Expose smoke simulation velocities in Python API

This patch exposes smoke simulation velocities in the Python API,
similar to how density and flame grids are exposed.

This is useful to export velocities to an external renderer using Python.

Reviewers: campbellbarton, sergey

Reviewed By: sergey

Subscribers: sergey

Projects: #bf_blender

Differential Revision: https://developer.blender.org/D1366

1 files changed, 60 insertions, 0 deletions

diff --git a/source/blender/makesrna/intern/rna_smoke.c b/source/blender/makesrna/intern/rna_smoke.c
index 55262a98b2e..03fca130047 100644
--- a/source/blender/makesrna/intern/rna_smoke.c
+++ b/source/blender/makesrna/intern/rna_smoke.c
@@ -165,6 +165,31 @@ static int rna_SmokeModifier_color_grid_get_length(PointerRNA *ptr, int length[R
 	return length[0];
 }
 
+static int rna_SmokeModifier_velocity_grid_get_length(PointerRNA *ptr, int length[RNA_MAX_ARRAY_DIMENSION])
+{
+#ifdef WITH_SMOKE
+	SmokeDomainSettings *sds = (SmokeDomainSettings *)ptr->data;
+	float *vx = NULL;
+	float *vy = NULL;
+	float *vz = NULL;
+	int size = 0;
+
+	/* Velocity data is always low-resolution. */
+	if (sds->fluid) {
+		size = 3 * sds->res[0] * sds->res[1] * sds->res[2];
+		vx = smoke_get_velocity_x(sds->fluid);
+		vy = smoke_get_velocity_y(sds->fluid);
+		vz = smoke_get_velocity_z(sds->fluid);
+	}
+
+	length[0] = (vx && vy && vz) ? size : 0;
+#else
+	(void)ptr;
+	length[0] = 0;
+#endif
+	return length[0];
+}
+
 static void rna_SmokeModifier_density_grid_get(PointerRNA *ptr, float *values)
 {
 #ifdef WITH_SMOKE
@@ -189,6 +214,33 @@ static void rna_SmokeModifier_density_grid_get(PointerRNA *ptr, float *values)
 #endif
 }
 
+static void rna_SmokeModifier_velocity_grid_get(PointerRNA *ptr, float *values)
+{
+#ifdef WITH_SMOKE
+	SmokeDomainSettings *sds = (SmokeDomainSettings *)ptr->data;
+	int length[RNA_MAX_ARRAY_DIMENSION];
+	int size = rna_SmokeModifier_velocity_grid_get_length(ptr, length);
+	float *vx, *vy, *vz;
+	int i;
+
+	BLI_rw_mutex_lock(sds->fluid_mutex, THREAD_LOCK_READ);
+
+	vx = smoke_get_velocity_x(sds->fluid);
+	vy = smoke_get_velocity_y(sds->fluid);
+	vz = smoke_get_velocity_z(sds->fluid);
+
+	for (i=0; i<size; i+=3) {
+		*(values++) = *(vx++);
+		*(values++) = *(vy++);
+		*(values++) = *(vz++);
+	}
+
+	BLI_rw_mutex_unlock(sds->fluid_mutex);
+#else
+	(void)ptr;
+#endif
+}
+
 static void rna_SmokeModifier_color_grid_get(PointerRNA *ptr, float *values)
 {
 #ifdef WITH_SMOKE
@@ -453,6 +505,14 @@ static void rna_def_smoke_domain_settings(BlenderRNA *brna)
 	RNA_def_property_float_funcs(prop, "rna_SmokeModifier_density_grid_get", NULL, NULL);
 	RNA_def_property_ui_text(prop, "Density Grid", "Smoke density grid");
 
+	prop = RNA_def_property(srna, "velocity_grid", PROP_FLOAT, PROP_NONE);
+	RNA_def_property_array(prop, 32);
+	RNA_def_property_flag(prop, PROP_DYNAMIC);
+	RNA_def_property_clear_flag(prop, PROP_EDITABLE);
+	RNA_def_property_dynamic_array_funcs(prop, "rna_SmokeModifier_velocity_grid_get_length");
+	RNA_def_property_float_funcs(prop, "rna_SmokeModifier_velocity_grid_get", NULL, NULL);
+	RNA_def_property_ui_text(prop, "Velocity Grid", "Smoke velocity grid");
+
 	prop = RNA_def_property(srna, "flame_grid", PROP_FLOAT, PROP_NONE);
 	RNA_def_property_array(prop, 32);
 	RNA_def_property_flag(prop, PROP_DYNAMIC);