Threejs渐变光柱效果_three.js渐变色_~在水一方的博客

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2、创建shader材质

            let c = new Color(color);
            let mat = new ShaderMaterial({
                uniforms: {
                    targetColor:{value:new Vector3(c.r,c.g,c.b)},
                    height: { value: height},
                side: DoubleSide,
                transparent:true,
                //depthTest:false,
                depthWrite:false,
                vertexShader: [
                    "varying vec3 modelPos;",
                    "void main() {",
                    "   modelPos = position;",
                    "	gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );",
                ].join("\n"),
                fragmentShader: [
                    "uniform vec3 targetColor;",
                    "uniform float height;",
                    "varying vec3 modelPos;",
                    "void main() {",
                    "   gl_FragColor = vec4(targetColor.xyz,(1.0 - modelPos.y/height)*(1.0 - modelPos.y/height));",
                ].join("\n")
            });
需要注意的是使用双面渲染、打开透明、关闭深度写入以及alpha的获取（这里使用二次方程，比线性函数过度更自然）




    
 
三、完整代码
 
     * 生成并返回柱状渐变光环
     * @param {*} radius 半径
     * @param {*} height 高度
     * @param {*} color 颜色
     * @returns 
    getAureole(radius,height,color){
        let geo,mat;
        let segment = 64;
        //geo
            /*let bottomPos = [];
            let topPos = [];
            let angleOffset = Math.PI*2/segment;
            for(var i=0;i<segment;i++){
                let x = Math.cos(angleOffset * i)*radius;
                let z = Math.sin(angleOffset * i)*radius;
                bottomPos.push(new Vector3(x,0,z));
                topPos.push(new Vector3(x,height,z));
            bottomPos = bottomPos.concat(topPos);
            let face = []
            for(var i=0;i<segment;i++){
                if(i != segment - 1){
                    face.push(new Face3(i+segment+1,i,i+segment));
                    face.push(new Face3(i,i+segment+1,i+1));
                else{
                    face.push(new Face3(segment,i,i+segment));
                    face.push(new Face3(i,segment,0));
            geo = new Geometry();
            geo.vertices = bottomPos;
            geo.faces = face;*/
            //更新为BufferGeometry
            let bottomPos = []
    		let topPos = []
    		let angleOffset = (Math.PI * 2) / segment
    		for (var i = 0; i < segment; i++) {
      			let x = Math.cos(angleOffset * i) * radius
      			let z = Math.sin(angleOffset * i) * radius
      			bottomPos.push(x, 0, z)
      			topPos.push(x, height, z)
    		bottomPos = bottomPos.concat(topPos)
    		let face = []
    		for (var i = 0; i < segment; i++) {
      			if (i != segment - 1) {
        			face.push(i + segment + 1, i, i + segment)
        			face.push(i, i + segment + 1, i + 1)
      			} else {
        			face.push(segment, i, i + segment)
        			face.push(i, segment, 0)
    		let geo = new BufferGeometry()
    		geo.setAttribute('position', new BufferAttribute(new Float32Array(bottomPos), 3))
    		geo.setIndex(new BufferAttribute(new Uint16Array(face), 1))
        //mat
            let c = new Color(color);
            mat = new ShaderMaterial({
                uniforms: {
                    targetColor:{value:new Vector3(c.r,c.g,c.b)},
                    height: { value: height},
                side: DoubleSide,
                transparent:true,
                //depthTest:false,
                depthWrite:false,
                vertexShader: [
                    "varying vec3 modelPos;",
                    "void main() {",
                    "   modelPos = position;",
                    "	gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );",
                ].join("\n"),
                fragmentShader: [
                    "uniform vec3 targetColor;",
                    "uniform float height;",
                    "varying vec3 modelPos;",
                    "void main() {",
                    "   gl_FragColor = vec4(targetColor.xyz,(1.0 - modelPos.y/height)*(1.0 - modelPos.y/height));",
                ].join("\n")
            });
        let mesh = new Mesh(geo,mat);
        mesh.renderOrder = 9999
        return mesh;
                    一、实现原理通过shader，将物体的透明度由下往上，从1到0渐变即可（只需要两圈顶点，底下一圈alpha设为1，上面一圈alpha设为0）二、实现步骤1、创建geometry这个几何体类似于圆柱，只是没有上下两个底面			let bottomPos = [];			let topPos = [];			let angleOffset = Math.PI*2/segment;			for(var i=0;i&lt;segment;i++){                let x = .
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8
方案1利用两个光柱进行贴图，两两垂直成九十度。
depthWrite: false,注意把深度影响关了，官方解释：
Whether rendering this material has any effect on the depth buffer. Default is true.
.depthWrite : Boolean：
When drawing 2D overlays it can be useful to disable the depth writing in order to lay
    let texture = new THREE.TextureLoader().load('./lightray_yellow.jpg'),
        material = new THREE.MeshBasicMaterial({
            map: texture,
            transparent: true,
    const color = "#5588aa";
    // 创建box 
    const geometry = new THREE.PlaneBufferGeometry(width, width, 1, 1);
    const vertexShader = `  
    varying vec2 vUv;
				要实现渐变色矩形，你可以使用Three.js的渐变色材质（`THREE.MeshBasicMaterial`）和平面几何体（`THREE.PlaneGeometry`）。
首先，你需要创建一个渐变色材质，并将其作为参数传递给平面几何体的构造函数。在创建渐变色材质时，你可以设置其颜色属性，以指定从哪种颜色到哪种颜色的渐变。你还可以设置渐变的起始点和终止点，以控制渐变的方向和大小。
下面是一个实现渐变色矩形的基本代码示例：
```javascript
// 创建渐变色材质
var material = new THREE.MeshBasicMaterial({
    color: new THREE.Color(0xff0000),  // 渐变起始颜色
    vertexColors: THREE.VertexColors  // 开启顶点颜色插值
// 创建平面几何体
var geometry = new THREE.PlaneGeometry(2, 2);
// 设置顶点颜色
geometry.faces.forEach(function(face) {
    var colors = face.vertexColors;
    colors[0] = new THREE.Color(0xff0000);  // 左上角为起点
    colors[1] = new THREE.Color(0x00ff00);  // 右上角为终点
    colors[2] = new THREE.Color(0x0000ff);  // 左下角为起点
// 创建渐变色矩形
var mesh = new THREE.Mesh(geometry, material);
这段代码会创建一个渐变色从红色到绿色再到蓝色的矩形。你可以根据需要修改起始颜色、终止颜色和顶点颜色来实现自定义的渐变效果。