Added basic filtering feature for velocity smoothing.

This is part of the original method from "Volumetric Methods for
Simulation and Rendering of Hair". The current filter is a simple box
filter. Other energy-preserving filters such as gaussian filtering
can be implemented later.

The filter size is currently given as a cell count. This is not ideal,
rather it should use a geometrical length value, but this is too
abstract for proper artistical use. Eventually defining the whole grid
in terms of spatial size might work better (possibly using an external
object).

1 files changed, 3 insertions, 0 deletions

diff --git a/source/blender/physics/intern/BPH_mass_spring.cpp b/source/blender/physics/intern/BPH_mass_spring.cpp
index 0fa14fa4eab..4d8f853a16b 100644
--- a/source/blender/physics/intern/BPH_mass_spring.cpp
+++ b/source/blender/physics/intern/BPH_mass_spring.cpp
@@ -431,6 +431,9 @@ static void cloth_calc_volume_force(ClothModifierData *clmd)
 		}
 		BPH_hair_volume_normalize_vertex_grid(vertex_grid);
 		
+		/* apply velocity filter */
+		BPH_hair_volume_vertex_grid_filter_box(vertex_grid, clmd->sim_parms->voxel_filter_size);
+		
 		for (i = 0; i < numverts; i++) {
 			float x[3], v[3], f[3], dfdx[3][3], dfdv[3][3];