source-engine/particles/builtin_particle_forces.cpp
FluorescentCIAAfricanAmerican 3bf9df6b27 1
2020-04-22 12:56:21 -04:00

545 lines
17 KiB
C++

//========= Copyright Valve Corporation, All rights reserved. ============//
//
// Purpose: particle system code
//
//===========================================================================//
#include "tier0/platform.h"
#include "particles/particles.h"
#include "filesystem.h"
#include "tier2/tier2.h"
#include "tier2/fileutils.h"
#include "tier1/UtlStringMap.h"
#include "tier1/strtools.h"
#ifdef USE_BLOBULATOR
// TODO: These should be in public by the time the SDK ships
#include "../common/blobulator/Physics/PhysParticle.h"
#include "../common/blobulator/Physics/PhysParticleCache_inl.h"
#include "../common/blobulator/Physics/PhysTiler.h"
#endif
// memdbgon must be the last include file in a .cpp file!!!
#include "tier0/memdbgon.h"
class C_OP_RandomForce : public CParticleOperatorInstance
{
DECLARE_PARTICLE_OPERATOR( C_OP_RandomForce );
uint32 GetWrittenAttributes( void ) const
{
return 0;
}
uint32 GetReadAttributes( void ) const
{
return 0;
}
virtual void AddForces( FourVectors *pAccumulatedForces,
CParticleCollection *pParticles,
int nBlocks,
float flStrength,
void *pContext ) const;
Vector m_MinForce;
Vector m_MaxForce;
};
void C_OP_RandomForce::AddForces( FourVectors *pAccumulatedForces,
CParticleCollection *pParticles,
int nBlocks,
float flStrength,
void *pContext ) const
{
FourVectors box_min,box_max;
box_min.DuplicateVector( m_MinForce * flStrength );
box_max.DuplicateVector( m_MaxForce * flStrength);
box_max -= box_min;
int nContext = GetSIMDRandContext();
for(int i=0;i<nBlocks;i++)
{
pAccumulatedForces->x = AddSIMD(
pAccumulatedForces->x, AddSIMD( box_min.x, MulSIMD( box_max.x, RandSIMD( nContext) ) ) );
pAccumulatedForces->y = AddSIMD(
pAccumulatedForces->y, AddSIMD( box_min.y, MulSIMD( box_max.y, RandSIMD( nContext) ) ) );
pAccumulatedForces->z = AddSIMD(
pAccumulatedForces->z, AddSIMD( box_min.z, MulSIMD( box_max.z, RandSIMD( nContext) ) ) );
pAccumulatedForces++;
}
ReleaseSIMDRandContext( nContext );
}
DEFINE_PARTICLE_OPERATOR( C_OP_RandomForce, "random force", OPERATOR_GENERIC );
BEGIN_PARTICLE_OPERATOR_UNPACK( C_OP_RandomForce )
DMXELEMENT_UNPACK_FIELD( "min force", "0 0 0", Vector, m_MinForce )
DMXELEMENT_UNPACK_FIELD( "max force", "0 0 0", Vector, m_MaxForce )
END_PARTICLE_OPERATOR_UNPACK( C_OP_RandomForce )
class C_OP_TwistAroundAxis : public CParticleOperatorInstance
{
DECLARE_PARTICLE_OPERATOR( C_OP_TwistAroundAxis );
uint32 GetWrittenAttributes( void ) const
{
return 0;
}
uint32 GetReadAttributes( void ) const
{
return PARTICLE_ATTRIBUTE_XYZ_MASK;
}
virtual void AddForces( FourVectors *pAccumulatedForces,
CParticleCollection *pParticles,
int nBlocks,
float flStrength,
void *pContext ) const;
float m_fForceAmount;
Vector m_TwistAxis;
bool m_bLocalSpace;
};
void C_OP_TwistAroundAxis::AddForces( FourVectors *pAccumulatedForces,
CParticleCollection *pParticles,
int nBlocks,
float flStrength,
void *pContext ) const
{
FourVectors Twist_AxisInWorldSpace;
