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[Godot Physics]: Correct typo in moment of inertia calculations. 

The moment of inertia calculation for BoxShape is:

```
Vector3(
    (p_mass / 3.0) * (ly * ly + lz * lz), 
    (p_mass / 3.0) * (lx * lx + lz * lz), 
    (p_mass / 3.0) * (lx * lx + ly * ly));
```

where the final line includes both the x and y extents.

However, for CapsuleShape3D, CylinderShape3D, ConvexPolygonShape3D, ConcavePolygonShape3D, and HeightMapShape3D, the final line read `(p_mass / 3.0) * (extents.y * extents.y + extents.y * extents.y)`.  I believe this is a mistake, considering the comment in each case mentions using an AABB approximation, which should follow the same approach as BoxShape.

This change corrects the final line to include both the x and y components of the shape's extent.
This commit is contained in:
Josh Jones 2021-03-22 20:23:39 -07:00
parent 863f6b44ec
commit 9327052bed
1 changed files with 5 additions and 5 deletions
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10
servers/physics/shape_sw.cpp
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@ -690,7 +690,7 @@ Vector3 CapsuleShapeSW::get_moment_of_inertia(real_t p_mass) const {
return Vector3(
(p_mass / 3.0) * (extents.y * extents.y + extents.z * extents.z),
(p_mass / 3.0) * (extents.x * extents.x + extents.z * extents.z),
(p_mass / 3.0) * (extents.y * extents.y + extents.y * extents.y));
(p_mass / 3.0) * (extents.x * extents.x + extents.y * extents.y));
}
void CapsuleShapeSW::_setup(real_t p_height, real_t p_radius) {
@ -874,7 +874,7 @@ Vector3 CylinderShapeSW::get_moment_of_inertia(real_t p_mass) const {
return Vector3(
(p_mass / 3.0) * (extents.y * extents.y + extents.z * extents.z),
(p_mass / 3.0) * (extents.x * extents.x + extents.z * extents.z),
(p_mass / 3.0) * (extents.y * extents.y + extents.y * extents.y));
(p_mass / 3.0) * (extents.x * extents.x + extents.y * extents.y));
}
void CylinderShapeSW::_setup(real_t p_height, real_t p_radius) {
@ -1144,7 +1144,7 @@ Vector3 ConvexPolygonShapeSW::get_moment_of_inertia(real_t p_mass) const {
return Vector3(
(p_mass / 3.0) * (extents.y * extents.y + extents.z * extents.z),
(p_mass / 3.0) * (extents.x * extents.x + extents.z * extents.z),
(p_mass / 3.0) * (extents.y * extents.y + extents.y * extents.y));
(p_mass / 3.0) * (extents.x * extents.x + extents.y * extents.y));
}
void ConvexPolygonShapeSW::_setup(const Vector<Vector3> &p_vertices) {
@ -1535,7 +1535,7 @@ Vector3 ConcavePolygonShapeSW::get_moment_of_inertia(real_t p_mass) const {
return Vector3(
(p_mass / 3.0) * (extents.y * extents.y + extents.z * extents.z),
(p_mass / 3.0) * (extents.x * extents.x + extents.z * extents.z),
(p_mass / 3.0) * (extents.y * extents.y + extents.y * extents.y));
(p_mass / 3.0) * (extents.x * extents.x + extents.y * extents.y));
}
struct _VolumeSW_BVH_Element {
@ -1798,7 +1798,7 @@ Vector3 HeightMapShapeSW::get_moment_of_inertia(real_t p_mass) const {
return Vector3(
(p_mass / 3.0) * (extents.y * extents.y + extents.z * extents.z),
(p_mass / 3.0) * (extents.x * extents.x + extents.z * extents.z),
(p_mass / 3.0) * (extents.y * extents.y + extents.y * extents.y));
(p_mass / 3.0) * (extents.x * extents.x + extents.y * extents.y));
}
void HeightMapShapeSW::_setup(PoolVector<real_t> p_heights, int p_width, int p_depth, real_t p_cell_size) {