Grease Pencil: WIP commit (nothing new)

Just a little commit so that I can transfer some changes back over to laptop. 
* Line drawing should now be improved for most cases, but acute angles still need more work to reduce 'shrinking' artifacts. As such, this is still hidden behind 'rt' setting
* Preparation work for Grease-Pencil in Image Editor, and also 'Stick to View' for Image/Sequence editors.

6 files changed, 147 insertions, 84 deletions

diff --git a/source/blender/include/BDR_gpencil.h b/source/blender/include/BDR_gpencil.h
index eb749cf28ec..7340a2e44e0 100644
--- a/source/blender/include/BDR_gpencil.h
+++ b/source/blender/include/BDR_gpencil.h
@@ -43,7 +43,6 @@ struct bGPDframe;
 /* Temporary 'Stroke Point' data */
 typedef struct tGPspoint {
 	short x, y;				/* x and y coordinates of cursor (in relative to area) */
-	float xf, yf;			/* same as x and y, but as floats */
 	float pressure;			/* pressure of tablet at this point */
 } tGPspoint;
 
diff --git a/source/blender/include/BIF_drawgpencil.h b/source/blender/include/BIF_drawgpencil.h
index 418446313df..eacafce058d 100644
--- a/source/blender/include/BIF_drawgpencil.h
+++ b/source/blender/include/BIF_drawgpencil.h
@@ -28,15 +28,18 @@
 #ifndef BIF_DRAWGPENCIL_H
 #define BIF_DRAWGPENCIL_H
 
+
+struct bGPdata;
 struct ScrArea;
 struct View3D;
 struct SpaceNode;
 struct SpaceSeq;
-struct bGPdata;
 struct uiBlock;
+struct ImBuf;
 
 short draw_gpencil_panel(struct uiBlock *block, struct bGPdata *gpd, struct ScrArea *sa); 
 
+void draw_gpencil_2dimage(struct ScrArea *sa, struct ImBuf *ibuf);
 void draw_gpencil_2dview(struct ScrArea *sa, short onlyv2d);
 void draw_gpencil_3dview(struct ScrArea *sa, short only3d);
 void draw_gpencil_oglrender(struct View3D *v3d, int winx, int winy);
diff --git a/source/blender/makesdna/DNA_gpencil_types.h b/source/blender/makesdna/DNA_gpencil_types.h
index dca4e28688d..13d412c2c42 100644
--- a/source/blender/makesdna/DNA_gpencil_types.h
+++ b/source/blender/makesdna/DNA_gpencil_types.h
@@ -59,8 +59,10 @@ typedef struct bGPDstroke {
 #define GP_STROKE_3DSPACE		(1<<0)
 	/* stroke is in 2d-space */
 #define GP_STROKE_2DSPACE		(1<<1)
+	/* stroke is in 2d-space (but with special 'image' scaling) */
+#define GP_STROKE_2DIMAGE		(1<<2)
 	/* stroke is an "eraser" stroke */
-#define GP_STROKE_ERASER		(1<<2)
+#define GP_STROKE_ERASER		(1<<15)
 
 
 /* Grease-Pencil Annotations - 'Frame'
diff --git a/source/blender/makesdna/DNA_space_types.h b/source/blender/makesdna/DNA_space_types.h
index a8694dfb7f5..39d457058c1 100644
--- a/source/blender/makesdna/DNA_space_types.h
+++ b/source/blender/makesdna/DNA_space_types.h
@@ -247,6 +247,7 @@ typedef struct SpaceImage {
 	float xof, yof;					/* user defined offset, image is centered */
 	float centx, centy;				/* storage for offset while render drawing */
 	
+	struct bGPdata *gpd;			/* grease pencil data */
 } SpaceImage;
 
 typedef struct SpaceNla {
diff --git a/source/blender/src/drawgpencil.c b/source/blender/src/drawgpencil.c
index ee28049e2c0..22f7fdc32f0 100644
--- a/source/blender/src/drawgpencil.c
+++ b/source/blender/src/drawgpencil.c
@@ -37,6 +37,9 @@
 
