Java 正在处理，无法为ArrayList中的对象设置alpha值

这是对此的后续行动

我希望让一堆粒子对象保持在某个“alpha”值。此alpha值将根据其与相邻粒子的接近程度增加/减少

目前，我的代码导致所有粒子都保持在max alpha。我相信这是由于对ArrayList的迭代导致alpha被多次重绘。程序也因此运行缓慢

  class Particle{

  PVector velocity, location; //PVector variables for each particle.

  Particle(){ //Constructor - random location and speed for each particle.
    velocity = new PVector(random(-0.5,0.5), random(-0.5,0.5));
    location = new PVector(random(0,width),random(0,width));
  }

  void update() { location.add(velocity); } //Motion method.

  void edge() {  //Wraparound case for particles.
    if (location.x > width) {location.x = 0;} 
    else if (location.x < 0) {location.x = width;}

    if (location.y > height) {location.y = 0;}
    else if (location.y < 0) {location.y = height;}
  }

  void display(ArrayList<Particle> p){ //Display method to show lines and ellipses between particles.

    for(Particle other: p){ //For every particle in the ArrayList.
     float d = PVector.dist(location,other.location); //Get distance between any two particle.
     float a = 255 - map(d,0,112,0,255); //Map variable 'a' as alpha based on distance. E.g. if distance is high, d = 100, alpha is low, a = 255 - 225 = 30.

if(other==this){continue;}

     println("Lowest distance of any two particle =" + d); //Debug output.

     if(d<112){ //If the distance of any two particle falls bellow 112.
      noStroke(); //No outline.
      fill(0,a); //Particle are coloured black, 'a' to vary alpha.
      ellipse(location.x, location.y, 8, 8); //Draw ellipse based on location of particle.

    }else{
      noStroke(); //No outline.
      fill(0,30); //For particles far away, set them to a fix alpha of '30'
      ellipse(location.x, location.y, 8, 8); //Draw ellipse based on location of particle.
    }
  }
}
}

ArrayList<Particle> particles = new ArrayList<Particle>(); //Create a new arraylist of type Particle.

void setup(){
  size(640,640,P2D); //Setup frame of sketch.

    for (int i=0; i<40; i++) { 
  particles.add(new Particle()); //Add five Particle elements into arraylist.
    }
}

void draw(){
 background(255); //Set white background.
 for(Particle p: particles){ //For every 'p' of type Particle in arraylist particles.
   p.update(); //Update location based on velocity.
   p.display(particles); //Display each particle in relation to other particles.
   p.edge(); //Wraparound if particle reaches edge of screen.
 }
}

类粒子{
PVector速度，位置；//每个粒子的PVector变量。
Particle（）{//Constructor-每个粒子的随机位置和速度。
速度=新PVector（随机（-0.5,0.5），随机（-0.5,0.5））；
位置=新PVector（随机（0，宽度），随机（0，宽度））；
}
void update（）{location.add（velocity）；}//运动方法。
void edge（）{//粒子的包围盒。
如果（location.x>width）{location.x=0；}
如果（location.x<0）{location.x=width；}
如果（location.y>height）{location.y=0；}
如果（location.y<0）{location.y=height；}
}
void display（ArrayList p）{//显示粒子之间的直线和椭圆的显示方法。
对于（Particle other:p）{//对于ArrayList中的每个粒子。
float d=PVector.dist（location，other.location）；//获取任意两个粒子之间的距离。
浮点a=255-映射（d，0112，0255）；//根据距离将变量“a”映射为alpha。例如，如果距离高，d=100，alpha低，a=255-225=30。
如果（other==this）{continue；}
println（“任意两个粒子的最小距离=”+d）；//调试输出。
如果（d你也有同样的问题：对于每个
粒子
，你正在循环通过每个其他
粒子
，因此你最终为每个
粒子
绘制了40个椭圆。相反，你需要循环通过
粒子
找到最近的邻居，然后根据你的阿尔法计算一个
粒子

换句话说，您的绘图代码应该发生在for

循环的之后

查找最近的邻居如下所示：

Particle closestNeighbor = null;
float closestDistance = 100000;

for (Particle other : p) { //For every particle in the ArrayList.

  if (other == this) {
    continue;
  }


  float d = PVector.dist(location, other.location);
  if (d < closestDistance) {
    closestDistance = d;
    closestNeighbor = other;
  }
}

---

请在交叉柱之间链接：

float a = 255 - map(closestDistance, 0, 112, 0, 255); //Map variable 'a' as alpha based on distance. E.g. if distance is high, d = 100, alpha is low, a = 255 - 225 = 30.

if (closestDistance<112) {
  noStroke(); //No outline.
  fill(0, a); //Particle are coloured black, 'a' to vary alpha.
  ellipse(location.x, location.y, 8, 8); //Draw ellipse based on location of particle.
} else {
  noStroke(); //No outline.
  fill(0, 30); //For particles far away, set them to a fix alpha of '30'
  ellipse(location.x, location.y, 8, 8); //Draw ellipse based on location of particle.
}