问题描述
但我仍然无法获得有效的模拟。是否有任何我不知道的调试选项？
我从 https://github.com/NVIDIAGameWorks/FleX 获得了 Flex
这是我的代码：
#pragma once
#include "FlexPhysics.h"
#include "NvFlex.h"
#include "NvFlexExt.h"
#include <iostream>
NvFlexBuffer* particleBuffer;
NvFlexBuffer* veLocityBuffer;
NvFlexBuffer* phaseBuffer;
struct Vec4struct {
float x,y,z,w;
};
void MyErrorCallback(NvFlexErrorSeverity severity,const char* msg,const char* file,int line)
{
std::cout << "Flex: %s - %s:%d\n" << msg << file << line << std::endl;
}
int n = 10000;
int main() {
NvFlexLibrary* library = NvFlexInit(120,MyErrorCallback);
// create new solver
NvFlexSolverDesc solverDesc;
NvFlexSetSolverDescDefaults(&solverDesc);
solverDesc.maxParticles = n;
solverDesc.maxDiffuseParticles = 0;
NvFlexSolver* solver = NvFlexCreateSolver(library,&solverDesc);
particleBuffer = NvFlexAllocBuffer(library,n,sizeof(Vec4struct),eNvFlexBufferHost);
veLocityBuffer = NvFlexAllocBuffer(library,eNvFlexBufferHost);
phaseBuffer = NvFlexAllocBuffer(library,sizeof(int),eNvFlexBufferHost);
//set params
NvFlexParams p;
p.gravity[0] = -10.0f;
p.radius = 0.01f;
p.drag = 0.1f;
p.damping = 0.0f;
NvFlexSetParams(solver,&p);
//spawn particles
int particle_count = 6;
float particle_mass = 100;
//map buffers
Vec4struct* particles = (Vec4struct*)NvFlexMap(particleBuffer,eNvFlexMapWait);
Vec4struct* veLocities = (Vec4struct*)NvFlexMap(veLocityBuffer,eNvFlexMapWait);
int* phases = (int*)NvFlexMap(phaseBuffer,eNvFlexMapWait);
for (int i = 0; i < particle_count; ++i)
{
particles[i] = { i * 5.0f,1.0f / particle_mass };
veLocities[i] = { 0.0f,0.0f,0.0f};
phases[i] = NvFlexMakePhase(0,1);
}
//unmap buffers
NvFlexUnmap(particleBuffer);
NvFlexUnmap(veLocityBuffer);
NvFlexUnmap(phaseBuffer);
NvFlexSetParticles(solver,particleBuffer,NULL);
NvFlexSetVeLocities(solver,veLocityBuffer,NULL);
NvFlexSetPhases(solver,phaseBuffer,NULL);
float delta_time = 1 / 60.0f;
while (true)
{
//map buffers
Vec4struct* particles = (Vec4struct*)NvFlexMap(particleBuffer,eNvFlexMapWait);
Vec4struct* veLocities = (Vec4struct*)NvFlexMap(veLocityBuffer,eNvFlexMapWait);
int* phases = (int*)NvFlexMap(phaseBuffer,eNvFlexMapWait);
//"draw" particles
std::cout << "x:" << particles[0].x << " y:" << particles[0].y << " z:" << particles[0].z << std::endl;
//unmap buffers
NvFlexUnmap(particleBuffer);
NvFlexUnmap(veLocityBuffer);
NvFlexUnmap(phaseBuffer);
// set active count
NvFlexSetActiveCount(solver,particle_count);
// tick
NvFlexUpdateSolver(solver,delta_time,1,false);
// read back (async)
NvFlexGetParticles(solver,NULL);
NvFlexGetVeLocities(solver,NULL);
NvFlexGetPhases(solver,NULL);
}
NvFlexFreeBuffer(particleBuffer);
NvFlexFreeBuffer(veLocityBuffer);
NvFlexFreeBuffer(phaseBuffer);
NvFlexDestroySolver(solver);
NvFlexShutdown(library);
return 0;
}
这是一些输出：
x:0 y:0 z:0
x:0 y:0 z:0
x:0 y:0 z:0
x:0 y:0 z:0
x:0 y:0 z:0
x:0 y:0 z:0
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00274073 y:1.26542e+06 z:1.26542e+06
x:0.00550891 y:2.53083e+06 z:2.53083e+06
x:0.00550891 y:2.53083e+06 z:2.53083e+06
x:0.00550891 y:2.53083e+06 z:2.53083e+06
x:0.00550891 y:2.53083e+06 z:2.53083e+06
x:0.00550891 y:2.53083e+06 z:2.53083e+06
x:0.00550891 y:2.53083e+06 z:2.53083e+06
x:0.00550891 y:2.53083e+06 z:2.53083e+06
x:0.00550891 y:2.53083e+06 z:2.53083e+06
x:0.00550891 y:2.53083e+06 z:2.53083e+06
现在我希望粒子开始向右下落。我不确定我加载到粒子缓冲区中的数据是否正确，我该如何检查？所有的文档都说是 [浮动x，浮动y，浮动z，inverse_mass]。我应该检查哪些参数？
我能找到的缓冲区是：
/**
* Opaque type representing a data buffer,type and contents depends on usage,see NvFlexAllocBuffer()
*/
typedef struct NvFlexBuffer NvFlexBuffer;
解决方法
你必须初始化所有的 Flex 参数，否则它很简单就行不通，我认为这是因为它们保存在一个结构中。
#pragma once
#include "FlexPhysics.h"
#include "NvFlex.h"
#include "NvFlexExt.h"
#include <iostream>
NvFlexBuffer* particleBuffer;
NvFlexBuffer* velocityBuffer;
NvFlexBuffer* phaseBuffer;
struct Vec4struct {
