Fixes and improvements

src/com/modsim/gui/Menu.java

@@ -64,6 +64,8 @@ private void addEditMenu() {
         edit.add(new JMenuItem(Ops.rotateCCW));
         edit.add(new JMenuItem(Ops.rotate180));
         edit.addSeparator();
+        edit.add(new JMenuItem(Ops.toggleSnap));
+        edit.addSeparator();
         edit.add(new JMenuItem(Ops.labelEdit));
 
         app_menu.add(edit);

src/com/modsim/gui/view/View.java

@@ -300,7 +300,7 @@ public void setTool(BaseTool newTool) {
      * @param y Y-coordinate
      */
     public void zoom(int x, int y, double amount) {
-        Vec2 zmPt = ViewUtil.screenToWorld(new Vec2(x, y));
+        Vec2 zmPt = ViewUtil.screenToWorld(new Vec2(x, y), true);
 
         zoom -= zoom * amount * ZOOM_MULTIPLIER;
         if (zoom < minZoom) {

src/com/modsim/gui/view/ViewUtil.java

@@ -27,6 +27,9 @@ public class ViewUtil implements MouseListener, MouseMotionListener, MouseWheelL
     private double oldCX, oldCY;
     private boolean camDrag = false;
 
+    public static boolean snap = true;
+    public static int snapGridSize = 25;
+
     /**
      * Finds a clicked link by approximate (binary-search) closest point on curve
      * @param pt World-space point to check
@@ -208,14 +211,19 @@ public static List<PickableEntity> screenSpace_entitiesWithin(double x, double y
     /**
      * Adjusts an on-screen point to world-space
      */
-    public static Vec2 screenToWorld(Vec2 p) {
+    public static Vec2 screenToWorld(Vec2 p, boolean noSnap) {
         double[] pt = p.asArray();
 
         try {Main.ui.view.wToV.inverseTransform(pt, 0, pt, 0, 1);}
         catch (Exception e) {
             return null;
         }
 
+        if (snap && !noSnap) {
+            pt[0] = snapGridSize*(Math.round(pt[0]/snapGridSize));
+            pt[1] = snapGridSize*(Math.round(pt[1]/snapGridSize));
+        }
+
         return new Vec2(pt);
     }
 
@@ -277,20 +285,22 @@ public void mousePressed(MouseEvent e) {
                 else {
                     Port p = screenSpace_portAt(e.getX(), e.getY());
 
-                    Main.selection.clear();
-
                     //Link behaviour
                     if (p != null) {
+                        Main.selection.clear();
+
                         tool = new MakeLinkTool();
                         Main.ui.view.curTool = tool.lbDown(e.getX(), e.getY(), e.isShiftDown());
                     }
                     else {
                         // Link edit if we haven't hit a module
                         if (targ == null) {
-                            Vec2 worldSpace = screenToWorld(new Vec2(e.getX(), e.getY()));
+                            Vec2 worldSpace = screenToWorld(new Vec2(e.getX(), e.getY()) , true);
                             Link l = worldSpace_linkAt(worldSpace);
 
                             if (l != null) {
+                                Main.selection.clear();
+
                                 tool = new EditLinkTool(l);
                                 Main.ui.view.curTool = tool.mouseMove(e.getX(), e.getY());
                                 return;

src/com/modsim/operations/Ops.java

@@ -2,6 +2,7 @@
 
 import com.modsim.Main;
 import com.modsim.gui.HelpWindow;
+import com.modsim.gui.view.ViewUtil;
 import com.modsim.modules.BaseModule;
 import com.modsim.simulator.PickableEntity;
 import com.modsim.tools.PlaceTool;
@@ -134,7 +135,11 @@ public static void fileNew() {
     }
 
     // Core application actions
-    public static final DesignAction undo, redo, copy, paste, delete, rotateCW, rotateCCW, rotate180,
+    public static final DesignAction
+            undo, redo,
+            copy, paste, delete,
+            rotateCW, rotateCCW, rotate180,
+            toggleSnap,
             labelEdit, labelBig, labelSmall,
             pause, run, step, toggleRun, zoomIn, zoomOut, resetView, toggleAA, open, save, saveAs, fileNew, quit;
 
@@ -204,6 +209,8 @@ public static void fileNew() {
         rotate180 = new DesignAction(event -> doRotate(BaseModule.rotationDir.ROT_180),
                 "Rotate 180");
 
+        toggleSnap = new DesignAction(event -> ViewUtil.snap = !ViewUtil.snap, "Toggle Snap");
+
         // Label editing
         labelEdit = new DesignAction(event -> {
             String labelStr = JOptionPane.showInputDialog(Main.ui.frame, "");

src/com/modsim/tools/EditLinkTool.java

@@ -38,7 +38,7 @@ public EditLinkTool(Link link) {
 
     @Override
     public BaseTool mouseMove(int x, int y) {
-        Vec2 worldPoint = ViewUtil.screenToWorld(new Vec2(x, y));
+        Vec2 worldPoint = ViewUtil.screenToWorld(new Vec2(x, y), false);
 
         CtrlPt pickCtrl = link.path.closestCtrlPt(worldPoint);
         nearbyInfo = link.path.approxClosestPoint(worldPoint, 10);
@@ -65,7 +65,7 @@ public boolean handlesRbDown() {
     public BaseTool rbDown(int x, int y) {
         if (placePoint != null) return this; // do nothing if we're placing a point
 
