(
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[ new THREE.Vector2(u0, v0), new THREE.Vector2(um, vm), new THREE.Vector2(u1, v0) ],
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[ new THREE.Vector2(u1, v0), new THREE.Vector2(um, vm), new THREE.Vector2(u1, v1) ],
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[ new THREE.Vector2(u1, v1), new THREE.Vector2(um, vm), new THREE.Vector2(u0, v1) ],
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[ new THREE.Vector2(u0, v1), new THREE.Vector2(um, vm), new THREE.Vector2(u0, v0) ],
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);
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}
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}
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geometry.computeFaceNormals();
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// center the geometry
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geometry.translate(width / -2, 0, height / -2);
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const loader = new THREE.TextureLoader();
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const texture = loader.load('resources/images/star.png');
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const material = new THREE.MeshPhongMaterial({color: 'green', map: texture});
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const cube = new THREE.Mesh(geometry, material);
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scene.add(cube);
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}
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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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function render() {
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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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renderer.render(scene, camera);
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requestAnimationFrame(render);
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}
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requestAnimationFrame(render);
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}
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main();
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</script>
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</html>
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