Cloth refactor: Remove goal springs and some other cleanup

This removes the goal springs, in favor of simply calculating the goal forces on the vertices directly. The vertices already store all the necessary data for the goal forces, thus the springs were redundant, and just defined both ends as being the same vertex.

The main advantage of removing the goal springs, is an increase in flexibility, allowing us to much more nicely do some neat dynamic stuff with the goals/pins, such as animated vertex weights. But this also has the advantage of simpler code, and a slightly reduced memory footprint.

This also removes the `f`, `dfdx` and `dfdv` fields from the `ClothSpring` struct, as that data is only used by the solver, and is re-computed on each step, and thus does not need to be stored throughout the simulation.

Reviewers: sergey

Reviewed By: sergey

Tags: #physics

Differential Revision: https://developer.blender.org/D2514

1 files changed, 3 insertions, 31 deletions

diff --git a/source/blender/physics/intern/implicit_blender.c b/source/blender/physics/intern/implicit_blender.c
index 2ad8ee0547f..16cd335dc0c 100644
--- a/source/blender/physics/intern/implicit_blender.c
+++ b/source/blender/physics/intern/implicit_blender.c
@@ -1579,8 +1579,7 @@ BLI_INLINE void apply_spring(Implicit_Data *data, int i, int j, const float f[3]
 }
 
 bool BPH_mass_spring_force_spring_linear(Implicit_Data *data, int i, int j, float restlen,
-                                         float stiffness, float damping, bool no_compress, float clamp_force,
-                                         float r_f[3], float r_dfdx[3][3], float r_dfdv[3][3])
+                                         float stiffness, float damping, bool no_compress, float clamp_force)
 {
 	float extent[3], length, dir[3], vel[3];
 	
@@ -1608,25 +1607,15 @@ bool BPH_mass_spring_force_spring_linear(Implicit_Data *data, int i, int j, floa
 		
 		apply_spring(data, i, j, f, dfdx, dfdv);
 		
-		if (r_f) copy_v3_v3(r_f, f);
-		if (r_dfdx) copy_m3_m3(r_dfdx, dfdx);
-		if (r_dfdv) copy_m3_m3(r_dfdv, dfdv);
-		
 		return true;
 	}
 	else {
-		if (r_f) zero_v3(r_f);
-		if (r_dfdx) zero_m3(r_dfdx);
-		if (r_dfdv) zero_m3(r_dfdv);
-		
 		return false;
 	}
 }
 
 /* See "Stable but Responsive Cloth" (Choi, Ko 2005) */
-bool BPH_mass_spring_force_spring_bending(Implicit_Data *data, int i, int j, float restlen,
-                                          float kb, float cb,
-                                          float r_f[3], float r_dfdx[3][3], float r_dfdv[3][3])
+bool BPH_mass_spring_force_spring_bending(Implicit_Data *data, int i, int j, float restlen, float kb, float cb)
 {
 	float extent[3], length, dir[3], vel[3];
 	
@@ -1646,17 +1635,9 @@ bool BPH_mass_spring_force_spring_bending(Implicit_Data *data, int i, int j, flo
 		
 		apply_spring(data, i, j, f, dfdx, dfdv);
 		
-		if (r_f) copy_v3_v3(r_f, f);
-		if (r_dfdx) copy_m3_m3(r_dfdx, dfdx);
-		if (r_dfdv) copy_m3_m3(r_dfdv, dfdv);
-		
 		return true;
 	}
 	else {
-		if (r_f) zero_v3(r_f);
-		if (r_dfdx) zero_m3(r_dfdx);
-		if (r_dfdv) zero_m3(r_dfdv);
-		
 		return false;
 	}
 }
@@ -1945,8 +1926,7 @@ bool BPH_mass_spring_force_spring_bending_angular(Implicit_Data *data, int i, in
 }
 
 bool BPH_mass_spring_force_spring_goal(Implicit_Data *data, int i, const float goal_x[3], const float goal_v[3],
-                                       float stiffness, float damping,
-                                       float r_f[3], float r_dfdx[3][3], float r_dfdv[3][3])
+                                       float stiffness, float damping)
 {
 	float root_goal_x[3], root_goal_v[3], extent[3], length, dir[3], vel[3];
 	float f[3], dfdx[3][3], dfdv[3][3];
@@ -1973,17 +1953,9 @@ bool BPH_mass_spring_force_spring_goal(Implicit_Data *data, int i, const float g
 		add_m3_m3m3(data->dFdX[i].m, data->dFdX[i].m, dfdx);
 		add_m3_m3m3(data->dFdV[i].m, data->dFdV[i].m, dfdv);
 		
-		if (r_f) copy_v3_v3(r_f, f);
-		if (r_dfdx) copy_m3_m3(r_dfdx, dfdx);
-		if (r_dfdv) copy_m3_m3(r_dfdv, dfdv);
-		
 		return true;
 	}
 	else {
-		if (r_f) zero_v3(r_f);
-		if (r_dfdx) zero_m3(r_dfdx);
-		if (r_dfdv) zero_m3(r_dfdv);
-		
 		return false;
 	}
 }