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Fixes division by zero when 3d body does not have valid shape (3.2 only)

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Fixes #46738 by setting the default inertia to a valid value when there are no valid shapes for a 3d body.
This commit is contained in:
Kyle 2021-03-08 20:32:16 -05:00
parent 0ddba5b712
commit 1c208d6baa
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() { void BodySW::update_inertias() {
//update shapes and motions // Update shapes and motions.
switch (mode) { switch (mode) {
case PhysicsServer::BODY_MODE_RIGID: { 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; real_t total_area = 0;
for (int i = 0; i < get_shape_count(); i++) { for (int i = 0; i < get_shape_count(); i++) {
@ -67,7 +67,7 @@ void BodySW::update_inertias() {
total_area += get_shape_area(i); 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(); center_of_mass_local.zero();
for (int i = 0; i < get_shape_count(); i++) { 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; 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 * get_shape_transform(i).origin;
} }
center_of_mass_local /= mass; center_of_mass_local /= mass;
// Recompute the inertia tensor // Recompute the inertia tensor.
Basis inertia_tensor; Basis inertia_tensor;
inertia_tensor.set_zero(); inertia_tensor.set_zero();
bool inertia_set = false;
for (int i = 0; i < get_shape_count(); i++) { for (int i = 0; i < get_shape_count(); i++) {
@ -91,6 +92,8 @@ void BodySW::update_inertias() {
continue; continue;
} }
inertia_set = true;
const ShapeSW *shape = get_shape(i); const ShapeSW *shape = get_shape(i);
real_t area = get_shape_area(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; 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(); principal_inertia_axes_local = inertia_tensor.diagonalize().transposed();
_inv_inertia = inertia_tensor.get_main_diagonal().inverse(); _inv_inertia = inertia_tensor.get_main_diagonal().inverse();