Grease Pencil: Add LineArt modifier

This adds the LineArt grease pencil modifier.

It takes objects or collections as input and generates various grease
pencil lines from these objects with the help of the active scene
camera. For example it can generate contour lines, intersection lines
and crease lines to name a few.

This is really useful as artists can then use 3D meshes to automatically
generate grease pencil lines for characters, enviroments or other
visualization purposes.

These lines can then be baked and edited as regular grease pencil lines.

Reviewed By: Sebastian Parborg, Antonio Vazquez, Matias Mendiola

Differential Revision: http://developer.blender.org/D8758

1 files changed, 73 insertions, 0 deletions

diff --git a/source/blender/makesdna/DNA_gpencil_modifier_types.h b/source/blender/makesdna/DNA_gpencil_modifier_types.h
index b2d62e0a5f6..a9262bf7ca4 100644
--- a/source/blender/makesdna/DNA_gpencil_modifier_types.h
+++ b/source/blender/makesdna/DNA_gpencil_modifier_types.h
@@ -53,6 +53,7 @@ typedef enum GpencilModifierType {
   eGpencilModifierType_Time = 16,
   eGpencilModifierType_Multiply = 17,
   eGpencilModifierType_Texture = 18,
+  eGpencilModifierType_Lineart = 19,
   /* Keep last. */
   NUM_GREASEPENCIL_MODIFIER_TYPES,
 } GpencilModifierType;
@@ -809,6 +810,78 @@ typedef enum eTextureGpencil_Mode {
   STROKE_AND_FILL = 2,
 } eTextureGpencil_Mode;
 
+typedef enum eLineartGpencilModifierSource {
+  LRT_SOURCE_COLLECTION = 0,
+  LRT_SOURCE_OBJECT = 1,
+  LRT_SOURCE_SCENE = 2,
+} eLineartGpencilModifierSource;
+
+typedef enum eLineArtGPencilModifierFlags {
+  LRT_GPENCIL_INVERT_SOURCE_VGROUP = (1 << 0),
+  LRT_GPENCIL_MATCH_OUTPUT_VGROUP = (1 << 1),
+  LRT_GPENCIL_SOFT_SELECTION = (1 << 2),
+  LRT_GPENCIL_IS_BAKED = (1 << 3),
+} eLineArtGPencilModifierFlags;
+
+typedef enum eLineartGpencilTransparencyFlags {
+  LRT_GPENCIL_TRANSPARENCY_ENABLE = (1 << 0),
+  /** Set to true means using "and" instead of "or" logic on mask bits. */
+  LRT_GPENCIL_TRANSPARENCY_MATCH = (1 << 1),
+} eLineartGpencilTransparencyFlags;
+
+typedef struct LineartGpencilModifierData {
+  GpencilModifierData modifier;
+
+  short line_types; /* line type enable flags, bits in eLineartEdgeFlag */
+
+  char source_type; /* Object or Collection, from eLineartGpencilModifierSource */
+
+  char use_multiple_levels;
+  short level_start;
+  short level_end;
+
+  struct Object *source_object;
+  struct Collection *source_collection;
+
+  struct Material *target_material;
+  char target_layer[64];
+
+  /** These two variables are to pass on vertex group information from mesh to strokes.
+   * vgname specifies which vertex groups our strokes from source_vertex_group will go to. */
+  char source_vertex_group[64];
+  char vgname[64];
+
+  float opacity;
+  short thickness;
+
+  unsigned char transparency_flags; /* eLineartGpencilTransparencyFlags */
+  unsigned char transparency_mask;
+
+  /** 0-1 range for cosine angle */
+  float crease_threshold;
+
+  /**  0-PI angle, for splitting strokes at sharp points */
+  float angle_splitting_threshold;
+
+  /* CPU mode */
+  float chaining_geometry_threshold;
+  float chaining_image_threshold;
+
+  float pre_sample_length;
+
+  /* Ported from SceneLineArt flags. */
+  int calculation_flags;
+
+  /* Additional Switches. */
+  int flags;
+
+  int _pad;
+
+  /* Runtime only. */
+  void *render_buffer;
+
+} LineartGpencilModifierData;
+
 #ifdef __cplusplus
 }
 #endif