threejs-shaders

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• SKILL.md

SKILL.md (first lines)

# Three.js Shaders

Targets three.js r186. Examples use WebGLRenderer; the WebGPU and TSL section uses WebGPURenderer.

## Quick Start

```javascript
import * as THREE from "three";

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

const scene = new THREE.Scene();
const camera = new THREE.PerspectiveCamera(60, window.innerWidth / window.innerHeight, 0.1, 100);
camera.position.set(0, 0, 2);

const material = new THREE.ShaderMaterial({
  uniforms: {
    time: { value: 0 },
    color: { value: new THREE.Color(0x0066ff) }, // hex converted to the linear working space
  },
  vertexShader: /* glsl */ `
    varying vec2 vUv;

    void main() {
      vUv = uv;
      gl_Position = projectionMatrix * modelViewMatrix * vec4(position, 1.0);
    }
  `,
  fragmentShader: /* glsl */ `
    uniform float time;
    uniform vec3 color;
    varying vec2 vUv;

    void main() {
      float wave = sin(vUv.x * 10.0 + time * 2.0) * 0.5 + 0.5;
      gl_FragColor = vec4(color * wave, 1.0);
      #include <tonemapping_fragment>
      #include <colorspace_fragment>
    }
  `,
});

const mesh = new THREE.Mesh(new THREE.PlaneGeometry(2, 2), material);
scene.add(mesh);

const timer = new THREE.Timer();
timer.connect(document);

renderer.setAnimationLoop(animate);

function animate() {
  timer.update();
  material.uniforms.time.value = timer.getElapsed();
  renderer.render(scene, camera);
}
```

## ShaderMaterial vs RawShaderMaterial

Every `ShaderMaterial` compiles as GLSL ES 3.00 — three.js always prepends `#version 300 es` (WebGL 1 support is gone). `texture()`, `textureLod()`, `textureSize()` and `dFdx`/`fwidth` work with no flags; `texture2D`, `textureCube`, `attribute`, `varying` and `gl_FragColor` are `#define` aliases, so most GLSL ES 1.00 shaders compile unchanged (not ones that name a variable `texture`, write `gl_FragData` or keep an `#extension` line, which fails because three.js puts declarations before your source; delete it, the features are core). Leave `glslVersion` unset: setting `THREE.GLSL3` only removes the `gl_FragColor` alias, forcing you to declare your own output variable. ShaderMaterial injects the usual declarations:

```javascript
const material = new THREE.ShaderMaterial({
  vertexShader: /* glsl */ `
    // Declared for you: uniforms modelMatrix, modelViewMatrix, projectionMatrix,
    // viewMatrix, normalMatrix, cameraPosition; attributes position, normal, uv,
    // instanceMatrix (InstancedMesh) and color (vertexColors: true)

    varying vec3 vNormal;

    void main() {
      vNormal = normalize(normalMatrix * normal); // view-space normal
      gl_Position = projectionMatrix * modelViewMatrix * vec4(position, 1.0);
    }
  `,
  fragmentShader: /* glsl */ `
    varying vec3 vNormal;

    void main() {
      gl_FragColor = vec4(vNormal * 0.5 + 0.5, 1.0);
      #include <tonemapping_fragment>
      #include <colorspace_fragment>
    }
  `,
});
```

RawShaderMaterial gets only `#define SHADER_TYPE`, `#define SHADER_NAME` and your `defines` (plus `#version 300 es` once `glslVersion` is set): no declarations and no precision statement. Always set `glslVersion: THREE.GLSL3` (without it the shader is GLSL ES 1.00, which has no `texture()`), write `precision highp float;`, use `in`/`out` and declare your own output. Declare the matrices you need in the shader and never pass them through `uniforms`: the renderer sets `modelMatrix`, `modelViewMatrix`, `projectionMatrix`, `viewMatrix`, `normalMatrix` and `cameraPosition` for any program that declares them, and a same-named entry in `uniforms` is either overwritten every draw (`modelMatrix`, `modelViewMatrix`, `normalMatrix`) or replaces the camera's value (`projectionMatrix`, `viewMatrix`, `cameraPosition`).

```javascript
const material = new THREE.RawShaderMaterial({
  glslVersion: THREE.GLSL3,
  vertexShader: /* glsl */ `
    precision highp float;

    in vec3 position;

    uniform mat4 modelViewMatrix;
    uniform mat4 projectionMatrix;

    void main() {
      gl_Position = projectionMatrix * modelViewMatrix * vec4(position, 1.0);
    }
  `,
  fragmentShader: /* glsl */ `
    precision highp float;

    out highp vec4 fragColor;

    void main() {
      fragColor = vec4(1.0, 0.0, 0.0, 1.0);
    }
  `,
});
```

From CloudAI-X/threejs-skills, MIT.

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