own recent commits caused crash with the grease pencil in camera view, always pass rv3d argument now.

also found a bug where hex_to_rgb could use un-initialized memory.

source/blender/blenlib/intern/math_color.c

@@ -194,6 +194,10 @@ void hex_to_rgb(char *hexcol, float *r, float *g, float *b)
 		CLAMP(*g, 0.0f, 1.0f);
 		CLAMP(*b, 0.0f, 1.0f);
 	}
+	else {
+		/* avoid using un-initialized vars */
+		*r= *g= *b= 0.0f;
+	}
 }
 
 void rgb_to_hsv(float r, float g, float b, float *lh, float *ls, float *lv)

source/blender/editors/gpencil/gpencil_edit.c

@@ -453,7 +453,7 @@ static int gp_camera_view_subrect(bContext *C, rctf *subrect)
 
 		/* for camera view set the subrect */
 		if (rv3d->persp == RV3D_CAMOB) {
-			ED_view3d_calc_camera_border(scene, ar, v3d, NULL, subrect, -1); /* negative shift */
+			ED_view3d_calc_camera_border(scene, ar, v3d, rv3d, subrect, -1); /* negative shift */
 			return 1;
 		}
 	}

source/blender/editors/gpencil/gpencil_paint.c

@@ -1131,7 +1131,7 @@ static void gp_paint_initstroke (tGPsdata *p, short paintmode)
 
 			/* for camera view set the subrect */
 			if (rv3d->persp == RV3D_CAMOB) {
-				ED_view3d_calc_camera_border(p->scene, p->ar, v3d, NULL, &p->subrect_data, -1); /* negative shift */
+				ED_view3d_calc_camera_border(p->scene, p->ar, v3d, rv3d, &p->subrect_data, -1); /* negative shift */
 				p->subrect= &p->subrect_data;
 			}
 		}

source/blender/editors/space_view3d/view3d_draw.c

@@ -876,9 +876,6 @@ void ED_view3d_calc_camera_border(Scene *scene, ARegion *ar, View3D *v3d, Region
 	float dx= 0.0f, dy= 0.0f;
 	
 	view3d_viewborder_size_get(scene, ar, size);
-	
-	if (rv3d == NULL)
-		rv3d = ar->regiondata;
 
 	size[0]= size[0]*zoomfac;
 	size[1]= size[1]*zoomfac;