Collision detection on Shapes

[Dan Ebberts]

Hmmm…. You might have a fighting chance if each of your squares was a separate layer. Then you could use sourceRectAtTime() to get the bounding box of the square and use the bounding box of each circle to calculate its center and radius and then calculate if there’s a collision. I don’t think you have the right tools to do it with individual shapes in the same shape layer.

Scratch all that… you do have size and location of each square, and that may be enough. I’ll be back…

[Dan Ebberts]

I think this gets pretty close. If the center of the square gets inside a circle, it should pick up that circle’s color, otherwise black. To make it work if any part of the square touches the circle would take a bunch more code. You might also need to decide what to do if the center of the square is inside both circles. But it’s an encouraging start, I think.

C1 = thisComp.layer("RADIAL EFFECTOR 01");
C2 = thisComp.layer("RADIAL EFFECTOR 02");
r1 = C1.sourceRectAtTime(time,false);
radius1 = r1.width/2;
p1 = C1.toComp([r1.left+r1.width/2,r1.top+r1.height/2]);
r2 = C2.sourceRectAtTime(time,false);
radius2 = r2.width/2;
p2 = C2.toComp([r2.left+r2.width/2,r2.top+r2.height/2]);
myPos = thisProperty.propertyGroup(3)("Transform")("Position").value;
d1 = length(toComp(myPos),p1);
d2 = length(toComp(myPos),p2);
if (d1<radius1)
  C1("Contents")("Ellipse 1")("Contents")("Fill 1")("Color")
else if (d2 < radius2)
  C2("Contents")("Ellipse 1")("Contents")("Fill 1")("Color")
else
 [0,0,0,1]

[Justin Productions]

Dan,

This snippet of code is better than “pretty close”. It’s exactly what I’ve envisioned. I also made sure to study the code and understand it so I could make small tweaks of my own (see additions below). Thank you so very much! I appreciate it immensely.

Additions:

I wanted to “fake” the Lighten color mode on the clones that were simultaneously intersected by the 2 Radial effectors. To do so, I combined Dan’s code with Oleg Pirogov’s solution to mix 2 color vectors. The result is as follows:

function lighten(r1, r2){
if(r1 <= r2)
return r2
else if(r1 > r2)
return r1
};
C1 = thisComp.layer("RADIAL EFFECTOR 01");
C2 = thisComp.layer("RADIAL EFFECTOR 02");
r1 = C1.sourceRectAtTime(time,false);
radius1 = r1.width/2;
p1 = C1.toComp([r1.left+r1.width/2,r1.top+r1.height/2]);
r2 = C2.sourceRectAtTime(time,false);
radius2 = r2.width/2;
p2 = C2.toComp([r2.left+r2.width/2,r2.top+r2.height/2]);
myPos = thisProperty.propertyGroup(3)("Transform")("Position").value;
d1 = length(toComp(myPos),p1);
d2 = length(toComp(myPos),p2);
if (d1<radius1 && d2 < radius2){
  C1_color = C1("Contents")("Ellipse 1")("Contents")("Fill 1")("Color");
  C2_color = C2("Contents")("Ellipse 1")("Contents")("Fill 1")("Color");
  a2=C2_color[3];
  a1=C1_color[3];
  a=a2+a1-a2*a1;
  B = [lighten(C1_color[0], C2_color[0]), lighten(C1_color[1], C2_color[1]), lighten(C1_color[2], C2_color[2])];
  aC=(a - a2)*C1_color+(a2)*((1-a1)*C2_color+a1*B);
  z=[aC[0]/a, aC[1]/a, aC[2]/a, a];
}else if (d1 < radius1){
  C1("Contents")("Ellipse 1")("Contents")("Fill 1")("Color")
}else if (d2 < radius2){
  C2("Contents")("Ellipse 1")("Contents")("Fill 1")("Color")
}else{
 [0,0,0,1]
}

Dan, I can’t thank you enough for your assistance. I’ve been a member of CC since 2005 and I can’t tell you how grateful I am for all that you’ve done, for me and other members of this community.

Thanks a million once again.