Balls now bounce off each other

Co-authored-by: sigonasr2 <sigonasr2@gmail.com>

main.cpp

@@ -20,6 +20,7 @@ class MiniGolfPro : public olc::PixelGameEngine
 public:
 	std::vector<Ball>balls;
 	Ball*selectedBall;
+	std::vector<std::pair<Ball*,Ball*>>collidingPairs;
 
 	MiniGolfPro()
 	{
@@ -108,6 +109,39 @@ public:
 				b.vel.y=0;
 			}
 		}
+
+		for(Ball&b:balls){
+			for(Ball&b2:balls){
+				if(&b!=&b2){
+					if(DoCirclesOverlap(b.pos,b.radius,b2.pos,b2.radius)){
+						collidingPairs.push_back({&b,&b2});
+						float dist=sqrtf((b.pos.x-b2.pos.x)*(b.pos.x-b2.pos.x)+(b.pos.y-b2.pos.y)*(b.pos.y-b2.pos.y));
+						float overlap=0.5f*(dist-b.radius-b2.radius);
+						b.pos.x-=overlap*(b.pos.x-b2.pos.x)/dist;
+						b.pos.y-=overlap*(b.pos.y-b2.pos.y)/dist;
+						b2.pos.x+=overlap*(b.pos.x-b2.pos.x)/dist;
+						b2.pos.y+=overlap*(b.pos.y-b2.pos.y)/dist;
+					}
+				}
+			}
+		}
+
+		for(std::pair<Ball*,Ball*>&pair:collidingPairs){
+			Ball*b1=pair.first;
+			Ball*b2=pair.second;
+			float dist=sqrtf((b1->pos.x-b2->pos.x)*(b1->pos.x-b2->pos.x)+(b1->pos.y-b2->pos.y)*(b1->pos.y-b2->pos.y));
+			vf2d normal={(b2->pos.x-b1->pos.x)/dist,(b2->pos.y-b1->pos.y)/dist};
+			vf2d tangent={-normal.y,normal.x};
+			vf2d dpTangent={tangent.dot(b1->vel),tangent.dot(b2->vel)};
+			vf2d dpNormal={normal.dot(b1->vel),normal.dot(b2->vel)};
+			vf2d momentum={(dpNormal.x*(b1->mass-b2->mass)+2.f*b2->mass*dpNormal.y)/(b1->mass+b2->mass),(dpNormal.y*(b2->mass-b1->mass)+2.f*b1->mass*dpNormal.x)/(b1->mass+b2->mass)};
+			b1->vel.x=tangent.x*dpTangent.x+normal.x*momentum.x;
+			b1->vel.y=tangent.y*dpTangent.x+normal.y*momentum.x;
+			b2->vel.x=tangent.x*dpTangent.y+normal.x*momentum.y;
+			b2->vel.y=tangent.y*dpTangent.y+normal.y*momentum.y;
+		}
+
+		collidingPairs.clear();
 		
 		for(Ball&b:balls){
 			if(selectedBall==&b){