ThreeJS Shader的效果樣例光影牆、擴散面(四)

一、實現一個光影牆 1. 根據自定義坐標點，輸出一個光影牆 /** * 添加光影牆 */ function addLightWall() { const geometry = new THREE.BufferGeometry(); const vertices = new Float32Array( ...

一、實現一個光影牆

　　1. 根據自定義坐標點，輸出一個光影牆

/**
 * 添加光影牆
 */
function addLightWall() {
  const geometry = new THREE.BufferGeometry();
  const vertices = new Float32Array([
    5, 0, 2,
    3, 0, 5,
    -2, 0, 5,
    -4, 0, 2,
    -4, 5, 2,
    -2, 5, 5,
    3, 5, 5,
    5, 5, 2
  ]);
  const indices = new Uint16Array([
    0, 1, 7,
    1, 6, 7,
    1, 2, 6,
    2, 5, 6,
    2, 3, 5,
    3, 4, 5
  ])

  geometry.setAttribute('position', new THREE.BufferAttribute(vertices, 3));
  geometry.setIndex(new THREE.BufferAttribute(indices, 1));
  geometry.setAttribute('aHeight', new THREE.BufferAttribute(new Float32Array(new Array(geometry.getAttribute('position').count).fill(5.0)), 1));
  
  const uniforms = {
    uTime: { value: 0.01 },
  };
  setShader(geometry, vertex, frag, [0, 2.5, 0], uniforms)
}

function setShader(geometry, vertexShader, fragmentShader, position = [0, 0, 0], uniforms = {}, isLine = false) {
  material = new THREE.ShaderMaterial({
    vertexShader: vertexShader,
    fragmentShader: fragmentShader,
    side: THREE.DoubleSide,
    uniforms: uniforms,
    transparent: true,
    // blending: THREE.AdditiveBlending, // 多個元素的顏色相互疊加，顏色可能會變亮，會疊加setClearColor設置的背景色
  });
  material.depthTest = true;
  material.depthWrite = false;
  let planeMesh = new THREE.Mesh(geometry, material);
  if (isLine) {
    planeMesh = new THREE.Points(geometry, material);
  }
  planeMesh.position.x = position[0];
  planeMesh.position.y = position[1];
  planeMesh.position.z = position[2];
  scene.add(planeMesh);
}

自定義坐標

　　2. 圓柱體的光影牆

/**
 * 添加光影牆
 */
function addLightWall() {
  const geometry = new THREE.CylinderGeometry(3, 3, 5.0, 32, 32, true);
  geometry.setAttribute('aHeight', new THREE.BufferAttribute(new Float32Array(new Array(geometry.getAttribute('position').count).fill(5.0)), 1));
  
  // 生成一個漸變色的光影牆
  const vertex = `
      varying vec3 vPosition;
      varying vec2 vUv;
      varying float vHeight;
      attribute float aHeight;
      void main() {
        vHeight = aHeight;
        vUv = uv;
        vPosition = position;
        gl_Position = projectionMatrix * modelViewMatrix * vec4(position, 1.0);
      }
  `;

  const frag = `
      varying vec3 vPosition;
      varying vec2 vUv;
      varying float vHeight;
      void main() {
        float d = (vHeight - distance(vPosition, vec3(vPosition.x, -2.5, vPosition.z))) / vHeight;
        gl_FragColor = vec4(0.0, 1.0, 1.0, d);
      }
  `;

  const uniforms = {
    uTime: { value: 0.01 },
  };
  setShader(geometry, vertex, frag, [0, 2.5, 0], uniforms)
}

function setShader(geometry, vertexShader, fragmentShader, position = [0, 0, 0], uniforms = {}, isLine = false) {
  material = new THREE.ShaderMaterial({
    vertexShader: vertexShader,
    fragmentShader: fragmentShader,
    side: THREE.DoubleSide,
    uniforms: uniforms,
    transparent: true,
    // blending: THREE.AdditiveBlending, // 多個元素的顏色相互疊加，顏色可能會變亮，會疊加setClearColor設置的背景色
  });
  material.depthTest = true;
  material.depthWrite = false;
  let planeMesh = new THREE.Mesh(geometry, material);
  if (isLine) {
    planeMesh = new THREE.Points(geometry, material);
  }
  planeMesh.position.x = position[0];
  planeMesh.position.y = position[1];
  planeMesh.position.z = position[2];
  scene.add(planeMesh);
}

