Support cloth self friction, thickness. Small refactor

include/bounce/cloth/cloth.h

@@ -29,6 +29,8 @@ class b3World;
 class b3Shape;
 
 class b3Particle;
+class b3ClothTriangle;
+
 class b3Force;
 struct b3ParticleBodyContact;
 
@@ -62,6 +64,8 @@ struct b3ClothDef
 		structural = 0.0f;
 		bending = 0.0f;
 		damping = 0.0f;
+		thickness = 0.0f;
+		friction = 0.2f;
 	}
 
 	// Cloth mesh 
@@ -78,6 +82,12 @@ struct b3ClothDef
 
 	// Damping stiffness
 	float32 damping;
+
+	// Cloth thickness
+	float32 thickness;
+
+	// Cloth coefficient of friction
+	float32 friction;
 };
 
 // A cloth represents a deformable surface as a collection of particles.
@@ -126,6 +136,9 @@ public:
 	// Return the particle associated with the given vertex.
 	b3Particle* GetVertexParticle(u32 i);
 
+	// Return the cloth triangle given the triangle index.
+	b3ClothTriangle* GetTriangle(u32 i);
+
 	// Return the list of particles in this cloth.
 	const b3List2<b3Particle>& GetParticleList() const;
 
@@ -142,6 +155,7 @@ public:
 	void Draw() const;
 private:
 	friend class b3Particle;
+	friend class b3ClothTriangle;
 	friend class b3ClothContactManager;
 
 	// Compute mass of each particle.
@@ -153,12 +167,6 @@ private:
 	// Solve
 	void Solve(float32 dt, const b3Vec3& gravity, u32 velocityIterations, u32 positionIterations);
 
-	// Synchronize triangle AABB.
-	void SynchronizeTriangle(u32 triangleIndex);
-
-	// Time-step
-	float32 m_dt;
-
 	// Stack allocator
 	b3StackAllocator m_stackAllocator;
 
@@ -174,8 +182,8 @@ private:
 	// Vertex particles
 	b3Particle** m_vertexParticles;
 
-	// Triangle proxies
-	b3ClothAABBProxy* m_triangleProxies;
+	// Triangles
+	b3ClothTriangle* m_triangles;
 
 	// Cloth density
 	float32 m_density;

include/bounce/cloth/cloth_contact.h

@@ -22,8 +22,7 @@
 #include <bounce/common/template/list.h>
 
 class b3Particle;
-struct b3ClothMeshTriangle;
-struct b3ClothAABBProxy;
+class b3ClothTriangle;
 
 // Contact between particle and a triangle
 class b3ParticleTriangleContact
@@ -32,6 +31,7 @@ public:
 private:
 	friend class b3Cloth;
 	friend class b3Particle;
+	friend class b3ClothTriangle;
 	friend class b3ClothContactManager;
 	friend class b3List2<b3ParticleTriangleContact>;
 	friend class b3ClothContactSolver;
@@ -45,16 +45,17 @@ private:
 	b3Particle* m_p1;
 
 	// Triangle
-	b3ClothMeshTriangle* m_triangle;
-	b3ClothAABBProxy* m_triangleProxy;
+	b3ClothTriangle* m_t2;
 	b3Particle* m_p2;
 	b3Particle* m_p3;
 	b3Particle* m_p4;
 
-	float32 m_normalImpulse;
-
 	float32 m_w2, m_w3, m_w4;
 
+	float32 m_normalImpulse;
+	float32 m_tangentImpulse1;
+	float32 m_tangentImpulse2;
+
 	bool m_active;
 
 	b3ParticleTriangleContact* m_prev;

include/bounce/cloth/cloth_contact_solver.h

@@ -96,9 +96,17 @@ struct b3ClothSolverTriangleContactVelocityConstraint
 	float32 wB, wC, wD;
 
 	b3Vec3 normal;
-
 	float32 normalMass;
 	float32 normalImpulse;
+
+	float32 friction;
+
+	b3Vec3 tangent1;
+	b3Vec3 tangent2;
+	float32 tangentMass1;
+	float32 tangentMass2;
+	float32 tangentImpulse1;
+	float32 tangentImpulse2;
 };
 
