Simple hair children: Initial implementation of twist control

It allows to have children hair to be twisted around parent curve, which is
quite an essential feature when creating hair braids.

There are currently two controls:

- Number of turns around parent children.
- Influence curve, which allows to modify "twistness" along the strand.

1 files changed, 5 insertions, 0 deletions

diff --git a/source/blender/makesdna/DNA_particle_types.h b/source/blender/makesdna/DNA_particle_types.h
index f6bed37dfa2..371b53567a6 100644
--- a/source/blender/makesdna/DNA_particle_types.h
+++ b/source/blender/makesdna/DNA_particle_types.h
@@ -261,6 +261,10 @@ typedef struct ParticleSettings {
 	short use_modifier_stack;
 	short pad5[3];
 
+	float twist;
+	float pad6;
+	struct CurveMapping *twistcurve;
+	void *pad7;
 } ParticleSettings;
 
 typedef struct ParticleSystem {
@@ -435,6 +439,7 @@ typedef enum eParticleChildFlag {
 	PART_CHILD_USE_CLUMP_NOISE  = (1<<0),
 	PART_CHILD_USE_CLUMP_CURVE  = (1<<1),
 	PART_CHILD_USE_ROUGH_CURVE  = (1<<2),
+	PART_CHILD_USE_TWIST_CURVE  = (1<<3),
 } eParticleChildFlag;
 
 /* part->draw_col */