version: "1.0.0" name: threejs-shaders description: "Custom GLSL vertex and fragment shaders: uniforms, varyings, shader chunks, extending built-in materials, instanced attributes, plus the same effects as node materials with TSL on WebGPU. Use when writing a shader, a custom material or effect, moving vertices in a shader, or porting GLSL to TSL."

Three.js Shaders

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

Quick Start

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:

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).

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);
    }
  `,
});

Uniforms

const texture = await new THREE.TextureLoader().loadAsync("textures/diffuse.jpg");
texture.colorSpace = THREE.SRGBColorSpace; // a color image: decoded to linear when sampled
const material = new THREE.ShaderMaterial({
  uniforms: {
    floatValue: { value: 1.5 },
    vec3Value: { value: new THREE.Vector3(1, 2, 3) },
    colorValue: { value: new THREE.Color(0xff0000) }, // hex converted to the linear working space
    mat4Value: { value: new THREE.Matrix4() },
    mapValue: { value: texture },
  },
  // vertexShader and fragmentShader as usual
});

The matching GLSL declarations — sample the texture with texture(mapValue, vUv):

uniform float floatValue;
uniform vec3 vec3Value;
uniform vec3 colorValue;    // a THREE.Color arrives as vec3
uniform mat4 mat4Value;
uniform sampler2D mapValue;

Update a uniform by assigning .value from the frame loop (material.uniforms.floatValue.value = 2.0;); vectors and colors mutate in place (material.uniforms.vec3Value.value.set(1, 2, 3);). Never name a uniform position, normal, uv, modelViewMatrix or cameraPosition — three.js already declares those in the vertex shader, and the redeclaration is a compile error.

Output Color and Tone Mapping

THREE.Color converts hex input from sRGB to the linear working color space, so a color uniform holds linear values. A ShaderMaterial writes its output as-is: tone mapping and the output color space conversion happen only if the fragment shader ends with the two includes:

gl_FragColor = vec4(color, 1.0);
#include <tonemapping_fragment>
#include <colorspace_fragment>

tonemapping_fragment applies renderer.toneMapping (a no-op with NoToneMapping); colorspace_fragment encodes to renderer.outputColorSpace (SRGBColorSpace by default). Without them, mid-tone colors render darker than the same hex on a built-in material. Both chunks write gl_FragColor, so they require glslVersion unset. An 8-bit RGBA texture with texture.colorSpace = THREE.SRGBColorSpace decodes to linear on sampling, so sampled colors combine correctly with the includes in place. A VideoTexture does not: three.js uploads it without sRGB decoding and decodes it only inside built-in materials, so decode it yourself with sRGBTransferEOTF(texture(videoMap, vUv)) (the ShaderMaterial prefix declares that function). Rendering into a render target, as inside an EffectComposer, both includes leave the color linear and OutputPass encodes it at the end.

Common Shader Patterns

Vertex Displacement

const material = new THREE.ShaderMaterial({
  uniforms: {
    time: { value: 0 },
    amplitude: { value: 0.2 },
  },
  vertexShader: /* glsl */ `
    uniform float time;
    uniform float amplitude;
    void main() {
      vec3 pos = position;
      pos.z += sin(pos.x * 5.0 + time) * amplitude;
      gl_Position = projectionMatrix * modelViewMatrix * vec4(pos, 1.0);
    }
  `,
  fragmentShader: /* glsl */ `
    void main() {
      gl_FragColor = vec4(0.5, 0.8, 1.0, 1.0);
      #include <tonemapping_fragment>
      #include <colorspace_fragment>
    }
  `,
});
const mesh = new THREE.Mesh(new THREE.PlaneGeometry(2, 2, 64, 64), material); // displacement needs subdivisions

Fresnel

Use one space consistently. World space with cameraPosition:

const material = new THREE.ShaderMaterial({
  vertexShader: /* glsl */ `
    varying vec3 vWorldNormal;
    varying vec3 vWorldPosition;
    void main() {
      vWorldNormal = normalize(mat3(modelMatrix) * normal); // world space, uniform scale assumed
      vWorldPosition = (modelMatrix * vec4(position, 1.0)).xyz;
      gl_Position = projectionMatrix * modelViewMatrix * vec4(position, 1.0);
    }
  `,
  fragmentShader: /* glsl */ `
    varying vec3 vWorldNormal;
    varying vec3 vWorldPosition;
    void main() {
      vec3 viewDirection = normalize(cameraPosition - vWorldPosition);
      float fresnel = pow(1.0 - max(dot(viewDirection, vWorldNormal), 0.0), 3.0);
      gl_FragColor = vec4(mix(vec3(0.0, 0.0, 0.5), vec3(0.5, 0.8, 1.0), fresnel), 1.0);
      #include <tonemapping_fragment>
      #include <colorspace_fragment>
    }
  `,
});

