From c5acdcd5246a7dbd7ad1fc065c16333856c5823d Mon Sep 17 00:00:00 2001
From: Muzychenko Andrey <33288308+k4zmu2a@users.noreply.github.com>
Date: Sun, 12 Mar 2023 11:12:41 +0300
Subject: [PATCH] FT collision part4: ball to ball collision. TBall uses
 multiple inheritance, interesting.

---
 SpaceCadetPinball/TBall.cpp         | 70 +++++++++++++++++++++++++----
 SpaceCadetPinball/TBall.h           | 13 +++---
 SpaceCadetPinball/TCircle.cpp       |  4 +-
 SpaceCadetPinball/TCircle.h         |  2 +-
 SpaceCadetPinball/TEdgeManager.cpp  |  4 +-
 SpaceCadetPinball/TEdgeSegment.cpp  |  2 +-
 SpaceCadetPinball/TEdgeSegment.h    |  4 +-
 SpaceCadetPinball/TFlipperEdge.cpp  |  4 +-
 SpaceCadetPinball/TFlipperEdge.h    |  2 +-
 SpaceCadetPinball/TLine.cpp         |  4 +-
 SpaceCadetPinball/TLine.h           |  2 +-
 SpaceCadetPinball/TPinballTable.cpp | 12 ++++-
 SpaceCadetPinball/TPinballTable.h   |  1 +
 SpaceCadetPinball/pb.cpp            | 41 ++++++++++++++---
 SpaceCadetPinball/pb.h              |  5 ++-
 15 files changed, 132 insertions(+), 38 deletions(-)

diff --git a/SpaceCadetPinball/TBall.cpp b/SpaceCadetPinball/TBall.cpp
index ab440a6..9c9493f 100644
--- a/SpaceCadetPinball/TBall.cpp
+++ b/SpaceCadetPinball/TBall.cpp
@@ -11,7 +11,8 @@
 #include "TPinballTable.h"
 #include "TTableLayer.h"
 
-TBall::TBall(TPinballTable* table) : TPinballComponent(table, -1, false)
+TBall::TBall(TPinballTable* table, int groupIndex) : TCollisionComponent(table, groupIndex, false),
+                                                     TEdgeSegment(this, &ActiveFlag, 0)
 {
 	visualStruct visual{};
 	char ballGroupName[10]{"ball"};
@@ -22,19 +23,29 @@ TBall::TBall(TPinballTable* table) : TPinballComponent(table, -1, false)
 	CollisionComp = nullptr;
 	EdgeCollisionCount = 0;
 	TimeDelta = 0.0;
-	CollisionMask = 1;
 	CollisionFlag = 0;
 	Speed = 0.0;
 	Direction.Y = 0.0;
 	Direction.X = 0.0;
-	Position.X = 0.0;
-	Position.Y = 0.0;
-	HasGroupFlag = false;
-
 	ListBitmap = new std::vector<SpriteData>();
 
+	if (groupIndex == -1)
+	{
+		HasGroupFlag = false;
+		Position = {0, 0, 0};
+		CollisionMask = 1;
+	}
+	else
+	{
+		HasGroupFlag = true;
+		loader::query_visual(groupIndex, 0, &visual);
+		CollisionMask = visual.CollisionGroup;
+		auto floatArr = loader::query_float_attribute(groupIndex, 0, 408);
+		Position = {floatArr[0], floatArr[1], floatArr[3]};
+	}
+
 	/*Full tilt: ball is ballN, where N[0,2] resolution*/
-	auto groupIndex = loader::query_handle(ballGroupName);
+	groupIndex = loader::query_handle(ballGroupName);
 	if (groupIndex < 0)
 	{
 		ballGroupName[4] = '0' + fullscrn::GetResolution();
@@ -70,7 +81,7 @@ void TBall::Repaint()
 