圓柱體光影牆

　　3. 為圓柱體添加可移動的線圈

/**
 * 添加光影牆
 */
function addLightWall() {
  const geometry = new THREE.CylinderGeometry(3, 3, 5.0, 32, 32, true);
  geometry.setAttribute('aHeight', new THREE.BufferAttribute(new Float32Array(new Array(geometry.getAttribute('position').count).fill(5.0)), 1));

  // 生成一個可以向上移動的牆體線
  const vertex = `
      varying vec3 vPosition;
      varying vec2 vUv;
      varying float vHeight;
      attribute float aHeight;
      void main() {
        vHeight = aHeight;
        vUv = uv;
        vPosition = position;
        gl_Position = projectionMatrix * modelViewMatrix * vec4(position, 1.0);
      }
  `;

  const frag = `
      uniform float uTime;
      varying vec3 vPosition;
      varying vec2 vUv;
      varying float vHeight;
      void main() {
        float dis = distance(vPosition, vec3(vPosition.x, -2.5, vPosition.z));
        float highlightPos = mod(uTime * 5.0, vHeight) - 2.5;
        float highlightDis = distance(vec3(vPosition.x, highlightPos, vPosition.z), vec3(vPosition.x, -2.5, vPosition.z));
        float highlightOpa = (vHeight - highlightDis) / vHeight;
        float opacity = (vHeight - dis) / vHeight;
        if (abs(dis - highlightDis) < 0.05) {
          gl_FragColor = vec4(0.04, 0.95, 0.95, highlightOpa + 0.2);
        } else {
          gl_FragColor = vec4(0.0, 1.0, 1.0, opacity);
        }
      }
  `;

  const uniforms = {
    uTime: { value: 0.01 },
  };
  setShader(geometry, vertex, frag, [0, 2.5, 0], uniforms)
}

function setShader(geometry, vertexShader, fragmentShader, position = [0, 0, 0], uniforms = {}, isLine = false) {
  material = new THREE.ShaderMaterial({
    vertexShader: vertexShader,
    fragmentShader: fragmentShader,
    side: THREE.DoubleSide,
    uniforms: uniforms,
    transparent: true,
    // blending: THREE.AdditiveBlending, // 多個元素的顏色相互疊加，顏色可能會變亮，會疊加setClearColor設置的背景色
  });
  material.depthTest = true;
  material.depthWrite = false;
  let planeMesh = new THREE.Mesh(geometry, material);
  if (isLine) {
    planeMesh = new THREE.Points(geometry, material);
  }
  planeMesh.position.x = position[0];
  planeMesh.position.y = position[1];
  planeMesh.position.z = position[2];
  scene.add(planeMesh);
}

移動線圈光影牆

二、實現一個漸變色的波紋圓圈

　　1. 實現一個固定的漸變色圓圈

　　原理：

　　　　1) UV點的範圍是[0, 1]，所以各個像素點距離圓心的距離範圍是0~0.5，如果乘以2剛好是透明度的範圍(0~1)，這樣就可以實現一個簡單的漸變圓

　　　　2) 假設厚度為t，那麼顏色的透明度的範圍是[1, 1-t]，而我們實際需要的是[1, 0]，可以用圖二來表示兩個線性關係，可以得到兩個方程式

　　　　　　方程式1：y = -x + 1;

　　　　　　方程式2：y = -t + 1;

　　　　　　現在我們知道方程式二中的y的值(像素點到中心的距離distance),通過解方程式就可以得到方程式1中所對應的透明度的值為 (distance - 1) / t + 1；

/**
 * 添加一個擴散面
 */
function addDiffuseCircle() {
  const geometry = new THREE.CircleGeometry(3, 48);