normalMatrix * normal is view space — pair it with the view-space direction to the camera, never with cameraPosition. For rim lighting keep both in view space: in the vertex shader vec4 mvPosition = modelViewMatrix * vec4(position, 1.0); vViewDir = -mvPosition.xyz; vNormal = normalMatrix * normal;, in the fragment shader float rim = pow(1.0 - max(dot(normalize(vViewDir), normalize(vNormal)), 0.0), 4.0);.

Dissolve

uniform float progress;
uniform sampler2D noiseMap;
varying vec2 vUv;
 
void main() {
  float noise = texture(noiseMap, vUv).r;
  if (noise < progress) discard;
 
  float edge = smoothstep(progress, progress + 0.1, noise);
  gl_FragColor = vec4(mix(vec3(1.0, 0.5, 0.0), vec3(0.5), edge), 1.0);
  #include <tonemapping_fragment>
  #include <colorspace_fragment>
}

Instanced Meshes and Custom Attributes

Three.js declares position, normal, uv, instanceMatrix (for an InstancedMesh), instanceColor (once setColorAt has been called) and color (with vertexColors: true). Anything else — a custom per-vertex attribute, uv1 to uv3, tangent — you declare yourself with attribute (the alias for in).

const instanceCount = 100;
const geometry = new THREE.PlaneGeometry(0.2, 0.2);
const offsets = new Float32Array(instanceCount * 3);
// fill offsets with one vec3 per instance
geometry.setAttribute("aOffset", new THREE.InstancedBufferAttribute(offsets, 3));
const material = new THREE.ShaderMaterial({
  vertexShader: /* glsl */ `
    attribute vec3 aOffset;
    void main() {
      // instanceMatrix is declared by three.js; the shader must apply it
      gl_Position = projectionMatrix * modelViewMatrix * instanceMatrix * vec4(position + aOffset, 1.0);
    }
  `,
  fragmentShader: /* glsl */ `
    void main() {
      gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);
    }
  `,
});
const mesh = new THREE.InstancedMesh(geometry, material, instanceCount);
mesh.frustumCulled = false; // the bounds come from instanceMatrix and ignore aOffset

For a per-vertex attribute use geometry.setAttribute("aOffset", new THREE.BufferAttribute(new Float32Array(geometry.attributes.position.count * 3), 3)); — the shader declaration is the same.

Extending Built-in Materials

onBeforeCompile rewrites the shader strings of a built-in material. It runs once per program, before includes are resolved.

const material = new THREE.MeshStandardMaterial({ color: 0x00ff00 });
material.onBeforeCompile = (shader) => {
  shader.uniforms.time = { value: 0 };
  material.userData.shader = shader; // keep the reference for updates
  shader.vertexShader = "uniform float time;\n" + shader.vertexShader;
  shader.vertexShader = shader.vertexShader.replace(
    "#include <begin_vertex>",
    `
    #include <begin_vertex>
    transformed.y += sin(position.x * 10.0 + time) * 0.1;
    `,
  );
};
// in the frame loop, with timer.update() first as in the Quick Start:
// if (material.userData.shader) material.userData.shader.uniforms.time.value = timer.getElapsed();

Injection points in the built-in shaders: vertex #include <begin_vertex> (declares vec3 transformed = vec3(position)), #include <beginnormal_vertex> (vec3 objectNormal) and #include <project_vertex> (sets gl_Position); fragment #include <color_fragment> (diffuseColor after map and vertex colors), #include <opaque_fragment> (writes gl_FragColor before tone mapping) and #include <fog_fragment> (after tone mapping, color space and fog).

If onBeforeCompile produces different shaders for different materials (for example depending on material.userData values), also define material.customProgramCacheKey() returning a distinct string per variant, or the renderer reuses one cached program for all of them.

Shader Chunks

#include <chunk> works in ShaderMaterial and RawShaderMaterial source and reuses three.js helper functions; perspectiveDepthToViewZ below comes from the packing chunk.

const fragmentShader = /* glsl */ `
  #include <packing>
  uniform sampler2D depthTexture;
  uniform float cameraNear; // set from camera.near
  uniform float cameraFar; // set from camera.far
  varying vec2 vUv;
  void main() {
    float viewZ = perspectiveDepthToViewZ(texture(depthTexture, vUv).r, cameraNear, cameraFar);
    gl_FragColor = vec4(vec3(-viewZ / cameraFar), 1.0);
  }
`;

Only use chunk keys that exist in this release (log Object.keys(THREE.ShaderChunk) to check): there is no output_fragment chunk — the final output chunk is opaque_fragment.