 	auto pos2D = proj::xform_to_2d(Position);
 	auto zDepth = proj::z_distance(Position);
-	
+
 	auto index = 0u;
 	for (; index < ListBitmap->size() - 1; ++index)
 	{
@@ -112,7 +123,7 @@ int TBall::Message(MessageCode code, float value)
 {
 	if (code == MessageCode::Reset)
 	{
-		SpriteSetBall(-1, { 0,0 }, 0.0f);
+		SpriteSetBall(-1, {0, 0}, 0.0f);
 		Position.X = 0.0;
 		CollisionComp = nullptr;
 		Position.Y = 0.0;
@@ -139,6 +150,47 @@ void TBall::throw_ball(vector3* direction, float angleMult, float speedMult1, fl
 	Speed = (1.0f - (rnd + rnd)) * (speedMult1 * speedMult2) + speedMult1;
 }
 
+void TBall::EdgeCollision(TBall* ball, float distance)
+{
+	ball->AsEdgeCollisionFlag = true;
+	vector2 nextPos{
+		        ball->Position.X + ball->Direction.X * distance,
+		        ball->Position.Y + ball->Direction.Y * distance
+	        },
+	        collDir{nextPos.X - Position.X, nextPos.Y - Position.Y};
+	maths::normalize_2d(collDir);
+	vector2 invCollDir{ -collDir.X, -collDir.Y };
+
+	ball->Position.X = nextPos.X;
+	ball->Position.Y = nextPos.Y;
+	ball->Direction.X *= ball->Speed;
+	ball->Direction.Y *= ball->Speed;
+	Direction.X *= Speed;
+	Direction.Y *= Speed;
+
+	auto coef = -maths::DotProduct(ball->Direction, collDir);
+	vector2 v44{collDir.X * coef, collDir.Y * coef};
+	vector2 v13{ball->Direction.X + v44.X, ball->Direction.Y + v44.Y};
+	
+	coef = -maths::DotProduct(Direction, invCollDir);
+	vector2 v11{invCollDir.X * coef, invCollDir.Y * coef};
+	vector2 v10{Direction.X + v11.X, Direction.Y + v11.Y};
+
+	ball->Direction.X = -v11.X + v13.X;
+	ball->Direction.Y = -v11.Y + v13.Y;
+	ball->Speed = maths::normalize_2d(ball->Direction);
+	Direction.X = -v44.X + v10.X;
+	Direction.Y = -v44.Y + v10.Y;
+	Speed = maths::normalize_2d(Direction);
+}
+
+float TBall::FindCollisionDistance(const ray_type& ray)
+{
+	// Original inherits TCircle and aliases position.
+	const circle_type ballCircle{{Position.X, Position.Y}, Radius * Radius * 4.0f};
+	return maths::ray_intersect_circle(ray, ballCircle);
+}
+
 vector2 TBall::get_coordinates()
 {
 	return TTableLayer::edge_manager->NormalizeBox(Position);
diff --git a/SpaceCadetPinball/TBall.h b/SpaceCadetPinball/TBall.h
index 19a0c83..724cf49 100644
--- a/SpaceCadetPinball/TBall.h
+++ b/SpaceCadetPinball/TBall.h
@@ -1,14 +1,12 @@
 #pragma once
 #include "maths.h"
-#include "TPinballComponent.h"
+#include "TCollisionComponent.h"
+#include "TEdgeSegment.h"
 
-class TCollisionComponent;
-class TEdgeSegment;
-
-class TBall : public TPinballComponent
+class TBall : public TCollisionComponent, public TEdgeSegment
 {
 public :
-	TBall(TPinballTable* table);
+	TBall(TPinballTable* table, int groupIndex);
 	void Repaint();
 	void not_again(TEdgeSegment* edge);
 	bool already_hit(TEdgeSegment* edge);
@@ -16,6 +14,9 @@ public :
 	vector2 get_coordinates() override;
 	void Disable();
 	void throw_ball(vector3* direction, float angleMult, float speedMult1, float speedMult2);
+	void place_in_grid(RectF* aabb) override {}
+	void EdgeCollision(TBall* ball, float distance) override;
+	float FindCollisionDistance(const ray_type& ray) override;
 
