Randomness factor for hair bending stiffness.

This helps to create some variation in a hair system, which can
otherwise become very uniform and boring. It's yet another confusing
setting in a system that should have been nodified, but only option for
now (broken windows ...)

Conflicts:
	source/blender/blenkernel/intern/particle_system.c
	source/blender/physics/intern/BPH_mass_spring.cpp

10 files changed, 65 insertions, 35 deletions

diff --git a/release/scripts/startup/bl_ui/properties_particle.py b/release/scripts/startup/bl_ui/properties_particle.py
index 97b835dd18c..adff53d56f9 100644
--- a/release/scripts/startup/bl_ui/properties_particle.py
+++ b/release/scripts/startup/bl_ui/properties_particle.py
@@ -313,8 +313,10 @@ class PARTICLE_PT_hair_dynamics(ParticleButtonsPanel, Panel):
         col = split.column()
         col.label(text="Structure")
         col.prop(cloth, "mass")
-        sub = col.row(align=True)
-        sub.prop(cloth, "bending_stiffness", text="Stiffness")
+        sub = col.column(align=True)
+        subsub = sub.row(align=True)
+        subsub.prop(cloth, "bending_stiffness", text="Stiffness")
+        subsub.prop(psys.settings, "bending_random", text="Random")
         sub.prop(cloth, "bending_damping", text="Damping")
         # XXX has no noticable effect with stiff hair structure springs
         #col.prop(cloth, "spring_damping", text="Damping")
diff --git a/source/blender/blenkernel/BKE_cloth.h b/source/blender/blenkernel/BKE_cloth.h
index 3a9bb9cfc01..ccb45cb4de2 100644
--- a/source/blender/blenkernel/BKE_cloth.h
+++ b/source/blender/blenkernel/BKE_cloth.h
@@ -61,11 +61,12 @@ typedef enum eClothVertexFlag {
 	CLOTH_VERT_FLAG_NOSELFCOLL  = 2, /* vertex NOT used for self collisions */
 } eClothVertexFlag;
 
-typedef struct ClothHairRoot {
+typedef struct ClothHairData {
 	float loc[3];
 	float rot[3][3];
 	float rest_target[3]; /* rest target direction for each segment */
-} ClothHairRoot;
+	float bending_stiffness;
+} ClothHairData;
 
 typedef struct ClothSolverResult {
 	int status;
diff --git a/source/blender/blenkernel/intern/cloth.c b/source/blender/blenkernel/intern/cloth.c
index 2b4cbf62bb8..98da1cf630d 100644
--- a/source/blender/blenkernel/intern/cloth.c
+++ b/source/blender/blenkernel/intern/cloth.c
@@ -1072,15 +1072,15 @@ static void cloth_update_bending_targets(ClothModifierData *clmd)
 	prev_mn = -1;
 	for (search = cloth->springs; search; search = search->next) {
 		ClothSpring *spring = search->link;
-		ClothHairRoot *hair_ij, *hair_kl;
+		ClothHairData *hair_ij, *hair_kl;
 		bool is_root = spring->kl != prev_mn;
 		
 		if (spring->type != CLOTH_SPRING_TYPE_BENDING_ANG) {
 			continue;
 		}
 		
-		hair_ij = &clmd->roots[spring->ij];
-		hair_kl = &clmd->roots[spring->kl];
+		hair_ij = &clmd->hairdata[spring->ij];
+		hair_kl = &clmd->hairdata[spring->kl];
 		if (is_root) {
 			/* initial hair frame from root orientation */
 			copy_m3_m3(hair_frame, hair_ij->rot);
@@ -1144,15 +1144,15 @@ static void cloth_update_bending_rest_targets(ClothModifierData *clmd)
 	prev_mn = -1;
 	for (search = cloth->springs; search; search = search->next) {
 		ClothSpring *spring = search->link;
-		ClothHairRoot *hair_ij, *hair_kl;
+		ClothHairData *hair_ij, *hair_kl;
 		bool is_root = spring->kl != prev_mn;
 		