Debugging

// While renderer.debug.checkShaderErrors is true (the default), a failed program logs each failing shader's errors
// with the numbered source lines around the first one. A handler replaces that report and runs only on a compile or link failure:
renderer.debug.onShaderError = (gl, program, vertexShader, fragmentShader) => {
  console.error(gl.getProgramInfoLog(program));
  for (const shader of [vertexShader, fragmentShader]) {
    const log = gl.getShaderInfoLog(shader);
    if (log) console.error(log, gl.getShaderSource(shader)); // the fully assembled shader
  }
};

Debug visually by writing the value under test to the output: gl_FragColor = vec4(vUv, 0.0, 1.0); for UVs, gl_FragColor = vec4(vNormal * 0.5 + 0.5, 1.0); for normals.

WebGPU and TSL

ShaderMaterial, RawShaderMaterial and onBeforeCompile run only under WebGLRenderer. Under WebGPURenderer a ShaderMaterial logs Material "ShaderMaterial" is not compatible and falls back to a plain node material, and onBeforeCompile is never called — build the effect as a node material with TSL instead. WebGPURenderer falls back to WebGL 2 by itself when WebGPU is unavailable, so one TSL code path covers both backends.

Node materials

An unlit effect uses MeshBasicNodeMaterial; MeshStandardNodeMaterial is lit and renders black without lights or an environment. A ShaderMaterial maps to MeshBasicNodeMaterial (unlit) or to the node slots of MeshStandardNodeMaterial (lit); replacing the whole fragment output uses fragmentNode. The familiar slots exist as node properties: colorNode, opacityNode, emissiveNode, normalNode, positionNode.

import * as THREE from "three/webgpu";
import { color, mix, sin, time, uv } from "three/tsl";
const renderer = new THREE.WebGPURenderer({ antialias: true });
await renderer.init(); // before any other use of the renderer
renderer.setPixelRatio(window.devicePixelRatio);
renderer.setSize(window.innerWidth, window.innerHeight);
document.body.appendChild(renderer.domElement);
const scene = new THREE.Scene();
scene.background = new THREE.Color(0x111827); // the WebGPU canvas is transparent by default
const camera = new THREE.PerspectiveCamera(60, window.innerWidth / window.innerHeight, 0.1, 100);
camera.position.set(0, 0, 2);
const material = new THREE.MeshBasicNodeMaterial();
material.colorNode = mix(color(0x004466), color(0x66ddff), sin(uv().x.mul(20).add(time)).mul(0.5).add(0.5));
scene.add(new THREE.Mesh(new THREE.PlaneGeometry(2, 2), material));
renderer.setAnimationLoop(animate);
function animate() {
  renderer.render(scene, camera);
}

Uniforms and time

uniform(value) creates an updatable uniform; time is a built-in node that updates itself every frame and replaces a hand-fed time uniform.

import * as THREE from "three/webgpu";
import { abs, mx_fractal_noise_float, time, uniform, uv, vec3 } from "three/tsl";
const material = new THREE.MeshBasicNodeMaterial();
const amplitude = uniform(0.5);
material.colorNode = vec3(abs(mx_fractal_noise_float(uv().mul(10).add(time.mul(0.2)))).mul(amplitude));
// update from JS without touching the node graph:
amplitude.value = 1.0;

Textures and discard

texture(map, uvNode) samples a texture (texture(map) uses the mesh UVs); .discard() on a condition drops the fragment, as discard does in GLSL. The Dissolve shader above as TSL:

import * as THREE from "three/webgpu";
import { Fn, color, mix, smoothstep, texture, uniform, uv } from "three/tsl";
const noiseMap = await new THREE.TextureLoader().loadAsync("textures/noise.png"); // scalar data: keep NoColorSpace
const progress = uniform(0); // animate progress.value from 0 to 1
const material = new THREE.MeshBasicNodeMaterial();
material.colorNode = Fn(() => {
  const n = texture(noiseMap, uv()).r;
  n.lessThan(progress).discard();
  return mix(color(1, 0.5, 0), color(0.5, 0.5, 0.5), smoothstep(progress, progress.add(0.1), n));
})();