 	vector3 Position{};
 	vector3 PrevPosition{};
diff --git a/SpaceCadetPinball/TCircle.cpp b/SpaceCadetPinball/TCircle.cpp
index a3bd49a..8752174 100644
--- a/SpaceCadetPinball/TCircle.cpp
+++ b/SpaceCadetPinball/TCircle.cpp
@@ -12,9 +12,9 @@ TCircle::TCircle(TCollisionComponent* collComp, char* activeFlag, unsigned colli
 	Circle.Center = *center;
 }
 
-float TCircle::FindCollisionDistance(ray_type* ray)
+float TCircle::FindCollisionDistance(const ray_type& ray)
 {
-	return maths::ray_intersect_circle(*ray, Circle);
+	return maths::ray_intersect_circle(ray, Circle);
 }
 
 void TCircle::EdgeCollision(TBall* ball, float distance)
diff --git a/SpaceCadetPinball/TCircle.h b/SpaceCadetPinball/TCircle.h
index 7cac2e4..c763e4e 100644
--- a/SpaceCadetPinball/TCircle.h
+++ b/SpaceCadetPinball/TCircle.h
@@ -10,7 +10,7 @@ public:
 
 	TCircle(TCollisionComponent* collComp, char* activeFlag, unsigned int collisionGroup, vector2* center,
 	        float radius);
-	float FindCollisionDistance(ray_type* ray) override;
+	float FindCollisionDistance(const ray_type& ray) override;
 	void EdgeCollision(TBall* ball, float distance) override;
 	void place_in_grid(RectF* aabb) override;
 };
diff --git a/SpaceCadetPinball/TEdgeManager.cpp b/SpaceCadetPinball/TEdgeManager.cpp
index 8eeaa16..70e5fb7 100644
--- a/SpaceCadetPinball/TEdgeManager.cpp
+++ b/SpaceCadetPinball/TEdgeManager.cpp
@@ -76,7 +76,7 @@ int TEdgeManager::TestGridBox(int x, int y, float* distPtr, TEdgeSegment** edgeD
 		for (auto it = edgeBox->EdgeList.rbegin(); it != edgeBox->EdgeList.rend(); ++it)
 		{
 			auto edge = *it;
-			if (!edge->ProcessedFlag && *edge->ActiveFlag && (edge->CollisionGroup & ray->CollisionMask))
+			if (!edge->ProcessedFlag && *edge->ActiveFlagPtr && (edge->CollisionGroup & ray->CollisionMask))
 			{
 				if (!ball->already_hit(edge))
 				{
@@ -84,7 +84,7 @@ int TEdgeManager::TestGridBox(int x, int y, float* distPtr, TEdgeSegment** edgeD
 					*edgePtr = edge;
 					++edgePtr;
 					edge->ProcessedFlag = 1;
-					auto dist = edge->FindCollisionDistance(ray);
+					auto dist = edge->FindCollisionDistance(*ray);
 					if (dist < *distPtr)
 					{
 						*distPtr = dist;
diff --git a/SpaceCadetPinball/TEdgeSegment.cpp b/SpaceCadetPinball/TEdgeSegment.cpp
index 2d78f8b..707a560 100644
--- a/SpaceCadetPinball/TEdgeSegment.cpp
+++ b/SpaceCadetPinball/TEdgeSegment.cpp
@@ -8,7 +8,7 @@
 TEdgeSegment::TEdgeSegment(TCollisionComponent* collComp, char* activeFlag, unsigned collisionGroup)
 {
 	CollisionComponent = collComp;
-	ActiveFlag = activeFlag;
+	ActiveFlagPtr = activeFlag;
 	CollisionGroup = collisionGroup;
 	ProcessedFlag = 0;
 }
diff --git a/SpaceCadetPinball/TEdgeSegment.h b/SpaceCadetPinball/TEdgeSegment.h
index 28e75aa..98f4da6 100644
--- a/SpaceCadetPinball/TEdgeSegment.h
+++ b/SpaceCadetPinball/TEdgeSegment.h
@@ -15,7 +15,7 @@ class TEdgeSegment
 {
 public:
 	TCollisionComponent* CollisionComponent;
-	char* ActiveFlag;
+	char* ActiveFlagPtr;
 	char ProcessedFlag;
 	void* WallValue{};
 	unsigned int CollisionGroup;
@@ -26,7 +26,7 @@ public:
 	virtual void EdgeCollision(TBall* ball, float distance) = 0;
 	virtual void port_draw();
 	virtual void place_in_grid(RectF* aabb) = 0;
-	virtual float FindCollisionDistance(ray_type* ray) = 0;
+	virtual float FindCollisionDistance(const ray_type& ray) = 0;
 
