Enhancing material appearance by incorporating color gradient through the extension of three.js Material class using the onBeforeCompile method

Question

Enhancing material appearance by incorporating color gradient through the extension of three.js Material class using the onBeforeCompile method

In my three.js scene, I have successfully loaded an .obj file using THREE.OBJLoader.

Now, I am looking to add a linear color gradient along the z-axis to this object while keeping the MeshStandardMaterial shaders intact. Below is an example of a 2-color linear gradient applied to an object.

To achieve this, I believe I need to manipulate the vertexShader and materialShaders of the MeshStandardMaterial class with some custom code.

While there are some solutions provided in response to a similar query on StackOverflow, they involve creating a new shader material without inheriting the properties of MeshStandardMaterial, which is not what I require.

I have attempted to use the onBeforeCompile method, but I am unsure where to integrate the related code outlined in the solutions mentioned earlier. My knowledge of shaders is quite basic.

The material of my object is currently using the THREE.MeshStandardMaterial class with properties like metalness, roughness, transparency, and opacity set. Additionally, I have applied textures to the map and envmap properties.

javascript three.js geometry vertex-shader

Answer 1

Answer №1

Understanding shader chunks can be challenging, but it's definitely not impossible.

body{
  overflow: hidden;
  margin: 0;
}

<script type="module">
import * as THREE from "https://cdn.jsdelivr.net/npm/<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="5d29352f38381d6d736c6f6c736c">[email protected]</a>/build/three.module.js";
import {OrbitControls} from "https://cdn.jsdelivr.net/npm/<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="84f0ecf6e1e1c4b4aab5b6b5aab5">[email protected]</a>/examples/jsm/controls/OrbitControls.js";

let scene = new THREE.Scene();
let camera = new THREE.PerspectiveCamera(60, innerWidth / innerHeight, 1, 1000);
camera.position.set(0, 10, 20);
let renderer = new THREE.WebGLRenderer();
renderer.setSize(innerWidth, innerHeight);
document.body.appendChild(renderer.domElement);

let controls = new OrbitControls(camera, renderer.domElement);

let light = new THREE.DirectionalLight(0xffffff, 1);
light.position.setScalar(10);
scene.add(light);
scene.add(new THREE.AmbientLight(0xffffff, 1));

let g = new THREE.TorusKnotBufferGeometry(5, 1, 128, 16);
g.rotateX(-Math.PI * 0.5);
g.computeBoundingBox();

let uniforms = {
    bbMin: {value: g.boundingBox.min},
  bbMax: {value: g.boundingBox.max},
  color1: {value: new THREE.Color(0xff0000)},
  color2: {value: new THREE.Color(0xffff00)}
}
console.log(g);
let m = new THREE.MeshStandardMaterial({
    roughness: 0.25,
  metalness: 0.75,
  map: new THREE.TextureLoader().load("https://threejs.org/examples/textures/floors/FloorsCheckerboard_S_Diffuse.jpg", tex => {
    tex.wrapS = THREE.RepeatWrapping;
    tex.wrapT = THREE.RepeatWrapping;
    tex.repeat.set( 16, 1 );
  }),
  onBeforeCompile: shader => {
    shader.uniforms.bbMin = uniforms.bbMin;
    shader.uniforms.bbMax = uniforms.bbMax;
    shader.uniforms.color1 = uniforms.color1;
    shader.uniforms.color2 = uniforms.color2;
    shader.vertexShader = `
        varying vec3 vPos;
      ${shader.vertexShader}
    `.replace(
    `#include <begin_vertex>`,
    `#include <begin_vertex>
    vPos = transformed;
    `
    );
    shader.fragmentShader = `
        uniform vec3 bbMin;
      uniform vec3 bbMax;
      uniform vec3 color1;
      uniform vec3 color2;
      varying vec3 vPos;
      ${shader.fragmentShader}
    `.replace(
        `vec4 diffuseColor = vec4( diffuse, opacity );`,
      `
      float f = clamp((vPos.z - bbMin.z) / (bbMax.z - bbMin.z), 0., 1.);
      vec3 col = mix(color1, color2, f);
      vec4 diffuseColor = vec4( col, opacity );`
    );
    console.log(shader.vertexShader);
    console.log(shader.fragmentShader);
  }
});

let o = new THREE.Mesh(g, m);
scene.add(o);


renderer.setAnimationLoop(()=>{
    renderer.render(scene, camera);
});
</script>

Answer 2

Understanding shader chunks can be challenging, but it's definitely not impossible.