 		if (spring->type != CLOTH_SPRING_TYPE_BENDING_ANG) {
 			continue;
 		}
 		
-		hair_ij = &clmd->roots[spring->ij];
-		hair_kl = &clmd->roots[spring->kl];
+		hair_ij = &clmd->hairdata[spring->ij];
+		hair_kl = &clmd->hairdata[spring->kl];
 		if (is_root) {
 			/* initial hair frame from root orientation */
 			copy_m3_m3(hair_frame, hair_ij->rot);
@@ -1198,6 +1198,16 @@ static void cloth_update_springs( ClothModifierData *clmd )
 		else if (spring->type == CLOTH_SPRING_TYPE_BENDING) {
 			spring->stiffness = (cloth->verts[spring->kl].bend_stiff + cloth->verts[spring->ij].bend_stiff) / 2.0f;
 		}
+		else if (spring->type == CLOTH_SPRING_TYPE_BENDING_ANG) {
+			ClothVertex *v1 = &cloth->verts[spring->ij];
+			ClothVertex *v2 = &cloth->verts[spring->kl];
+			if (clmd->hairdata) {
+				/* copy extra hair data to generic cloth vertices */
+				v1->bend_stiff = clmd->hairdata[spring->ij].bending_stiffness;
+				v2->bend_stiff = clmd->hairdata[spring->kl].bending_stiffness;
+			}
+			spring->stiffness = (v1->bend_stiff + v2->bend_stiff) / 2.0f;
+		}
 		else if (spring->type == CLOTH_SPRING_TYPE_GOAL) {
 			/* Warning: Appending NEW goal springs does not work because implicit solver would need reset! */
 
diff --git a/source/blender/blenkernel/intern/particle_system.c b/source/blender/blenkernel/intern/particle_system.c
index 6956766f5ea..01a44e8c6b5 100644
--- a/source/blender/blenkernel/intern/particle_system.c
+++ b/source/blender/blenkernel/intern/particle_system.c
@@ -2993,11 +2993,12 @@ static MDeformVert *hair_set_pinning(MDeformVert *dvert, float weight)
 	return dvert;
 }
 
-static void hair_create_input_dm(ParticleSimulationData *sim, int totpoint, int totedge, DerivedMesh **r_dm, ClothHairRoot **r_roots)
+static void hair_create_input_dm(ParticleSimulationData *sim, int totpoint, int totedge, DerivedMesh **r_dm, ClothHairData **r_hairdata)
 {
 	ParticleSystem *psys = sim->psys;
+	ParticleSettings *part = psys->part;
 	DerivedMesh *dm;
-	ClothHairRoot *roots;
+	ClothHairData *hairdata;
 	MVert *mvert;
 	MEdge *medge;
 	MDeformVert *dvert;
@@ -3016,9 +3017,9 @@ static void hair_create_input_dm(ParticleSimulationData *sim, int totpoint, int
 	medge = CDDM_get_edges(dm);
 	dvert = DM_get_vert_data_layer(dm, CD_MDEFORMVERT);
 	
-	roots = *r_roots;
-	if (!roots) {
-		*r_roots = roots = MEM_mallocN(sizeof(ClothHairRoot) * totpoint, "hair roots");
+	hairdata = *r_hairdata;
+	if (!hairdata) {
+		*r_hairdata = hairdata = MEM_mallocN(sizeof(ClothHairData) * totpoint, "hair data");
 	}
 	
 	/* calculate maximum segment length */
@@ -3037,6 +3038,7 @@ static void hair_create_input_dm(ParticleSimulationData *sim, int totpoint, int
 	hair_index = 1;
 	LOOP_PARTICLES {
 		float root_mat[4][4];
+		float bending_stiffness;
 		bool use_hair;
 		
 		pa->hair_index = hair_index;
@@ -3046,8 +3048,10 @@ static void hair_create_input_dm(ParticleSimulationData *sim, int totpoint, int
 		mul_m4_m4m4(root_mat, sim->ob->obmat, hairmat);
 		normalize_m4(root_mat);
 		
+		bending_stiffness = 1.0f - part->bending_random * psys_frand(psys, p + 666);
+		
 		for (k=0, key=pa->hair; k<pa->totkey; k++,key++) {
-			ClothHairRoot *root;
+			ClothHairData *hair;
 			float *co, *co_next;
 			
 			co = key->co;
@@ -3055,9 +3059,11 @@ static void hair_create_input_dm(ParticleSimulationData *sim, int totpoint, int
 			