 	static TEdgeSegment* install_wall(float* floatArr, TCollisionComponent* collComp, char* activeFlagPtr,
 	                                  unsigned int collisionGroup, float offset, size_t wallValue);
diff --git a/SpaceCadetPinball/TFlipperEdge.cpp b/SpaceCadetPinball/TFlipperEdge.cpp
index 1f5c18c..810dc1a 100644
--- a/SpaceCadetPinball/TFlipperEdge.cpp
+++ b/SpaceCadetPinball/TFlipperEdge.cpp
@@ -104,12 +104,12 @@ void TFlipperEdge::port_draw()
 	set_control_points(CurrentAngle);
 }
 
-float TFlipperEdge::FindCollisionDistance(ray_type* ray)
+float TFlipperEdge::FindCollisionDistance(const ray_type& ray)
 {
 	ray_type dstRay{};
 	if (ControlPointDirtyFlag)
 		set_control_points(CurrentAngle);
-	auto distance = maths::distance_to_flipper(this, *ray, dstRay);
+	auto distance = maths::distance_to_flipper(this, ray, dstRay);
 	if (distance >= 1e9f)
 		return 1e9f;
 
diff --git a/SpaceCadetPinball/TFlipperEdge.h b/SpaceCadetPinball/TFlipperEdge.h
index 710f8d9..ab8124c 100644
--- a/SpaceCadetPinball/TFlipperEdge.h
+++ b/SpaceCadetPinball/TFlipperEdge.h
@@ -12,7 +12,7 @@ public:
 	             vector3* origin, vector3* vecT1, vector3* vecT2, float extendSpeed, float retractSpeed, float collMult,
 	             float elasticity, float smoothness);
 	void port_draw() override;
-	float FindCollisionDistance(ray_type* ray) override;
+	float FindCollisionDistance(const ray_type& ray) override;
 	void EdgeCollision(TBall* ball, float distance) override;
 	void place_in_grid(RectF* aabb) override;
 	void set_control_points(float angle);
diff --git a/SpaceCadetPinball/TLine.cpp b/SpaceCadetPinball/TLine.cpp
index 3d95fb3..f79ee70 100644
--- a/SpaceCadetPinball/TLine.cpp
+++ b/SpaceCadetPinball/TLine.cpp
@@ -36,9 +36,9 @@ void TLine::Offset(float offset)
 	maths::line_init(Line, X0, Y0, X1, Y1);
 }
 
