Grease Pencil - Storyboarding Features (merge from GPencil_EditStrokes branch)

This merge-commit brings in a number of new features and workflow/UI improvements for
working with Grease Pencil. While these were originally targetted at improving
the workflow for creating 3D storyboards in Blender using the Grease Pencil,
many of these changes should also prove useful in other workflows too.

The main highlights here are:
1) It is now possible to edit Grease Pencil strokes
   - Use D Tab, or toggle the "Enable Editing" toggles in the Toolbar/Properties regions
     to enter "Stroke Edit Mode". In this mode, many common editing tools will
     operate on Grease Pencil stroke points instead.
   - Tools implemented include Select, Select All/Border/Circle/Linked/More/Less,
     Grab, Rotate, Scale, Bend, Shear, To Sphere, Mirror, Duplicate, Delete.
   - Proportional Editing works when using the transform tools

2) Grease Pencil stroke settings can now be animated
   NOTE: Currently drivers don't work, but if time allows, this may still be
         added before the release.

3) Strokes can be drawn with "filled" interiors, using a separate set of
   colour/opacity settings to the ones used for the lines themselves.

   This makes use of OpenGL filled polys, which has the limitation of only
   being able to fill convex shapes. Some artifacts may be visible on concave
   shapes (e.g. pacman's mouth will be overdrawn)

4) "Volumetric Strokes" - An alternative drawing technique for stroke drawing
   has been added which draws strokes as a series of screen-aligned discs.

   While this was originally a partial experimental technique at getting better
   quality 3D lines, the effects possible using this technique were interesting
   enough to warrant making this a dedicated feature. Best results when partial
   opacity and large stroke widths are used.

5) Improved Onion Skinning Support
   - Different colours can be selected for the before/after ghosts. To do so,
     enable the "colour wheel" toggle beside the Onion Skinning toggle, and set
     the colours accordingly.
   - Different numbers of ghosts can be shown before/after the current frame

6) Grease Pencil datablocks are now attached to the scene by default instead of
   the active object.
   - For a long time, the object-attachment has proved to be quite problematic
     for users to keep track of. Now that this is done at scene level, it is
     easier for most users to use.
   - An exception for old files (and for any addons which may benefit from object
     attachment instead), is that if the active object has a Grease Pencil datablock,
     that will be used instead.
   - It is not currently possible to choose object-attachment from the UI, but
     it is simple to do this from the console instead, by doing:
     context.active_object.grease_pencil = bpy.data.grease_pencil["blah"]

7) Various UI Cleanups
   - The layers UI has been cleaned up to use a list instead of the nested-panels
     design. Apart from saving space, this is also much nicer to look at now.

   - The UI code is now all defined in Python. To support this, it has been necessary
     to add some new context properties to make it easier to access these settings.
     e.g. "gpencil_data" for the datablock
          "active_gpencil_layer" and "active_gpencil_frame" for active data,
          "editable_gpencil_strokes" for the strokes that can be edited

   - The "stroke placement/alignment" settings (previously "Drawing Settings" at the
     bottom of the Grease Pencil panel in the Properties Region) is now located in
     the toolbar. These were more toolsettings than properties for how GPencil got drawn.

   - "Use Sketching Sessions" has been renamed "Continuous Drawing", as per a
     suggestion for an earlier discussion on developer.blender.org

   - By default, the painting operator will wait for a mouse button to be pressed
     before it starts creating the stroke. This is to make it easier to include
     this operator in various toolbars/menus/etc.   To get it immediately starting
     (as when you hold down DKEy to draw), set "wait_for_input" to False.

   - GPencil Layers can be rearranged in the "Grease Pencil" mode of the Action Editor

   - Toolbar panels have been added to all the other editors which support these.

8) Pie menus for quick-access to tools
   A set of experimental pie menus has been included for quick access to many
   tools and settings. It is not necessary to use these to get things done,
   but they have been designed to help make certain common tasks easier.

   - Ctrl-D = The main pie menu. Reveals tools in a context sensitive and
              spatially stable manner.
   - D Q    = "Quick Settings" pie. This allows quick access to the active
              layer's settings. Notably, colours, thickness, and turning
              onion skinning on/off.