Vertex displacement

positionNode replaces the transformed local position. Build it on positionLocal, which already carries skinning, morph targets, displacement maps, batching and InstancedMesh transforms; positionGeometry is the raw attribute, for rest-pose input only. Displacement needs a subdivided mesh.

import * as THREE from "three/webgpu";
import { normalLocal, positionLocal, sin, time } from "three/tsl";
const sun = new THREE.DirectionalLight(0xffffff, 2);
sun.position.set(1, 2, 3);
scene.add(sun, new THREE.HemisphereLight(0xffffff, 0x223344, 1)); // lit material: black without lights or scene.environment
const material = new THREE.MeshStandardNodeMaterial({ flatShading: true }); // normals from the displaced surface; vertex normals ignore positionNode
material.positionNode = positionLocal.add(normalLocal.mul(sin(positionLocal.y.mul(4).add(time))).mul(0.2));
const mesh = new THREE.Mesh(new THREE.PlaneGeometry(2, 2, 96, 96), material);
mesh.rotation.x = -Math.PI / 3; // tilt so the displacement along the normal is visible
scene.add(mesh);

Reusable logic

Write reusable logic as a TSL Fn; it compiles to both GLSL and WGSL. varying(node, "name") passes a value from the vertex stage to the fragment stage.

import * as THREE from "three/webgpu";
import { Fn, color, mix, positionWorld, sin, varying } from "three/tsl";
const heightFade = Fn(([y]) => mix(color(0x003344), color(0x88eeff), sin(y.mul(3)).mul(0.5).add(0.5)));
const material = new THREE.MeshBasicNodeMaterial();
const vWorldY = varying(positionWorld.y, "vWorldY"); // interpolated from vertex to fragment stage
material.colorNode = heightFade(vWorldY);

Porting GLSL

Rewrite GLSL functions as Fns instead of pasting shader strings: glslFn runs only on the WebGL 2 backend and wgslFn only on the WebGPU backend, so neither is portable. Compute shaders dispatch through renderer.compute() after await renderer.init().

Debugging

await renderer.debug.getShaderAsync(scene, camera, mesh) returns the generated { vertexShader, fragmentShader } for one mesh.