 			/* create fake root before actual root to resist bending */
 			if (k==0) {
-				root = &psys->clmd->roots[pa->hair_index - 1];
-				copy_v3_v3(root->loc, root_mat[3]);
-				copy_m3_m4(root->rot, root_mat);
+				hair = &psys->clmd->hairdata[pa->hair_index - 1];
+				copy_v3_v3(hair->loc, root_mat[3]);
+				copy_m3_m4(hair->rot, root_mat);
+				
+				hair->bending_stiffness = bending_stiffness;
 				
 				add_v3_v3v3(mvert->co, co, co);
 				sub_v3_v3(mvert->co, co_next);
@@ -3073,9 +3079,11 @@ static void hair_create_input_dm(ParticleSimulationData *sim, int totpoint, int
 			}
 			
 			/* store root transform in cloth data */
-			root = &psys->clmd->roots[pa->hair_index + k];
-			copy_v3_v3(root->loc, root_mat[3]);
-			copy_m3_m4(root->rot, root_mat);
+			hair = &psys->clmd->hairdata[pa->hair_index + k];
+			copy_v3_v3(hair->loc, root_mat[3]);
+			copy_m3_m4(hair->rot, root_mat);
+			
+			hair->bending_stiffness = bending_stiffness;
 			
 			copy_v3_v3(mvert->co, co);
 			mul_m4_v3(hairmat, mvert->co);
@@ -3137,14 +3145,14 @@ static void do_hair_dynamics(ParticleSimulationData *sim)
 		}
 	}
 	
-	if (!psys->hair_in_dm || !psys->clmd->roots || realloc_roots) {
-		if (psys->clmd->roots) {
-			MEM_freeN(psys->clmd->roots);
-			psys->clmd->roots = NULL;
+	if (!psys->hair_in_dm || !psys->clmd->hairdata || realloc_roots) {
+		if (psys->clmd->hairdata) {
+			MEM_freeN(psys->clmd->hairdata);
+			psys->clmd->hairdata = NULL;
 		}
 	}
 	
-	hair_create_input_dm(sim, totpoint, totedge, &psys->hair_in_dm, &psys->clmd->roots);
+	hair_create_input_dm(sim, totpoint, totedge, &psys->hair_in_dm, &psys->clmd->hairdata);
 	
 	if (psys->hair_out_dm)
 		psys->hair_out_dm->release(psys->hair_out_dm);
diff --git a/source/blender/blenloader/intern/readfile.c b/source/blender/blenloader/intern/readfile.c
index 80dc6db8f98..3b2179e9c47 100644
--- a/source/blender/blenloader/intern/readfile.c
+++ b/source/blender/blenloader/intern/readfile.c
@@ -3934,7 +3934,7 @@ static void direct_link_particlesystems(FileData *fd, ListBase *particles)
 		if (psys->clmd) {
 			psys->clmd = newdataadr(fd, psys->clmd);
 			psys->clmd->clothObject = NULL;
-			psys->clmd->roots = NULL;
+			psys->clmd->hairdata = NULL;
 			
 			psys->clmd->sim_parms= newdataadr(fd, psys->clmd->sim_parms);
 			psys->clmd->coll_parms= newdataadr(fd, psys->clmd->coll_parms);
@@ -4664,7 +4664,7 @@ static void direct_link_modifiers(FileData *fd, ListBase *lb)
 			ClothModifierData *clmd = (ClothModifierData *)md;
 			
 			clmd->clothObject = NULL;
-			clmd->roots = NULL;
+			clmd->hairdata = NULL;
 			
 			clmd->sim_parms= newdataadr(fd, clmd->sim_parms);
 			clmd->coll_parms= newdataadr(fd, clmd->coll_parms);
diff --git a/source/blender/makesdna/DNA_modifier_types.h b/source/blender/makesdna/DNA_modifier_types.h
index f001463944b..27e01cf7d29 100644
--- a/source/blender/makesdna/DNA_modifier_types.h
+++ b/source/blender/makesdna/DNA_modifier_types.h
@@ -565,7 +565,7 @@ typedef struct ClothModifierData {
 	struct PointCache *point_cache;       /* definition is in DNA_object_force.h */
 	struct ListBase ptcaches;
 	/* XXX nasty hack, remove once hair can be separated from cloth modifier data */
-	struct ClothHairRoot *roots;
+	struct ClothHairData *hairdata;
 	/* grid geometry values of hair continuum */
 	float hair_grid_min[3];
 	float hair_grid_max[3];
diff --git a/source/blender/makesdna/DNA_particle_types.h b/source/blender/makesdna/DNA_particle_types.h
index 44ef2746159..0b1f85c043a 100644
--- a/source/blender/makesdna/DNA_particle_types.h
+++ b/source/blender/makesdna/DNA_particle_types.h
@@ -234,6 +234,10 @@ typedef struct ParticleSettings {
 	/* keyed particles */
 	int keyed_loops;
 