4 files changed, 264 insertions, 10 deletions

diff --git a/source/blender/editors/transform/transform.c b/source/blender/editors/transform/transform.c
index b0e334345ec..b87a823ce92 100644
--- a/source/blender/editors/transform/transform.c
+++ b/source/blender/editors/transform/transform.c
@@ -2013,6 +2013,12 @@ bool initTransform(bContext *C, TransInfo *t, wmOperator *op, const wmEvent *eve
 			options |= CTX_TEXTURE;
 		}
 	}
+	
+	if ((prop = RNA_struct_find_property(op->ptr, "gpencil_strokes")) && RNA_property_is_set(op->ptr, prop)) {
+		if (RNA_property_boolean_get(op->ptr, prop)) {
+			options |= CTX_GPENCIL_STROKES;
+		}
+	}
 
 	t->options = options;
 
diff --git a/source/blender/editors/transform/transform_conversions.c b/source/blender/editors/transform/transform_conversions.c
index 5b3d5b776be..104120448c9 100644
--- a/source/blender/editors/transform/transform_conversions.c
+++ b/source/blender/editors/transform/transform_conversions.c
@@ -105,6 +105,7 @@
 #include "ED_uvedit.h"
 #include "ED_clip.h"
 #include "ED_mask.h"
+#include "ED_gpencil.h"
 
 #include "WM_api.h"  /* for WM_event_add_notifier to deal with stabilization nodes */
 #include "WM_types.h"
@@ -5613,7 +5614,10 @@ void special_aftertrans_update(bContext *C, TransInfo *t)
 	}
 
 
-	if (t->spacetype == SPACE_SEQ) {
+	if (t->options & CTX_GPENCIL_STROKES) {
+		/* pass */
+	}
+	else if (t->spacetype == SPACE_SEQ) {
 		/* freeSeqData in transform_conversions.c does this
 		 * keep here so the else at the end wont run... */
 