Common Mistakes

• const clock = new THREE.Clock(); → const timer = new THREE.Timer(); timer.connect(document);: Clock is deprecated in r183; call timer.update() first in each frame, then timer.getElapsed() or timer.getDelta().
• "#include <output_fragment>" → "#include <opaque_fragment>": output_fragment does not exist, so a string replace targeting it silently matches nothing.
• fragmentShader: "uniform vec3 color;\nvoid main() {\n gl_FragColor = vec4(color, 1.0);\n}" → fragmentShader: "uniform vec3 color;\nvoid main() {\n gl_FragColor = vec4(color, 1.0);\n #include <tonemapping_fragment>\n #include <colorspace_fragment>\n}": color uniforms hold linear values and without the two includes, each on its own line, the output is never encoded, so mid-tones render darker than on built-in materials.
• const renderer = new THREE.WebGPURenderer(); const material = new THREE.ShaderMaterial({ vertexShader, fragmentShader }); → const material = new THREE.MeshBasicNodeMaterial(); material.colorNode = color(0xff0000);: under WebGPURenderer ShaderMaterial logs "not compatible" and onBeforeCompile never runs; these APIs work only under WebGLRenderer.
• material.positionNode = positionGeometry.add(offset) → material.positionNode = positionLocal.add(offset): positionLocal already carries skinning, morph targets, batching and instanced transforms; positionGeometry is the raw attribute.
• import { time } from "three/nodes" → import { time } from "three/tsl": the three/nodes module does not exist; TSL names come from three/tsl, node materials from three/webgpu.
• import { toVarying } from "three/tsl" → varying(node, "vName"): the exported function is varying(); toVarying exists only as the method form node.toVarying("vName").
• import { uniforms, PI2 } from "three/tsl" → import { uniformArray, TWO_PI } from "three/tsl": uniformArray() was renamed from uniforms() in r168 and TWO_PI from PI2 in r181.
• amplitude.label("amp") → amplitude.setName("amp"): setName() was renamed from label() in r179; label() still sets the name but logs a deprecation warning.
• texture(map).uv(uvNode) → texture(map).sample(uvNode): TextureNode.sample() was renamed from uv() in r172.
• import { screen, viewportTopLeft, directionToColor } from "three/tsl" → import { blendScreen, viewportUV, packNormalToRGB } from "three/tsl": blendScreen was renamed from screen() in r171, viewportUV from viewportTopLeft in r168 and packNormalToRGB from directionToColor() in r185.
• rangeFog(color, near, far) → fog(color, rangeFogFactor(near, far)): three/tsl no longer exports rangeFog(); fog() takes a factor node.
• const t = uniform(0); t.value = timer.getElapsed(); → time: the built-in time node updates itself every frame, so the uniform round-trip is unnecessary.
• const n = glslFn(glslSource); → const n = Fn(([p]) => mx_noise_float(p));: glslFn runs only on the WebGL 2 backend and wgslFn only on the WebGPU backend; a TSL Fn compiles for both.
• uniforms: { modelViewMatrix: { value: new THREE.Matrix4() } } → uniform mat4 modelViewMatrix;: the renderer sets the built-in matrices for any program that declares them, so a uniforms entry is overwritten every draw (modelMatrix, modelViewMatrix, normalMatrix) or replaces the camera's value (projectionMatrix, viewMatrix, cameraPosition); the GLSL declaration is for a RawShaderMaterial, since a ShaderMaterial already declares the matrices and redeclaring one fails to compile.
• new THREE.ShaderMaterial({ transparent: true, opacity: 0.5 }) → new THREE.ShaderMaterial({ transparent: true, uniforms: { opacity: { value: 0.5 } } }): ShaderMaterial never uploads material.opacity, so declare uniform float opacity and write it to the alpha channel.
• uniforms: { position: { value: new THREE.Vector3() } } → uniforms: { offset: { value: new THREE.Vector3() } }: position collides with the attribute three.js declares in every ShaderMaterial vertex shader.
• new THREE.ShaderMaterial({ glslVersion: THREE.GLSL3, vertexShader, fragmentShader }) → new THREE.ShaderMaterial({ vertexShader, fragmentShader }): ShaderMaterial always compiles as GLSL ES 3.00, and GLSL3 only removes the gl_FragColor alias, so a shader that still writes gl_FragColor stops compiling.
• new THREE.RawShaderMaterial({ vertexShader, fragmentShader }) → new THREE.RawShaderMaterial({ vertexShader, fragmentShader, glslVersion: THREE.GLSL3 }): without glslVersion a RawShaderMaterial compiles as GLSL ES 1.00, which has no texture().
• new THREE.ShaderMaterial({ vertexShader, fragmentShader, extensions: { derivatives: true, fragDepth: true } }) → new THREE.ShaderMaterial({ vertexShader, fragmentShader }): the WebGL 1 extension keys were removed in r163 and are ignored; dFdx, gl_FragDepth and textureLod are core in GLSL ES 3.00, and extensions now holds only clipCullDistance and multiDraw.
• blending: THREE.MultiplyBlending → blending: THREE.MultiplyBlending, premultipliedAlpha: true: MultiplyBlending and SubtractiveBlending set no blend function and log an error unless premultiplied alpha is on, and a ShaderMaterial with alpha below 1 must then premultiply its own output with #include <premultiplied_alpha_fragment>.
• gl_Position = projectionMatrix * modelViewMatrix * vec4(position, 1.0); → gl_Position = projectionMatrix * modelViewMatrix * instanceMatrix * vec4(position, 1.0);: on an InstancedMesh three.js declares instanceMatrix but the shader must apply it, or every instance draws at the mesh's own transform.
• varying vec2 vUv1; void main() { vUv1 = uv1; } → attribute vec2 uv1; varying vec2 vUv1; void main() { vUv1 = uv1; }: three.js declares position, normal and uv for a ShaderMaterial; uv1 to uv3 and tangent need your own declaration.
• dot(normalize(cameraPosition - vWorldPosition), normalize(normalMatrix * normal)) → dot(normalize(cameraPosition - vWorldPosition), normalize(mat3(modelMatrix) * normal)): normalMatrix produces view-space normals while cameraPosition is world space, so the term drifts as the camera rotates.
• material.onBeforeCompile = (shader) => console.log(shader.fragmentShader); → renderer.debug.onShaderError = (gl, program, vs, fs) => console.error(gl.getShaderSource(fs));: onBeforeCompile runs before includes are resolved and the prefix is added, while onShaderError receives the assembled shaders when a program fails to compile or link.

See Also

• threejs-materials — built-in materials and their texture maps, when a standard material already does the job
• threejs-textures — loading textures, color spaces and UV channels for maps sampled in shaders
• threejs-postprocessing — full-screen passes (bloom, outline) instead of per-object shaders