在 THREE.JS 中设置与两个网格的最小距离

Posted 2023-02-22

【中文标题】在 THREE.JS 中设置与两个网格的最小距离

【英文标题】：set minimum distance from two meshes in THREE.JS

【发布时间】：2022-01-14 18:44:46

【问题描述】：

我有这段代码可以生成一些随机位置、旋转和随机比例的云。由于它们可以在另一个网格旁边或另一个网格旁边生成，因此它们可以夹在一起。我想设置一个最小距离，比如if(cloud position x and z is < 10 FROM ANOTHER CLOUD) then set distance我该怎么办？代码如下：

for(let i = 0; i < 10; i+= 1)

loader.load('/clouds/clouds2/scene.gltf', function (clouds2) 


 
 const cloud = clouds2.scene

 const child1 = cloud.children[0].children[0].children[0].children[2].children[0]
 const child2 = cloud.children[0].children[0].children[0].children[3].children[0]
 const child3 = cloud.children[0].children[0].children[0].children[4].children[0]
 
 child1.material = new THREE.MeshStandardMaterial( emissive: 'white', emissiveIntensity: 0.3)
 child2.material = new THREE.MeshStandardMaterial( emissive: 'white', emissiveIntensity: 0.3)
 child3.material = new THREE.MeshStandardMaterial( emissive: 'white', emissiveIntensity: 0.3)

 cloud.scale.x = (Math.random() * (0.06 - 0.04 ) + 0.04)
 cloud.scale.y = (Math.random() * (0.06 - 0.04 ) + 0.04)
 cloud.scale.z = (Math.random() * (0.06 - 0.04 ) + 0.04)

 cloud.position.x = (Math.random() - 0.5) * 500
 cloud.position.y = (Math.random() + 80)
 cloud.position.z = (Math.random() - 1) * 500

 cloud.rotation.x = Math.random()
 cloud.rotation.y = Math.random() 
 cloud.rotation.z = Math.random() 

 scene.add(cloud)


)

【参考方案1】：

首先，静态放置事物，然后使用随机值来创建差异并不可耻。例如，考虑一组排列在正方形角落的 4 朵云。如果您随后使用固定范围的随机值修改它们的位置，您将获得随机效果，同时仍保持分离。

const clouds = [...] // cloud meshes
const maxChange = ... // the maximum amount of position change in one direction

const staticPositions = [
  new THREE.Vector3(...),
  new THREE.Vector3(...),
  new THREE.Vector3(...),
  new THREE.Vector3(...)
]

for(let i = 0; i < 4; ++i)

  let cloud = clouds[i]

  cloud.position.copy(staticPositions[i])

  // random variance
  cloud.position.x += (Math.random() * (maxChange * 2)) - maxChange
  cloud.position.y += (Math.random() * (maxChange * 2)) - maxChange
  cloud.position.z += (Math.random() * (maxChange * 2)) - maxChange

但如果你真的想完全随机，那么你需要在提交之前对照所有其他云检查新位置。

const clouds = [...] // cloud meshes
const minDistanceSquared = ... // the minimum (squared) distance allowed between clouds

// checks if a cloud is far enough away from all other clouds
function isFarEnoughAway(cloud)
  let retVal = true

  for(let i = 0, l = clouds.length; i < l && retVal; ++i)
    if(cloud !== clouds[i] && cloud.position.distanceToSquared(clouds[i].position) < minDistSquared)
      retVal = false
    
  

  return retVal