Fix T55958: allow the user to select between spring and spring2.

The old springs with damping 1.0 operate in a special way that
is more similar to plastic deformation than a spring. Some users
rely on that, so let the user choose which implementation to use.
This also restores full backward compatibility with 2.79.

Reviewers: sergof

Differential Revision: https://developer.blender.org/D3544

1 files changed, 43 insertions, 23 deletions

diff --git a/source/blender/blenkernel/intern/rigidbody.c b/source/blender/blenkernel/intern/rigidbody.c
index 502b6a81c76..5d6695e6598 100644
--- a/source/blender/blenkernel/intern/rigidbody.c
+++ b/source/blender/blenkernel/intern/rigidbody.c
@@ -700,6 +700,35 @@ static void rigidbody_validate_sim_object(RigidBodyWorld *rbw, Object *ob, bool
 
 /* --------------------- */
 
+static void rigidbody_constraint_init_spring(
+	RigidBodyCon *rbc, void (*set_spring)(rbConstraint*,int,int),
+	void (*set_stiffness)(rbConstraint*,int,float), void (*set_damping)(rbConstraint*,int,float)
+) {
+	set_spring(rbc->physics_constraint, RB_LIMIT_LIN_X, rbc->flag & RBC_FLAG_USE_SPRING_X);
+	set_stiffness(rbc->physics_constraint, RB_LIMIT_LIN_X, rbc->spring_stiffness_x);
+	set_damping(rbc->physics_constraint, RB_LIMIT_LIN_X, rbc->spring_damping_x);
+
+	set_spring(rbc->physics_constraint, RB_LIMIT_LIN_Y, rbc->flag & RBC_FLAG_USE_SPRING_Y);
+	set_stiffness(rbc->physics_constraint, RB_LIMIT_LIN_Y, rbc->spring_stiffness_y);
+	set_damping(rbc->physics_constraint, RB_LIMIT_LIN_Y, rbc->spring_damping_y);
+
+	set_spring(rbc->physics_constraint, RB_LIMIT_LIN_Z, rbc->flag & RBC_FLAG_USE_SPRING_Z);
+	set_stiffness(rbc->physics_constraint, RB_LIMIT_LIN_Z, rbc->spring_stiffness_z);
+	set_damping(rbc->physics_constraint, RB_LIMIT_LIN_Z, rbc->spring_damping_z);
+
+	set_spring(rbc->physics_constraint, RB_LIMIT_ANG_X, rbc->flag & RBC_FLAG_USE_SPRING_ANG_X);
+	set_stiffness(rbc->physics_constraint, RB_LIMIT_ANG_X, rbc->spring_stiffness_ang_x);
+	set_damping(rbc->physics_constraint, RB_LIMIT_ANG_X, rbc->spring_damping_ang_x);
+
+	set_spring(rbc->physics_constraint, RB_LIMIT_ANG_Y, rbc->flag & RBC_FLAG_USE_SPRING_ANG_Y);
+	set_stiffness(rbc->physics_constraint, RB_LIMIT_ANG_Y, rbc->spring_stiffness_ang_y);
+	set_damping(rbc->physics_constraint, RB_LIMIT_ANG_Y, rbc->spring_damping_ang_y);
+
+	set_spring(rbc->physics_constraint, RB_LIMIT_ANG_Z, rbc->flag & RBC_FLAG_USE_SPRING_ANG_Z);
+	set_stiffness(rbc->physics_constraint, RB_LIMIT_ANG_Z, rbc->spring_stiffness_ang_z);
+	set_damping(rbc->physics_constraint, RB_LIMIT_ANG_Z, rbc->spring_damping_ang_z);
+}
+
 static void rigidbody_constraint_set_limits(RigidBodyCon *rbc, void (*set_limits)(rbConstraint*,int,float,float))
 {
 	if (rbc->flag & RBC_FLAG_USE_LIMIT_LIN_X)
@@ -824,35 +853,24 @@ static void rigidbody_validate_sim_constraint(RigidBodyWorld *rbw, Object *ob, b
 					RB_constraint_set_limits_piston(rbc->physics_constraint, lin_lower, lin_upper, ang_lower, ang_upper);
 					break;
 				case RBC_TYPE_6DOF_SPRING:
-					rbc->physics_constraint = RB_constraint_new_6dof_spring(loc, rot, rb1, rb2);
-
-					RB_constraint_set_spring_6dof_spring(rbc->physics_constraint, RB_LIMIT_LIN_X, rbc->flag & RBC_FLAG_USE_SPRING_X);
-					RB_constraint_set_stiffness_6dof_spring(rbc->physics_constraint, RB_LIMIT_LIN_X, rbc->spring_stiffness_x);
-					RB_constraint_set_damping_6dof_spring(rbc->physics_constraint, RB_LIMIT_LIN_X, rbc->spring_damping_x);
-
-					RB_constraint_set_spring_6dof_spring(rbc->physics_constraint, RB_LIMIT_LIN_Y, rbc->flag & RBC_FLAG_USE_SPRING_Y);
-					RB_constraint_set_stiffness_6dof_spring(rbc->physics_constraint, RB_LIMIT_LIN_Y, rbc->spring_stiffness_y);
-					RB_constraint_set_damping_6dof_spring(rbc->physics_constraint, RB_LIMIT_LIN_Y, rbc->spring_damping_y);
+					if (rbc->spring_type == RBC_SPRING_TYPE2) {
+						rbc->physics_constraint = RB_constraint_new_6dof_spring2(loc, rot, rb1, rb2);
 
