Basic snapping in node transform operator.

Snapping actually was working already, but grid spacing was set to 1.0, which is basically pixel size in the node editor. Increased this to 1x grid step for fine snapping and 5x grid step for rough snapping.

Grid drawing in node editor now draws 2 levels in slightly different shades to indicate the different snapping modes better.

Node editor also supports the general use_snap tool setting to enable automatic snapping during transform. For now only the incremental snapping is supported, in future could be extended to enable alignment between nodes in a number of ways.

6 files changed, 63 insertions, 2 deletions

diff --git a/release/scripts/startup/bl_ui/space_node.py b/release/scripts/startup/bl_ui/space_node.py
index 70f0f300f86..d7f25a597ed 100644
--- a/release/scripts/startup/bl_ui/space_node.py
+++ b/release/scripts/startup/bl_ui/space_node.py
@@ -32,6 +32,7 @@ class NODE_HT_header(Header):
         snode = context.space_data
         snode_id = snode.id
         id_from = snode.id_from
+        toolsettings = context.tool_settings
 
         row = layout.row(align=True)
         row.template_header()
@@ -86,6 +87,10 @@ class NODE_HT_header(Header):
 
         layout.separator()
 
+        # Snap
+        row = layout.row(align=True)
+        row.prop(toolsettings, "use_snap", text="")
+
         layout.template_running_jobs()
 
 
diff --git a/source/blender/editors/include/UI_view2d.h b/source/blender/editors/include/UI_view2d.h
index 469388219d6..5039a30b61a 100644
--- a/source/blender/editors/include/UI_view2d.h
+++ b/source/blender/editors/include/UI_view2d.h
@@ -166,6 +166,7 @@ void UI_view2d_view_restore(const struct bContext *C);
 View2DGrid *UI_view2d_grid_calc(struct Scene *scene, struct View2D *v2d, short xunits, short xclamp, short yunits, short yclamp, int winx, int winy);
 void UI_view2d_grid_draw(struct View2D *v2d, View2DGrid *grid, int flag);
 void UI_view2d_constant_grid_draw(struct View2D *v2d);
+void UI_view2d_multi_grid_draw(struct View2D *v2d, float step, int level_size, int totlevels);
 void UI_view2d_grid_size(View2DGrid *grid, float *r_dx, float *r_dy);
 void UI_view2d_grid_free(View2DGrid *grid);
 
diff --git a/source/blender/editors/interface/view2d.c b/source/blender/editors/interface/view2d.c
index 51e1b30f0bf..9a783b461a0 100644
--- a/source/blender/editors/interface/view2d.c
+++ b/source/blender/editors/interface/view2d.c
@@ -1328,6 +1328,54 @@ void UI_view2d_constant_grid_draw(View2D *v2d)
 	glEnd();
 }
 
+/* Draw a multi-level grid in given 2d-region */
+void UI_view2d_multi_grid_draw(View2D *v2d, float step, int level_size, int totlevels)
+{
+	int offset = -10;
+	float lstep = step;
+	int level;
+	
+	for (level = 0; level < totlevels; ++level) {
+		int i;
+		float start;
+		
+		UI_ThemeColorShade(TH_BACK, offset);
+		
+		i = (v2d->cur.xmin >= 0.0f ? -(int)(-v2d->cur.xmin / lstep) : (int)(v2d->cur.xmin / lstep));
+		start = i * lstep;
+		
+		glBegin(GL_LINES);
+		for (; start < v2d->cur.xmax; start += lstep, ++i) {
+			if (i == 0 || (level < totlevels-1 && i % level_size == 0))
+				continue;
+			glVertex2f(start, v2d->cur.ymin);
+			glVertex2f(start, v2d->cur.ymax);
+		}
+		
+		i = (v2d->cur.ymin >= 0.0f ? -(int)(-v2d->cur.ymin / lstep) : (int)(v2d->cur.ymin / lstep));
+		start = i * lstep;
+		
+		for (; start < v2d->cur.ymax; start += lstep, ++i) {
+			if (i == 0 || (level < totlevels-1 && i % level_size == 0))
+				continue;
+			glVertex2f(v2d->cur.xmin, start);
+			glVertex2f(v2d->cur.xmax, start);
+		}
+		
+		/* X and Y axis */
+		UI_ThemeColorShade(TH_BACK, offset-8);
+		glVertex2f(0.0f, v2d->cur.ymin);
+		glVertex2f(0.0f, v2d->cur.ymax);
+		glVertex2f(v2d->cur.xmin, 0.0f);
+		glVertex2f(v2d->cur.xmax, 0.0f);
+		
+		glEnd();
+		
+		lstep *= level_size;
+		offset -= 6;
+	}
+}
+
 /* the price we pay for not exposting structs :( */
 void UI_view2d_grid_size(View2DGrid *grid, float *r_dx, float *r_dy)
 {
diff --git a/source/blender/editors/space_node/node_draw.c b/source/blender/editors/space_node/node_draw.c
index c65bbd6e15f..f9aa0dfd582 100644
--- a/source/blender/editors/space_node/node_draw.c
+++ b/source/blender/editors/space_node/node_draw.c
@@ -1095,7 +1095,9 @@ void drawnodespace(const bContext *C, ARegion *ar, View2D *v2d)
 	snode->aspect= (v2d->cur.xmax - v2d->cur.xmin)/((float)ar->winx);
 	// XXX snode->curfont= uiSetCurFont_ext(snode->aspect);
 
-	UI_view2d_constant_grid_draw(v2d);
+	/* grid */
+	UI_view2d_multi_grid_draw(v2d, 25.0f, 5, 2);
+
 	/* backdrop */
 	draw_nodespace_back_pix(ar, snode, color_manage);
 	
diff --git a/source/blender/editors/transform/transform.c b/source/blender/editors/transform/transform.c
index 9965214af6f..4dee3514142 100644
--- a/source/blender/editors/transform/transform.c
+++ b/source/blender/editors/transform/transform.c
@@ -3542,6 +3542,11 @@ void initTranslation(TransInfo *t)
 		t->snap[1] = 0.125f;
 		t->snap[2] = 0.0625f;
 	}
+	else if (t->spacetype == SPACE_NODE) {
+		t->snap[0] = 0.0f;
+		t->snap[1] = 125.0f;
+		t->snap[2] = 25.0f;
+	}
 	else {
 		t->snap[0] = 0.0f;
 		t->snap[1] = t->snap[2] = 1.0f;
diff --git a/source/blender/editors/transform/transform_snap.c b/source/blender/editors/transform/transform_snap.c
index 90b67951614..d485b886ea7 100644
--- a/source/blender/editors/transform/transform_snap.c
+++ b/source/blender/editors/transform/transform_snap.c
@@ -459,7 +459,7 @@ void initSnapping(TransInfo *t, wmOperator *op)
 	}
 	/* use scene defaults only when transform is modal */
 	else if (t->flag & T_MODAL) {
-		if (ELEM(t->spacetype, SPACE_VIEW3D, SPACE_IMAGE)) {
+		if (ELEM3(t->spacetype, SPACE_VIEW3D, SPACE_IMAGE, SPACE_NODE)) {
 			if (ts->snap_flag & SCE_SNAP) {
 				t->modifiers |= MOD_SNAP;
 			}