@@ -7280,6 +7284,230 @@ void flushTransPaintCurve(TransInfo *t)
 }
 
 
+static void createTransGPencil(bContext *C, TransInfo *t)
+{
+	bGPdata *gpd = ED_gpencil_data_get_active(C);
+	bGPDlayer *gpl;
+	TransData *td = NULL;
+	float mtx[3][3], smtx[3][3];
+	
+	const Scene *scene = CTX_data_scene(C);
+	const int cfra = CFRA;
+	
+	const int propedit = (t->flag & T_PROP_EDIT);
+	const int propedit_connected = (t->flag & T_PROP_CONNECTED);
+	
+	
+	/* == Grease Pencil Strokes to Transform Data ==
+	 * Grease Pencil stroke points can be a mixture of 2D (screen-space),
+	 * or 3D coordinates. However, they're always saved as 3D points.
+	 * For now, we just do these without creating TransData2D for the 2D
+	 * strokes. This may cause issues in future though.
+	 */
+	t->total = 0;
+	
+	if (gpd == NULL)
+		return;
+	
+	/* First Pass: Count the number of datapoints required for the strokes, 
+	 * (and additional info about the configuration - e.g. 2D/3D?)
+	 */
+	for (gpl = gpd->layers.first; gpl; gpl = gpl->next) {
+		/* only editable and visible layers are considered */
+		if ((gpl->flag & (GP_LAYER_HIDE | GP_LAYER_LOCKED)) == 0 &&
+		    (gpl->actframe != NULL))
+		{
+			bGPDframe *gpf = gpl->actframe;
+			bGPDstroke *gps;
+			
+			for (gps = gpf->strokes.first; gps; gps = gps->next) {
+				if (propedit) {
+					/* Proportional Editing... */
+					if (propedit_connected) {
+						/* connected only - so only if selected */
+						if (gps->flag & GP_STROKE_SELECT)
+							t->total += gps->totpoints;
+					}
+					else {
+						/* everything goes - connection status doesn't matter */
+						t->total += gps->totpoints;
+					}
+				}
+				else {
+					/* only selected stroke points are considered */
+					if (gps->flag & GP_STROKE_SELECT) {
+						bGPDspoint *pt;
+						int i;
+						
+						// TODO: 2D vs 3D?
+						for (i = 0, pt = gps->points; i < gps->totpoints; i++, pt++) {
+							if (pt->flag & GP_SPOINT_SELECT)
+								t->total++;
+						}
+					}
+				}				
+			}
+		}
+	}
+	
+	/* Stop trying if nothing selected */
+	if (t->total == 0) {
+		return;
+	}
+	
+	/* Allocate memory for data */
+	t->data = MEM_callocN(t->total * sizeof(TransData), "TransData(GPencil)");
+	td = t->data;
+	
+	unit_m3(smtx);
+	unit_m3(mtx);
+	
+	/* Second Pass: Build transdata array */
+	for (gpl = gpd->layers.first; gpl; gpl = gpl->next) {
+		/* only editable and visible layers are considered */
+		if ((gpl->flag & (GP_LAYER_HIDE | GP_LAYER_LOCKED)) == 0 &&
+		    (gpl->actframe != NULL))
+		{
+			bGPDframe *gpf = gpl->actframe;
+			bGPDstroke *gps;
+			
+			/* Make a new frame to work on if the layer's frame and the current scene frame don't match up 
+			 * - This is useful when animating as it saves that "uh-oh" moment when you realise you've
+			 *   spent too much time editing the wrong frame...
+			 */
+			// XXX: should this be allowed when framelock is enabled?
+			if (gpf->framenum != cfra) {
+				bGPDframe *new_frame = gpencil_frame_duplicate(gpf);
+				bGPDframe *gf;
+				bool found = false;
+				
+				/* Find frame to insert it before */
+				for (gf = gpf->next; gf; gf = gf->next) {
+					if (gf->framenum > cfra) {
+						/* Add it here */
+						BLI_insertlinkbefore(&gpl->frames, gf, new_frame);
+						
+						found = true;
+						break;
+					}
+					else if (gf->framenum == cfra) {
+						/* This only happens when we're editing with framelock on...
+						 * - Delete the new frame and don't do anything else here...
+						 */
+						//printf("GP Frame convert to TransData - Copy aborted for frame %d -> %d\n", gpf->framenum, gf->framenum);
+						free_gpencil_strokes(new_frame);
+						MEM_freeN(new_frame);
+						new_frame = NULL;
+						
+						found = true;
+						break;
+					}
+				}
+				
+				if (found == false) {
+					/* Add new frame to the end */
+					BLI_addtail(&gpl->frames, new_frame);
+				}
+				
+				/* Edit the new frame instead, if it did get created + added */
+				if (new_frame) {
+					// TODO: tag this one as being "newly created" so that we can remove it if the edit is cancelled
+					new_frame->framenum = cfra;
+					
+					gpf = new_frame;
+				}
+			}
+			
+			/* Loop over strokes, adding TransData for points as needed... */
+			for (gps = gpf->strokes.first; gps; gps = gps->next) {
+				TransData *head = td;
+				TransData *tail = td;
+				bool stroke_ok;
+				
+				/* What we need to include depends on proportional editing settings... */
+				if (propedit) {
+					if (propedit_connected) {
+						/* A) "Connected" - Only those in selected strokes */
+						stroke_ok = (gps->flag & GP_STROKE_SELECT) != 0;
+					}