Twist_AxisInWorldSpace.DuplicateVector( pParticles->TransformAxis( m_TwistAxis, m_bLocalSpace ) );
Twist_AxisInWorldSpace.VectorNormalize();
Vector vecCenter;
pParticles->GetControlPointAtTime( 0, pParticles->m_flCurTime, &vecCenter );
FourVectors Center;
Center.DuplicateVector( vecCenter );
size_t nPosStride;
fltx4 ForceScale = ReplicateX4( m_fForceAmount * flStrength );
const FourVectors *pPos=pParticles->Get4VAttributePtr( PARTICLE_ATTRIBUTE_XYZ, &nPosStride );
for(int i=0;i<nBlocks;i++)
{
FourVectors ofs=*pPos;
ofs -= Center;
fltx4 bGoodLen = CmpGtSIMD( ofs*ofs, Four_Epsilons );
ofs.VectorNormalize();
FourVectors parallel_comp=ofs;
parallel_comp *= ( ofs*Twist_AxisInWorldSpace );
ofs-=parallel_comp;
bGoodLen = AndSIMD( bGoodLen, CmpGtSIMD( ofs*ofs, Four_Epsilons ) );
ofs.VectorNormalize();
FourVectors TangentialForce = ofs ^ Twist_AxisInWorldSpace;
TangentialForce *= ForceScale;
TangentialForce.x = AndSIMD( TangentialForce.x, bGoodLen );
TangentialForce.y = AndSIMD( TangentialForce.y, bGoodLen );
TangentialForce.z = AndSIMD( TangentialForce.z, bGoodLen );
*(pAccumulatedForces++) += TangentialForce;
pPos += nPosStride;
}
}
DEFINE_PARTICLE_OPERATOR( C_OP_TwistAroundAxis, "twist around axis", OPERATOR_GENERIC );
BEGIN_PARTICLE_OPERATOR_UNPACK( C_OP_TwistAroundAxis )
DMXELEMENT_UNPACK_FIELD( "amount of force", "0", float, m_fForceAmount )
DMXELEMENT_UNPACK_FIELD( "twist axis", "0 0 1", Vector, m_TwistAxis )
DMXELEMENT_UNPACK_FIELD( "object local space axis 0/1","0", bool, m_bLocalSpace )
END_PARTICLE_OPERATOR_UNPACK( C_OP_TwistAroundAxis )
class C_OP_AttractToControlPoint : public CParticleOperatorInstance
{
DECLARE_PARTICLE_OPERATOR( C_OP_AttractToControlPoint );
uint32 GetWrittenAttributes( void ) const
{
return 0;
}
uint32 GetReadAttributes( void ) const
{
return 0;
}
virtual uint64 GetReadControlPointMask() const
{
return 1ULL << m_nControlPointNumber;
}
virtual void AddForces( FourVectors *pAccumulatedForces,
CParticleCollection *pParticles,
int nBlocks,
float flStrength,
void *pContext ) const;
float m_fForceAmount;
float m_fFalloffPower;
int m_nControlPointNumber;
};
void C_OP_AttractToControlPoint::AddForces( FourVectors *pAccumulatedForces,
CParticleCollection *pParticles,
int nBlocks,
float flStrength,
void *pContext ) const
{
int power_frac=-4.0*m_fFalloffPower; // convert to what pow_fixedpoint_exponent_simd wants
fltx4 fForceScale=ReplicateX4( -m_fForceAmount * flStrength );
Vector vecCenter;
pParticles->GetControlPointAtTime( m_nControlPointNumber, pParticles->m_flCurTime, &vecCenter );
FourVectors Center;
Center.DuplicateVector( vecCenter );
size_t nPosStride;
const FourVectors *pPos=pParticles->Get4VAttributePtr( PARTICLE_ATTRIBUTE_XYZ, &nPosStride );
for(int i=0;i<nBlocks;i++)
{
FourVectors ofs=*pPos;
ofs -= Center;
fltx4 len = ofs.length();
ofs *= MulSIMD( fForceScale, ReciprocalSaturateSIMD( len )); // normalize and scale
ofs *= Pow_FixedPoint_Exponent_SIMD( len, power_frac ); // * 1/pow(dist, exponent)
fltx4 bGood = CmpGtSIMD( len, Four_Epsilons );
ofs.x = AndSIMD( bGood, ofs.x );
ofs.y = AndSIMD( bGood, ofs.y );
