Improve attach_arrow

Author: BruceSherwood

vpython/vpython.py

@@ -543,7 +543,7 @@ class standardAttributes(baseObj):
                         ['v0', 'v1', 'v2', 'v3'] ],
                  'attach_arrow': [ [ 'color', 'attrval'],
                         [],
-                        ['shaftwidth', 'scale', 'obj', 'attr'],
+                        ['shaftwidth', 'round', 'scale', 'obj', 'attr'],
                         [] ],
                  'attach_trail': [ ['color'],
                         [],
@@ -612,6 +612,7 @@ def setup(self, args):
         self._pickable = True
         self._save_oldaxis = None # used in linking axis and up
         self._save_oldup = None # used in linking axis and up
+        self._round = False
         _special_clone = None
         if '_cloneid' in args: # text, extrusion, or compound is being cloned
             _special_clone = args['_cloneid']
@@ -1287,17 +1288,27 @@ class attach_arrow(standardAttributes):
     def __init__(self, obj, attr, **args):
         attrs = ['pos', 'size', 'axis', 'up', 'color']
         args['_default_size'] = None
+        a = getattr(obj, attr) # This raises an error if obj does not have attr
+        if not isinstance(a, vector): raise AttributeError('The attach_arrow attribute "'+attr+ '" is not a vector.')
         self.obj = args['obj'] = obj.idx
         self.attr = args['attr'] = attr # could be for example "velocity"
         self.attrval = args['attrval'] = getattr(baseObj.object_registry[self.obj], attr)
         args['_objName'] = "attach_arrow"
         self._last_val = None
         self._scale = 1
         self._shaftwidth = 0
+        self._round = False
         super(attach_arrow, self).setup(args)
         # Only if the attribute is a user attribute do we need to add to attach_arrows:
         if attr not in attrs: baseObj.attach_arrows.append(self)
 
+    @property
+    def round(self):
+        return self._round
+    @round.setter
+    def round(self,value):
+        raise AttributeError('Cannot change the "round" attribute of an attach_arrow.')
+
     @property
     def scale(self):
         return self._scale

vpython/vpython_libraries/glow.min.js

@@ -544,7 +544,7 @@
 	for (var d in data) {
 		for (var i in data[d]) console.log(i, JSON.stringify(data[d][i]))
 	}
-    */
+        */
 
 	if (data.cmds !== undefined && data.cmds.length > 0) handle_cmds(data.cmds)
 	if (data.methods !== undefined && data.methods.length > 0) handle_methods(data.methods)
@@ -731,15 +731,15 @@
 					//$("<div id='fps'/>").appendTo(glowObjs[idx].title)
 			}
 			case 'attach_arrow':  {
-                var attrs = ['pos', 'size', 'axis', 'up', 'color']
+				var attrs = ['pos', 'size', 'axis', 'up', 'color']
 				var o = glowObjs[cfg['obj']]
 				delete cfg['obj']
 				var attr = cfg['attr']
 				delete cfg['attr']
-                var val = cfg['attrval']
-                delete cfg['attrval']
-                if (attrs.indexOf(attr) < 0) attr = '_attach_arrow'
-                o.attr = val
+				var val = cfg['attrval']
+				delete cfg['attrval']
+				if (attrs.indexOf(attr) < 0) attr = '_attach_arrow'
+				o.attr = val
 				glowObjs[idx] = attach_arrow( o, attr, cfg )
 				break
 			}
@@ -962,4 +962,4 @@
 
 </script>
 </div>
-</body>
+</body>

vpython/vpython_libraries/glowcomm.html

@@ -794,10 +794,10 @@ function handle_cmds(dcmds) {
 				delete cfg['obj']
 				var attr = cfg['attr']
 				delete cfg['attr']
-                var val = cfg['attrval']
-                delete cfg['attrval']
-                if (attrs.indexOf(attr) < 0) attr = '_attach_arrow'
-                o.attr = val
+				var val = cfg['attrval']
+				delete cfg['attrval']
+				if (attrs.indexOf(attr) < 0) attr = '_attach_arrow'
+				o.attr = val
 				glowObjs[idx] = attach_arrow( o, attr, cfg )
 				break
 			}