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, 16 insertions, 5 deletions

diff --git a/source/blender/draw/engines/workbench/workbench_shader.c b/source/blender/draw/engines/workbench/workbench_shader.c
index af3b5d31b2b..b3b9e11ae58 100644
--- a/source/blender/draw/engines/workbench/workbench_shader.c
+++ b/source/blender/draw/engines/workbench/workbench_shader.c
@@ -111,7 +111,7 @@ static struct {
   struct GPUShader *aa_accum_sh;
   struct GPUShader *smaa_sh[3];
 
-  struct GPUShader *volume_sh[2][2][2][2];
+  struct GPUShader *volume_sh[2][2][3][2];
 
   struct DRWShaderLibrary *lib;
 } e_data = {{{{NULL}}}};
@@ -463,9 +463,12 @@ GPUShader *workbench_shader_antialiasing_get(int stage)
   return e_data.smaa_sh[stage];
 }
 
-GPUShader *workbench_shader_volume_get(bool slice, bool coba, bool cubic, bool smoke)
+GPUShader *workbench_shader_volume_get(bool slice,
+                                       bool coba,
+                                       eWORKBENCH_VolumeInterpType interp_type,
+                                       bool smoke)
 {
-  GPUShader **shader = &e_data.volume_sh[slice][coba][cubic][smoke];
+  GPUShader **shader = &e_data.volume_sh[slice][coba][interp_type][smoke];
 
   if (*shader == NULL) {
     DynStr *ds = BLI_dynstr_new();
@@ -476,8 +479,16 @@ GPUShader *workbench_shader_volume_get(bool slice, bool coba, bool cubic, bool s
     if (coba) {
       BLI_dynstr_append(ds, "#define USE_COBA\n");
     }
-    if (cubic) {
-      BLI_dynstr_append(ds, "#define USE_TRICUBIC\n");
+    switch (interp_type) {
+      case WORKBENCH_VOLUME_INTERP_LINEAR:
+        BLI_dynstr_append(ds, "#define USE_TRILINEAR\n");
+        break;
+      case WORKBENCH_VOLUME_INTERP_CUBIC:
+        BLI_dynstr_append(ds, "#define USE_TRICUBIC\n");
+        break;
+      case WORKBENCH_VOLUME_INTERP_CLOSEST:
+        BLI_dynstr_append(ds, "#define USE_CLOSEST\n");
+        break;
     }
     if (smoke) {
       BLI_dynstr_append(ds, "#define VOLUME_SMOKE\n");