-float TLine::FindCollisionDistance(ray_type* ray)
+float TLine::FindCollisionDistance(const ray_type& ray)
 {
-	return maths::ray_intersect_line(*ray, Line);
+	return maths::ray_intersect_line(ray, Line);
 }
 
 void TLine::EdgeCollision(TBall* ball, float distance)
diff --git a/SpaceCadetPinball/TLine.h b/SpaceCadetPinball/TLine.h
index 9a05508..dd6b911 100644
--- a/SpaceCadetPinball/TLine.h
+++ b/SpaceCadetPinball/TLine.h
@@ -11,7 +11,7 @@ public:
 	TLine(TCollisionComponent* collCmp, char* activeFlag, unsigned int collisionGroup, float x0, float y0, float x1, float y1);
 	TLine(TCollisionComponent* collCmp, char* activeFlag, unsigned int collisionGroup, const vector2& start, const vector2& end);
 	void Offset(float offset);
-	float FindCollisionDistance(ray_type* ray) override;
+	float FindCollisionDistance(const ray_type& ray) override;
 	void EdgeCollision(TBall* ball, float distance) override;
 	void place_in_grid(RectF* aabb) override;
 };
diff --git a/SpaceCadetPinball/TPinballTable.cpp b/SpaceCadetPinball/TPinballTable.cpp
index 28c73b4..58c1416 100644
--- a/SpaceCadetPinball/TPinballTable.cpp
+++ b/SpaceCadetPinball/TPinballTable.cpp
@@ -625,7 +625,7 @@ TBall* TPinballTable::AddBall(float x, float y)
 	{
 		if (BallList.size() >= 20)
 			return nullptr;
-		ball = new TBall(this);
+		ball = new TBall(this, -1);
 		BallList.push_back(ball);
 	}
 
@@ -655,6 +655,16 @@ int TPinballTable::BallCountInRect(const RectF& rect)
 	return count;
 }
 
+int TPinballTable::BallCountInRect(const vector2& pos, float margin)
+{
+	RectF rect{};
+	rect.XMin = pos.X - margin;
+	rect.XMax = pos.X + margin;
+	rect.YMin = pos.Y - margin;
+	rect.YMax = pos.Y + margin;
+	return BallCountInRect(rect);
+}
+
 void TPinballTable::EndGame_timeout(int timerId, void* caller)
 {
 	auto table = static_cast<TPinballTable*>(caller);
diff --git a/SpaceCadetPinball/TPinballTable.h b/SpaceCadetPinball/TPinballTable.h
index 190f334..22e76ef 100644
--- a/SpaceCadetPinball/TPinballTable.h
+++ b/SpaceCadetPinball/TPinballTable.h
@@ -37,6 +37,7 @@ public:
 	int Message(MessageCode code, float value) override;
 	TBall* AddBall(float x, float y);
 	int BallCountInRect(const RectF& rect);
+	int BallCountInRect(const vector2& pos, float margin);
 
 	static void EndGame_timeout(int timerId, void* caller);
 	static void LightShow_timeout(int timerId, void* caller);
diff --git a/SpaceCadetPinball/pb.cpp b/SpaceCadetPinball/pb.cpp
index 4da44b2..de33a59 100644
--- a/SpaceCadetPinball/pb.cpp
+++ b/SpaceCadetPinball/pb.cpp
@@ -33,7 +33,7 @@ DatFile* pb::record_table = nullptr;
 int pb::time_ticks = 0;
 GameModes pb::game_mode = GameModes::GameOver;
 float pb::time_now = 0, pb::time_next = 0, pb::time_ticks_remainder = 0;
-float pb::BallMaxSpeed, pb::BallHalfRadius, pb::ball_collision_dist;
+float pb::BallMaxSpeed, pb::BallHalfRadius, pb::BallToBallCollisionDistance;
 bool pb::FullTiltMode = false, pb::FullTiltDemoMode = false, pb::cheat_mode = false, pb::demo_mode = false;
 std::string pb::DatFileName, pb::BasePath;
 ImU32 pb::TextBoxColor;
@@ -106,7 +106,7 @@ int pb::init()
 	auto ball = MainTable->BallList.at(0);
 	BallMaxSpeed = ball->Radius * 200.0f;
 	BallHalfRadius = ball->Radius * 0.5f;
-	ball_collision_dist = (ball->Radius + BallHalfRadius) * 2.0f;
+	BallToBallCollisionDistance = (ball->Radius + BallHalfRadius) * 2.0f;
 
