Curve-based control for child path tapering.

This is an alternative method to the current fixed function with a
clump factor and "shape" parameter. This function is quite limited and
does not give the desired result in many cases (e.g. long, parallel
rasta strands are problematic). So rather than trying to add more
parameters there is now a fully user-defined optional curve for setting
the tapering shape.

1 files changed, 33 insertions, 5 deletions

diff --git a/source/blender/blenkernel/intern/particle.c b/source/blender/blenkernel/intern/particle.c
index efcc0ebca21..1001dde2561 100644
--- a/source/blender/blenkernel/intern/particle.c
+++ b/source/blender/blenkernel/intern/particle.c
@@ -64,6 +64,7 @@
 
 #include "BKE_boids.h"
 #include "BKE_cloth.h"
+#include "BKE_colortools.h"
 #include "BKE_effect.h"
 #include "BKE_global.h"
 #include "BKE_group.h"
@@ -373,6 +374,10 @@ void BKE_particlesettings_free(ParticleSettings *part)
 	MTex *mtex;
 	int a;
 	BKE_free_animdata(&part->id);
+	
+	if (part->clumpcurve)
+		curvemapping_free(part->clumpcurve);
+	
 	free_partdeflect(part->pd);
 	free_partdeflect(part->pd2);
 
@@ -1665,7 +1670,7 @@ void psys_particle_on_emitter(ParticleSystemModifierData *psmd, int from, int in
 
 extern void do_kink(ParticleKey *state, ParticleKey *par, float *par_rot, float time, float freq, float shape, float amplitude, float flat,
                     short type, short axis, float obmat[4][4], int smooth_start);
-extern float do_clump(ParticleKey *state, ParticleKey *par, float time, float clumpfac, float clumppow, float pa_clump);
+extern float do_clump(ParticleKey *state, ParticleKey *par, float time, float clumpfac, float clumppow, float pa_clump, CurveMapping *clumpcurve);
 
 void precalc_guides(ParticleSimulationData *sim, ListBase *effectors)
 {
@@ -1708,7 +1713,7 @@ void precalc_guides(ParticleSimulationData *sim, ListBase *effectors)
 	}
 }
 
-int do_guides(ListBase *effectors, ParticleKey *state, int index, float time)
+int do_guides(ParticleSettings *part, ListBase *effectors, ParticleKey *state, int index, float time)
 {
 	EffectorCache *eff;
 	PartDeflect *pd;
@@ -1777,10 +1782,14 @@ int do_guides(ListBase *effectors, ParticleKey *state, int index, float time)
 					mul_v3_fl(vec_to_point, radius);
 				}
 			}
+			
+			if (part->clumpcurve)
+				curvemapping_changed_all(part->clumpcurve);
+			
 			par.co[0] = par.co[1] = par.co[2] = 0.0f;
 			copy_v3_v3(key.co, vec_to_point);
 			do_kink(&key, &par, 0, guidetime, pd->kink_freq, pd->kink_shape, pd->kink_amp, 0.f, pd->kink, pd->kink_axis, 0, 0);
-			do_clump(&key, &par, guidetime, pd->clump_fac, pd->clump_pow, 1.0f);
+			do_clump(&key, &par, guidetime, pd->clump_fac, pd->clump_pow, 1.0f, part->clumpcurve);
 			copy_v3_v3(vec_to_point, key.co);
 
 			add_v3_v3(vec_to_point, guidevec);
@@ -1979,6 +1988,10 @@ static bool psys_thread_context_init_path(ParticleThreadContext *ctx, ParticleSi
 	if (psys->part->flag & PART_CHILD_EFFECT)
 		ctx->vg_effector = psys_cache_vgroup(ctx->dm, psys, PSYS_VG_EFFECTOR);
 
+	/* prepare curvemapping tables */
+	if (part->clumpcurve)
+		curvemapping_changed_all(part->clumpcurve);
+
 	return true;
 }
 
@@ -2545,7 +2558,7 @@ void psys_cache_paths(ParticleSimulationData *sim, float cfra)
 			if (sim->psys->effectors && (psys->part->flag & PART_CHILD_EFFECT) == 0) {
 				for (k = 0, ca = cache[p]; k <= steps; k++, ca++)
 					/* ca is safe to cast, since only co and vel are used */
-					do_guides(sim->psys->effectors, (ParticleKey *)ca, p, (float)k / (float)steps);
+					do_guides(sim->psys->part, sim->psys->effectors, (ParticleKey *)ca, p, (float)k / (float)steps);
 			}
 
 			/* lattices have to be calculated separately to avoid mixups between effector calculations */
@@ -3141,6 +3154,18 @@ ParticleSettings *psys_new_settings(const char *name, Main *main)
 	return part;
 }
 
+void BKE_particlesettings_clump_curve_init(ParticleSettings *part)
+{
+	CurveMapping *cumap = curvemapping_add(1, 0.0f, 0.0f, 1.0f, 1.0f);
+	
+	cumap->cm[0].curve[0].x = 0.0f;
+	cumap->cm[0].curve[0].y = 1.0f;
+	cumap->cm[0].curve[1].x = 1.0f;
+	cumap->cm[0].curve[1].y = 1.0f;
+	
+	part->clumpcurve = cumap;
+}
+
 ParticleSettings *BKE_particlesettings_copy(ParticleSettings *part)
 {
 	ParticleSettings *partn;
@@ -3152,6 +3177,9 @@ ParticleSettings *BKE_particlesettings_copy(ParticleSettings *part)
 	partn->effector_weights = MEM_dupallocN(part->effector_weights);
 	partn->fluid = MEM_dupallocN(part->fluid);
 
+	if (part->clumpcurve)
+		partn->clumpcurve = curvemapping_copy(part->clumpcurve);
+	
 	partn->boids = boid_copy_settings(part->boids);
 
 	for (a = 0; a < MAX_MTEX; a++) {
@@ -3604,7 +3632,7 @@ void psys_get_particle_on_path(ParticleSimulationData *sim, int p, ParticleKey *
 					mul_mat3_m4_v3(hairmat, state->vel);
 
 					if (sim->psys->effectors && (part->flag & PART_CHILD_GUIDE) == 0) {
-						do_guides(sim->psys->effectors, state, p, state->time);
+						do_guides(sim->psys->part, sim->psys->effectors, state, p, state->time);
 						/* TODO: proper velocity handling */
 					}