From 7075e6add62c905296ce6347b29d60007c308e66 Mon Sep 17 00:00:00 2001
From: Robin Engman <robinengman@hotmail.com>
Date: Tue, 11 Feb 2014 13:36:14 +0100
Subject: [PATCH] Gravity well

---
 .../Implementation/PhysicsAPI_Impl.cpp         | 18 ++++++++++++++++++
 .../Implementation/PhysicsAPI_Impl.h           |  6 ++++++
 Code/GamePhysics/PhysicsAPI.h                  |  2 ++
 3 files changed, 26 insertions(+)

diff --git a/Code/GamePhysics/Implementation/PhysicsAPI_Impl.cpp b/Code/GamePhysics/Implementation/PhysicsAPI_Impl.cpp
index e68c860f..43e86a30 100644
--- a/Code/GamePhysics/Implementation/PhysicsAPI_Impl.cpp
+++ b/Code/GamePhysics/Implementation/PhysicsAPI_Impl.cpp
@@ -26,6 +26,9 @@ API_Impl::API_Impl()
 	this->dynamicsWorld = NULL;
 
 	this->timeStep = 1.0f/120.0f;
+
+	this->gravityPoint = Float3(0.0f, 0.0f, 0.0f);
+	this->gravity = 10.0f;
 }
 
 API_Impl::~API_Impl() 
@@ -48,6 +51,16 @@ API_Impl::~API_Impl()
 	}
 }
 
+void API_Impl::SetGravityPoint(::Oyster::Math::Float3 gravityPoint)
+{
+	this->gravityPoint = gravityPoint;
+}
+
+void API_Impl::SetGravity(float gravity)
+{
+	this->gravity = gravity;
+}
+
 // Bullet physics
 ICustomBody* API_Impl::AddCollisionSphere(float radius, ::Oyster::Math::Float4 rotation, ::Oyster::Math::Float3 position, float mass, float restitution, float staticFriction, float dynamicFriction)
 {
@@ -173,6 +186,11 @@ void API_Impl::SetTimeStep(float timeStep)
 
 void API_Impl::UpdateWorld()
 {
+	for(unsigned int i = 0; i < this->customBodies.size(); i++ )
+	{
+		this->customBodies[i]->SetGravity(-(this->customBodies[i]->GetState().centerPos - this->gravityPoint).GetNormalized()*this->gravity);	
+	}
+
 	this->dynamicsWorld->stepSimulation(this->timeStep, 1, this->timeStep);
 
 	ICustomBody::State state;
diff --git a/Code/GamePhysics/Implementation/PhysicsAPI_Impl.h b/Code/GamePhysics/Implementation/PhysicsAPI_Impl.h
index 2d4c55ed..3cef6373 100644
--- a/Code/GamePhysics/Implementation/PhysicsAPI_Impl.h
+++ b/Code/GamePhysics/Implementation/PhysicsAPI_Impl.h
@@ -21,6 +21,9 @@ namespace Oyster
 			void MoveToLimbo( const ICustomBody* objRef );
 			void ReleaseFromLimbo( const ICustomBody* objRef );
 
+			void SetGravityPoint(::Oyster::Math::Float3 gravityPoint);
+			void SetGravity(float gravity);
+
 			// Bullet physics
 			ICustomBody* AddCollisionSphere(float radius, ::Oyster::Math::Float4 rotation, ::Oyster::Math::Float3 position, float mass, float restitution, float staticFriction, float dynamicFriction);
 			ICustomBody* AddCollisionBox(::Oyster::Math::Float3 halfSize, ::Oyster::Math::Float4 rotation, ::Oyster::Math::Float3 position, float mass, float restitution, float staticFriction, float dynamicFriction);
@@ -41,6 +44,9 @@ namespace Oyster
 			std::vector<ICustomBody*> customBodies;
 
 			float timeStep;
+
+			::Oyster::Math::Float3 gravityPoint;
+			float gravity;
 		};
 
 		namespace Default
diff --git a/Code/GamePhysics/PhysicsAPI.h b/Code/GamePhysics/PhysicsAPI.h
index d44cb2db..ff2ba374 100644
--- a/Code/GamePhysics/PhysicsAPI.h
+++ b/Code/GamePhysics/PhysicsAPI.h
@@ -78,6 +78,8 @@ namespace Oyster
 			 ********************************************************/
 			virtual void ReleaseFromLimbo( const ICustomBody* objRef ) = 0;
 
+			virtual void SetGravityPoint(::Oyster::Math::Float3 gravityPoint) = 0; 
+			virtual void SetGravity(float gravity) = 0; 
 
 			// Bullet physics
 			virtual ICustomBody* AddCollisionSphere(float radius, ::Oyster::Math::Float4 rotation, ::Oyster::Math::Float3 position, float mass, float restitution, float staticFriction, float dynamicFriction) = 0;