rigidbody: Add rigid body constraints

Constraints connect two rigid bodies.
Depending on which constraint is used different degrees of freedom
are limited, e.g. a hinge constraint only allows the objects to rotate
around a common axis.

Constraints are implemented as individual objects and bahave similar to
rigid bodies in terms of adding/removing/validating.

The position and orientation of the constraint object is the pivot point
of the constraint.

Constraints have their own group in the rigid body world.

To make connecting rigid bodies easier, there is a "Connect" operator that
creates an empty objects with a rigid body constraint connecting the selected
objects to active.

Currently the following constraints are implemented:
* Fixed
* Point
* Hinge
* Slider
* Piston
* Generic

Note: constraint limits aren't animatable yet).

1 files changed, 5 insertions, 0 deletions

diff --git a/source/blender/makesrna/intern/rna_object.c b/source/blender/makesrna/intern/rna_object.c
index 99cecb01140..47b775801f6 100644
--- a/source/blender/makesrna/intern/rna_object.c
+++ b/source/blender/makesrna/intern/rna_object.c
@@ -2433,6 +2433,11 @@ static void rna_def_object(BlenderRNA *brna)
 	RNA_def_property_pointer_sdna(prop, NULL, "rigidbody_object");
 	RNA_def_property_struct_type(prop, "RigidBodyObject");
 	RNA_def_property_ui_text(prop, "Rigid Body Settings", "Settings for rigid body simulation");
+
+	prop = RNA_def_property(srna, "rigid_body_constraint", PROP_POINTER, PROP_NONE);
+	RNA_def_property_pointer_sdna(prop, NULL, "rigidbody_constraint");
+	RNA_def_property_struct_type(prop, "RigidBodyConstraint");
+	RNA_def_property_ui_text(prop, "Rigid Body Constraint", "Constraint constraining rigid bodies");
 	
 	/* restrict */
 	prop = RNA_def_property(srna, "hide", PROP_BOOLEAN, PROP_NONE);