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Fix capsule-cylinder collision in godot physics 

Test specific axes before falling back to GJK-EPA algorithm to get more
accurate separation axes for common cases, the same way it's done for
cylinder-cylinder collision.
This commit is contained in:
PouleyKetchoupp 2021-03-16 19:11:06 -07:00
parent 3ddab1c9d1
commit 27a01d054d
1 changed files with 45 additions and 0 deletions
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45
servers/physics/collision_solver_sat.cpp
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@ -1632,6 +1632,51 @@ static void _collision_capsule_cylinder(const ShapeSW *p_a, const Transform &p_t
SeparatorAxisTest<CapsuleShapeSW, CylinderShapeSW, withMargin> separator(capsule_A, p_transform_a, cylinder_B, p_transform_b, p_collector, p_margin_a, p_margin_b);
if (!separator.test_previous_axis()) {
return;
}
// Cylinder B end caps.
Vector3 cylinder_B_axis = p_transform_b.basis.get_axis(1).normalized();
if (!separator.test_axis(cylinder_B_axis)) {
return;
}
// Cylinder edge against capsule balls.
Vector3 capsule_A_axis = p_transform_a.basis.get_axis(2);
Vector3 capsule_A_ball_1 = p_transform_a.origin + capsule_A_axis * (capsule_A->get_height() * 0.5);
Vector3 capsule_A_ball_2 = p_transform_a.origin - capsule_A_axis * (capsule_A->get_height() * 0.5);
if (!separator.test_axis((p_transform_b.origin - capsule_A_ball_1).cross(cylinder_B_axis).cross(cylinder_B_axis).normalized())) {
return;
}
if (!separator.test_axis((p_transform_b.origin - capsule_A_ball_2).cross(cylinder_B_axis).cross(cylinder_B_axis).normalized())) {
return;
}
// Cylinder edge against capsule edge.
Vector3 center_diff = p_transform_b.origin - p_transform_a.origin;
if (!separator.test_axis(capsule_A_axis.cross(center_diff).cross(capsule_A_axis).normalized())) {
return;
}
if (!separator.test_axis(cylinder_B_axis.cross(center_diff).cross(cylinder_B_axis).normalized())) {
return;
}
real_t proj = capsule_A_axis.cross(cylinder_B_axis).cross(cylinder_B_axis).dot(capsule_A_axis);
if (Math::is_zero_approx(proj)) {
// Parallel capsule and cylinder axes, handle with specific axes only.
// Note: GJKEPA with no margin can lead to degenerate cases in this situation.
separator.generate_contacts();
return;
}
CollisionSolverSW::CallbackResult callback = SeparatorAxisTest<CapsuleShapeSW, CylinderShapeSW, withMargin>::test_contact_points;
// Fallback to generic algorithm to find the best separating axis.