float x,y,z,w;
};
void MyErrorCallback(NvFlexErrorSeverity severity,const char* msg,const char* file,int line)
{
std::cout << "Flex: %s - %s:%d\n" << msg << file << line << std::endl;
}
int n = 10000;
int main() {
NvFlexLibrary* library = NvFlexInit(120,MyErrorCallback);
// create new solver
NvFlexSolverDesc solverDesc;
NvFlexSetSolverDescDefaults(&solverDesc);
solverDesc.maxParticles = n;
solverDesc.maxDiffuseParticles = 0;
NvFlexSolver* solver = NvFlexCreateSolver(library,&solverDesc);
particleBuffer = NvFlexAllocBuffer(library,n,sizeof(Vec4struct),eNvFlexBufferHost);
velocityBuffer = NvFlexAllocBuffer(library,eNvFlexBufferHost);
phaseBuffer = NvFlexAllocBuffer(library,sizeof(int),eNvFlexBufferHost);
//set params
NvFlexParams p;
int numIterations = 2; //!< Number of solver iterations to perform per-substep
p.gravity[0] = 0;
p.gravity[1] = -10.0f;
p.gravity[2] = 0; //!< Constant acceleration applied to all particles
p.radius = 0.01; //!< The maximum interaction radius for particles
p.solidRestDistance = 0.005; //!< The distance non-fluid particles attempt to maintain from each other,must be in the range (0,radius]
p.fluidRestDistance = 0.001; //!< The distance fluid particles are spaced at the rest density,radius],for fluids this should generally be 50-70% of mRadius,for rigids this can simply be the same as the particle radius
// common params
p.dynamicFriction = 1; //!< Coefficient of friction used when colliding against shapes
p.staticFriction = 1; //!< Coefficient of static friction used when colliding against shapes
p.particleFriction = 1; //!< Coefficient of friction used when colliding particles
p.restitution = 1; //!< Coefficient of restitution used when colliding against shapes,particle collisions are always inelastic
p.adhesion = 1; //!< Controls how strongly particles stick to surfaces they hit,default 0.0,range [0.0,+inf]
p.sleepThreshold = 1; //!< Particles with a velocity magnitude < this threshold will be considered fixed
p.maxSpeed = 1000; //!< The magnitude of particle velocity will be clamped to this value at the end of each step
p.maxAcceleration = 1000; //!< The magnitude of particle acceleration will be clamped to this value at the end of each step (limits max velocity change per-second),useful to avoid popping due to large interpenetrations
p.shockPropagation = 0; //!< Artificially decrease the mass of particles based on height from a fixed reference point,this makes stacks and piles converge faster
p.dissipation = 1; //!< Damps particle velocity based on how many particle contacts it has
p.damping = 10; //!< Viscous drag force,applies a force proportional,and opposite to the particle velocity
// cloth params
p.wind[0] = 0;
p.wind[0] = 0;
p.wind[0] = 0; //!< Constant acceleration applied to particles that belong to dynamic triangles,drag needs to be > 0 for wind to affect triangles
p.drag = 1; //!< Drag force applied to particles belonging to dynamic triangles,proportional to velocity^2*area in the negative velocity direction
p.lift = 1; //!< Lift force applied to particles belonging to dynamic triangles,proportional to velocity^2*area in the direction perpendicular to velocity and (if possible),parallel to the plane normal
// fluid params
p.cohesion = 0.025; //!< Control how strongly particles hold each other together,default: 0.025,+inf]
p.surfaceTension = 0; //!< Controls how strongly particles attempt to minimize surface area,default: 0.0,range: [0.0,+inf]
p.viscosity = 1; //!< Smoothes particle velocities using XSPH viscosity
p.vorticityConfinement = 0; //!< Increases vorticity by applying rotational forces to particles
p.anisotropyScale = 0; //!< Control how much anisotropy is present in resulting ellipsoids for rendering,if zero then anisotropy will not be calculated,see NvFlexGetAnisotropy()
