[Bf-committers] Patch to SPH particles moving emitter issue

[Raul Fernandez Hernandez]

Hi all :)

  When you play a fluid sim and start moving the emitter, particle fluids
inherit the moving emitter speed which is not a desired feature and a
second bug caused from the previous code was the ignore of the absolute
particle velocity Damp factor.
 Here's the patch (is fairly simple, just a line of code):

//-------------------------------------

Index: source/blender/blenkernel/intern/particle_system.c
===================================================================
--- source/blender/blenkernel/intern/particle_system.c	(revision 28047)
+++ source/blender/blenkernel/intern/particle_system.c	(working copy)
@@ -2308,8 +2308,7 @@
 	VECCOPY(start, pa->prev_state.co);
 	VECCOPY(end, pa->state.co);

-	sub_v3_v3v3(v, end, start);
-	mul_v3_fl(v, 1.f/dtime);
+	VECCOPY(v, pa->state.vel);

 	neighbours = BLI_kdtree_range_search(tree, radius, start, NULL, &ptn);


//-------------------------------------

While the previous approach aparently is more stable, when the user move
the emitter, the difference between end and start position, quickly jump
and is no longer a measure of the particle initial velocity moreover, that
older approach ignore completely the particle speed Damp factor, you could
change it and nothing happens, that is the second issue that is now solved
with the new approach.

   The random particle explossions issue is something we are working on,
it dosen't happen in older builds (27326 and olders)