 struct b3ClothSolverTriangleContactPositionConstraint

include/bounce/cloth/cloth_triangle.h

@@ -0,0 +1,98 @@
+/*
+* Copyright (c) 2016-2019 Irlan Robson https://irlanrobson.github.io
+*
+* This software is provided 'as-is', without any express or implied
+* warranty.  In no event will the authors be held liable for any damages
+* arising from the use of this software.
+* Permission is granted to anyone to use this software for any purpose,
+* including commercial applications, and to alter it and redistribute it
+* freely, subject to the following restrictions:
+* 1. The origin of this software must not be misrepresented; you must not
+* claim that you wrote the original software. If you use this software
+* in a product, an acknowledgment in the product documentation would be
+* appreciated but is not required.
+* 2. Altered source versions must be plainly marked as such, and must not be
+* misrepresented as being the original software.
+* 3. This notice may not be removed or altered from any source distribution.
+*/
+
+#ifndef B3_CLOTH_TRIANGLE_H
+#define B3_CLOTH_TRIANGLE_H
+
+#include <bounce/cloth/particle.h>
+
+// A cloth triangle
+class b3ClothTriangle
+{
+public:
+	// Return the triangle index.
+	u32 GetTriangle() const;
+
+	// Set the triangle radius.
+	void SetRadius(float32 radius);
+
+	// Return the triangle radius.
+	float32 GetRadius() const;
+
+	// Set the triangle coefficient of friction.
+	void SetFriction(float32 friction);
+
+	// Return the triangle coefficient of friction.
+	float32 GetFriction() const;
+private:
+	friend class b3Cloth;
+	friend class b3Particle;
+	friend class b3ClothContactManager;
+	friend class b3ParticleTriangleContact;
+	friend class b3ClothSolver;
+	friend class b3ClothContactSolver;
+
+	b3ClothTriangle() { }
+	~b3ClothTriangle() { }
+
+	// Synchronize AABB
+	void Synchronize(const b3Vec3& displacement);
+
+	// Cloth
+	b3Cloth* m_cloth;
+
+	// Triangle index
+	u32 m_triangle;
+
+	// Radius
+	float32 m_radius;
+
+	// Coefficient of friction
+	float32 m_friction;
+
+	// AABB Proxy
+	b3ClothAABBProxy m_aabbProxy;
+};
+
+inline u32 b3ClothTriangle::GetTriangle() const
+{
+	return m_triangle;
+}
+
+inline void b3ClothTriangle::SetRadius(float32 radius) 
+{
+	m_radius = radius;
+	Synchronize(b3Vec3_zero);
+}
+
+inline float32 b3ClothTriangle::GetRadius() const
+{
+	return m_radius;
+}
+
+inline void b3ClothTriangle::SetFriction(float32 friction)
+{
+	m_friction = friction;
+}
+
+inline float32 b3ClothTriangle::GetFriction() const
+{
+	return m_friction;
+}
+
+#endif

include/bounce/cloth/particle.h

@@ -103,7 +103,6 @@ struct b3ClothAABBProxy
 {
 	b3ClothAABBProxyType type;
 	void* data;
-	u32 index;
 	u32 broadPhaseId;
 };
 
@@ -160,6 +159,7 @@ public:
 private:
 	friend class b3List2<b3Particle>;
 	friend class b3Cloth;
+	friend class b3ClothTriangle;
 	friend class b3ClothSolver;
 	friend class b3ClothContactManager;
 	friend class b3ParticleTriangleContact;
@@ -171,7 +171,7 @@ private:
 	~b3Particle();
 
 	// Synchronize particle AABB
-	void Synchronize();
+	void Synchronize(const b3Vec3& displacement);
 
 	// Synchronize triangles AABB
 	void SynchronizeTriangles();
@@ -246,10 +246,12 @@ inline u32 b3Particle::GetVertex() const
 
 inline void b3Particle::SetPosition(const b3Vec3& position)
 {
+	b3Vec3 displacement = position - m_position;
+
 	m_position = position;
 	m_translation.SetZero();
 
-	Synchronize();
+	Synchronize(displacement);
 	SynchronizeTriangles();
 }
 
@@ -281,7 +283,7 @@ inline void b3Particle::SetRadius(float32 radius)
 {
 	m_radius = radius;
 	
-	Synchronize();
+	Synchronize(b3Vec3_zero);
 }
 
 inline float32 b3Particle::GetRadius() const