GPencil: New Outline modifier

This modifier converts any stroke (no fill strokes) into perimeter
from camera view.  Also, it's possible to define an alternative 
material for the outline.

There is an option to include a target object to manipulate the start 
point of the strokes. The start point will be the nearest point 
to the target object.

Reviewed By: mendio, frogstomp

Maniphest Tasks: T100826

Differential Revision: https://developer.blender.org/D15882

Note: Icon will be updated in T101155

3 files changed, 48 insertions, 0 deletions

diff --git a/source/blender/makesdna/DNA_gpencil_modifier_defaults.h b/source/blender/makesdna/DNA_gpencil_modifier_defaults.h
index 324252ca369..56e317adca5 100644
--- a/source/blender/makesdna/DNA_gpencil_modifier_defaults.h
+++ b/source/blender/makesdna/DNA_gpencil_modifier_defaults.h
@@ -172,6 +172,19 @@
     .curve_intensity = NULL, \
   }
 
+#define _DNA_DEFAULT_OutlineGpencilModifierData \
+  { \
+    .material = NULL, \
+    .layername = "", \
+    .pass_index = 0, \
+    .flag = GP_OUTLINE_KEEP_SHAPE, \
+    .thickness = 1, \
+    .sample_length = 0.0f, \
+    .subdiv = 3, \
+    .layer_pass = 0, \
+    .outline_material = NULL, \
+  }
+
 #define _DNA_DEFAULT_SimplifyGpencilModifierData \
   { \
     .material = NULL, \
diff --git a/source/blender/makesdna/DNA_gpencil_modifier_types.h b/source/blender/makesdna/DNA_gpencil_modifier_types.h
index ca1eac0bde8..629be51893a 100644
--- a/source/blender/makesdna/DNA_gpencil_modifier_types.h
+++ b/source/blender/makesdna/DNA_gpencil_modifier_types.h
@@ -47,6 +47,7 @@ typedef enum GpencilModifierType {
   eGpencilModifierType_WeightAngle = 23,
   eGpencilModifierType_Shrinkwrap = 24,
   eGpencilModifierType_Envelope = 25,
+  eGpencilModifierType_Outline = 26,
   /* Keep last. */
   NUM_GREASEPENCIL_MODIFIER_TYPES,
 } GpencilModifierType;
@@ -313,6 +314,38 @@ typedef enum eOpacityGpencil_Flag {
   GP_OPACITY_WEIGHT_FACTOR = (1 << 8),
 } eOpacityGpencil_Flag;
 
+typedef struct OutlineGpencilModifierData {
+  GpencilModifierData modifier;
+  /** Target stroke origin. */
+  struct Object *object;
+  /** Material for filtering. */
+  struct Material *material;
+  /** Layer name. */
+  char layername[64];
+  /** Custom index for passes. */
+  int pass_index;
+  /** Flags. */
+  int flag;
+  /** Thickness. */
+  int thickness;
+  /** Sample Length. */
+  float sample_length;
+  /** Subdivisions. */
+  int subdiv;
+  /** Custom index for passes. */
+  int layer_pass;
+  /** Material for outline. */
+  struct Material *outline_material;
+} OutlineGpencilModifierData;
+
+typedef enum eOutlineGpencil_Flag {
+  GP_OUTLINE_INVERT_LAYER = (1 << 0),
+  GP_OUTLINE_INVERT_PASS = (1 << 1),
+  GP_OUTLINE_INVERT_LAYERPASS = (1 << 2),
+  GP_OUTLINE_INVERT_MATERIAL = (1 << 3),
+  GP_OUTLINE_KEEP_SHAPE = (1 << 4),
+} eOutlineGpencil_Flag;
+
 typedef struct ArrayGpencilModifierData {
   GpencilModifierData modifier;
   struct Object *object;
diff --git a/source/blender/makesdna/intern/dna_defaults.c b/source/blender/makesdna/intern/dna_defaults.c
index 197a863db72..3cd0cbcc3d6 100644
--- a/source/blender/makesdna/intern/dna_defaults.c
+++ b/source/blender/makesdna/intern/dna_defaults.c
@@ -302,6 +302,7 @@ SDNA_DEFAULT_DECL_STRUCT(MultiplyGpencilModifierData);
 SDNA_DEFAULT_DECL_STRUCT(NoiseGpencilModifierData);
 SDNA_DEFAULT_DECL_STRUCT(OffsetGpencilModifierData);
 SDNA_DEFAULT_DECL_STRUCT(OpacityGpencilModifierData);
+SDNA_DEFAULT_DECL_STRUCT(OutlineGpencilModifierData);
 SDNA_DEFAULT_DECL_STRUCT(SimplifyGpencilModifierData);
 SDNA_DEFAULT_DECL_STRUCT(SmoothGpencilModifierData);
 SDNA_DEFAULT_DECL_STRUCT(SubdivGpencilModifierData);
@@ -542,6 +543,7 @@ const void *DNA_default_table[SDNA_TYPE_MAX] = {
     SDNA_DEFAULT_DECL(NoiseGpencilModifierData),
     SDNA_DEFAULT_DECL(OffsetGpencilModifierData),
     SDNA_DEFAULT_DECL(OpacityGpencilModifierData),
+    SDNA_DEFAULT_DECL(OutlineGpencilModifierData),
     SDNA_DEFAULT_DECL(SimplifyGpencilModifierData),
     SDNA_DEFAULT_DECL(SmoothGpencilModifierData),
     SDNA_DEFAULT_DECL(SubdivGpencilModifierData),