ofs.z = AndSIMD( bGood, ofs.z );
*(pAccumulatedForces++) += ofs;
pPos += nPosStride;
}
}
DEFINE_PARTICLE_OPERATOR( C_OP_AttractToControlPoint, "Pull towards control point", OPERATOR_GENERIC );
BEGIN_PARTICLE_OPERATOR_UNPACK( C_OP_AttractToControlPoint )
DMXELEMENT_UNPACK_FIELD( "amount of force", "0", float, m_fForceAmount )
DMXELEMENT_UNPACK_FIELD( "falloff power", "2", float, m_fFalloffPower )
DMXELEMENT_UNPACK_FIELD( "control point number", "0", int, m_nControlPointNumber )
END_PARTICLE_OPERATOR_UNPACK( C_OP_AttractToControlPoint )
#undef USE_BLOBULATOR // TODO (Ilya): Must fix this code
#ifdef USE_BLOBULATOR
class C_OP_LennardJonesForce : public CParticleOperatorInstance
{
DECLARE_PARTICLE_OPERATOR( C_OP_LennardJonesForce );
uint32 GetWrittenAttributes( void ) const
{
return 0;
}
uint32 GetReadAttributes( void ) const
{
return 0;
}
void InitParams( CParticleSystemDefinition *pDef, CDmxElement *pElement )
{
//m_pParticleCache = new ParticleCache(m_fInteractionRadius);
m_pPhysTiler = new PhysTiler(m_fInteractionRadius);
}
virtual void AddForces( FourVectors *pAccumulatedForces,
CParticleCollection *pParticles,
int nBlocks,
float flStrength,
void *pContext ) const;
// TODO: Have to destroy PhysTiler in destructor somewhere!!!!
//ParticleCache* m_pParticleCache;
PhysTiler* m_pPhysTiler;
float m_fInteractionRadius;
float m_fSurfaceTension;
float m_fLennardJonesRepulsion;
float m_fLennardJonesAttraction;
float m_fMaxRepulsion;
float m_fMaxAttraction;
private:
//virtual void addParticleForce(PhysParticle* a, PhysParticleCacheNode* bcn, float flStrength, float ts) const;
virtual void addParticleForce(PhysParticle* a, PhysParticle* b, float distSq, float flStrength, float ts) const;
};
// TODO: I should make sure I don't have divide by zero errors.
// TODO: ts is not used
void C_OP_LennardJonesForce::addParticleForce(PhysParticle* a, PhysParticle* b, float distSq, float flStrength, float ts) const
{
float d = sqrtf(distSq);
//========================================================
// based on equation of force between two molecules which is
// factor * ((distance/bond_length)^-7 - (distance/bond_length)^-13)
float f;
if(a->group == b->group) // In the same group
{
float p = a->radius * 2.0f / (d+FLT_EPSILON);
float p2 = p * p;
float p4 = p2 * p2;
// Surface tension:
//Notes:
// Can average the neighbor count between the two particles...
// I tried this, and discovered that rather than averaging, I can take maybe take the
// larger of the two neighbor counts, so the attraction between two particles on the surface will be strong, but
// the attraction between a particle inside and a particle on the surface will be weak. I can also try
// taking the min so that the attraction between a particle on the surface and a particle inside the fluid will
// be strong, but the attraction between two particles completely on the inside will be weak.
//
// int symmetric_neighbor_count = min(a->neighbor_count, b->neighbor_count);
//
// Can try having neighbors only cause stronger attraction (no repulsion)
// Can try lower exponents for the LennardJones forces.
