GPencil: Keep original stroke when reproject

When reproject a stroke sometimes is good to keep the copy of the original stroke to create volume effects

Related to T77639

{F8603513}

Reviewed By: mendio, pepeland

Maniphest Tasks: T77639

Differential Revision: https://developer.blender.org/D7963
50258

source/blender/editors/include/ED_gpencil.h

@@ -64,6 +64,22 @@ struct bAnimContext;
 struct wmKeyConfig;
 struct wmOperator;
 
+/* Reproject stroke modes. */
+typedef enum eGP_ReprojectModes {
+  /* Axis */
+  GP_REPROJECT_FRONT = 0,
+  GP_REPROJECT_SIDE,
+  GP_REPROJECT_TOP,
+  /* On same plane, parallel to view-plane. */
+  GP_REPROJECT_VIEW,
+  /* Reprojected on to the scene geometry */
+  GP_REPROJECT_SURFACE,
+  /* Reprojected on 3D cursor orientation */
+  GP_REPROJECT_CURSOR,
+  /* Keep equals (used in some operators) */
+  GP_REPROJECT_KEEP,
+} eGP_ReprojectModes;
+
 /* ------------- Grease-Pencil Runtime Data ---------------- */
 
 /* Temporary 'Stroke Point' data (2D / screen-space)
@@ -246,6 +262,15 @@ void ED_gpencil_project_stroke_to_view(struct bContext *C,
                                        struct bGPDlayer *gpl,
                                        struct bGPDstroke *gps);
 
+void ED_gpencil_stroke_reproject(struct Depsgraph *depsgraph,
+                                 const struct GP_SpaceConversion *gsc,
+                                 struct SnapObjectContext *sctx,
+                                 struct bGPDlayer *gpl,
+                                 struct bGPDframe *gpf,
+                                 struct bGPDstroke *gps,
+                                 const eGP_ReprojectModes mode,
+                                 const bool keep_original);
+
 /* set sculpt cursor */
 void ED_gpencil_toggle_brush_cursor(struct bContext *C, bool enable, void *customdata);