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, 2 insertions, 1 deletions

diff --git a/source/blender/draw/engines/overlay/overlay_private.h b/source/blender/draw/engines/overlay/overlay_private.h
index c8b29c6bbbb..c684f420b19 100644
--- a/source/blender/draw/engines/overlay/overlay_private.h
+++ b/source/blender/draw/engines/overlay/overlay_private.h
@@ -685,7 +685,8 @@ GPUShader *OVERLAY_shader_paint_wire(void);
 GPUShader *OVERLAY_shader_particle_dot(void);
 GPUShader *OVERLAY_shader_particle_shape(void);
 GPUShader *OVERLAY_shader_sculpt_mask(void);
-GPUShader *OVERLAY_shader_volume_velocity(bool use_needle);
+GPUShader *OVERLAY_shader_volume_velocity(bool use_needle, bool use_mac);
+GPUShader *OVERLAY_shader_volume_gridlines(bool color_with_flags, bool color_range);
 GPUShader *OVERLAY_shader_wireframe(bool custom_bias);
 GPUShader *OVERLAY_shader_wireframe_select(void);
 GPUShader *OVERLAY_shader_xray_fade(void);