[Bf-blender-cvs] [7463892] GPencil_Editing_Stage3: GP Sculpt: Initial implementation of "Pinch" Brush

[Joshua Leung]

Commit: 74638921a6ad8b235ef1a22a61944668a6824a4f
Author: Joshua Leung
Date:   Wed Jul 15 02:42:49 2015 +1200
Branches: GPencil_Editing_Stage3
https://developer.blender.org/rB74638921a6ad8b235ef1a22a61944668a6824a4f

GP Sculpt: Initial implementation of "Pinch" Brush

This brush draws all the points inwards towards the midpoint of the brush.
I'm not sure if this brush is really that useful or not, so I'll leave it
as-is for now.

Watch out for how strong you set the brush to be; even with 0.3, you can already
get some really strong/rapidly changing results.

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

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

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

diff --git a/source/blender/editors/gpencil/gpencil_brush.c b/source/blender/editors/gpencil/gpencil_brush.c
index 9b985a6..354ab82 100644
--- a/source/blender/editors/gpencil/gpencil_brush.c
+++ b/source/blender/editors/gpencil/gpencil_brush.c
@@ -395,6 +395,7 @@ static void gp_brush_grab_calc_dvec(tGP_BrushEditData *gso)
 {
 	/* Convert mouse-movements to movement vector */
 	// TODO: incorporate pressure into this?
+	// XXX: screen-space strokes in 3D space will suffer!
 	if (gso->sa->spacetype == SPACE_VIEW3D) {
 		View3D *v3d = gso->sa->spacedata.first;
 		RegionView3D *rv3d = gso->ar->regiondata;
@@ -471,6 +472,69 @@ static bool gp_brush_push_apply(tGP_BrushEditData *gso, bGPDstroke *gps, int i,
 	return true;
 }
 
+/* ----------------------------------------------- */
+/* Pinch Brush */
+
+/* Compute reference midpoint for the brush - this is what we'll be moving towards */
+static void gp_brush_calc_midpoint(tGP_BrushEditData *gso)
+{
+	if (gso->sa->spacetype == SPACE_VIEW3D) {
+		/* Convert mouse position to 3D space
+		 * See: gpencil_paint.c :: gp_stroke_convertcoords()
+		 */
+		View3D *v3d = gso->sa->spacedata.first;
+		RegionView3D *rv3d = gso->ar->regiondata;
+		float *rvec = ED_view3d_cursor3d_get(gso->scene, v3d);
+		float zfac = ED_view3d_calc_zfac(rv3d, rvec, NULL);
+		
+		float mval_f[2] = {UNPACK2(gso->mval)};
+		float mval_prj[2];
+		float dvec[3];
+		
+		
+		if (ED_view3d_project_float_global(gso->ar, rvec, mval_prj, V3D_PROJ_TEST_NOP) == V3D_PROJ_RET_OK) {
+			sub_v2_v2v2(mval_f, mval_prj, mval_f);
+			ED_view3d_win_to_delta(gso->ar, mval_f, dvec, zfac);
+			sub_v3_v3v3(gso->dvec, rvec, dvec);
+		}
+		else {
+			zero_v3(gso->dvec);
+		}
+	}
+	else {
+		/* Just 2D coordinates */
+		// XXX: fix View2D offsets later
+		gso->dvec[0] = (float)gso->mval[0];
+		gso->dvec[1] = (float)gso->mval[1];
+		gso->dvec[2] = 0.0f;
+	}
+}
+
+/* Shrink distance between midpoint and this point... */
+static bool gp_brush_pinch_apply(tGP_BrushEditData *gso, bGPDstroke *gps, int i,
+                                 const int radius, const int co[2])
+{
+	bGPDspoint *pt = gps->points + i;
+	float inf = gp_brush_influence_calc(gso, radius, co);
+	
+	float vec[3];
+	float fac;
+	
+	/* 1) Make this point relative to the cursor/midpoint (dvec) */
+	sub_v3_v3v3(vec, &pt->x, gso->dvec);
+	
+	/* 2) Shrink the distance by pulling the point towards the midpoint
+	 *    (0.0 = at midpoint, 1 = at edge of brush region) 
+	 */
+	fac = 1.0f - (inf * inf); /* squared to temper the effect... */
+	mul_v3_fl(vec, fac);
+	
+	/* 3) Translate back to original space, with the shrinkage applied */
+	add_v3_v3v3(&pt->x, gso->dvec, vec);
+	
+	/* done */
+	return true;
+}
 
 /* ************************************************ */
 /* Cursor drawing */
@@ -736,6 +800,13 @@ static void gpsculpt_brush_apply(bContext *C, wmOperator *op, PointerRNA *itempt
 			break;
 		}
 		
+		case GP_EDITBRUSH_TYPE_PINCH: /* Pinch points */
+		{
+			/* calculate midpoint of the brush (in data space) */
+			gp_brush_calc_midpoint(gso);
+			break;
+		}
+		
 		default:
 			break;
 	}
@@ -781,6 +852,12 @@ static void gpsculpt_brush_apply(bContext *C, wmOperator *op, PointerRNA *itempt
 			}
 			break;
 			
+			case GP_EDITBRUSH_TYPE_PINCH: /* Pinch points */
+			{
+				changed |= gpsculpt_brush_do_stroke(gso, gps, gp_brush_pinch_apply);
+			}
+			break;
+			
 			case GP_EDITBRUSH_TYPE_RANDOMISE: /* Apply jitter */
 			{
 				//changed |= gpsculpt_brush_do_stroke(gso, gps, apply);
@@ -881,7 +958,7 @@ static int gpsculpt_brush_invoke(bContext *C, wmOperator *op, const wmEvent *eve
 	
 	gso = op->customdata;
 	
-	/* initialise type-specific data */
+	/* initialise type-specific data (used for the entire session) */
 	switch (gso->brush_type) {
 		case GP_EDITBRUSH_TYPE_GRAB:
 			/* initialise the cache needed for this brush */