 #include "MEM_guardedalloc.h"
 
+#include "IMB_imbuf.h"
+#include "IMB_imbuf_types.h"
+
 #include "BMF_Api.h"
 
 #include "BLI_arithb.h"
@@ -317,6 +320,7 @@ enum {
 	GP_DRAWDATA_NOSTATUS 	= (1<<0),	/* don't draw status info */
 	GP_DRAWDATA_ONLY3D		= (1<<1),	/* only draw 3d-strokes */
 	GP_DRAWDATA_ONLYV2D		= (1<<2),	/* only draw 'canvas' strokes */
+	GP_DRAWDATA_ONLYI2D		= (1<<3),	/* only draw 'image' strokes */
 };
 
 /* ----- Tool Buffer Drawing ------ */
@@ -466,18 +470,22 @@ static void gp_draw_stroke (bGPDspoint *points, int totpoints, short thickness,
 	}
 	else { /* tesselation code: currently only enabled with rt != 0 */
 		bGPDspoint *pt1, *pt2;
-		float p0[2], p1[2], pm[2];
+		float pm[2];
 		int i;
+		short n;
 		
 		glShadeModel(GL_FLAT);
-		glBegin(GL_QUAD_STRIP);
+		
+		glPointSize(3.0f); // temp
+		
+		for (n= 0; n < 2; n++) { // temp
+		glBegin((n)?GL_POINTS:GL_QUADS);
 		
 		for (i=0, pt1=points, pt2=points+1; i < (totpoints-1); i++, pt1++, pt2++) {
 			float s0[2], s1[2];		/* segment 'center' points */
 			float t0[2], t1[2];		/* tesselated coordinates */
 			float m1[2], m2[2];		/* gradient and normal */
-			float pthick, dist;		/* thickness at segment point, and length of segment */
-			float sminorang;		/* minor angle between strokes */
+			float pthick;			/* thickness at segment point */
 			
 			/* get x and y coordinates from points */
 			if (sflag & GP_STROKE_2DSPACE) {
@@ -494,94 +502,74 @@ static void gp_draw_stroke (bGPDspoint *points, int totpoints, short thickness,
 			/* calculate gradient and normal - 'angle'=(ny/nx) */
 			m1[1]= s1[1] - s0[1];		
 			m1[0]= s1[0] - s0[0];
-			dist = Vec2Lenf(s0, s1);
-			m2[1]= -(m1[0]) / dist;
-			m2[0]= m1[1] / dist;
+			m2[1]= -m1[0];
+			m2[0]= m1[1];
+			Normalize2(m2);
 			
-			/* if the first segment, initialise the first segment using segment's normal */
-			if (i == 0) {	
-				pthick= (pt1->pressure * thickness);
-				
+			/* always use pressure from first point here */
+			pthick= (pt1->pressure * thickness);
+			
+			/* if the first segment, start of segment is segment's normal */
+			if (i == 0) {
 				// TODO: also draw/do a round end-cap first
 				
-				p0[0]= s0[0] - (pthick * m2[0]);
-				p0[1]= s0[1] - (pthick * m2[1]);
-				p1[0]= s1[0] + (pthick * m2[0]);
-				p1[1]= s1[1] + (pthick * m2[1]);
+				/* calculate points for start of segment */
+				t0[0]= s0[0] - (pthick * m2[0]);
+				t0[1]= s0[1] - (pthick * m2[1]);
+				t1[0]= s0[0] + (pthick * m2[0]);
+				t1[1]= s0[1] + (pthick * m2[1]);
 				
