デジタルアート制作におけるWebManテクノロジーの応用と最適化

const canvas = document.getElementById('canvas');
const context = canvas.getContext('webgl');

const fragmentShaderSource = `
  precision highp float;

  uniform sampler2D texture;
  varying vec2 uv;

  void main() {
    vec4 color = texture2D(texture, uv);
    float gray = (color.r + color.g + color.b) / 3.0;
    gl_FragColor = vec4(gray, gray, gray, color.a);
  }
`;

const vertexShaderSource = `
  attribute vec2 position;
  attribute vec2 uv;
  varying vec2 v_uv;

  void main() {
    gl_Position = vec4(position, 0.0, 1.0);
    v_uv = uv;
  }
`;

const vertexBuffer = context.createBuffer();
context.bindBuffer(context.ARRAY_BUFFER, vertexBuffer);
context.bufferData(context.ARRAY_BUFFER, new Float32Array([-1, -1, 1, -1, -1, 1, 1, 1]), context.STATIC_DRAW);

const program = context.createProgram();
const vertexShader = context.createShader(context.VERTEX_SHADER);
const fragmentShader = context.createShader(context.FRAGMENT_SHADER);
context.shaderSource(vertexShader, vertexShaderSource);
context.shaderSource(fragmentShader, fragmentShaderSource);
context.compileShader(vertexShader);
context.compileShader(fragmentShader);
context.attachShader(program, vertexShader);
context.attachShader(program, fragmentShader);
context.linkProgram(program);
context.useProgram(program);

const positionLocation = context.getAttribLocation(program, 'position');
const uvLocation = context.getAttribLocation(program, 'uv');
context.enableVertexAttribArray(positionLocation);
context.enableVertexAttribArray(uvLocation);
context.vertexAttribPointer(positionLocation, 2, context.FLOAT, false, 0, 0);
context.vertexAttribPointer(uvLocation, 2, context.FLOAT, false, 0, 0);

const texture = context.createTexture();
const image = new Image();
image.onload = () => {
  context.bindTexture(context.TEXTURE_2D, texture);
  context.texParameteri(context.TEXTURE_2D, context.TEXTURE_WRAP_S, context.CLAMP_TO_EDGE);
  context.texParameteri(context.TEXTURE_2D, context.TEXTURE_WRAP_T, context.CLAMP_TO_EDGE);
  context.texParameteri(context.TEXTURE_2D, context.TEXTURE_MIN_FILTER, context.LINEAR);
  context.texParameteri(context.TEXTURE_2D, context.TEXTURE_MAG_FILTER, context.LINEAR);
  context.texImage2D(context.TEXTURE_2D, 0, context.RGBA, context.RGBA, context.UNSIGNED_BYTE, image);
  context.drawArrays(context.TRIANGLE_STRIP, 0, 4);
};

image.src = 'image.jpg';

// 粒子属性
const particleCount = 1000;
const particleSize = 4.0;

// 粒子位置和速度
const positions = new Float32Array(particleCount * 2);
const velocities = new Float32Array(particleCount * 2);

for (let i = 0; i < particleCount; i++) {
  positions[i * 2] = Math.random() * 2 - 1;
  positions[i * 2 + 1] = Math.random() * 2 - 1;
  velocities[i * 2] = Math.random() * 0.02 - 0.01;
  velocities[i * 2 + 1] = Math.random() * 0.02 - 0.01;
}

// 渲染粒子
function renderParticles() {
  context.clear(context.COLOR_BUFFER_BIT);
  context.viewport(0, 0, canvas.width, canvas.height);
  context.uniform2fv(context.getUniformLocation(program, 'positions'), positions);
  context.uniform2fv(context.getUniformLocation(program, 'velocities'), velocities);
  context.uniform1f(context.getUniformLocation(program, 'particleSize'), particleSize);
  context.drawArrays(context.POINTS, 0, particleCount);
}

// 更新粒子位置
function updateParticles() {
  for (let i = 0; i < particleCount; i++) {
    positions[i * 2] += velocities[i * 2];
    positions[i * 2 + 1] += velocities[i * 2 + 1];
    if (positions[i * 2] < -1 || positions[i * 2] > 1) velocities[i * 2] *= -1;
    if (positions[i * 2 + 1] < -1 || positions[i * 2 + 1] > 1) velocities[i * 2 + 1] *= -1;
  }
}

// 主循环
function mainLoop() {
  updateParticles();
  renderParticles();
  requestAnimationFrame(mainLoop);
}

mainLoop();