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Physics2D: Automatically compute center of mass

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This commit is contained in:
Lynix
2019-03-17 15:56:38 +01:00
parent b6c1bfb5d0
commit 439a62a7f8
5 changed files with 54 additions and 4 deletions
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40
src/Nazara/Physics2D/Collider2D.cpp
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@@ -20,7 +20,7 @@ namespace Nz
{
cpShape* shape = (*shapes)[i];
cpShapeSetCollisionType(shape, cpFloat(m_collisionId));
cpShapeSetCollisionType(shape, m_collisionId);
cpShapeSetElasticity(shape, cpFloat(m_elasticity));
cpShapeSetFilter(shape, filter);
cpShapeSetFriction(shape, cpFloat(m_friction));
@@ -44,6 +44,11 @@ namespace Nz
{
}
Nz::Vector2f BoxCollider2D::ComputeCenterOfMass() const
{
return m_rect.GetCenter();
}
float BoxCollider2D::ComputeMomentOfInertia(float mass) const
{
return static_cast<float>(cpMomentForBox2(mass, cpBBNew(m_rect.x, m_rect.y, m_rect.x + m_rect.width, m_rect.y + m_rect.height)));
@@ -68,6 +73,11 @@ namespace Nz
{
}
Nz::Vector2f CircleCollider2D::ComputeCenterOfMass() const
{
return m_offset + Nz::Vector2f(m_radius, m_radius);
}
float CircleCollider2D::ComputeMomentOfInertia(float mass) const
{
return static_cast<float>(cpMomentForCircle(mass, 0.f, m_radius, cpv(m_offset.x, m_offset.y)));
@@ -92,6 +102,15 @@ namespace Nz
{
}
Nz::Vector2f CompoundCollider2D::ComputeCenterOfMass() const
{
Nz::Vector2f centerOfMass = Nz::Vector2f::Zero();
for (const auto& geom : m_geoms)
centerOfMass += geom->ComputeCenterOfMass();
return centerOfMass / float(m_geoms.size());
}
float CompoundCollider2D::ComputeMomentOfInertia(float mass) const
{
///TODO: Correctly compute moment using parallel axis theorem:
@@ -144,6 +163,15 @@ namespace Nz
m_vertices[i].Set(*vertices++);
}
Nz::Vector2f ConvexCollider2D::ComputeCenterOfMass() const
{
static_assert(sizeof(cpVect) == sizeof(Vector2d), "Chipmunk vector is not equivalent to Vector2d");
cpVect center = cpCentroidForPoly(int(m_vertices.size()), reinterpret_cast<const cpVect*>(m_vertices.data()));
return Nz::Vector2f(float(center.x), float(center.y));
}
float ConvexCollider2D::ComputeMomentOfInertia(float mass) const
{
static_assert(sizeof(cpVect) == sizeof(Vector2d), "Chipmunk vector is not equivalent to Vector2d");
@@ -169,6 +197,11 @@ namespace Nz
return ColliderType2D_Null;
}
Nz::Vector2f NullCollider2D::ComputeCenterOfMass() const
{
return Nz::Vector2f::Zero();
}
float NullCollider2D::ComputeMomentOfInertia(float mass) const
{
return (mass > 0.f) ? 1.f : 0.f; //< Null inertia is only possible for static/kinematic objects
@@ -181,6 +214,11 @@ namespace Nz
/******************************** SegmentCollider2D *********************************/
Nz::Vector2f SegmentCollider2D::ComputeCenterOfMass() const
{
return (m_first + m_second) / 2.f;
}
float SegmentCollider2D::ComputeMomentOfInertia(float mass) const
{
return static_cast<float>(cpMomentForSegment(mass, cpv(m_first.x, m_first.y), cpv(m_second.x, m_second.y), m_thickness));