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 - d*2.5; //Map variable 'a' as alpha based on distance. E.g. if distance is high, d = 100, alpha is low, a = 255 - 225 = 30.
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.
stroke(0,a); //Lines are coloured black, 'a' to vary alpha.
strokeWeight(0.7);
line(location.x,location.y,other.location.x,other.location.y); //Draw line between four coordinates, between two particle.
}
}
}
}
ArrayList<Particle> particles = new ArrayList<Particle>(); //Create a new arraylist of type Particle.
void setup(){
size(640,640,P2D); //Setup frame of sketch.
particles.add(new Particle()); //Add five Particle elements into arraylist.
particles.add(new Particle());
particles.add(new Particle());
particles.add(new Particle());
particles.add(new Particle());
}
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.
}
}
在上面的代码中,有形状对象、线条和椭圆。其透明度受变量 a 的影响。
变量 'a' 或 alpha 是从距离 'd' 推断出来的。因此,当对象更远时,对象的 alpha 值会下降。
在这种情况下,线的 alpha 值不会随着时间而改变,例如随着距离而变淡。然而,尽管代码非常相似,但椭圆似乎卡在了 alpha '255' 上。
如果 'a' 的值是硬编码的,例如
if(d<112){ //If the distance of any two particle falls bellow 112.
noStroke(); //No outline.
fill(0,100); //Particle are coloured black, set alpha 'a' to be 100, grey tint.
ellipse(location.x, location.y, 8, 8); //Draw ellipse based on location of particle.
椭圆按预期将颜色更改为灰色。
编辑:我相信我已经找到了问题的根源。变量“a”不区分正在迭代的粒子。因此,alpha 可能会卡住/加起来 255。