  // 繪製一個漸變圈寬度可控的圓弧
  const vertex = `
      varying vec2 vUv;
      void main() {
        vUv = uv;
        gl_Position = projectionMatrix * modelViewMatrix * vec4(position, 1.0);
      }
  `;

  const frag = `
      uniform float uTime;
      uniform float uThickness;
      varying vec2 vUv;
      void main() {
        // 使用UV坐標計算各個點到中心點的距離，需要減0.5，將圓心移動到(0.5, 0.5)的位置，半徑為0.5，透明度範圍為0~1，所以需要乘以2
        float distance = length(vUv - 0.5) * 2.0;
        float opacity = (distance - 1.0) / uThickness + 1.0;
        gl_FragColor = vec4(0.0, 1.0, 1.0, opacity);
      }
  `;

  const uniforms = {
    uThickness: { value: 0.8, range: [0, 1] }, // 漸變色的厚度
    uSpeed: { value: 0.5, range: [0, 5] },
    uTime: { value: 0.01 },
  };
  setGui(uniforms);
  setShader(geometry, vertex, frag, [0,0,0], uniforms);
}

function setShader(geometry, vertexShader, fragmentShader, position = [0, 0, 0], uniforms = {}, isLine = false) {
  material = new THREE.ShaderMaterial({
    vertexShader: vertexShader,
    fragmentShader: fragmentShader,
    side: THREE.DoubleSide,
    uniforms: uniforms,
    transparent: true,
    // blending: THREE.AdditiveBlending, // 多個元素的顏色相互疊加，顏色可能會變亮，會疊加setClearColor設置的背景色
  });
  material.depthTest = true;
  material.depthWrite = false;
  let planeMesh = new THREE.Mesh(geometry, material);
  if (isLine) {
    planeMesh = new THREE.Points(geometry, material);
  }
  planeMesh.position.x = position[0];
  planeMesh.position.y = position[1];
  planeMesh.position.z = position[2];

  planeMesh.rotateX(Math.PI / 2);
  scene.add(planeMesh);
}

厚度可變的漸變圓

　　2. 半徑自動縮放的漸變圓

/**
 * 添加一個擴散面
 */
function addDiffuseCircle() {
  const geometry = new THREE.CircleGeometry(3, 48);

  // 創建一個大小可控的漸變圓弧
  const vertex = `
      varying vec2 vUv;
      void main() {
        vUv = uv;
        gl_Position = projectionMatrix * modelViewMatrix * vec4(position, 1.0);
      }
  `;

  const frag = `
      uniform float uTime;
      uniform float uThickness;
      uniform float uSpeed;
      varying vec2 vUv;
      void main() {
        // 使用UV坐標計算各個點到中心點的距離，需要減0.5，將圓心移動到(0.5, 0.5)的位置，半徑為0.5，透明度範圍為0~1，所以需要乘以2
        // 假設從內像外開始擴散，距離和時間關係是 最內部: 距離0，時間0；最外部：距離1，時間1，如果用1-時間的話，
        // 所以此時1-時間+距離和樣例1中的透明度相同
        float timeDis = fract(uTime * uSpeed);
        float distance = length(vUv - 0.5) * 2.0;
        if (timeDis < distance) {
          gl_FragColor = vec4(0.0, 0.0, 1.0, 0.0);
        } else {
          float opacity = (1.0 - timeDis + distance - 1.0) / uThickness + 1.0;
          gl_FragColor = vec4(0.0, 1.0, 1.0, opacity);
        }
      }
  `;

  const uniforms = {
    uThickness: { value: 0.8, range: [0, 1] }, // 漸變色的厚度
    uSpeed: { value: 0.5, range: [0, 5] },
    uTime: { value: 0.01 },
  };
 
  setShader(geometry, vertex, frag, [0,0,0], uniforms);
}

function setShader(geometry, vertexShader, fragmentShader, position = [0, 0, 0], uniforms = {}, isLine = false) {
  material = new THREE.ShaderMaterial({
    vertexShader: vertexShader,
    fragmentShader: fragmentShader,
    side: THREE.DoubleSide,
    uniforms: uniforms,
    transparent: true,
    // blending: THREE.AdditiveBlending, // 多個元素的顏色相互疊加，顏色可能會變亮，會疊加setClearColor設置的背景色
  });
  material.depthTest = true;
  material.depthWrite = false;
  let planeMesh = new THREE.Mesh(geometry, material);
  if (isLine) {
    planeMesh = new THREE.Points(geometry, material);
  }
  planeMesh.position.x = position[0];
  planeMesh.position.y = position[1];
  planeMesh.position.z = position[2];

  planeMesh.rotateX(Math.PI / 2);
  scene.add(planeMesh);
}

自動縮放的漸變圓