Partial response force for hair collisions.

This implements a penalty force as well as a repulsion force to avoid
further penetration, as suggested in
"Simulating Complex Hair with Robust Collision Handling"
(http://graphics.snu.ac.kr/publications/2005-choe-HairSim/Choe_2005_SCA.pdf)

Friction forces are still missing. More problematic is handling of
moving colliders, when face swap places with the hair vertex and a
collision is missed, putting the vertex inside the mesh volume. Larger
margins might help, but ultimately using Bullet collision detection is
probably more reliable and failsafe.

1 files changed, 7 insertions, 0 deletions

diff --git a/source/blender/makesrna/intern/rna_cloth.c b/source/blender/makesrna/intern/rna_cloth.c
index 9ab6791b5fa..4b2d2dac25d 100644
--- a/source/blender/makesrna/intern/rna_cloth.c
+++ b/source/blender/makesrna/intern/rna_cloth.c
@@ -589,6 +589,13 @@ static void rna_def_cloth_collision_settings(BlenderRNA *brna)
 	RNA_def_property_ui_text(prop, "Friction", "Friction force if a collision happened (higher = less movement)");
 	RNA_def_property_update(prop, 0, "rna_cloth_update");
 
+	prop = RNA_def_property(srna, "damping", PROP_FLOAT, PROP_FACTOR);
+	RNA_def_property_float_sdna(prop, NULL, "damping");
+	RNA_def_property_range(prop, 0.0f, 1.0f);
+	RNA_def_property_float_default(prop, 1.0f);
+	RNA_def_property_ui_text(prop, "Restitution", "Amount of velocity lost on collision");
+	RNA_def_property_update(prop, 0, "rna_cloth_update");
+
 	prop = RNA_def_property(srna, "collision_quality", PROP_INT, PROP_NONE);
 	RNA_def_property_int_sdna(prop, NULL, "loop_count");
 	RNA_def_property_range(prop, 1, 20);