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Fix polygon inertia calculation

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This commit is contained in:
rikaphys 2024-11-23 11:41:33 +09:00
parent 5efd124ca1
commit 46dec43257
1 changed files with 12 additions and 4 deletions
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16
modules/godot_physics_2d/godot_shape_2d.cpp
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@ -560,13 +560,21 @@ bool GodotConvexPolygonShape2D::intersect_segment(const Vector2 &p_begin, const
real_t GodotConvexPolygonShape2D::get_moment_of_inertia(real_t p_mass, const Size2 &p_scale) const {
ERR_FAIL_COND_V_MSG(point_count == 0, 0, "Convex polygon shape has no points.");
Rect2 aabb_new;
aabb_new.position = points[0].pos * p_scale;
Vector2 pos[point_count+1];
for (int i = 0; i < point_count; i++) {
aabb_new.expand_to(points[i].pos * p_scale);
pos[i] = points[i].pos * p_scale;
}
pos[point_count] = points[0].pos * p_scale;
real_t inertia = 0.;
real_t area = 0.;
for (int i = 0; i < point_count; i++) {
real_t a = pos[i].x * pos[i+1].y - pos[i+1].x * pos[i].y;
inertia += a * (pos[i].dot(pos[i]) + pos[i].dot(pos[i+1]) + pos[i+1].dot(pos[i+1]));
area += a / 2.;
}
return p_mass * aabb_new.size.dot(aabb_new.size) / 12.0;
return p_mass * inertia / (12. * area);
}
void GodotConvexPolygonShape2D::set_data(const Variant &p_data) {