+					else {
+						/* B) All points, always */
+						stroke_ok = true;
+					}
+				}
+				else {
+					/* C) Only selected points in selected strokes */
+					stroke_ok = (gps->flag & GP_STROKE_SELECT) != 0;
+				}
+				
+				/* Do stroke... */
+				if (stroke_ok && gps->totpoints) {
+					bGPDspoint *pt;
+					int i;
+					
+#if 0	/* XXX: this isn't needed anymore; cannot calculate center this way or propedit breaks */				
+					const float ninv = 1.0f / gps->totpoints;
+					float center[3] = {0.0f};
+					
+					/* compute midpoint of stroke */
+					for (i = 0, pt = gps->points; i < gps->totpoints; i++, pt++) {
+						madd_v3_v3v3fl(center, center, &pt->x, ninv);
+					}
+#endif
+					
+					/* add all necessary points... */
+					for (i = 0, pt = gps->points; i < gps->totpoints; i++, pt++) {
+						bool point_ok;
+						
+						/* include point? */
+						if (propedit) {
+							/* Always all points in strokes that get included */
+							point_ok = true;
+						}
+						else {
+							/* Only selected points in selected strokes */
+							point_ok = (pt->flag & GP_SPOINT_SELECT) != 0;
+						}
+						
+						/* do point... */
+						if (point_ok) {
+							copy_v3_v3(td->iloc, &pt->x);
+							copy_v3_v3(td->center, &pt->x); // XXX: what about  t->around == local?
+							
+							td->loc = &pt->x;
+							
+							td->flag = 0;
+							
+							if (pt->flag & GP_SPOINT_SELECT)
+								td->flag |= TD_SELECTED;
+							
+							/* configure 2D points so that they don't play up... */
+							if (gps->flag & (GP_STROKE_2DSPACE | GP_STROKE_2DIMAGE)) {
+								td->protectflag = OB_LOCK_LOCZ | OB_LOCK_ROTZ | OB_LOCK_SCALEZ;
+								// XXX: matrices may need to be different?
+							}
+							
+							copy_m3_m3(td->smtx, smtx);
+							copy_m3_m3(td->mtx, mtx);
+							unit_m3(td->axismtx); // XXX?
+							
+							td++;
+							tail++;
+						}
+					}
+					
+					/* March over these points, and calculate the proportional editing distances */
+					if (propedit && (head != tail)) {
+						/* XXX: for now, we are similar enough that this works... */
+						calc_distanceCurveVerts(head, tail - 1);
+					}
+				}
+			}
+		}
+	}
+}
+
+
 void createTransData(bContext *C, TransInfo *t)
 {
 	Scene *scene = t->scene;
@@ -7300,6 +7528,16 @@ void createTransData(bContext *C, TransInfo *t)
 			sort_trans_data_dist(t);
 		}
 	}
+	else if (t->options & CTX_GPENCIL_STROKES) {
+		t->flag |= T_POINTS; // XXX...
+		createTransGPencil(C, t);
+		
+		if (t->data && (t->flag & T_PROP_EDIT)) {
+			sort_trans_data(t); // makes selected become first in array
+			set_prop_dist(t, 1);
+			sort_trans_data_dist(t);
+		}
+	}
 	else if (t->spacetype == SPACE_IMAGE) {
 		t->flag |= T_POINTS | T_2D_EDIT;
 		if (t->options & CTX_MASK) {
diff --git a/source/blender/editors/transform/transform_generics.c b/source/blender/editors/transform/transform_generics.c
index f5d4f341600..fcf789546e8 100644
--- a/source/blender/editors/transform/transform_generics.c
+++ b/source/blender/editors/transform/transform_generics.c
@@ -961,6 +961,9 @@ void recalcData(TransInfo *t)
 	else if (t->options & CTX_PAINT_CURVE) {
 		flushTransPaintCurve(t);
 	}
+	else if (t->options & CTX_GPENCIL_STROKES) {
+		/* pass? */
+	}
 	else if (t->spacetype == SPACE_IMAGE) {
 		recalcData_image(t);
 	}
@@ -1315,6 +1318,9 @@ void initTransInfo(bContext *C, TransInfo *t, wmOperator *op, const wmEvent *eve
 					if (t->obedit) {
 						t->flag |= initTransInfo_edit_pet_to_flag(ts->proportional);
 					}
+					else if (t->options & CTX_GPENCIL_STROKES) {
+						t->flag |= initTransInfo_edit_pet_to_flag(ts->proportional);
+					}
 					else if (t->options & CTX_MASK) {
 						if (ts->proportional_mask) {
 							t->flag |= T_PROP_EDIT;
diff --git a/source/blender/editors/transform/transform_ops.c b/source/blender/editors/transform/transform_ops.c
index b2cda9a350f..25dee50a192 100644
--- a/source/blender/editors/transform/transform_ops.c
+++ b/source/blender/editors/transform/transform_ops.c
@@ -546,7 +546,11 @@ void Transform_Properties(struct wmOperatorType *ot, int flags)
 			}
 		}
 	}
-
+	
+	if (flags & P_GPENCIL_EDIT) {
+		RNA_def_boolean(ot->srna, "gpencil_strokes", 0, "Edit Grease Pencil", "Edit selected Grease Pencil strokes");
+	}
+	
 	if ((flags & P_OPTIONS) && !(flags & P_NO_TEXSPACE)) {
 		RNA_def_boolean(ot->srna, "texture_space", 0, "Edit Texture Space", "Edit Object data texture space");
 		prop = RNA_def_boolean(ot->srna, "remove_on_cancel", 0, "Remove on Cancel", "Remove elements on cancel");
@@ -581,7 +585,7 @@ static void TRANSFORM_OT_translate(struct wmOperatorType *ot)
 