-        Vec2 worldPoint = ViewUtil.screenToWorld(new Vec2(x, y));
+        Vec2 worldPoint = ViewUtil.screenToWorld(new Vec2(x, y), false);
         CtrlPt pickCtrl = link.path.closestCtrlPt(worldPoint);
 
         if (pickCtrl != null && pickCtrl.pos.dist(worldPoint) < 25) {
@@ -79,7 +79,7 @@ public BaseTool rbDown(int x, int y) {
     @Override
     public BaseTool lbDown(int x, int y, boolean isShiftDown) {
         // Try picking nearest control point
-        Vec2 worldPoint = ViewUtil.screenToWorld(new Vec2(x, y));
+        Vec2 worldPoint = ViewUtil.screenToWorld(new Vec2(x, y), false);
         CtrlPt pickCtrl = link.path.closestCtrlPt(worldPoint);
 
         if (pickCtrl != null && pickCtrl.pos.dist(worldPoint) < 25) {
@@ -109,7 +109,7 @@ else if (nearbyInfo.pt.dist(worldPoint) < 20) {
     @Override
     public BaseTool mouseDrag(int x, int y) {
         if (placePoint != null) {
-            Vec2 worldPoint = ViewUtil.screenToWorld(new Vec2(x, y));
+            Vec2 worldPoint = ViewUtil.screenToWorld(new Vec2(x, y), false);
             placePoint.pos.set(worldPoint);
             editPoint.set(placePoint.pos);
             link.path.calcCurves();

src/com/modsim/tools/MakeLinkTool.java

@@ -48,7 +48,7 @@ public BaseTool lbDown(int x, int y, boolean isShiftDown) {
 	@Override
 	public BaseTool mouseMove(int x, int y) {
 		if (working) {
-			current = ViewUtil.screenToWorld(new Vec2(x, y));
+			current = ViewUtil.screenToWorld(new Vec2(x, y), false);
 
 			Port p = ViewUtil.screenSpace_portAt(x, y);
 			if (p != null) {

src/com/modsim/tools/MoveTool.java

@@ -17,7 +17,7 @@ public class MoveTool extends BaseTool {
 	 * Start a move operation. Assumes a selection exists in the View.
 	 */
 	public MoveTool(int x, int y) {
-		startPt = ViewUtil.screenToWorld(new Vec2(x,y));
+		startPt = ViewUtil.screenToWorld(new Vec2(x,y), false);
 		entities = Main.selection.getEntities();
 
 		for (PickableEntity e : entities) {
@@ -28,7 +28,7 @@ public MoveTool(int x, int y) {
 
 	@Override
 	public BaseTool mouseDrag(int x, int y) {
-		Vec2 p = ViewUtil.screenToWorld(new Vec2(x, y));
+		Vec2 p = ViewUtil.screenToWorld(new Vec2(x, y), false);
         p.sub(startPt);
 
         for (PickableEntity e : entities) {
@@ -40,7 +40,7 @@ public BaseTool mouseDrag(int x, int y) {
 
 	@Override
 	public BaseTool lbUp(int x, int y) {
-		Vec2 p = ViewUtil.screenToWorld(new Vec2(x, y));
+		Vec2 p = ViewUtil.screenToWorld(new Vec2(x, y), false);
 		p.sub(startPt);
 
 		// We're done - store the operation

src/com/modsim/tools/PlaceTool.java

@@ -28,7 +28,7 @@ public PlaceTool(PickableEntity e) {
         Main.opStack.pushOp(new CreateOperation(e));
 
         Vec2 p = new Vec2(-200, -200);
-        p = ViewUtil.screenToWorld(p);
+        p = ViewUtil.screenToWorld(p, false);
         e.move(p);
     }
 
@@ -47,7 +47,7 @@ public PlaceTool(ModuleClipboard clipboard) {
 
     @Override
     public BaseTool mouseMove(int x, int y) {
-        Vec2 cur = ViewUtil.screenToWorld(new Vec2(x, y));
+        Vec2 cur = ViewUtil.screenToWorld(new Vec2(x, y), false);
 
         if (start == null) {
             start = new Vec2(cur);

src/com/modsim/tools/SelectTool.java

@@ -65,7 +65,7 @@ public BaseTool lbDown(int x, int y, boolean isShiftDown) {
         synchronized (this) {
             // Don't actually set dragging=true till we get a mouseDrag() event
             screenDragStart.set(x, y);
-            dragStart.set(ViewUtil.screenToWorld(screenDragStart));
+            dragStart.set(ViewUtil.screenToWorld(screenDragStart, true));
 
             // Need to base contextual action on the item at the START of the drag
             pickedEntity = ViewUtil.screenSpace_entityAt(x, y);
@@ -95,7 +95,7 @@ public BaseTool mouseDrag(int x, int y) {
                     dragging = true;
 
                     // N.B. dragStart is already set thanks to lbDown() handler
-                    dragPos.set(ViewUtil.screenToWorld(new Vec2(x, y)));
+                    dragPos.set(ViewUtil.screenToWorld(new Vec2(x, y), true));
                 }
             }
         }
@@ -127,7 +127,7 @@ else if (y > Main.ui.view.getHeight() - edgeWidth) {
         }
 
         //System.out.println("More dragging " + x + ", " + y);
-        dragPos.set(ViewUtil.screenToWorld(new Vec2(x, y)));
+        dragPos.set(ViewUtil.screenToWorld(new Vec2(x, y), true));
 
         Vec2 delta = new Vec2(dragPos);
         delta.sub(dragStart);

src/com/modsim/util/BinData.java

@@ -243,11 +243,8 @@ else if (b0 == 2) {
         else if (b1 == 2) {
             return b0;
         }
-        else if (b0 == b1) {
-            return b0;
-        }
         else {
-            return 2;
+            return b0 | b1;
         }
     }
 }