+	/* hair dynamics */
+	float bending_random;
+	int pad3;
+
 	struct MTex *mtex[18];		/* MAX_MTEX */
 
 	struct Group *dup_group;
diff --git a/source/blender/makesrna/intern/rna_particle.c b/source/blender/makesrna/intern/rna_particle.c
index f97230144d6..0dffaba8cd8 100644
--- a/source/blender/makesrna/intern/rna_particle.c
+++ b/source/blender/makesrna/intern/rna_particle.c
@@ -2318,6 +2318,11 @@ static void rna_def_particle_settings(BlenderRNA *brna)
 	RNA_def_property_ui_text(prop, "Segments", "Number of hair segments");
 	RNA_def_property_update(prop, 0, "rna_Particle_reset");
 
+	prop = RNA_def_property(srna, "bending_random", PROP_FLOAT, PROP_NONE);
+	RNA_def_property_float_sdna(prop, NULL, "bending_random");
+	RNA_def_property_range(prop, 0.0f, 1.0f);
+	RNA_def_property_ui_text(prop, "Random Bending Stiffness", "Random stiffness of hairs");
+	RNA_def_property_update(prop, 0, "rna_Particle_reset");
 
 	/*TODO: not found in UI, readonly? */
 	prop = RNA_def_property(srna, "keys_step", PROP_INT, PROP_NONE);
diff --git a/source/blender/modifiers/intern/MOD_cloth.c b/source/blender/modifiers/intern/MOD_cloth.c
index 1b513dd5727..3d5caf6570b 100644
--- a/source/blender/modifiers/intern/MOD_cloth.c
+++ b/source/blender/modifiers/intern/MOD_cloth.c
@@ -178,7 +178,7 @@ static void copyData(ModifierData *md, ModifierData *target)
 	tclmd->point_cache = BKE_ptcache_add(&tclmd->ptcaches);
 	tclmd->point_cache->step = 1;
 	tclmd->clothObject = NULL;
-	tclmd->roots = NULL;
+	tclmd->hairdata = NULL;
 	tclmd->solver_result = NULL;
 	tclmd->debug_data = NULL;
 }
@@ -209,8 +209,8 @@ static void freeData(ModifierData *md)
 		BKE_ptcache_free_list(&clmd->ptcaches);
 		clmd->point_cache = NULL;
 		
-		if (clmd->roots)
-			MEM_freeN(clmd->roots);
+		if (clmd->hairdata)
+			MEM_freeN(clmd->hairdata);
 		
 		if (clmd->solver_result)
 			MEM_freeN(clmd->solver_result);
diff --git a/source/blender/physics/intern/BPH_mass_spring.cpp b/source/blender/physics/intern/BPH_mass_spring.cpp
index 67b2aec7863..b59a80ddbcc 100644
--- a/source/blender/physics/intern/BPH_mass_spring.cpp
+++ b/source/blender/physics/intern/BPH_mass_spring.cpp
@@ -114,11 +114,11 @@ void BKE_cloth_solver_set_positions(ClothModifierData *clmd)
 	Cloth *cloth = clmd->clothObject;

 	ClothVertex *verts = cloth->verts;

 	unsigned int numverts = cloth->numverts, i;

-	ClothHairRoot *cloth_roots = clmd->roots;

+	ClothHairData *cloth_hairdata = clmd->hairdata;

 	Implicit_Data *id = cloth->implicit;

 	

 	for (i = 0; i < numverts; i++) {

-		ClothHairRoot *root = &cloth_roots[i];

+		ClothHairData *root = &cloth_hairdata[i];

 		

 		BPH_mass_spring_set_rest_transform(id, i, root->rot);

 		BPH_mass_spring_set_motion_state(id, i, verts[i].x, verts[i].v);