 	RNA_def_float_vector_xyz(ot->srna, "value", 3, NULL, -FLT_MAX, FLT_MAX, "Vector", "", -FLT_MAX, FLT_MAX);
 
-	Transform_Properties(ot, P_CONSTRAINT | P_PROPORTIONAL | P_MIRROR | P_ALIGN_SNAP | P_OPTIONS);
+	Transform_Properties(ot, P_CONSTRAINT | P_PROPORTIONAL | P_MIRROR | P_ALIGN_SNAP | P_OPTIONS | P_GPENCIL_EDIT);
 }
 
 static void TRANSFORM_OT_resize(struct wmOperatorType *ot)
@@ -601,7 +605,7 @@ static void TRANSFORM_OT_resize(struct wmOperatorType *ot)
 
 	RNA_def_float_vector(ot->srna, "value", 3, VecOne, -FLT_MAX, FLT_MAX, "Vector", "", -FLT_MAX, FLT_MAX);
 
-	Transform_Properties(ot, P_CONSTRAINT | P_PROPORTIONAL | P_MIRROR | P_GEO_SNAP | P_OPTIONS);
+	Transform_Properties(ot, P_CONSTRAINT | P_PROPORTIONAL | P_MIRROR | P_GEO_SNAP | P_OPTIONS | P_GPENCIL_EDIT);
 }
 
 static int skin_resize_poll(bContext *C)
@@ -655,7 +659,7 @@ static void TRANSFORM_OT_trackball(struct wmOperatorType *ot)
 	prop = RNA_def_float_vector(ot->srna, "value", 2, NULL, -FLT_MAX, FLT_MAX, "Angle", "", -FLT_MAX, FLT_MAX);
 	RNA_def_property_subtype(prop, PROP_ANGLE);
 
-	Transform_Properties(ot, P_PROPORTIONAL | P_MIRROR | P_SNAP);
+	Transform_Properties(ot, P_PROPORTIONAL | P_MIRROR | P_SNAP | P_GPENCIL_EDIT);
 }
 
 static void TRANSFORM_OT_rotate(struct wmOperatorType *ot)
@@ -678,7 +682,7 @@ static void TRANSFORM_OT_rotate(struct wmOperatorType *ot)
 	prop = RNA_def_float(ot->srna, "value", 0.0f, -FLT_MAX, FLT_MAX, "Angle", "", -M_PI * 2, M_PI * 2);
 	RNA_def_property_subtype(prop, PROP_ANGLE);
 
-	Transform_Properties(ot, P_AXIS | P_CONSTRAINT | P_PROPORTIONAL | P_MIRROR | P_GEO_SNAP);
+	Transform_Properties(ot, P_AXIS | P_CONSTRAINT | P_PROPORTIONAL | P_MIRROR | P_GEO_SNAP | P_GPENCIL_EDIT);
 }
 
 static void TRANSFORM_OT_tilt(struct wmOperatorType *ot)
@@ -724,7 +728,7 @@ static void TRANSFORM_OT_bend(struct wmOperatorType *ot)
 
 	RNA_def_float_rotation(ot->srna, "value", 1, NULL, -FLT_MAX, FLT_MAX, "Angle", "", -M_PI * 2, M_PI * 2);
 
-	Transform_Properties(ot, P_PROPORTIONAL | P_MIRROR | P_SNAP);
+	Transform_Properties(ot, P_PROPORTIONAL | P_MIRROR | P_SNAP | P_GPENCIL_EDIT);
 }
 
 static void TRANSFORM_OT_shear(struct wmOperatorType *ot)
@@ -744,7 +748,7 @@ static void TRANSFORM_OT_shear(struct wmOperatorType *ot)
 
 	RNA_def_float(ot->srna, "value", 0, -FLT_MAX, FLT_MAX, "Offset", "", -FLT_MAX, FLT_MAX);
 
-	Transform_Properties(ot, P_PROPORTIONAL | P_MIRROR | P_SNAP);
+	Transform_Properties(ot, P_PROPORTIONAL | P_MIRROR | P_SNAP | P_GPENCIL_EDIT);
 	// XXX Shear axis?
 }
 
@@ -806,7 +810,7 @@ static void TRANSFORM_OT_tosphere(struct wmOperatorType *ot)
 
 	RNA_def_float_factor(ot->srna, "value", 0, 0, 1, "Factor", "", 0, 1);
 
-	Transform_Properties(ot, P_PROPORTIONAL | P_MIRROR | P_SNAP);
+	Transform_Properties(ot, P_PROPORTIONAL | P_MIRROR | P_SNAP | P_GPENCIL_EDIT);
 }
 
 static void TRANSFORM_OT_mirror(struct wmOperatorType *ot)
@@ -824,7 +828,7 @@ static void TRANSFORM_OT_mirror(struct wmOperatorType *ot)
 	ot->cancel = transform_cancel;
 	ot->poll   = ED_operator_screenactive;
 
-	Transform_Properties(ot, P_CONSTRAINT | P_PROPORTIONAL);
+	Transform_Properties(ot, P_CONSTRAINT | P_PROPORTIONAL | P_GPENCIL_EDIT);
 }
 
 static void TRANSFORM_OT_edge_slide(struct wmOperatorType *ot)