From 506b5f99ae5ec0a7c60c5481b4cd1b14ce18cabc Mon Sep 17 00:00:00 2001
From: sigonasr2 <sigonasr2@gmail.com>
Date: Sat, 17 Aug 2024 00:12:06 -0500
Subject: [PATCH] Add basic collision resolution between Hamsters.

---
 src/Hamster.cpp | 50 +++++++++++++++++++++++++++++++++++++++++++++++--
 src/Hamster.h   | 10 ++++++++++
 2 files changed, 58 insertions(+), 2 deletions(-)

diff --git a/src/Hamster.cpp b/src/Hamster.cpp
index 1736473..7331df5 100644
--- a/src/Hamster.cpp
+++ b/src/Hamster.cpp
@@ -60,8 +60,20 @@ void Hamster::UpdateHamsters(const float fElapsedTime){
 	for(Hamster&h:HAMSTER_LIST){
 		h.animations.UpdateState(h.internalAnimState,fElapsedTime);
 		h.frictionEnabled=true;
-		if(h.IsPlayerControlled){
-			h.HandlePlayerControls();
+		h.bumpTimer-=fElapsedTime;
+		h.HandleCollision();
+		switch(h.state){
+			case NORMAL:{
+				//TODO: NPC controls.
+				if(h.IsPlayerControlled){
+					h.HandlePlayerControls();
+				}
+			}break;
+			case BUMPED:{
+				if(h.bumpTimer<=0.f){
+					h.state=NORMAL;
+				}
+			}break;
 		}
 		h.TurnTowardsTargetDirection();
 		h.MoveHamster();
@@ -134,4 +146,38 @@ void Hamster::MoveHamster(){
 			vel=vf2d{std::max(0.f,currentVel.polar().x-friction*HamsterGame::Game().GetElapsedTime()),currentVel.polar().y}.cart();
 		}
 	#pragma endregion
+}
+
+void Hamster::HandleCollision(){
+	for(Hamster&h:HAMSTER_LIST){
+		if(this==&h)continue;
+		if(geom2d::overlaps(geom2d::circle<float>(GetPos(),GetRadius()),geom2d::circle<float>(h.GetPos(),h.GetRadius()))){
+			if(geom2d::line<float>(GetPos(),h.GetPos()).length()==0.f){ //Push these two in random directions, they are on top of each other!
+				float randDir{util::random(2*geom2d::pi)};
+				vf2d collisionResolve1{GetPos()+vf2d{GetRadius(),randDir}.cart()};
+				vf2d collisionResolve2{h.GetPos()+vf2d{h.GetRadius(),float(randDir+geom2d::pi)}.cart()};
+				pos=collisionResolve1;
+				h.pos=collisionResolve2;
+				vel=vf2d{100.f,randDir}.cart();
+				h.vel=vf2d{100.f,float(randDir+geom2d::pi)}.cart();
+			}else{
+				geom2d::line<float>collisionLine{geom2d::line<float>(GetPos(),h.GetPos())};
+				float distance{collisionLine.length()};
+				float totalRadii{GetRadius()+h.GetRadius()};
+				float bumpDistance{totalRadii-distance};
+				vf2d collisionResolve1{GetPos()+vf2d{bumpDistance/2.f,float(collisionLine.vector().polar().y+geom2d::pi)}.cart()};
+				vf2d collisionResolve2{h.GetPos()+vf2d{bumpDistance/2.f,collisionLine.vector().polar().y}.cart()};
+				pos=collisionResolve1;
+				h.pos=collisionResolve2;
+				vel=vf2d{100.f,float(collisionLine.vector().polar().y+geom2d::pi)}.cart();
+				h.vel=vf2d{100.f,collisionLine.vector().polar().y}.cart();
+			}
+			state=h.state=BUMPED;
+			bumpTimer=h.bumpTimer=0.12f;
+		}
+	}
+}
+
+const float Hamster::GetRadius()const{
+	return collisionRadius;
 }
\ No newline at end of file
diff --git a/src/Hamster.h b/src/Hamster.h
index 1f22d67..82757ab 100644
--- a/src/Hamster.h
+++ b/src/Hamster.h
@@ -47,6 +47,11 @@ class Hamster{
 		NPC=false,
 	};
 
+	enum PlayerState{
+		NORMAL,
+		BUMPED,
+	};
+
 	static std::vector<Hamster>HAMSTER_LIST;
 
 	static const uint8_t MAX_HAMSTER_COUNT;
@@ -64,11 +69,14 @@ class Hamster{
 	float timeToMaxSpd{0.5f};
 	float friction{400.f};
 	bool frictionEnabled{false};
+	float collisionRadius{12.f};
+	float bumpTimer{};
 	std::string img;
 	Animate2D::Animation<HamsterGame::AnimationState>animations;
 	Animate2D::AnimationState internalAnimState;
 	PlayerControlled IsPlayerControlled;
 	static std::optional<Hamster*>playerHamster;
+	PlayerState state{NORMAL};
 public:
 	Hamster(const vf2d spawnPos,const std::string_view img,const PlayerControlled IsPlayerControlled=NPC);
 	static const Hamster&GetPlayer();
@@ -80,4 +88,6 @@ public:
 	void HandlePlayerControls();
 	void TurnTowardsTargetDirection();
 	void MoveHamster();
+	void HandleCollision();
+	const float GetRadius()const;
 };
\ No newline at end of file