在glsl和三个js中将粒子从鼠标位置推开

Question

我的THREE.Points对象有以下设置：

        this.particleGeometry = new THREE.BufferGeometry()
        this.particleMaterial = new THREE.ShaderMaterial(
            {
                vertexShader: vshader,
                fragmentShader: fshader,
                blending: THREE.AdditiveBlending,
                depthWrite: false,
                uniforms: {
                    uTime: new THREE.Uniform(0),
                    uMousePosition: this.mousePosition
                }
            }
        )

然后一些代码将点放置在BufferGeometry球体上。那工作正常。

我还设置了一个 Raycaster 来跟踪与隐藏平面相交的鼠标位置，然后相应地更新制服uMousePosition。这也很好用，我将鼠标位置发送到我的顶点着色器。

现在我试图让离d鼠标有一定距离的粒子远离它，当然最接近的粒子被推开，并且还将重力施加回它们的原始位置以在一段时间后恢复一切。

所以这是我的顶点着色器中的内容：

void main() {
float lerp(float a, float b, float amount) {
    return a + (b - a) * amount;
}

void main() {
    vec3 p = position;

    float dist = min(distance(p, mousePosition), 1.);

    float lerpFactor = .2;

    p.x = lerp(p.x, position.x * dist, lerpFactor);
    p.y = lerp(p.y, position.y * dist, lerpFactor);
    p.z = lerp(p.z, position.z * dist, lerpFactor);//Mouse is always in z=0

    vec4 mvPosition = modelViewMatrix * vec4(p, 1.);
    gl_PointSize = 30. * (1. / -mvPosition.z );
    gl_Position = projectionMatrix * mvPosition;
}
}

这是鼠标在球体外时的样子（添加了一个随鼠标位置移动的小球体以指示鼠标位置）

当鼠标在里面时：

外部看起来已经有点正确了，但是鼠标内部只会将粒子移动到更接近其原始位置的位置，而应该将它们推向更远的外部。我想我必须以某种方式确定距离的方向。

另外， lerp 方法不 lerp，粒子直接跳到它们的位置。

所以我想知道如何获得与鼠标的正确距离以始终在特定区域移动粒子，以及如何为 lerp/重力效果设置动画。

Answer 1

这就是您可以将其作为第一个近似值的方法：

body{
  overflow: hidden;
  margin: 0;
}

<script type="module">
import * as THREE from "https://threejs.org/build/three.module.js";
import {OrbitControls} from "https://threejs.org/examples/jsm/controls/OrbitControls.js";
import {BufferGeometryUtils} from "https://threejs.org/examples/jsm/utils/BufferGeometryUtils.js";

let scene = new THREE.Scene();
let camera = new THREE.PerspectiveCamera(60, innerWidth / innerHeight, 1, 100);
camera.position.set(0, 0, 10);
let renderer = new THREE.WebGLRenderer();
renderer.setSize(innerWidth, innerHeight);
document.body.appendChild(renderer.domElement);

let controls = new OrbitControls(camera, renderer.domElement);

let marker = new THREE.Mesh(new THREE.SphereGeometry(0.5, 16, 8), new THREE.MeshBasicMaterial({color: "red", wireframe: true}));
scene.add(marker);

let g = new THREE.IcosahedronGeometry(4, 20);
g = BufferGeometryUtils.mergeVertices(g);
let uniforms = {
  mousePos: {value: new THREE.Vector3()}
}
let m = new THREE.PointsMaterial({
  size: 0.1,
  onBeforeCompile: shader => {
    shader.uniforms.mousePos = uniforms.mousePos;
    shader.vertexShader = `
      uniform vec3 mousePos;
      ${shader.vertexShader}
    `.replace(
      `#include <begin_vertex>`,
      `#include <begin_vertex>
        
        vec3 seg = position - mousePos;
        vec3 dir = normalize(seg);
        float dist = length(seg);
        if (dist < 2.){
          float force = clamp(1. / (dist * dist), 0., 1.);
          transformed += dir * force;
        }
      
      `
    );
    console.log(shader.vertexShader);
  }
});
let p = new THREE.Points(g, m);
scene.add(p);

let clock = new THREE.Clock();

renderer.setAnimationLoop( _ => {
  let t = clock.getElapsedTime();
  marker.position.x = Math.sin(t * 0.5) * 5;
  marker.position.y = Math.cos(t * 0.3) * 5;
  uniforms.mousePos.value.copy(marker.position);
  renderer.render(scene, camera);
})
</script>