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MTL Loader

Video Lecture

MTL Loader MTL Loader MTL Loader

Description

MTL is the material information used by an OBJ file. You can set the colours, specular, emissive, alpha, smoothness, image maps, and there coordinates.

Since it is a MeshPhongMaterial by default, we can only set properties affecting the meshPhongMaterial.

If you create your OBJ and MTL using Blender, then you can change

  • Base Color
  • Specular
  • Emission
  • Alpha
  • Smooth/Flat Shaded

Resources

The 3D models used in this lesson can be easily created using Blender. If you don't want to use blender to create the models, then you can download them from the zip file named models2.zip. Extract the models2.zip contents into the ./dist/client/models/ folder.

models2.zip

Start Script

./src/client/client.ts

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import * as THREE from 'three'
import { OrbitControls } from 'three/examples/jsm/controls/OrbitControls'
import { OBJLoader } from 'three/examples/jsm/loaders/OBJLoader'
import { MTLLoader } from 'three/examples/jsm/loaders/MTLLoader'
import Stats from 'three/examples/jsm/libs/stats.module'

const scene = new THREE.Scene()
scene.add(new THREE.AxesHelper(5))

const light = new THREE.PointLight()
light.position.set(2.5, 7.5, 15)
scene.add(light)

const camera = new THREE.PerspectiveCamera(
    75,
    window.innerWidth / window.innerHeight,
    0.1,
    1000
)
camera.position.z = 3

const renderer = new THREE.WebGLRenderer()
renderer.setSize(window.innerWidth, window.innerHeight)
document.body.appendChild(renderer.domElement)

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

const mtlLoader = new MTLLoader()
mtlLoader.load(
    'models/monkey.mtl',
    (materials) => {
        materials.preload()
        console.log(materials)
        // const objLoader = new OBJLoader()
        // objLoader.setMaterials(materials)
        // objLoader.load(
        //     'models/monkey.obj',
        //     (object) => {
        //         scene.add(object)
        //     },
        //     (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')
    }
)

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

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

function animate() {
    requestAnimationFrame(animate)

    controls.update()

    render()

    stats.update()
}

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

animate()

Final Script

./src/client/client.ts

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import * as THREE from 'three'
import { OrbitControls } from 'three/examples/jsm/controls/OrbitControls'
import { OBJLoader } from 'three/examples/jsm/loaders/OBJLoader'
import { MTLLoader } from 'three/examples/jsm/loaders/MTLLoader'
import Stats from 'three/examples/jsm/libs/stats.module'

const scene = new THREE.Scene()
scene.add(new THREE.AxesHelper(5))

const light = new THREE.PointLight()
light.position.set(2.5, 7.5, 15)
scene.add(light)

const camera = new THREE.PerspectiveCamera(
    75,
    window.innerWidth / window.innerHeight,
    0.1,
    1000
)
camera.position.z = 3

const renderer = new THREE.WebGLRenderer()
renderer.setSize(window.innerWidth, window.innerHeight)
document.body.appendChild(renderer.domElement)

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

const mtlLoader = new MTLLoader()
mtlLoader.load(
    'models/monkey.mtl',
    (materials) => {
        materials.preload()

        const objLoader = new OBJLoader()
        objLoader.setMaterials(materials)
        objLoader.load(
            'models/monkey.obj',
            (object) => {
                scene.add(object)
            },
            (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')
    }
)

mtlLoader.load(
    'models/monkeyTextured.mtl',
    (materials) => {
        materials.preload()

        const objLoader = new OBJLoader()
        objLoader.setMaterials(materials)
        objLoader.load(
            'models/monkeyTextured.obj',
            (object) => {
                object.position.x = 2.5
                scene.add(object)
            },
            (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')
    }
)

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

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

function animate() {
    requestAnimationFrame(animate)

    controls.update()

    render()

    stats.update()
}

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

animate()

Wavefront .obj File Format

MTLLoader (Official Documentation)