// This is a trick to prevent single particles from floating off... the less neighbors a particle has.. the more it sticks
// This also tends to simulate surface tension
float surface_tension_modifier = ((24.0f * m_fSurfaceTension) / (a->neighbor_count + b->neighbor_count + 0.1f)) + 1.0f;
//float lennard_jones_force = fLennardJones * 2.0f * (p2 - (p4 * p4));
float lennard_jones_force = m_fLennardJonesAttraction * p2 - m_fLennardJonesRepulsion*p4;
f = surface_tension_modifier * lennard_jones_force;
// This is some older code:
//f = ((35.0f * LampScene::simulationSurfaceTension) / (a->neighbor_count + 0.1f)) * (p2 - (p4 * p4));
// used to be 68'
//float factor = (b->neighbor_count < 13 && neighbor_count < 13 ? 4.0f : 0.5f);
//f = factor * (p2 - (p2 * p2 * p2 * p2));
}
else
{
// This was 3.5 ... made 3.0 so particles get closer when they collide
if(d > a->radius * 3.0f) return;
float p = a->radius * 4.0f / d;
f = -1.0f * p * p;
}
// These checks are great to have, but are they really necessary?
// It might also be good to have a limit on velocity
// Attraction is a positive value.
// Repulsion is negative.
if(f < -m_fMaxRepulsion) f = -m_fMaxRepulsion;
if(f > m_fMaxAttraction) f = m_fMaxAttraction;
Point3D scaledr = (b->center - a->center) * (f/(d+FLT_EPSILON)); // Dividing by d scales distance down to a unit vector
a->force.add(scaledr);
b->force.subtract(scaledr);
}
void C_OP_LennardJonesForce::AddForces( FourVectors *pAccumulatedForces,
CParticleCollection *pParticles,
int nBlocks,
float flStrength,
void *pContext ) const
{
int nParticles = pParticles->m_nActiveParticles; // Not sure if this is correct!
size_t nPosStride;
const FourVectors *pPos=pParticles->Get4VAttributePtr( PARTICLE_ATTRIBUTE_XYZ, &nPosStride );
// The +4 is because particles are stored by PET in blocks of 4
// However, not every block is full. Thus, nParticles may be
// less than nBlocks*4. Could get rid of this if the swizzling/unswizzling
// loop were better written.
static SmartArray<PhysParticle> imp_particles_sa; // This doesn't specify alignment, might have problems with SSE
while(imp_particles_sa.size < nParticles+4)
{
imp_particles_sa.pushAutoSize(PhysParticle());
}
/*
size_t nPrevPosStride;
const FourVectors *pPrevPos=pParticles->Get4VAttributePtr( PARTICLE_ATTRIBUTE_PREV_XYZ, &nPrevPosStride );
*/
//m_pParticleCache->beginFrame();
//m_pParticleCache->beginTile(nParticles);
m_pPhysTiler->beginFrame(Point3D(0.0f, 0.0f, 0.0f));
// Unswizzle from the FourVectors format into particles
for(int i=0, p=0;i<nBlocks;i++)
{
FourVectors ofs=*pPos;
PhysParticle* particle = &(imp_particles_sa[p]);
particle->force.clear();
if(p < nParticles)
{
particle->center = ofs.Vec(0);
particle->group = 0;
particle->neighbor_count = 0;
m_pPhysTiler->insertParticle(particle);
}
p++;
particle = &(imp_particles_sa[p]);
particle->force.clear();
if(p < nParticles)
{
particle->center = ofs.Vec(1);
particle->group = 0;
particle->neighbor_count = 0;
m_pPhysTiler->insertParticle(particle);
}
p++;
particle = &(imp_particles_sa[p]);
particle->force.clear();
if(p < nParticles)
{
particle->center = ofs.Vec(2);
particle->group = 0;
particle->neighbor_count = 0;
m_pPhysTiler->insertParticle(particle);
}
p++;
particle = &(imp_particles_sa[p]);
particle->force.clear();
if(p < nParticles)
{
particle->center = ofs.Vec(3);
particle->group = 0;
particle->neighbor_count = 0;
m_pPhysTiler->insertParticle(particle);
}
p++;
pPos += nPosStride;
}
m_pPhysTiler->processTiles();
float timeStep = 1.0f; // This should be customizable
float nearNeighborInteractionRadius = 2.3f;
float nearNeighborInteractionRadiusSq = nearNeighborInteractionRadius * nearNeighborInteractionRadius;
PhysParticleCache* pCache = m_pPhysTiler->getParticleCache();
// Calculate number of near neighbors for each particle
for(int i = 0; i < nParticles; i++)
{
PhysParticle *b1 = &(imp_particles_sa[i]);
PhysParticleAndDist* node = pCache->get(b1);
while(node->particle != NULL)
{
PhysParticle* b2 = node->particle;
// Compare addresses of the two particles. This makes sure we apply a force only once between a pair of particles.
