Shader

VertexShader
- ジオメトリなどの情報をもとに、表示するものの位置を与える
Fragment Shader
- 各フラグメント（≒ピクセル）をどのように表示するかを与える

vite-plugin-glsl

zsh

bun i -D vite-plugin-glsl

vite.config.ts

import glsl from "vite-plugin-glsl"
export default {
  plugins: [glsl()],
}

tsconfig.json

{
  "compilerOptions": {
    "types": ["./src/global.d.ts", "node", "vite-plugin-glsl/ext"],
  }
}

t12u

最初のshader

main.ts

const geometry = new THREE.PlaneGeometry(3, 3)
const material = new THREE.RawShaderMaterial({
  vertexShader,
  fragmentShader,
})
const plane = new THREE.Mesh(geometry, material)
scene.add(plane)

実際の点の座標は変換せずに、あくまで表示するときに変えているだけ
The modelMatrix will apply all transformations relative to the Mesh. If we scale, rotate or move the Mesh, these transformations will be contained in the modelMatrix and applied to the position.
The viewMatrix will apply transformations relative to the camera. If we rotate the camera to the left, the vertices should be on the right. If we move the camera in direction of the Mesh, the vertices should get bigger, etc.
The projectionMatrix will finally transform our coordinates into the final clip space coordinates.
geometry.attributeが持つ属性をattributeを使って受け取れる
- normal, position, uvのほかに自分で追加もできる

vertex.vert

uniform mat4 projectionMatrix;
uniform mat4 viewMatrix;
uniform mat4 modelMatrix;

attribute vec3 position;

void main() {
  gl_Position = projectionMatrix * viewMatrix * modelMatrix * vec4(position, 1.0);
}

fragment.frag

precision mediump float;

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

t12u

GLSL基本

Typed Language

float a = 1.0;
int b = 2;
float c = a + float(b);

Vec

vec3, vec4
- r, g, b, a は x, y, z, w のエイリアス

vec3 position = vec3(0.0);
vec3.y = 1.0;

vec3 color = vec3(0.0;
color.g = 1.0;
color.b = 0.5;

vec2 v = vec2(1.0, 2.0);
vec3 p = vec3(v.yx, 1.0); // swizzle

Functions

float loremIpsum()
{
    float a = 1.0;
    float b = 2.0;

    return a + b;
}

void justDoingStuff()
{
    float a = 1.0;
    float b = 2.0;
}

float add(float a, float b)
{
    return a + b;
}

Native Functions

sin, cos, max, min, pow, exp, mod, clamp, but also very practical functions like cross, dot, mix, step, smoothstep, length, distance, reflect, refract, normalize.

t12u

GLSL

uniform（定数）をシェーダーに送る
受け取れるのは Vertex Shader のみ。他のシェーダーで使うにはvaryingとして再エクスポートする

const material = new THREE.RawShaderMaterial({
  vertexShader,
  fragmentShader,
  uniforms: {
    uFrequency: { value: new THREE.Vector2(10, 5) },
    uTime: { value: 0 },
    uColor: { value: new THREE.Color("white") },
    uTexture: { value: doorTexture },
  },
})

vertex.vert

uniform mat4 projectionMatrix;
uniform mat4 viewMatrix;
uniform mat4 modelMatrix;
attribute vec3 position;
attribute vec2 uv;

uniform vec2 uFrequency;
uniform float uTime;

varying vec2 vUv;
varying float vElevation;

void main() {
  vec4 modelPosition = modelMatrix * vec4(position, 1.0);
  float elevation = sin(modelPosition.x * uFrequency.x - uTime) * 0.1;
  elevation += sin(modelPosition.y * uFrequency.y - uTime) * 0.1;
  modelPosition.z = elevation;
  vec4 viewPosition = viewMatrix * modelPosition;
  vec4 projectedPosition = projectionMatrix * viewPosition;
  gl_Position = projectedPosition;
  
  vRandom = aRandom;
  vUv = uv;
  vElevation = elevation;
}

fragment.frag

precision mediump float;

uniform vec3 uColor;
uniform sampler2D uTexture;

varying vec2 vUv; // どのようにテクスチャを貼るかを決めるための変数
varying float vElevation;

void main() {
  vec4 textureColor = texture2D(uTexture, vUv);
  gl_FragColor = vec4(textureColor.rgb + uColor * vElevation, 1.0);
}

t12u

Custom Attribute

デフォルトのattributesはposition, normal, uvの３つ
aRandomというカスタム属性を追加する

const count = geometry.attributes.position.count
const randoms = new Float32Array(count).map(() => Math.random())
geometry.setAttribute(
  "aRandom",
  new THREE.BufferAttribute(randoms, 1 /* 1 random value per fragment */)
)

このスクラップは2024/04/15にクローズされました