A bunch of fun stuff now possible because of new pointcache code:

* Baked normal particles can now use the "Path" visualization.
* Path "max length" & "abs length" are now history:
	- New option to set path start & end times + random variation to length.
	- Much more flexible (and calculated better) than previous options.
	- This works with parents, children, hair & normal particles unlike old length option.
	- Only known issue for now is that children from faces don't get calculated correctly when using path start time.
* New option "trails" for "halo", "line" and "billboard" visualizations:
	- Draws user controllable number of particle instances along particles path backwards from current position.
	- Works with children too for cool/weird visualizations that weren't possible before.
* Normal particle children's velocities are now approximated better when needed so that "line" visualization trails will look nice.
* New particle instance modifier options:
	- "path"-option works better and has controllable (max)position along path (with random variation possible).
	- "keep shape"-option for hair, keyed, or baked particles allows to place the instances to a single point (with random variation possible) along particle path.
	- "axis" option to make rotation handling better (still not perfect, but will have to do for now).

Some fixes & cleanup done along the way:
* Random path length didn't work for non-child particles.
* Cached & unborn particles weren't reset to emit locations.
* Particle numbers weren't drawn in the correct place.
* Setting proper render & draw visualizations was lost somewhere when initializing new particle settings.
* Changing child mode wasn't working correctly.
* Some cleanup & modularization of particle child effector code and particle drawing & rendering code.
* Object & group visualizations didn't work.
* Child simplification didn't work.

1 files changed, 5 insertions, 3 deletions

diff --git a/source/blender/makesdna/DNA_particle_types.h b/source/blender/makesdna/DNA_particle_types.h
index 05f1cc1f351..c793362c223 100644
--- a/source/blender/makesdna/DNA_particle_types.h
+++ b/source/blender/makesdna/DNA_particle_types.h
@@ -131,7 +131,7 @@ typedef struct ParticleSettings {
 
 	/* general values */
 	float sta, end, lifetime, randlife;
-	float timetweak, jitfac, keyed_time, eff_hair, rt;
+	float timetweak, jitfac, keyed_time, eff_hair;
 	int totpart, userjit, grid_res;
 
 	/* initial velocity factors */
@@ -159,6 +159,8 @@ typedef struct ParticleSettings {
 	float branch_thres;
 	/* drawing stuff */
 	float draw_line[2];
+	float path_start, path_end;
+	int trail_count;
 
 	/* boids */
 	float max_vel, max_lat_acc, max_tan_acc;
@@ -311,8 +313,8 @@ typedef struct ParticleSystem{				/* note, make sure all (runtime) are NULL's in
 #define PART_DRAW_SIZE		4
 #define PART_DRAW_EMITTER	8	/* render emitter also */
 //#define PART_DRAW_HEALTH	16
-//#define PART_DRAW_TIMED_PATH  32
-//#define PART_DRAW_CACHED_PATH 64
+#define PART_ABS_PATH_TIME  32
+//#define PART_DRAW_TRAIL		64
 #define PART_DRAW_BB_LOCK	128
 #define PART_DRAW_PARENT	256
 #define PART_DRAW_NUM		512