-					RB_constraint_set_spring_6dof_spring(rbc->physics_constraint, RB_LIMIT_LIN_Z, rbc->flag & RBC_FLAG_USE_SPRING_Z);
-					RB_constraint_set_stiffness_6dof_spring(rbc->physics_constraint, RB_LIMIT_LIN_Z, rbc->spring_stiffness_z);
-					RB_constraint_set_damping_6dof_spring(rbc->physics_constraint, RB_LIMIT_LIN_Z, rbc->spring_damping_z);
+						rigidbody_constraint_init_spring(rbc, RB_constraint_set_spring_6dof_spring2, RB_constraint_set_stiffness_6dof_spring2, RB_constraint_set_damping_6dof_spring2);
 
-					RB_constraint_set_spring_6dof_spring(rbc->physics_constraint, RB_LIMIT_ANG_X, rbc->flag & RBC_FLAG_USE_SPRING_ANG_X);
-					RB_constraint_set_stiffness_6dof_spring(rbc->physics_constraint, RB_LIMIT_ANG_X, rbc->spring_stiffness_ang_x);
-					RB_constraint_set_damping_6dof_spring(rbc->physics_constraint, RB_LIMIT_ANG_X, rbc->spring_damping_ang_x);
+						RB_constraint_set_equilibrium_6dof_spring2(rbc->physics_constraint);
 
-					RB_constraint_set_spring_6dof_spring(rbc->physics_constraint, RB_LIMIT_ANG_Y, rbc->flag & RBC_FLAG_USE_SPRING_ANG_Y);
-					RB_constraint_set_stiffness_6dof_spring(rbc->physics_constraint, RB_LIMIT_ANG_Y, rbc->spring_stiffness_ang_y);
-					RB_constraint_set_damping_6dof_spring(rbc->physics_constraint, RB_LIMIT_ANG_Y, rbc->spring_damping_ang_y);
+						rigidbody_constraint_set_limits(rbc, RB_constraint_set_limits_6dof_spring2);
+					}
+					else {
+						rbc->physics_constraint = RB_constraint_new_6dof_spring(loc, rot, rb1, rb2);
 
-					RB_constraint_set_spring_6dof_spring(rbc->physics_constraint, RB_LIMIT_ANG_Z, rbc->flag & RBC_FLAG_USE_SPRING_ANG_Z);
-					RB_constraint_set_stiffness_6dof_spring(rbc->physics_constraint, RB_LIMIT_ANG_Z, rbc->spring_stiffness_ang_z);
-					RB_constraint_set_damping_6dof_spring(rbc->physics_constraint, RB_LIMIT_ANG_Z, rbc->spring_damping_ang_z);
+						rigidbody_constraint_init_spring(rbc, RB_constraint_set_spring_6dof_spring, RB_constraint_set_stiffness_6dof_spring, RB_constraint_set_damping_6dof_spring);
 
-					RB_constraint_set_equilibrium_6dof_spring(rbc->physics_constraint);
+						RB_constraint_set_equilibrium_6dof_spring(rbc->physics_constraint);
 
-					rigidbody_constraint_set_limits(rbc, RB_constraint_set_limits_6dof_spring);
+						rigidbody_constraint_set_limits(rbc, RB_constraint_set_limits_6dof);
+					}
 					break;
 				case RBC_TYPE_6DOF:
 					rbc->physics_constraint = RB_constraint_new_6dof(loc, rot, rb1, rb2);
@@ -1071,6 +1089,8 @@ RigidBodyCon *BKE_rigidbody_create_constraint(Scene *scene, Object *ob, short ty
 	rbc->flag |= RBC_FLAG_ENABLED;
 	rbc->flag |= RBC_FLAG_DISABLE_COLLISIONS;
 
+	rbc->spring_type = RBC_SPRING_TYPE2;
+
 	rbc->breaking_threshold = 10.0f; /* no good default here, just use 10 for now */
 	rbc->num_solver_iterations = 10; /* 10 is Bullet default */