particle puff, volume option.

When combing long hair  it will often end up with no volume (flat on the head like its wet).
a way to fix this is to use the puff tool however when applied points at the root only this just gives a bit of volume at the roots and the rest of the hair stays flat.
 
This option moves the unselected parts of the hair without applying the puff tool to them, giving volume to the hair whilst preserving the desired style.

1 files changed, 55 insertions, 9 deletions

diff --git a/source/blender/editors/physics/particle_edit.c b/source/blender/editors/physics/particle_edit.c
index 7c67b261caf..fc86971b8ac 100644
--- a/source/blender/editors/physics/particle_edit.c
+++ b/source/blender/editors/physics/particle_edit.c
@@ -2846,7 +2846,15 @@ static void brush_puff(PEData *data, int point_index)
 	float mat[4][4], imat[4][4];
 	float obmat[4][4], obimat[4][4];
 
-	float lastco[3], rootco[3] = {0.0f, 0.0f, 0.0f}, co[3], nor[3], kco[3], dco[3], fac=0.0f, length=0.0f;
+	float lastco[3], rootco[3] = {0.0f, 0.0f, 0.0f}, co[3], nor[3], kco[3], dco[3], ofs[3] = {0.0f, 0.0f, 0.0f}, fac=0.0f, length=0.0f;
+	int puff_volume = 0;
+	int change= 0;
+
+	{
+		ParticleEditSettings *pset= PE_settings(data->scene);
+		ParticleBrushData *brush= &pset->brush[pset->brushtype];
+		puff_volume = brush->flag & PE_BRUSH_DATA_PUFF_VOLUME;
+	}
 
 	if(psys && !(psys->flag & PSYS_GLOBAL_HAIR)) {
 		psys_mat_hair_to_global(data->ob, data->dm, psys->part->from, psys->particles + point_index, mat);
@@ -2883,24 +2891,62 @@ static void brush_puff(PEData *data, int point_index)
 				fac= -fac;
 		}
 		else {
-			/* compute position as if hair was standing up straight */
+			/* compute position as if hair was standing up straight.
+			 * */
 			VECCOPY(lastco, co);
 			VECCOPY(co, key->co);
 			mul_m4_v3(mat, co);
 			length += len_v3v3(lastco, co);
+			if((key->flag & PEK_SELECT) && !(key->flag & PEK_HIDE)) {
+				VECADDFAC(kco, rootco, nor, length);
+
+				/* blend between the current and straight position */
+				VECSUB(dco, kco, co);
+				VECADDFAC(co, co, dco, fac);
 
-			VECADDFAC(kco, rootco, nor, length);
+				/* re-use dco to compare before and after translation and add to the offset  */
+				VECCOPY(dco, key->co);
 
-			/* blend between the current and straight position */
-			VECSUB(dco, kco, co);
-			VECADDFAC(co, co, dco, fac);
+				mul_v3_m4v3(key->co, imat, co);
 
-			VECCOPY(key->co, co);
-			mul_m4_v3(imat, key->co);
+				if(puff_volume) {
+					/* accumulate the total distance moved to apply to unselected
+					 * keys that come after */
+					ofs[0] += key->co[0] - dco[0];
+					ofs[1] += key->co[1] - dco[1];
+					ofs[2] += key->co[2] - dco[2];
+				}
+				change = 1;
+			}
+			else {
+
+				if(puff_volume) {
+#if 0
+					/* this is simple but looks bad, adds annoying kinks */
+					add_v3_v3(key->co, ofs);
+#else
+					/* translate (not rotate) the rest of the hair if its not selected  */
+					if(ofs[0] || ofs[1] || ofs[2]) {
+						float c1[3], c2[3];
+						VECSUB(dco, lastco, co);
+						mul_m4_v3(imat, dco); /* into particle space */
+
+						/* move the point allong a vector perpendicular to the
+						 * hairs direction, reduces odd kinks, */
+						cross_v3_v3v3(c1, ofs, dco);
+						cross_v3_v3v3(c2, c1, dco);
+						normalize_v3(c2);
+						mul_v3_fl(c2, len_v3(ofs));
+						add_v3_v3(key->co, c2);
+					}
+#endif
+				}
+			}
 		}
 	}
 
-	point->flag |= PEP_EDIT_RECALC;
+	if(change)
+		point->flag |= PEP_EDIT_RECALC;
 }
 
 static void brush_smooth_get(PEData *data, float mat[][4], float imat[][4], int point_index, int key_index, PTCacheEditKey *key)