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adjust velocity after solving PBD springs/links

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This commit is contained in:
erwincoumans
2013-09-06 23:18:14 -07:00
parent 40acf922e3
commit 01d62b12bb
2 changed files with 25 additions and 10 deletions
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9
Demos3/CpuDemos/deformable/CpuSoftBodyDemo.cpp
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@@ -23,8 +23,8 @@ extern bool gReset;
float clothWidth = 4; float clothWidth = 4;
float clothHeight= 4; float clothHeight= 4;
int width = 32;//64; int width = 64;
int height = 32;//64; int height = 64;
int numPoints = width*height; int numPoints = width*height;
float clothMass = 100.f; float clothMass = 100.f;
@@ -153,7 +153,7 @@ void CpuSoftClothDemo::clientMoveAndDisplay()
if (m_data->m_clothShapeIndex>=0 && m_data->m_clothVertices) if (m_data->m_clothShapeIndex>=0 && m_data->m_clothVertices)
{ {
float deltaTime = 1./1000.;//1./60.f; float deltaTime = 1./100.;//1./60.f;
//float deltaTime = 1./60.f; //float deltaTime = 1./60.f;
//write positions //write positions
@@ -266,9 +266,6 @@ void CpuSoftClothDemo::setupScene(const ConstructionInfo& ci)
{ {
for(int x = 0; x < width; x++) for(int x = 0; x < width; x++)
{ {
double coord = b3Sin(x/5.0)*0.01+1;
//coord = sin(y/);
float posX = (x/((float)(width-1)))*(clothWidth); float posX = (x/((float)(width-1)))*(clothWidth);
float posZ = ((y-height/2.f)/((float)(height-1)))*(clothHeight); float posZ = ((y-height/2.f)/((float)(height-1)))*(clothHeight);

26
Demos3/CpuDemos/deformable/PositionBasedDynamics.cpp
View File

@@ -6,15 +6,22 @@
void PositionBasedDynamics::solveLinks(struct CpuSoftClothDemoInternalData* clothData, char* vertexPositions, int vertexStride,float dt) void PositionBasedDynamics::solveLinks(struct CpuSoftClothDemoInternalData* clothData, char* vertexPositions, int vertexStride,float dt)
{ {
float kst = 1.f; float kst = 1.f;
float kLST = 1.f; float kLST = 1.f;//0.8f;
float damping = 0.999;
int numPoints = clothData->m_particleMasses.size();
b3AlignedObjectArray<b3Vector3> startPositions;
startPositions.resize(numPoints);
for (int i=0;i<numPoints;i++)
{
startPositions[i] = (b3Vector3&)vertexPositions[i*vertexStride];
}
for(int i=0; i<clothData->m_springs.size();i++) for(int i=0; i<clothData->m_springs.size();i++)
{ {
ClothSpring& link=clothData->m_springs[i]; ClothSpring& link=clothData->m_springs[i];
//if(l.m_c0>0)//avoid links between two particles with mass==0
//if(l.m_c0>0)
{ {
float invMassA = clothData->m_particleMasses[link.m_particleIndexA]? 1.f/clothData->m_particleMasses[link.m_particleIndexA] : 0.f; float invMassA = clothData->m_particleMasses[link.m_particleIndexA]? 1.f/clothData->m_particleMasses[link.m_particleIndexA] : 0.f;
@@ -37,6 +44,17 @@ void PositionBasedDynamics::solveLinks(struct CpuSoftClothDemoInternalData* clot
} }
} }
//adjust velocity
for (int i=0;i<numPoints;i++)
{
b3Vector3 endPosition = (b3Vector3&)vertexPositions[i*vertexStride];
b3Vector3 diff = endPosition-startPositions[i];
clothData->m_velocities[i]+=(diff/dt);
clothData->m_velocities[i]*=damping;
}
} }
void PositionBasedDynamics::solveConstraints(struct CpuSoftClothDemoInternalData* clothData, char* vtx, int vertexStride,float dt) void PositionBasedDynamics::solveConstraints(struct CpuSoftClothDemoInternalData* clothData, char* vtx, int vertexStride,float dt)