-				Vec2Copyf(pm, m1);
+				/* draw this line only once */
+				glVertex2fv(t0);
+				glVertex2fv(t1);
 			}
-			
-			/* if the minor angle between the current segment and the previous one is less than 90 degrees */
-			if (i)
-				sminorang= NormalizedVecAngle2_2D(pm, m1);
-			else
-				sminorang= 0.0f;
-			
-			if ((IS_EQ(sminorang, 0)==0) && (abs(sminorang) < M_PI_2) ) 
-			{
-				float closep[2];
+			/* if not the first segment, use bisector of angle between segments */
+			else {
+				float mb[2]; 	/* bisector normal */
 				
-				/* recalculate startpoint of segment, where the new start-line:
-				 * 	- starts a new gl-quad-strip
-				 *	- uses the vert of old startpoint closer to our endpoint
-				 *	- distance between new startpoints = distance between old startpoints
-				 *	- new startpoints occur on same gradient as old segment does (has potential for some 'minor' overlap, but ok)
-				 */
+				/* calculate gradient of bisector (as average of normals) */
+				mb[0]= (pm[0] + m2[0]) / 2;
+				mb[1]= (pm[1] + m2[1]) / 2;
+				Normalize2(mb);
 				
-				/* find the closer vertex, and distance between startpoints */
-				if (Vec2Lenf(p0, s1) > Vec2Lenf(p1, s1))
-					Vec2Copyf(closep, p1);
-				else
-					Vec2Copyf(closep, p0);
-					
-				/* determine which side this closer vertex should be on */
-				pthick= (pt1->pressure * thickness * 2);
-				if ( ((closep[0] - s0[0]) > 0) || ((closep[1] - s0[1]) > 0) ) {
-					/* assumes this is the 'second' point, (i.e. the 'plus' one), so the other is subtracting */
-					p0[0]= closep[0] - (pthick * pm[0]);
-					p0[1]= closep[1] - (pthick * pm[1]);
-					p1[0]= closep[0];
-					p1[1]= closep[1];
-				}
-				else if ( ((closep[0] - s0[0]) < 0) || ((closep[1] - s0[1]) < 0) ) {
-					/* assumes this is the 'first' point, (i.e. the 'minus' one), so the other is adding */
-					p0[0]= closep[0];
-					p0[1]= closep[1];
-					p1[0]= closep[0] + (pthick * pm[0]);
-					p1[1]= closep[1] + (pthick * pm[1]);
-				}
+				/* calculate points for start of segment */
+				// FIXME: do we need extra padding for acute angles?
+				t0[0]= s0[0] - (pthick * mb[0]);
+				t0[1]= s0[1] - (pthick * mb[1]);
+				t1[0]= s0[0] + (pthick * mb[0]);
+				t1[1]= s0[1] + (pthick * mb[1]);
 				
-				/* reset gl-states! */
-				glEnd();
-				glBegin(GL_QUAD_STRIP);				
+				/* draw this line twice (once for end of current segment, and once for start of next) */
+				glVertex2fv(t1);
+				glVertex2fv(t0);
+				glVertex2fv(t0);
+				glVertex2fv(t1);
 			}
 			
-			/* do the end of this segment */
-			pthick= (pt2->pressure * thickness);
-			t0[0] = s1[0] - (pthick * m2[0]);
-			t0[1] = s1[1] - (pthick * m2[1]);
-			t1[0] = s1[0] + (pthick * m2[0]);
-			t1[1] = s1[1] + (pthick * m2[1]);
-			
-			/* draw this segment */
-			glVertex2f(p0[0], p0[1]);
-			glVertex2f(p1[0], p1[1]);
-			glVertex2f(t0[0], t0[1]);
-			glVertex2f(t1[0], t1[1]);
-			
-			// TODO: draw end cap if last segment
+			/* if last segment, also draw end of segment (defined as segment's normal) */
 			if (i == totpoints-2) {
-			
+				/* for once, we use second point's pressure (otherwise it won't be drawn) */
+				pthick= (pt2->pressure * thickness);
+				
+				/* calculate points for end of segment */
+				t0[0]= s1[0] - (pthick * m2[0]);
+				t0[1]= s1[1] - (pthick * m2[1]);
+				t1[0]= s1[0] + (pthick * m2[0]);
+				t1[1]= s1[1] + (pthick * m2[1]);
+				
+				/* draw this line only once */
+				glVertex2fv(t1);
+				glVertex2fv(t0);
+				
+				// TODO: draw end cap as last step 
 			}
 			
