RANDOMLY DISTRIBUTE INSIDE CIRCLE

[Saulo Dal pozzo]

Found another thread that helped me get the distribution in the image (I also needed to avoid the area of the screen)

The expression ended up like this:

seedRandom(index,true);

var center = [width/2,height/2];

var r = center[0]+thisComp.layer(“NULL “).effect(“RADIUS”)(“Slider”);

var pX = random(center[0]-r,center[0]+r);

if (pX > 0 && pX < width){

pY = center[1];

while (pY > 0 && pY < height) pY = random(center[1]-r,center[1]+r);

}else{

pY = random(center[1]-r,center[1]+r);

}

var pos = [pX, pY];

if (length(center,pos)>r){

pos = center + r*(pos-center)/length(center,pos);

}

pos

Now I’ll try to find a way to avoid the layers from peeking in at the screen based on their size. I also feel that it’s not that evenly distributed, but it’s fine for now

[Dan Ebberts]

I think the whole problem gets simpler if you switch from rectangular coordinates to polar coordinates (radius and angle). Then a circular random distribution centered around the comp center becomes something like this:

c = [thisComp.width,thisComp.height]/2; // center
rMax = 500; // max radius
seedRandom(index,true);
a = random(Math.PI*2);
r = random(rMax);
x = r*Math.cos(a);
y = r*Math.sin(a);
c + [x,y]

It gets more complicated if you have a rectangular exclusion zone in the center of the field, but by using a little trig, you can avoid the while loop that can hang AE:

c = [thisComp.width,thisComp.height]/2; // center
w = 400; // width of rectangular exclusion area
h = 300; // height of rectangular exclusion area
rMax = 500; // max radius (must be big enough to enclose the rectangle)
seedRandom(index,true);
a = random(Math.PI/2);
aMid = Math.atan2(h/2,w/2);
if (a < aMid){
  rMin = (w/2)/Math.cos(a);
}else{
  rMin = (h/2)/Math.cos(Math.PI/2 - a);
}
r = random(rMin,rMax);
x = r*Math.cos(a);
y = r*Math.sin(a);
n = Math.floor(random(4));
if (n == 1){
  x = -x;
}else if (n == 2){
  x = -x;
  y = -y;
}else if (n == 3){
  y = -y;
}
c + [x,y]

[Saulo Dal pozzo]

Thanks Dan! I still have trouble with all the Math functions, so generally I avoid them. I’ll try to make sense of what you did 😉