body{
  overflow: hidden;
  margin: 0;
}

<script type="module">
import * as THREE from "https://cdn.jsdelivr.net/npm/<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="5d29352f38381d6d736c6f6c736c">[email protected]</a>/build/three.module.js";
import {OrbitControls} from "https://cdn.jsdelivr.net/npm/<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="84f0ecf6e1e1c4b4aab5b6b5aab5">[email protected]</a>/examples/jsm/controls/OrbitControls.js";

let scene = new THREE.Scene();
let camera = new THREE.PerspectiveCamera(60, innerWidth / innerHeight, 1, 1000);
camera.position.set(0, 10, 20);
let renderer = new THREE.WebGLRenderer();
renderer.setSize(innerWidth, innerHeight);
document.body.appendChild(renderer.domElement);

let controls = new OrbitControls(camera, renderer.domElement);

let light = new THREE.DirectionalLight(0xffffff, 1);
light.position.setScalar(10);
scene.add(light);
scene.add(new THREE.AmbientLight(0xffffff, 1));

let g = new THREE.TorusKnotBufferGeometry(5, 1, 128, 16);
g.rotateX(-Math.PI * 0.5);
g.computeBoundingBox();

let uniforms = {
    bbMin: {value: g.boundingBox.min},
  bbMax: {value: g.boundingBox.max},
  color1: {value: new THREE.Color(0xff0000)},
  color2: {value: new THREE.Color(0xffff00)}
}
console.log(g);
let m = new THREE.MeshStandardMaterial({
    roughness: 0.25,
  metalness: 0.75,
  map: new THREE.TextureLoader().load("https://threejs.org/examples/textures/floors/FloorsCheckerboard_S_Diffuse.jpg", tex => {
    tex.wrapS = THREE.RepeatWrapping;
    tex.wrapT = THREE.RepeatWrapping;
    tex.repeat.set( 16, 1 );
  }),
  onBeforeCompile: shader => {
    shader.uniforms.bbMin = uniforms.bbMin;
    shader.uniforms.bbMax = uniforms.bbMax;
    shader.uniforms.color1 = uniforms.color1;
    shader.uniforms.color2 = uniforms.color2;
    shader.vertexShader = `
        varying vec3 vPos;
      ${shader.vertexShader}
    `.replace(
    `#include <begin_vertex>`,
    `#include <begin_vertex>
    vPos = transformed;
    `
    );
    shader.fragmentShader = `
        uniform vec3 bbMin;
      uniform vec3 bbMax;
      uniform vec3 color1;
      uniform vec3 color2;
      varying vec3 vPos;
      ${shader.fragmentShader}
    `.replace(
        `vec4 diffuseColor = vec4( diffuse, opacity );`,
      `
      float f = clamp((vPos.z - bbMin.z) / (bbMax.z - bbMin.z), 0., 1.);
      vec3 col = mix(color1, color2, f);
      vec4 diffuseColor = vec4( col, opacity );`
    );
    console.log(shader.vertexShader);
    console.log(shader.fragmentShader);
  }
});

let o = new THREE.Mesh(g, m);
scene.add(o);


renderer.setAnimationLoop(()=>{
    renderer.render(scene, camera);
});
</script>

Answer 3

Answer №2

The complexity of the MeshStandardMaterial shader presents a challenge when trying to make precise color changes while preserving environmental reflections, lighting, metalness, roughness, and other properties. It may be best not to overthink the process. If a simple gradient effect is all that is required on the MeshStandardMaterial, consider creating a gradient texture and then applying it to the Material.map attribute. By adding a white AmbientLight, the gradient should display without any issues.

For a gradient unaffected by lighting, it is possible to assign the texture to the material's .emissive attribute.

If avoiding textures altogether is preferred, colors can be assigned to individual vertices, and then enabling Material.vertexColors.

Answer 4

The complexity of the MeshStandardMaterial shader presents a challenge when trying to make precise color changes while preserving environmental reflections, lighting, metalness, roughness, and other properties. It may be best not to overthink the process. If a simple gradient effect is all that is required on the MeshStandardMaterial, consider creating a gradient texture and then applying it to the Material.map attribute. By adding a white AmbientLight, the gradient should display without any issues.

For a gradient unaffected by lighting, it is possible to assign the texture to the material's .emissive attribute.

If avoiding textures altogether is preferred, colors can be assigned to individual vertices, and then enabling Material.vertexColors.

Enhancing material appearance by incorporating color gradient through the extension of three.js Material class using the onBeforeCompile method

Answer №1

Answer №2

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