if(b1 < b2 && node->distSq < nearNeighborInteractionRadiusSq)
{
b1->neighbor_count++;
b2->neighbor_count++;
}
node++;
}
}
// Calculate forces on particles due to other particles
for(int i = 0; i < nParticles; i++)
{
PhysParticle *b1 = &(imp_particles_sa[i]);
PhysParticleAndDist* node = pCache->get(b1);
while(node->particle != NULL)
{
PhysParticle* b2 = node->particle;
// Compare addresses of the two particles. This makes sure we apply a force only once between a pair of particles.
if(b1 < b2)
{
addParticleForce(b1, b2, node->distSq, flStrength, timeStep);
}
node++;
}
}
/*
for(ParticleListNode* bit3 = particles; bit3; bit3 = bit3->next)
{
Particle* b = bit3->particle;
b->prev_group = b->group; // Set prev group
//b1->addDirDragForce();
b->move(ts); // Move the particle (it should never be used again until next iteration)
}
*/
m_pPhysTiler->endFrame();
// Swizzle forces back into FourVectors format
for(int i=0;i<nBlocks;i++)
{
pAccumulatedForces->X(0) += imp_particles_sa[i*4].force[0];
pAccumulatedForces->Y(0) += imp_particles_sa[i*4].force[1];
pAccumulatedForces->Z(0) += imp_particles_sa[i*4].force[2];
pAccumulatedForces->X(1) += imp_particles_sa[i*4+1].force[0];
pAccumulatedForces->Y(1) += imp_particles_sa[i*4+1].force[1];
pAccumulatedForces->Z(1) += imp_particles_sa[i*4+1].force[2];
pAccumulatedForces->X(2) += imp_particles_sa[i*4+2].force[0];
pAccumulatedForces->Y(2) += imp_particles_sa[i*4+2].force[1];
pAccumulatedForces->Z(2) += imp_particles_sa[i*4+2].force[2];
pAccumulatedForces->X(3) += imp_particles_sa[i*4+3].force[0];
pAccumulatedForces->Y(3) += imp_particles_sa[i*4+3].force[1];
pAccumulatedForces->Z(3) += imp_particles_sa[i*4+3].force[2];
pAccumulatedForces++;
}
}
DEFINE_PARTICLE_OPERATOR( C_OP_LennardJonesForce, "lennard jones force", OPERATOR_GENERIC );
BEGIN_PARTICLE_OPERATOR_UNPACK( C_OP_LennardJonesForce )
DMXELEMENT_UNPACK_FIELD( "interaction radius", "4", float, m_fInteractionRadius )
DMXELEMENT_UNPACK_FIELD( "surface tension", "1", float, m_fSurfaceTension )
DMXELEMENT_UNPACK_FIELD( "lennard jones attractive force", "1", float, m_fLennardJonesAttraction )
DMXELEMENT_UNPACK_FIELD( "lennard jones repulsive force", "1", float, m_fLennardJonesRepulsion )
DMXELEMENT_UNPACK_FIELD( "max repulsion", "100", float, m_fMaxRepulsion )
DMXELEMENT_UNPACK_FIELD( "max attraction", "100", float, m_fMaxAttraction )
END_PARTICLE_OPERATOR_UNPACK( C_OP_LennardJonesForce )
#endif
void AddBuiltInParticleForceGenerators( void )
{
REGISTER_PARTICLE_OPERATOR( FUNCTION_FORCEGENERATOR, C_OP_RandomForce );
REGISTER_PARTICLE_OPERATOR( FUNCTION_FORCEGENERATOR, C_OP_TwistAroundAxis );
REGISTER_PARTICLE_OPERATOR( FUNCTION_FORCEGENERATOR, C_OP_AttractToControlPoint );
#ifdef USE_BLOBULATOR
REGISTER_PARTICLE_OPERATOR( FUNCTION_FORCEGENERATOR, C_OP_LennardJonesForce );
#endif
}