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<!-- Licensed under a BSD license. See license.html for license -->
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
<title>Three.js - Custom Geometry - Heightmap</title>
<style>
html, body {
height: 100%;
margin: 0;
}
#c {
width: 100%;
height: 100%;
display: block;
}
</style>
</head>
<body>
<canvas id="c"></canvas>
</body>
<!-- Import maps polyfill -->
<!-- Remove this when import maps will be widely supported -->
<script async src="https://unpkg.com/es-module-shims@1.3.6/dist/es-module-shims.js"></script>
<script type="importmap">
{
"imports": {
"three": "../../build/three.module.js",
"three/addons/": "../../examples/jsm/"
}
}
</script>
<script type="module">
import * as THREE from 'three';
import {OrbitControls} from 'three/addons/controls/OrbitControls.js';
function main() {
const canvas = document.querySelector('#c');
const renderer = new THREE.WebGLRenderer({canvas});
const fov = 75;
const aspect = 2; // the canvas default
const near = 0.1;
const far = 200;
const camera = new THREE.PerspectiveCamera(fov, aspect, near, far);
camera.position.set(20, 20, 20);
const controls = new OrbitControls(camera, canvas);
controls.target.set(0, 0, 0);
controls.update();
const scene = new THREE.Scene();
function addLight(...pos) {
const color = 0xFFFFFF;
const intensity = 1;
const light = new THREE.DirectionalLight(color, intensity);
light.position.set(...pos);
scene.add(light);
}
addLight(-1, 2, 4);
addLight(1, 2, -2);
const imgLoader = new THREE.ImageLoader();
imgLoader.load('resources/images/heightmap-96x64.png', createHeightmap);
function createHeightmap(image) {
// extract the data from the image by drawing it to a canvas
// and calling getImageData
const ctx = document.createElement('canvas').getContext('2d');
const {width, height} = image;
ctx.canvas.width = width;
ctx.canvas.height = height;
ctx.drawImage(image, 0, 0);
const {data} = ctx.getImageData(0, 0, width, height);
const geometry = new THREE.Geometry();
const cellsAcross = width - 1;
const cellsDeep = height - 1;
for (let z = 0; z < cellsDeep; ++z) {
for (let x = 0; x < cellsAcross; ++x) {
// compute row offsets into the height data
// we multiply by 4 because the data is R,G,B,A but we
// only care about R
const base0 = (z * width + x) * 4;
const base1 = base0 + (width * 4);
// look up the height for the for points
// around this cell
const h00 = data[base0] / 32;
const h01 = data[base0 + 4] / 32;
const h10 = data[base1] / 32;
const h11 = data[base1 + 4] / 32;
// compute the average height
const hm = (h00 + h01 + h10 + h11) / 4;
// the corner positions
const x0 = x;
const x1 = x + 1;
const z0 = z;
const z1 = z + 1;
// remember the first index of these 5 vertices
const ndx = geometry.vertices.length;
// add the 4 corners for this cell and the midpoint
geometry.vertices.push(
new THREE.Vector3(x0, h00, z0),
new THREE.Vector3(x1, h01, z0),
new THREE.Vector3(x0, h10, z1),
new THREE.Vector3(x1, h11, z1),
new THREE.Vector3((x0 + x1) / 2, hm, (z0 + z1) / 2),
);
// 2----3
// |\ /|
// | \/4|
// | /\ |
// |/ \|
// 0----1
// create 4 triangles
geometry.faces.push(
new THREE.Face3(ndx , ndx + 4, ndx + 1),
new THREE.Face3(ndx + 1, ndx + 4, ndx + 3),
new THREE.Face3(ndx + 3, ndx + 4, ndx + 2),
new THREE.Face3(ndx + 2, ndx + 4, ndx + 0),
);
// add the texture coordinates for each vertex of each face.
const u0 = x / cellsAcross;
const v0 = z / cellsDeep;
const u1 = (x + 1) / cellsAcross;
const v1 = (z + 1) / cellsDeep;
const um = (u0 + u1) / 2;
const vm = (v0 + v1) / 2;
geometry.faceVertexUvs[0].push(
[ new THREE.Vector2(u0, v0), new THREE.Vector2(um, vm), new THREE.Vector2(u1, v0) ],
[ new THREE.Vector2(u1, v0), new THREE.Vector2(um, vm), new THREE.Vector2(u1, v1) ],
[ new THREE.Vector2(u1, v1), new THREE.Vector2(um, vm), new THREE.Vector2(u0, v1) ],
[ new THREE.Vector2(u0, v1), new THREE.Vector2(um, vm), new THREE.Vector2(u0, v0) ],
);
}
}
geometry.computeFaceNormals();
// center the geometry
geometry.translate(width / -2, 0, height / -2);
const loader = new THREE.TextureLoader();
const texture = loader.load('resources/images/star.png');
const material = new THREE.MeshPhongMaterial({color: 'green', map: texture});
const cube = new THREE.Mesh(geometry, material);
scene.add(cube);
}
function resizeRendererToDisplaySize(renderer) {
const canvas = renderer.domElement;
const width = canvas.clientWidth;
const height = canvas.clientHeight;
const needResize = canvas.width !== width || canvas.height !== height;
if (needResize) {
renderer.setSize(width, height, false);
}
return needResize;
}
function render() {
if (resizeRendererToDisplaySize(renderer)) {
const canvas = renderer.domElement;
camera.aspect = canvas.clientWidth / canvas.clientHeight;
camera.updateProjectionMatrix();
}
renderer.render(scene, camera);
requestAnimationFrame(render);
}
requestAnimationFrame(render);
}
main();
</script>
</html>