Committing patch #27442: Adaptive time step for fluid particles. The number of

subframes can now be altered automatically while an SPH (fluid particle)
simulation is running.

1 files changed, 24 insertions, 3 deletions

diff --git a/source/blender/makesrna/intern/rna_particle.c b/source/blender/makesrna/intern/rna_particle.c
index 5dc2f2ccac5..56738dd9f11 100644
--- a/source/blender/makesrna/intern/rna_particle.c
+++ b/source/blender/makesrna/intern/rna_particle.c
@@ -19,6 +19,9 @@
  *
  * Contributor(s): Blender Foundation (2008).
  *
+ * Adaptive time step
+ * Copyright 2011 AutoCRC
+ *
  * ***** END GPL LICENSE BLOCK *****
  */
 
@@ -2049,12 +2052,23 @@ static void rna_def_particle_settings(BlenderRNA *brna)
 	RNA_def_property_float_funcs(prop, "rna_PartSettings_timestep_get", "rna_PartSetings_timestep_set", NULL);
 	RNA_def_property_range(prop, 0.0001, 100.0);
 	RNA_def_property_ui_range(prop, 0.01, 10, 1, 3);
-	RNA_def_property_ui_text(prop, "Timestep", "The simulation timestep per frame (in seconds)");
+	RNA_def_property_ui_text(prop, "Timestep", "The simulation timestep per frame (seconds per frame)");
 	RNA_def_property_update(prop, 0, "rna_Particle_reset");
-	
+
+	prop= RNA_def_property(srna, "adaptive_subframes", PROP_BOOLEAN, PROP_NONE);
+	RNA_def_property_boolean_sdna(prop, NULL, "time_flag", PART_TIME_AUTOSF);
+	RNA_def_property_ui_text(prop, "Automatic Subframes", "Automatically set the number of subframes");
+	RNA_def_property_update(prop, 0, "rna_Particle_reset");
+
 	prop= RNA_def_property(srna, "subframes", PROP_INT, PROP_NONE);
 	RNA_def_property_range(prop, 0, 1000);	
-	RNA_def_property_ui_text(prop, "Subframes", "Subframes to simulate for improved stability and finer granularity simulations");
+	RNA_def_property_ui_text(prop, "Subframes", "Subframes to simulate for improved stability and finer granularity simulations (dt = timestep / (subframes + 1))");
+	RNA_def_property_update(prop, 0, "rna_Particle_reset");
+
+	prop= RNA_def_property(srna, "courant_target", PROP_FLOAT, PROP_NONE);
+	RNA_def_property_range(prop, 0.01, 10);
+	RNA_def_property_float_default(prop, 0.2);
+	RNA_def_property_ui_text(prop, "Adaptive Subframe Threshold", "The relative distance a particle can move before requiring more subframes (target Courant number). 0.1-0.3 is the recommended range.");
 	RNA_def_property_update(prop, 0, "rna_Particle_reset");
 
 	prop= RNA_def_property(srna, "jitter_factor", PROP_FLOAT, PROP_NONE);
@@ -2862,6 +2876,13 @@ static void rna_def_particle_system(BlenderRNA *brna)
 	RNA_def_property_clear_flag(prop, PROP_EDITABLE);
 	RNA_def_property_ui_text(prop, "Edited", "Particle system has been edited in particle mode");
 
+	/* Read-only: this is calculated internally. Changing it would only affect
+	 * the next time-step. The user should change ParticlSettings.subframes or
+	 * ParticleSettings.courant_target instead. */
+	prop= RNA_def_property(srna, "dt_frac", PROP_FLOAT, PROP_NONE);
+	RNA_def_property_range(prop, 1.0f/101.0f, 1.0f);
+	RNA_def_property_ui_text(prop, "Timestep", "The current simulation time step size, as a fraction of a frame.");
+	RNA_def_property_clear_flag(prop, PROP_EDITABLE);
 
 	RNA_def_struct_path_func(srna, "rna_ParticleSystem_path");
 }