 	int red = 255, green = 255, blue = 255;
 	auto fontColor = get_rc_string(Msg::TextBoxColor);
@@ -424,8 +424,7 @@ void pb::timed_frame(float timeNow, float timeDelta, bool drawBalls)
 					auto distance = TTableLayer::edge_manager->FindCollisionDistance(&ray, ball, &edge);
 					if (distance > 0.0f)
 					{
-						// Todo: ball to ball collision
-						//distance = ball_to_ball_collision();
+						distance = BallToBallCollision(ray, *ball, &edge, distance);
 					}
 					if (ball->EdgeCollisionResetFlag)
 					{
@@ -605,9 +604,13 @@ void pb::InputDown(GameInput input)
 		switch (input.Value)
 		{
 		case 'b':
-			if (MainTable->AddBall(6.0f, 7.0f))
-				MainTable->MultiballCount++;
-			break;
+			{
+				vector2 pos{6.0f, 7.0f};
+				if (!MainTable->BallCountInRect(pos, MainTable->CollisionCompOffset * 1.2f) && MainTable->AddBall(
+					pos.X, pos.Y))
+					MainTable->MultiballCount++;
+				break;
+			}
 		case 'h':
 			{
 				high_score_struct entry{{0}, 1000000000};
@@ -754,3 +757,27 @@ void pb::ShowMessageBox(Uint32 flags, LPCSTR title, LPCSTR message)
 	fprintf(flags == SDL_MESSAGEBOX_ERROR ? stderr : stdout, "BL error: %s\n%s\n", title, message);
 	SDL_ShowSimpleMessageBox(flags, title, message, winmain::MainWindow);
 }
+
+float pb::BallToBallCollision(const ray_type& ray, const TBall& ball, TEdgeSegment** edge, float collisionDistance)
+{
+	for (auto curBall : MainTable->BallList)
+	{
+		if (curBall->ActiveFlagPtr && curBall != &ball && (curBall->CollisionMask & ball.CollisionMask) != 0 &&
+			std::abs(curBall->Position.X - ball.Position.X) < BallToBallCollisionDistance &&
+			std::abs(curBall->Position.Y - ball.Position.Y) < BallToBallCollisionDistance)
+		{
+			auto distance = curBall->FindCollisionDistance(ray);
+			if (distance < 1e9f)
+			{
+				distance = std::max(0.0f, distance - 0.002f);
+				if (collisionDistance > distance)
+				{
+					collisionDistance = distance;
+					*edge = curBall;
+				}
+			}
+		}
+	}
+
+	return collisionDistance;
+}
diff --git a/SpaceCadetPinball/pb.h b/SpaceCadetPinball/pb.h
index 3e79e56..2a5866c 100644
--- a/SpaceCadetPinball/pb.h
+++ b/SpaceCadetPinball/pb.h
@@ -1,6 +1,8 @@
 #pragma once
 #include "high_score.h"
 
+class TEdgeSegment;
+struct ray_type;
 struct GameInput;
 class TPinballTable;
 class DatFile;
@@ -43,7 +45,7 @@ class pb
 public:
 	static int time_ticks;
 	static float time_now, time_next, time_ticks_remainder;
-	static float BallMaxSpeed, BallHalfRadius, ball_collision_dist;
+	static float BallMaxSpeed, BallHalfRadius, BallToBallCollisionDistance;
 	static GameModes game_mode;
 	static bool cheat_mode;
 	static DatFile* record_table;
@@ -81,4 +83,5 @@ public:
 	static void ShowMessageBox(Uint32 flags, LPCSTR title, LPCSTR message);
 private:
 	static bool demo_mode;
+	static float BallToBallCollision(const ray_type& ray, const TBall& ball, TEdgeSegment** edge, float collisionDistance);
 };