-			/* store current points for next segment to use */
-			Vec2Copyf(p0, t0);
-			Vec2Copyf(p1, t1);
-			Vec2Copyf(pm, m1);
+			/* store stroke's 'natural' normal for next stroke to use */
+			Vec2Copyf(pm, m2);
 		}
 		
 		glEnd();
+		}
 	}
 	
 	/* draw debug points of curve on top? (original stroke points) */
@@ -626,6 +614,10 @@ static void gp_draw_strokes (bGPDframe *gpf, int winx, int winy, int dflag, shor
 			continue;
 		if (!(dflag & GP_DRAWDATA_ONLYV2D) && (gps->flag & GP_STROKE_2DSPACE))
 			continue;
+		if ((dflag & GP_DRAWDATA_ONLYI2D) && !(gps->flag & GP_STROKE_2DIMAGE))
+			continue;
+		if (!(dflag & GP_DRAWDATA_ONLYI2D) && (gps->flag & GP_STROKE_2DIMAGE))
+			continue;
 		if ((gps->points == 0) || (gps->totpoints < 1))
 			continue;
 		
@@ -796,6 +788,22 @@ static void gp_draw_data (bGPdata *gpd, int winx, int winy, int dflag)
 
 /* ----- Grease Pencil Sketches Drawing API ------ */
 
+/* draw grease-pencil sketches to specified 2d-view that uses ibuf corrections */
+void draw_gpencil_2dimage (ScrArea *sa, ImBuf *ibuf)
+{
+	bGPdata *gpd;
+	int dflag = 0;
+	
+	/* check that we have grease-pencil stuff to draw */
+	if (ELEM(NULL, sa, ibuf)) return;
+	gpd= gpencil_data_getactive(sa);
+	if (gpd == NULL) return;
+	
+	/* draw it! */
+	dflag = (GP_DRAWDATA_ONLYI2D|GP_DRAWDATA_NOSTATUS);
+	gp_draw_data(gpd, sa->winx, sa->winy, dflag);
+}
+
 /* draw grease-pencil sketches to specified 2d-view assuming that matrices are already set correctly 
  * Note: this gets called twice - first time with onlyv2d=1 to draw 'canvas' strokes, second time with onlyv2d=0 for screen-aligned strokes
  */
diff --git a/source/blender/src/gpencil.c b/source/blender/src/gpencil.c
index eef21323a44..9b250fc3ec0 100644
--- a/source/blender/src/gpencil.c
+++ b/source/blender/src/gpencil.c
@@ -39,6 +39,9 @@
 
 #include "BMF_Api.h"
 
+#include "IMB_imbuf.h"
+#include "IMB_imbuf_types.h"
+
 #include "BLI_arithb.h"
 #include "BLI_blenlib.h"
 
@@ -312,11 +315,17 @@ bGPdata *gpencil_data_getactive (ScrArea *sa)
 		{
 			SpaceSeq *sseq= sa->spacedata.first;
 			
-			/* only applicable for "Image Preview" mode */
+			/* only applicable for image modes */
 			if (sseq->mainb)
 				return sseq->gpd;
 		}
 			break;
+		case SPACE_IMAGE:
+		{
+			SpaceImage *sima= sa->spacedata.first;
+			return sima->gpd;
+		}
+			break;
 	}
 	
