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add comments, correct typo, correct energy computation

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This commit is contained in:
Irlan 2018-04-03 15:02:00 -03:00
parent 676fe352a6
commit 6e0e269f68
1 changed files with 26 additions and 23 deletions
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49
include/bounce/dynamics/cloth/spring_cloth.h
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@ -50,7 +50,7 @@ struct b3SpringClothDef
// Cloth mesh // Cloth mesh
b3Mesh* mesh; b3Mesh* mesh;
// Cloth density in kg/m^2 // Cloth density in kg/m^3
float32 density; float32 density;
// Streching stiffness // Streching stiffness
@ -130,55 +130,59 @@ public:
b3SpringCloth(); b3SpringCloth();
~b3SpringCloth(); ~b3SpringCloth();
// // Initialize this cloth from a definition.
void Initialize(const b3SpringClothDef& def); void Initialize(const b3SpringClothDef& def);
// // Return the cloth mesh used to initialize this cloth.
b3Mesh* GetMesh() const; b3Mesh* GetMesh() const;
// // Set the gravitational force applied to this cloth.
// This force is applied at each time step.
void SetGravity(const b3Vec3& gravity); void SetGravity(const b3Vec3& gravity);
// // Return the gravitational force applied to this cloth.
const b3Vec3& GetGravity() const; const b3Vec3& GetGravity() const;
// // Set the type of a given point mass.
void SetType(u32 i, b3MassType type); void SetType(u32 i, b3MassType type);
// // Return the type of a given point mass.
b3MassType GetType(u32 i) const; b3MassType GetType(u32 i) const;
// Note, the position will be changed only after performing a time step. // Set the position of a given point mass.
// This function will have effect on the position of the point mass
// after performing a time step.
void SetPosition(u32 i, const b3Vec3& translation); void SetPosition(u32 i, const b3Vec3& translation);
// // Return the position of a given point mass.
const b3Vec3& GetPosition(u32 i) const; const b3Vec3& GetPosition(u32 i) const;
// // Apply a force to a given point mass.
void ApplyForce(u32 i, const b3Vec3& force); void ApplyForce(u32 i, const b3Vec3& force);
// // Return the kinetic (or dynamic) energy in this system.
float32 GetKineticEnergy() const; float32 GetEnergy() const;
// // Add a shape to the list of shapes in this cloth.
// The cloth will be able to respond to collisions with each shape in the list of shapes.
void AddShape(b3Shape* shape); void AddShape(b3Shape* shape);
// // Return the number of shapes added to this cloth.
u32 GetShapeCount() const; u32 GetShapeCount() const;
// // Return the list of shapes added to this cloth.
b3Shape** GetShapes(); b3Shape** GetShapes();
// // Return the statistics of the last time step.
const b3SpringClothStep& GetStep() const; const b3SpringClothStep& GetStep() const;
// // Perform a time step (marches time forward).
void Step(float32 dt); void Step(float32 dt);
// // Set the positions of the mesh vertices to the positions of their associated point masses.
void Apply() const; void Apply() const;
// // Debug draw the cloth mesh.
void Draw(b3Draw* draw) const; void Draw(b3Draw* draw) const;
protected: protected:
friend class b3SpringSolver; friend class b3SpringSolver;
@ -280,15 +284,14 @@ inline void b3SpringCloth::ApplyForce(u32 i, const b3Vec3& force)
m_f[i] += force; m_f[i] += force;
} }
inline float32 b3SpringCloth::GetKineticEnergy() const inline float32 b3SpringCloth::GetEnergy() const
{ {
float32 E = 0.0f; float32 E = 0.0f;
for (u32 i = 0; i < m_massCount; ++i) for (u32 i = 0; i < m_massCount; ++i)
{ {
b3Vec3 P = m_m[i] * m_v[i]; E += m_m[i] * b3Dot(m_v[i], m_v[i]);
E += b3Dot(P, m_v[i]);
} }
return E; return 0.5f * E;
} }
inline u32 b3SpringCloth::GetShapeCount() const inline u32 b3SpringCloth::GetShapeCount() const