p.anisotropyMin = 0; //!< Clamp the anisotropy scale to this fraction of the radius
p.anisotropyMax = 0; //!< Clamp the anisotropy scale to this fraction of the radius
p.smoothing = 1; //!< Control the strength of Laplacian smoothing in particles for rendering,if zero then smoothed positions will not be calculated,see NvFlexGetSmoothParticles()
p.solidPressure = 0; //!< Add pressure from solid surfaces to particles
p.freeSurfaceDrag = 0; //!< Drag force applied to boundary fluid particles
p.buoyancy = 0; //!< Gravity is scaled by this value for fluid particles
// diffuse params
p.diffuseThreshold = 0; //!< Particles with kinetic energy + divergence above this threshold will spawn new diffuse particles
p.diffuseBuoyancy = 0; //!< Scales force opposing gravity that diffuse particles receive
p.diffuseDrag = 0; //!< Scales force diffuse particles receive in direction of neighbor fluid particles
p.diffuseBallistic = 0; //!< The number of neighbors below which a diffuse particle is considered ballistic
p.diffuseLifetime = 0; //!< Time in seconds that a diffuse particle will live for after being spawned,particles will be spawned with a random lifetime in the range [0,diffuseLifetime]
// collision params
p.collisionDistance = 0.01; //!< Distance particles maintain against shapes,note that for robust collision against triangle meshes this distance should be greater than zero
p.particleCollisionMargin = 1; //!< Increases the radius used during neighbor finding,this is useful if particles are expected to move significantly during a single step to ensure contacts aren't missed on subsequent iterations
p.shapeCollisionMargin = 0; //!< Increases the radius used during contact finding against kinematic shapes
for (int i = 0; i < 8; i++) {
for (int j = 0; j < 4; j++) {
p.planes[i][j] = 0;
}
} //!< Collision planes in the form ax + by + cz + d = 0
p.numPlanes = 0; //!< Num collision planes
p.relaxationMode = NvFlexRelaxationMode::eNvFlexRelaxationGlobal; //!< How the relaxation is applied inside the solver
p.relaxationFactor = 1; //!< Control the convergence rate of the parallel solver,default: 1,values greater than 1 may lead to instability
NvFlexSetParams(solver,&p);
//spawn particles
int particle_count = 6;
float particle_mass = 100;
//map buffers
Vec4struct* particles = (Vec4struct*)NvFlexMap(particleBuffer,eNvFlexMapWait);
Vec4struct* velocities = (Vec4struct*)NvFlexMap(velocityBuffer,eNvFlexMapWait);
int* phases = (int*)NvFlexMap(phaseBuffer,eNvFlexMapWait);
for (int i = 0; i < particle_count; ++i)
{
particles[i] = { i * 5.0f,1.0f / particle_mass };
velocities[i] = { 0.0f,0.0f,0.0f };
phases[i] = NvFlexMakePhase(0,1);
}
//unmap buffers
NvFlexUnmap(particleBuffer);
NvFlexUnmap(velocityBuffer);
NvFlexUnmap(phaseBuffer);
NvFlexSetParticles(solver,particleBuffer,NULL);
NvFlexSetVelocities(solver,velocityBuffer,NULL);
NvFlexSetPhases(solver,phaseBuffer,NULL);
float delta_time = 1 / 60.0f;
while (true)
{
//map buffers
Vec4struct* particles = (Vec4struct*)NvFlexMap(particleBuffer,eNvFlexMapWait);
Vec4struct* velocities = (Vec4struct*)NvFlexMap(velocityBuffer,eNvFlexMapWait);
int* phases = (int*)NvFlexMap(phaseBuffer,eNvFlexMapWait);
//"draw" particles
std::cout << "x:" << particles[0].x << " y:" << particles[0].y << " z:" << particles[0].z << std::endl;
//unmap buffers
NvFlexUnmap(particleBuffer);
NvFlexUnmap(velocityBuffer);
NvFlexUnmap(phaseBuffer);
// set active count
NvFlexSetActiveCount(solver,particle_count);
// tick
NvFlexUpdateSolver(solver,delta_time,1,false);
// read back (async)
NvFlexGetParticles(solver,NULL);
NvFlexGetVelocities(solver,NULL);
NvFlexGetPhases(solver,NULL);
}
NvFlexFreeBuffer(particleBuffer);
NvFlexFreeBuffer(velocityBuffer);
NvFlexFreeBuffer(phaseBuffer);
NvFlexDestroySolver(solver);
NvFlexShutdown(library);
return 0;
}