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bugfix in hull inertia

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This commit is contained in:
Irlan 2018-04-05 19:23:47 -03:00
parent 87b4efc6b5
commit ba3fb6deb6
1 changed files with 11 additions and 22 deletions
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29
src/bounce/dynamics/shapes/hull_shape.cpp
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@ -45,17 +45,6 @@ void b3HullShape::ComputeMass(b3MassData* massData, float32 density) const
b3Mat33 I;
I.SetZero();
// Pick reference point not too away from the origin
// to minimize floating point rounding errors.
b3Vec3 p1(0.0f, 0.0f, 0.0f);
// Put it inside the hull.
for (u32 i = 0; i < m_hull->vertexCount; ++i)
{
p1 += m_hull->vertices[i];
}
p1 *= 1.0f / float32(m_hull->vertexCount);
const float32 inv4 = 0.25f;
const float32 inv6 = 1.0f / 6.0f;
const float32 inv60 = 1.0f / 60.0f;
@ -64,7 +53,6 @@ void b3HullShape::ComputeMass(b3MassData* massData, float32 density) const
b3Vec3 diag(0.0f, 0.0f, 0.0f);
b3Vec3 off_diag(0.0f, 0.0f, 0.0f);
// Triangulate convex polygons
for (u32 i = 0; i < m_hull->faceCount; ++i)
{
const b3Face* face = m_hull->GetFace(i);
@ -82,9 +70,9 @@ void b3HullShape::ComputeMass(b3MassData* massData, float32 density) const
b3Vec3 p3 = m_hull->vertices[i2];
b3Vec3 p4 = m_hull->vertices[i3];
b3Vec3 e1 = p2 - p1;
b3Vec3 e2 = p3 - p1;
b3Vec3 e3 = p4 - p1;
b3Vec3 e1 = p2;
b3Vec3 e2 = p3;
b3Vec3 e3 = p4;
float32 D = b3Det(e1, e2, e3);
@ -122,18 +110,19 @@ void b3HullShape::ComputeMass(b3MassData* massData, float32 density) const
B3_ASSERT(volume > B3_EPSILON);
float32 inv_volume = 1.0f / volume;
center *= inv_volume;
massData->center = center + p1;
// Inertia tensor relative to the local origin (p1)
diag = inv_volume * diag;
off_diag = inv_volume * off_diag;
diag *= inv_volume;
off_diag *= inv_volume;
I.x.Set(diag.y + diag.z, -off_diag.z, -off_diag.y);
I.y.Set(-off_diag.z, diag.x + diag.z, -off_diag.x);
I.z.Set(-off_diag.y, -off_diag.x, diag.x + diag.y);
// Center of mass
massData->center = center;
// Inertia tensor relative to the local origin
massData->I = massData->mass * I;
massData->I = massData->I + massData->mass * b3Steiner(p1);
}
void b3HullShape::ComputeAABB(b3AABB3* aabb, const b3Transform& xf) const