Split up simulation into time steps

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

main.cpp

@@ -9,9 +9,16 @@ struct Ball{
 	vf2d pos={};
 	vf2d vel={};
 	vf2d acc={};
+	vf2d originalPos={};
 	float radius=0;
 	float mass=0;
+	float simTimeRemaining=0;
+};
 
+struct Line{
+	vf2d startPos={};
+	vf2d endPos={};
+	float radius=0;
 };
 
 class MiniGolfPro : public olc::PixelGameEngine
@@ -19,8 +26,11 @@ class MiniGolfPro : public olc::PixelGameEngine
 
 public:
 	std::vector<Ball>balls;
+	std::vector<Line>lines;
 	Ball*selectedBall;
+	Line*selectedLine;
 	std::vector<std::pair<Ball*,Ball*>>collidingPairs;
+	std::vector<Ball*>fakeBalls;
 
 	MiniGolfPro()
 	{
@@ -35,12 +45,26 @@ public:
 		balls.emplace_back(b);
 	}
 
+	void AddLine(vf2d pos1,vf2d pos2,float r){
+		Line l;
+		l.startPos=pos1;
+		l.endPos=pos2;
+		l.radius=r;
+		lines.push_back(l);
+	}
+
 public:
 	bool OnUserCreate() override
 	{
 		for (int i=0;i<20;i++){
 			AddBall({float(rand()%ScreenWidth()),float(rand()%ScreenHeight())},rand()%16+2);
 		}
+		AddLine({12,4},{64,4},5);
+		AddLine({76,4},{132,4},5);
+		AddLine({12,68},{64,68},5);
+		AddLine({76,68},{132,68},5);
+		AddLine({4,12},{4,60},5);
+		AddLine({140,12},{140,60},5);
 		return true;
 	}
 
@@ -83,13 +107,27 @@ public:
 		}
 
 		Clear(BLACK);
+
+		float stable=0.01f;
+		int simulationUpdates=4;
+		int maxSimulationSteps=15;
+		float simElapsedTime=fElapsedTime/(float)simulationUpdates;
+
+		for(int i=0;i<simulationUpdates;i++){
+			for(Ball&b:balls){
+				b.simTimeRemaining=simElapsedTime;
+			}
+			for(int j=0;j<maxSimulationSteps;j++){
 				for(Ball&b:balls){
+					if(b.simTimeRemaining>0){
+						b.originalPos.x=b.pos.x;
+						b.originalPos.y=b.pos.y;
 						b.acc.x=-b.vel.x*0.8f;
-			b.acc.y=-b.vel.y*0.8f;
+						b.acc.y=-b.vel.y*0.8f/*+100.f //Gravity constant*/;
-			b.vel.x+=b.acc.x*fElapsedTime;
+						b.vel.x+=b.acc.x*b.simTimeRemaining;
-			b.vel.y+=b.acc.y*fElapsedTime;
+						b.vel.y+=b.acc.y*b.simTimeRemaining;
-			b.pos.x+=b.vel.x*fElapsedTime;
+						b.pos.x+=b.vel.x*b.simTimeRemaining;
-			b.pos.y+=b.vel.y*fElapsedTime;
+						b.pos.y+=b.vel.y*b.simTimeRemaining;
 
 						if(b.pos.x<0){
 							b.pos.x+=ScreenWidth();
@@ -104,13 +142,35 @@ public:
 							b.pos.y-=ScreenHeight();
 						}
 
-			if(fabs(b.vel.x*b.vel.x+b.vel.y*b.vel.y)<0.01){
+						if(fabs(b.vel.x*b.vel.x+b.vel.y*b.vel.y)<stable){
 							b.vel.x=0;
 							b.vel.y=0;
 						}
 					}
+				}
 
 				for(Ball&b:balls){
+					float deltaTime=b.simTimeRemaining;
+					for(Line&l:lines){
+						vf2d line1={l.endPos.x-l.startPos.x,l.endPos.y-l.startPos.y};
+						vf2d line2={b.pos.x-l.startPos.x,b.pos.y-l.startPos.y};
+						float edgeLength=line1.x*line1.x+line1.y*line1.y;
+						float t=std::max(0.f,std::min(edgeLength,(line1.x*line2.x+line1.y*line2.y)))/edgeLength;
+						vf2d closestPoint={l.startPos.x+t*line1.x,l.startPos.y+t*line1.x};
+						float dist=sqrtf((b.pos.x-closestPoint.x)*(b.pos.x-closestPoint.x)+(b.pos.y-closestPoint.y)*(b.pos.y-closestPoint.y));
+						if(dist<=b.radius+l.radius){
+							Ball*fakeBall=new Ball();
+							fakeBall->radius=l.radius;
+							fakeBall->mass=b.mass*0.8f;
+							fakeBall->pos=closestPoint;
+							fakeBall->vel={-b.vel.x,-b.vel.y};
+							fakeBalls.push_back(fakeBall);
+							collidingPairs.push_back({&b,fakeBall});
+							float overlap=1.f*(dist-b.radius-fakeBall->radius);
+							b.pos.x-=overlap*(b.pos.x-fakeBall->pos.x)/dist;
+							b.pos.y-=overlap*(b.pos.y-fakeBall->pos.y)/dist;
+						}
+					}
 					for(Ball&b2:balls){
 						if(&b!=&b2){
 							if(DoCirclesOverlap(b.pos,b.radius,b2.pos,b2.radius)){
@@ -124,8 +184,13 @@ public:
 							}
 						}
 					}
+					float intendedSpeed=sqrtf(b.vel.x+b.vel.y*b.vel.y);
+					float intendedDist=intendedSpeed*b.simTimeRemaining;
+					float actualDist=sqrtf((b.pos.x-b.originalPos.x)*(b.pos.x-b.originalPos.x)+(b.pos.y-b.originalPos.y)*(b.pos.y-b.originalPos.y));
+					float actualTime=actualDist/intendedSpeed;
+					b.simTimeRemaining=b.simTimeRemaining-actualTime;
 				}
-
+				float efficiency=1;
 				for(std::pair<Ball*,Ball*>&pair:collidingPairs){
 					Ball*b1=pair.first;
 					Ball*b2=pair.second;
@@ -142,6 +207,12 @@ public:
 				}
 
 				collidingPairs.clear();
+				for(Ball*fb:fakeBalls){
+					delete fb;
+				}
+				fakeBalls.clear();
+			}
+		}
 
 		for(Ball&b:balls){
 			if(selectedBall==&b){
@@ -150,6 +221,15 @@ public:
 				FillCircle(b.pos,b.radius);
 			}
 		}
+		for(Line&l:lines){
+			FillCircle(l.startPos,l.radius);
+			FillCircle(l.endPos,l.radius);
+			vf2d normal={-(l.endPos.y-l.startPos.y),l.endPos.x-l.startPos.x};
+			float dist=sqrt(normal.x*normal.x+normal.y*normal.y);
+			normal/=dist;
+			DrawLine(l.startPos.x+normal.x*l.radius,l.startPos.y+normal.y*l.radius,l.endPos.x+normal.x*l.radius,l.endPos.y+normal.y*l.radius);
+			DrawLine(l.startPos.x-normal.x*l.radius,l.startPos.y-normal.y*l.radius,l.endPos.x-normal.x*l.radius,l.endPos.y-normal.y*l.radius);
+		}
 		return true;
 	}