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Merge pull request #46809 from likeich/fix_inertia_bug_3.2

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[3.2] Fixes division by zero when 3d body does not have valid shape
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Rémi Verschelde 2021-03-09 09:38:48 +01:00 committed by GitHub
parent 0ddba5b712 1c208d6baa
commit f79b8474ab
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GPG key ID: 4AEE18F83AFDEB23
1 changed files with 14 additions and 6 deletions
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20
servers/physics/body_sw.cpp
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@ -53,13 +53,13 @@ void BodySW::_update_transform_dependant() {
void BodySW::update_inertias() {
//update shapes and motions
// Update shapes and motions.
switch (mode) {
case PhysicsServer::BODY_MODE_RIGID: {
//update tensor for all shapes, not the best way but should be somehow OK. (inspired from bullet)
// Update tensor for all shapes, not the best way but should be somehow OK. (inspired from bullet)
real_t total_area = 0;
for (int i = 0; i < get_shape_count(); i++) {
@ -67,7 +67,7 @@ void BodySW::update_inertias() {
total_area += get_shape_area(i);
}
// We have to recompute the center of mass
// We have to recompute the center of mass.
center_of_mass_local.zero();
for (int i = 0; i < get_shape_count(); i++) {
@ -75,15 +75,16 @@ void BodySW::update_inertias() {
real_t mass = area * this->mass / total_area;
// NOTE: we assume that the shape origin is also its center of mass
// NOTE: we assume that the shape origin is also its center of mass.
center_of_mass_local += mass * get_shape_transform(i).origin;
}
center_of_mass_local /= mass;
// Recompute the inertia tensor
// Recompute the inertia tensor.
Basis inertia_tensor;
inertia_tensor.set_zero();
bool inertia_set = false;
for (int i = 0; i < get_shape_count(); i++) {
@ -91,6 +92,8 @@ void BodySW::update_inertias() {
continue;
}
inertia_set = true;
const ShapeSW *shape = get_shape(i);
real_t area = get_shape_area(i);
@ -108,7 +111,12 @@ void BodySW::update_inertias() {
inertia_tensor += shape_inertia_tensor + (Basis() * shape_origin.dot(shape_origin) - shape_origin.outer(shape_origin)) * mass;
}
// Compute the principal axes of inertia
// Set the inertia to a valid value when there are no valid shapes.
if (!inertia_set) {
inertia_tensor.set_diagonal(Vector3(1.0, 1.0, 1.0));
}
// Compute the principal axes of inertia.
principal_inertia_axes_local = inertia_tensor.diagonalize().transposed();
_inv_inertia = inertia_tensor.get_main_diagonal().inverse();