RopeSimulator.h

#pragma once
 
#include <Foundation/Containers/DynamicArray.h>
#include <Foundation/Math/Vec3.h>
#include <Foundation/SimdMath/SimdFloat.h>
#include <Foundation/SimdMath/SimdVec4f.h>
#include <GameEngine/GameEngineDLL.h>
 
class PL_GAMEENGINE_DLL plRopeSimulator
{
public:
  struct Node
  {
    plSimdVec4f m_vPosition = plSimdVec4f::MakeZero();
    plSimdVec4f m_vPreviousPosition = plSimdVec4f::MakeZero();
 
    // could add per node acceleration
    // could add per node mass
  };
 
public:
  plRopeSimulator();
  ~plRopeSimulator();
 
  plVec3 m_vAcceleration = plVec3(0, 0, -10);
 
  plDynamicArray<Node, plAlignedAllocatorWrapper> m_Nodes;
 
  float m_fDampingFactor = 0.995f;
 
  float m_fSegmentLength = 0.1f;
 
  bool m_bFirstNodeIsFixed = true;
  bool m_bLastNodeIsFixed = true;
 
  void SimulateRope(const plTime& diff);
  void SimulateStep(const plSimdFloat fDiffSqr, plUInt32 uiMaxIterations, plSimdFloat fAllowedError);
  void SimulateTillEquilibrium(plSimdFloat fAllowedMovement = 0.005f, plUInt32 uiMaxIterations = 1000);
  bool HasEquilibrium(plSimdFloat fAllowedMovement) const;
  float GetTotalLength() const;
  plSimdVec4f GetPositionAtLength(float fLength) const;
 
private:
  plSimdFloat EnforceDistanceConstraint();
  void UpdateNodePositions(const plSimdFloat tDiffSqr);
  plSimdVec4f MoveTowards(const plSimdVec4f posThis, const plSimdVec4f posNext, plSimdFloat factor, const plSimdVec4f fallbackDir, plSimdFloat& inout_fError);
 
  plTime m_LeftOverTimeStep;
};