[Bf-blender-cvs] [16e0f2fa866] greasepencil-object: Implement brush eraser quick switch

[Antonio Vazquez]

Commit: 16e0f2fa8660d278dce8701f466bafe628e5b872
Author: Antonio Vazquez
Date:   Sat Mar 3 10:39:33 2018 +0100
Branches: greasepencil-object
https://developer.blender.org/rB16e0f2fa8660d278dce8701f466bafe628e5b872

Implement brush eraser quick switch

This eraser switch works very similar to smooth sculpt brush in object sculpt mode.

When the user press Ctrl, the current drawing brush is replaced by the default eraser brush while hold the key.

After release the override key, the brush back to the drawing brush.

===================================================================

M	source/blender/editors/gpencil/gpencil_paint.c

===================================================================

diff --git a/source/blender/editors/gpencil/gpencil_paint.c b/source/blender/editors/gpencil/gpencil_paint.c
index 91a9d362e5e..4110a05a673 100644
--- a/source/blender/editors/gpencil/gpencil_paint.c
+++ b/source/blender/editors/gpencil/gpencil_paint.c
@@ -178,6 +178,7 @@ typedef struct tGPsdata {
 	PaletteColor *palettecolor; /* current palette color */
 	
 	bGPDbrush *brush;    /* current drawing brush */
+	bGPDbrush *eraser;   /* default eraser brush */
 	short straight[2];   /* 1: line horizontal, 2: line vertical, other: not defined, second element position */
 	int lock_axis;       /* lock drawing to one axis */
 	bool disable_fill;   /* the stroke is no fill mode */
@@ -1171,7 +1172,7 @@ static void gp_stroke_eraser_dostroke(tGPsdata *p,
                                       const int radius, const rcti *rect)
 {
 	Object *obact = (Object *)p->ownerPtr.data;
-	bGPDbrush *brush = p->brush;
+	bGPDbrush *eraser = p->eraser;
 	bGPDspoint *pt1, *pt2;
 	int pc1[2] = {0};
 	int pc2[2] = {0};
@@ -1201,7 +1202,7 @@ static void gp_stroke_eraser_dostroke(tGPsdata *p,
 			}
 		}
 	}
-	else if ((p->flags & GP_PAINTFLAG_STROKE_ERASER) || (brush->eraser_mode == GP_BRUSH_ERASER_STROKE)) {
+	else if ((p->flags & GP_PAINTFLAG_STROKE_ERASER) || (eraser->eraser_mode == GP_BRUSH_ERASER_STROKE)) {
 		for (i = 0; (i + 1) < gps->totpoints; i++) {
 
 			/* only process if it hasn't been masked out... */
@@ -1291,11 +1292,11 @@ static void gp_stroke_eraser_dostroke(tGPsdata *p,
 						pt2->pressure -= gp_stroke_eraser_calc_influence(p, mval, radius, pc2) * strength / 2.0f;
 						
 						/* 2) Tag any point with overly low influence for removal in the next pass */
-						if ((pt1->pressure < cull_thresh) || (p->flags & GP_PAINTFLAG_HARD_ERASER) || (brush->eraser_mode == GP_BRUSH_ERASER_HARD)) {
+						if ((pt1->pressure < cull_thresh) || (p->flags & GP_PAINTFLAG_HARD_ERASER) || (eraser->eraser_mode == GP_BRUSH_ERASER_HARD)) {
 							pt1->flag |= GP_SPOINT_TAG;
 							do_cull = true;
 						}
-						if ((pt2->pressure < cull_thresh) || (p->flags & GP_PAINTFLAG_HARD_ERASER) || (brush->eraser_mode == GP_BRUSH_ERASER_HARD)) {
+						if ((pt2->pressure < cull_thresh) || (p->flags & GP_PAINTFLAG_HARD_ERASER) || (eraser->eraser_mode == GP_BRUSH_ERASER_HARD)) {
 							pt2->flag |= GP_SPOINT_TAG;
 							do_cull = true;
 						}
@@ -1399,6 +1400,40 @@ static void gp_session_validatebuffer(tGPsdata *p)
 	}
 }
 
+/* helper to get default eraser and create one if no eraser brush */
+static bGPDbrush *gp_get_default_eraser(ToolSettings *ts)
+{
+	bGPDbrush *brush_dft = NULL;
+	for (bGPDbrush *brush = ts->gp_brushes.first; brush; brush = brush->next) {
+		if ((brush->type == GP_BRUSH_TYPE_ERASE)) {
+			/* save first eraser to use later if no default */
+			if (brush_dft == NULL) {
+				brush_dft = brush;
+			}
+			/* found default */
+			if(brush->flag & GP_BRUSH_DEFAULT_ERASER) {
+				return brush;
+			}
+		}
+	}
+
+	/* if no default, but exist eraser brush, return this */
+	if (brush_dft) {
+		return brush_dft;
+	}
+	/* create a new soft eraser brush */
+	else {
+		brush_dft = BKE_gpencil_brush_addnew(ts, "Soft Eraser", false);
+		brush_dft->thickness = 30.0f;
+		brush_dft->flag |= (GP_BRUSH_ENABLE_CURSOR | GP_BRUSH_DEFAULT_ERASER);
+		brush_dft->icon = GPBRUSH_ERASE;
+		brush_dft->type = GP_BRUSH_TYPE_ERASE;
+		brush_dft->eraser_mode = GP_BRUSH_ERASER_SOFT;
+
+		return brush_dft;
+	}
+}
+
 /* initialize a drawing brush */
 static void gp_init_drawing_brush(ToolSettings *ts, tGPsdata *p)
 {
@@ -1421,8 +1456,9 @@ static void gp_init_drawing_brush(ToolSettings *ts, tGPsdata *p)
 
 	/* asign to temp tGPsdata */
 	p->brush = brush;
-	/* use radius as eraser */
-	p->radius = (short)brush->thickness;
+	p->eraser = gp_get_default_eraser(ts);
+	/* use radius of eraser */
+	p->radius = (short)p->eraser->thickness;
 }
 
 
@@ -1988,7 +2024,7 @@ static void gpencil_draw_eraser(bContext *C, int x, int y, void *p_ptr)
 	tGPsdata *p = (tGPsdata *)p_ptr;
 
 	if ((p) && (p->paintmode == GP_PAINTMODE_ERASER)) {
-		ED_gpencil_brush_draw_eraser(C, p->brush, x, y);
+		ED_gpencil_brush_draw_eraser(C, p->eraser, x, y);
 	}
 }