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, 14 insertions, 5 deletions

diff --git a/source/blender/blenkernel/intern/particle_child.c b/source/blender/blenkernel/intern/particle_child.c
index fb261b248dc..68e11c9368e 100644
--- a/source/blender/blenkernel/intern/particle_child.c
+++ b/source/blender/blenkernel/intern/particle_child.c
@@ -34,13 +34,14 @@
 
 #include "DNA_material_types.h"
 
+#include "BKE_colortools.h"
 #include "BKE_particle.h"
 
 struct Material;
 
 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);
-float do_clump(ParticleKey *state, ParticleKey *par, float time, float clumpfac, float clumppow, float pa_clump);
+float do_clump(ParticleKey *state, ParticleKey *par, float time, float clumpfac, float clumppow, float pa_clump, CurveMapping *clumpcurve);
 void do_child_modifiers(ParticleSimulationData *sim,
                         ParticleTexture *ptex, ParticleKey *par, float *par_rot, ChildParticle *cpa,
                         const float orco[3], float mat[4][4], ParticleKey *state, float t);
@@ -359,11 +360,19 @@ void do_kink(ParticleKey *state, ParticleKey *par, float *par_rot, float time, f
 		copy_v3_v3(state->co, result);
 }
 
-float do_clump(ParticleKey *state, ParticleKey *par, float time, float clumpfac, float clumppow, float pa_clump)
+float do_clump(ParticleKey *state, ParticleKey *par, float time, float clumpfac, float clumppow, float pa_clump, CurveMapping *clumpcurve)
 {
 	float clump = 0.f;
 
-	if (par && clumpfac != 0.0f) {
+	if (!par)
+		return 0.0f;
+	
+	if (clumpcurve) {
+		clump = pa_clump * (1.0f - CLAMPIS(curvemapping_evaluateF(clumpcurve, 0, time), 0.0f, 1.0f));
+		
+		interp_v3_v3v3(state->co, state->co, par->co, clump);
+	}
+	else if (clumpfac != 0.0f) {
 		float cpow;
 
 		if (clumppow < 0.0f)
@@ -439,10 +448,10 @@ void do_child_modifiers(ParticleSimulationData *sim, ParticleTexture *ptex, Part
 
 	if (part->flag & PART_CHILD_EFFECT)
 		/* state is safe to cast, since only co and vel are used */
-		guided = do_guides(sim->psys->effectors, (ParticleKey *)state, cpa->parent, t);
+		guided = do_guides(sim->psys->part, sim->psys->effectors, (ParticleKey *)state, cpa->parent, t);
 
 	if (guided == 0) {
-		float clump = do_clump(state, par, t, part->clumpfac, part->clumppow, ptex ? ptex->clump : 1.f);
+		float clump = do_clump(state, par, t, part->clumpfac, part->clumppow, ptex ? ptex->clump : 1.f, part->clumpcurve);
 
 		if (kink_freq != 0.f) {
 			float kink_amp = part->kink_amp * (1.f - part->kink_amp_clump * clump);