Cascaded Shadow Maps (CSM)

Cascaded Shadow Maps are a concept where higher resolution shadows are used near the camera and lower resolution further away.

The default CSM object creates 4 frustums with 4 directional lights with shadows and different shadow map sizes.

It is a good solution for when you want to cast shadows across a very large area with many objects near and far.

Code

./src/server/server.ts

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import express from "express"
import path from "path"
import http from "http"

const port: number = 3000

class App {
    private server: http.Server
    private port: number

    constructor(port: number) {
        this.port = port
        const app = express()
        app.use(express.static(path.join(__dirname, '../client')))
        app.use('/build/three.module.js', express.static(path.join(__dirname, '../../node_modules/three/build/three.module.js')))
        app.use('/jsm/libs/dat.gui.module', express.static(path.join(__dirname, '../../node_modules/three/examples/jsm/libs/dat.gui.module.js')))
        app.use('/jsm/controls/OrbitControls', express.static(path.join(__dirname, '../../node_modules/three/examples/jsm/controls/OrbitControls.js')))
        app.use('/jsm/loaders/MTLLoader', express.static(path.join(__dirname, '../../node_modules/three/examples/jsm/loaders/MTLLoader.js')))
        app.use('/jsm/loaders/OBJLoader', express.static(path.join(__dirname, '../../node_modules/three/examples/jsm/loaders/OBJLoader.js')))
        app.use('/jsm/libs/stats.module', express.static(path.join(__dirname, '../../node_modules/three/examples/jsm/libs/stats.module.js')))
        app.use('/jsm/csm/CSM', express.static(path.join(__dirname, '../../node_modules/three/examples/jsm/csm/CSM.js')))
        app.use('/jsm/csm/CSMHelper', express.static(path.join(__dirname, '../../node_modules/three/examples/jsm/csm/CSMHelper.js')))
        app.use('/jsm/', express.static(path.join(__dirname, '../../node_modules/three/examples/jsm/')))

        this.server = new http.Server(app);
    }

    public Start() {
        this.server.listen(this.port, () => {
            console.log(`Server listening on port ${this.port}.`)
        })
    }
}

new App(port).Start()

./src/client/client.ts

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import * as THREE from '/build/three.module.js'
import { OrbitControls } from '/jsm/controls/OrbitControls'
import { OBJLoader } from '/jsm/loaders/OBJLoader'
import { MTLLoader } from '/jsm/loaders/MTLLoader'
import Stats from '/jsm/libs/stats.module'
import { GUI } from '/jsm/libs/dat.gui.module'
import { CSM } from '/jsm/csm/CSM'
import { CSMHelper } from '/jsm/csm/CSMHelper'

const scene: THREE.Scene = new THREE.Scene()
scene.background = new THREE.Color(0x87CEEB)

const camera: THREE.PerspectiveCamera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.1, 1000)
camera.position.x = 4
camera.position.y = 1
camera.position.z = 7

const csm = new CSM({
    maxFar: 1000,
    fade: true,
    far: camera.far,
    cascades: 4,
    shadowMapSize: 8192,
    lightDirection: new THREE.Vector3(-1, -1, 0),
    camera: camera,
    parent: scene,
    lightIntensity: 0.5
});

console.log(csm)

const csmHelper = new CSMHelper(csm)
csmHelper.displayFrustum = true
csmHelper.displayPlanes = true
csmHelper.displayShadowBounds = true
scene.add(csmHelper as any)

const renderer: THREE.WebGLRenderer = new THREE.WebGLRenderer({ antialias: true })
renderer.setSize(window.innerWidth, window.innerHeight)
renderer.shadowMap.enabled = true;
renderer.shadowMap.type = THREE.PCFSoftShadowMap;
document.body.appendChild(renderer.domElement)

const controls = new OrbitControls(camera, renderer.domElement)
controls.dampingFactor = 0.05
controls.enableDamping = true

const trees = ["birchTreeWithLeaves", "saplingTree", "tree1WithLeaves"]
const material = new THREE.MeshPhongMaterial({ color: 0x567d46 })

const mtlLoader = new MTLLoader();
trees.forEach((tree) => {
    mtlLoader.load('models/' + tree + '.mtl',
        (materials) => {
            materials.preload();

            const objLoader: OBJLoader = new OBJLoader();
            objLoader.setMaterials(materials);
            objLoader.load(
                'models/' + tree + '.obj',
                (object) => {
                    object.traverse(function (child) {
                        if ((<THREE.Mesh>child).isMesh) {
                            child.castShadow = true
                        }
                    })
                    for (let i = 0; i < 20; i++) {
                        const copy = object.clone()
                        copy.scale.multiplyScalar(Math.max(Math.random() / 50, .01))
                        copy.rotateY(Math.random() * Math.PI * 2)
                        copy.position.set((Math.random() * 20) - 10, 0, (Math.random() * 20) - 10)
                        scene.add(copy);
                    }
                },
                (xhr) => {
                    console.log((xhr.loaded / xhr.total * 100) + '% loaded');
                },
                (error) => {
                    console.log('An error happened');
                }
            );
        },
        (xhr) => {
            console.log((xhr.loaded / xhr.total * 100) + '% loaded');
        },
        (error) => {
            console.log('An error happened');
        }
    )
})

const planeGeometry: THREE.PlaneGeometry = new THREE.PlaneGeometry(25, 25)
const planeMesh: THREE.Mesh = new THREE.Mesh(planeGeometry, material)
planeMesh.rotateX(-Math.PI / 2)
planeMesh.receiveShadow = true;
scene.add(planeMesh)

window.addEventListener('resize', onWindowResize, false)
function onWindowResize() {
    camera.aspect = window.innerWidth / window.innerHeight
    camera.updateProjectionMatrix()
    renderer.setSize(window.innerWidth, window.innerHeight)
    render()
}

const gui = new GUI()
const csmFolder = gui.addFolder("CSM")
csmFolder.add(csm.lightDirection, "x", -1, 1, 0.01)
csmFolder.add(csm.lightDirection, "y", -1, 1, 0.01)
csmFolder.add(csm.lightDirection, "z", -1, 1, 0.01)
csmFolder.add(csm, "lightNear", 1, 1000, 1).onChange(function (value) {
    for (var i = 0; i < csm.lights.length; i++) {
        csm.lights[i].shadow.camera.near = value;
        csm.lights[i].shadow.camera.updateProjectionMatrix();
    }
})
csmFolder.add(csm, "lightFar", 1, 1000, 1).onChange(function (value) {
    for (var i = 0; i < csm.lights.length; i++) {
        csm.lights[i].shadow.camera.far = value;
        csm.lights[i].shadow.camera.updateProjectionMatrix();
    }
})
csmFolder.add(csm, "lightIntensity", .1, 2, .1).onChange(function (value) {
    for (var i = 0; i < csm.lights.length; i++) {
        csm.lights[i].intensity = value
    }
})
csmFolder.open()

const stats = Stats()
document.body.appendChild(stats.dom)

var animate = function () {
    requestAnimationFrame(animate)

    controls.update()

    csm.update();
    csmHelper.update();

    render()

    stats.update()
};

function render() {
    renderer.render(scene, camera)
}
animate();