 	/* nothing found */
@@ -379,6 +388,17 @@ short gpencil_data_setactive (ScrArea *sa, bGPdata *gpd)
 			}
 		}
 			break;
+		case SPACE_IMAGE:
+		{
+			SpaceImage *sima= sa->spacedata.first;
+			
+			if (sima->gpd)
+				free_gpencil_data(sima->gpd);
+			sima->gpd= gpd;
+			
+			return 1;
+		}
+			break;
 	}
 	
 	/* failed to add */
@@ -589,7 +609,7 @@ void gpencil_layer_delactive (bGPdata *gpd)
 }
 
 /* ************************************************** */
-/* GREASE-PENCIL EDITING MODE - Tools */
+/* GREASE-PENCIL EDITING - Tools */
 
 /* --------- Data Deletion ---------- */
 
@@ -679,6 +699,7 @@ void gpencil_delete_menu (void)
 typedef struct tGPsdata {
 	ScrArea *sa;		/* area where painting originated */
 	View2D *v2d;		/* needed for GP_STROKE_2DSPACE */
+	ImBuf *ibuf;		/* needed for GP_STROKE_2DIMAGE */
 	
 	bGPdata *gpd;		/* gp-datablock layer comes from */
 	bGPDlayer *gpl;		/* layer we're working on */
@@ -800,6 +821,16 @@ static void gp_session_initpaint (tGPsdata *p)
 			}
 		}
 			break;	
+		case SPACE_IMAGE:
+		{
+			SpaceImage *sima= curarea->spacedata.first;
+			
+			/* set the current area */
+			p->sa= curarea;
+			p->v2d= &sima->v2d;
+			//p->ibuf= BKE_image_get_ibuf(sima->image, &sima->iuser);
+		}
+			break;
 		/* unsupported views */
 		default:
 		{
@@ -869,6 +900,7 @@ static short gp_stroke_filtermval (tGPsdata *p, short mval[2], short pmval[2])
 		return 1;
 	
 	/* check if the distance since the last point is significant enough */
+	// future optimisation: sqrt here may be too slow?
 	else if (sqrt(dx*dx + dy*dy) > MIN_EUCLIDEAN_PX)
 		return 1;
 	
@@ -884,7 +916,7 @@ static void gp_stroke_convertcoords (tGPsdata *p, short mval[], float out[])
 	
 	/* in 3d-space - pt->x/y/z are 3 side-by-side floats */
 	if (gpd->sbuffer_sflag & GP_STROKE_3DSPACE) {
-		short mx=mval[0], my=mval[1];
+		const short mx=mval[0], my=mval[1];
 		float *fp= give_cursor();
 		float dvec[3];
 		
@@ -904,6 +936,26 @@ static void gp_stroke_convertcoords (tGPsdata *p, short mval[], float out[])
 		out[1]= y;
 	}
 	
+	/* 2d - on image 'canvas' (asume that p->v2d is set) */
+	else if ( (gpd->sbuffer_sflag & GP_STROKE_2DIMAGE) && 
+			  (p->v2d) && (p->ibuf) ) 
+	{
+		ImBuf *ibuf= p->ibuf;
+		float x, y;
+		
+		/* convert to 'canvas' coordinates, then adjust for view */
+		areamouseco_to_ipoco(p->v2d, mval, &x, &y);
+		
+		if (ibuf) {
+			out[0]= x*ibuf->x;
+			out[1]= y*ibuf->y;
+		}
+		else {
+			out[0]= x;
+			out[1]= y;
+		}
+	}
+	
 	/* 2d - relative to screen (viewport area) */
 	else {
 		out[0] = (float)(mval[0]) / (float)(p->sa->winx) * 1000;
@@ -927,8 +979,6 @@ static short gp_stroke_addpoint (tGPsdata *p, short mval[2], float pressure)
 	/* store settings */
 	pt->x= mval[0];
 	pt->y= mval[1];
-	pt->xf= (float)mval[0];
-	pt->yf= (float)mval[0];
 	pt->pressure= pressure;
 	
 	/* increment counters */