Liquid Simulation Display Options (GSoC 2020)

All the changes made in the branch `soc-2020-fluid-tools` are included in this patch.

**Major changes:**

=== Viewport Display ===

- //Raw voxel display// or //closest (nearest-neighbor)// interpolation for displaying the underlying voxel data of the simulation grids more clearly.
- An option to display //gridlines// when the slicing method is //single//.

==== Grid Display ====

- Visualization for flags, pressure and level-set representation grids with a fixed color coding based on Manta GUI.

==== Vector Display ====

- //**M**arker **A**nd **C**ell// grid visualization options for vector grids like velocity or external forces.
- Made vector display options available for external forces.

==== Coloring options for //gridlines// ====

- Range highlighting and cell filtering options for displaying the simulation grid data more precisely.
- Color gridlines with flags.

- Also, made slicing and interpolation options available for Volume Object.

Reviewed By: JacquesLucke, sebbas

Differential Revision: https://developer.blender.org/D8705

1 files changed, 54 insertions, 0 deletions

diff --git a/source/blender/makesrna/intern/rna_volume.c b/source/blender/makesrna/intern/rna_volume.c
index b03d6082cea..054f108099b 100644
--- a/source/blender/makesrna/intern/rna_volume.c
+++ b/source/blender/makesrna/intern/rna_volume.c
@@ -395,6 +395,39 @@ static void rna_def_volume_display(BlenderRNA *brna)
       {0, NULL, 0, NULL, NULL},
   };
 
+  static const EnumPropertyItem interpolation_method_items[] = {
+      {VOLUME_DISPLAY_INTERP_LINEAR, "LINEAR", 0, "Linear", "Good smoothness and speed"},
+      {VOLUME_DISPLAY_INTERP_CUBIC,
+       "CUBIC",
+       0,
+       "Cubic",
+       "Smoothed high quality interpolation, but slower"},
+      {VOLUME_DISPLAY_INTERP_CLOSEST, "CLOSEST", 0, "Closest", "No interpolation"},
+      {0, NULL, 0, NULL, NULL},
+  };
+
+  static const EnumPropertyItem axis_slice_method_items[] = {
+      {VOLUME_AXIS_SLICE_FULL, "FULL", 0, "Full", "Slice the whole domain object"},
+      {VOLUME_AXIS_SLICE_SINGLE,
+       "SINGLE",
+       0,
+       "Single",
+       "Perform a single slice of the domain object"},
+      {0, NULL, 0, NULL, NULL},
+  };
+
+  static const EnumPropertyItem axis_slice_position_items[] = {
+      {VOLUME_SLICE_AXIS_AUTO,
+       "AUTO",
+       0,
+       "Auto",
+       "Adjust slice direction according to the view direction"},
+      {VOLUME_SLICE_AXIS_X, "X", 0, "X", "Slice along the X axis"},
+      {VOLUME_SLICE_AXIS_Y, "Y", 0, "Y", "Slice along the Y axis"},
+      {VOLUME_SLICE_AXIS_Z, "Z", 0, "Z", "Slice along the Z axis"},
+      {0, NULL, 0, NULL, NULL},
+  };
+
   prop = RNA_def_property(srna, "wireframe_type", PROP_ENUM, PROP_NONE);
   RNA_def_property_enum_items(prop, wireframe_type_items);
   RNA_def_property_ui_text(prop, "Wireframe", "Type of wireframe display");
@@ -404,6 +437,27 @@ static void rna_def_volume_display(BlenderRNA *brna)
   RNA_def_property_enum_items(prop, wireframe_detail_items);
   RNA_def_property_ui_text(prop, "Wireframe Detail", "Amount of detail for wireframe display");
   RNA_def_property_update(prop, 0, "rna_Volume_update_display");
+
+  prop = RNA_def_property(srna, "interpolation_method", PROP_ENUM, PROP_NONE);
+  RNA_def_property_enum_items(prop, interpolation_method_items);
+  RNA_def_property_ui_text(
+      prop, "Interpolation", "Interpolation method to use for volumes in solid mode");
+  RNA_def_property_update(prop, 0, "rna_Volume_update_display");
+
+  prop = RNA_def_property(srna, "axis_slice_method", PROP_ENUM, PROP_NONE);
+  RNA_def_property_enum_items(prop, axis_slice_method_items);
+  RNA_def_property_ui_text(prop, "Method", "");
+  RNA_def_property_update(prop, 0, "rna_Volume_update_display");
+
+  prop = RNA_def_property(srna, "slice_axis", PROP_ENUM, PROP_NONE);
+  RNA_def_property_enum_items(prop, axis_slice_position_items);
+  RNA_def_property_ui_text(prop, "Axis", "");
+
+  prop = RNA_def_property(srna, "slice_depth", PROP_FLOAT, PROP_FACTOR);
+  RNA_def_property_range(prop, 0.0, 1.0);
+  RNA_def_property_ui_range(prop, 0.0, 1.0, 0.1, 3);
+  RNA_def_property_ui_text(prop, "Position", "Position of the slice");
+  RNA_def_property_update(prop, 0, "rna_Volume_update_display");
 }
 
 static void rna_def_volume_render(BlenderRNA *brna)