Melchior has already a nice collection of animation type nasal classes. These will be converted in a Nasal toolbox so everybody can use them without reinventing the wheel.

Nasal/aircraft.nas

@@ -0,0 +1,61 @@
+# door: class for objects moving at constant speed, with the ability to
+# reverse moving direction at any point. Appropriate for doors, canopies, etc.
+#
+# SYNOPSIS:
+#	door.new(<property>, <swingtime> [, <startpos>]);
+#
+#	property      ... parent property (available as door.base)
+#	swingtime     ... time in seconds for full movement (0 -> 1)
+#	startpos      ... initial position      (default: 0)
+#
+# PROPERTIES:
+#	<property>/position-norm   (type="double")
+#	<property>/enabled         (type="bool")
+#
+# EXAMPLE:
+#	canopy = aircraft.door.new("sim/model/foo/canopy", 5);
+#	canopy.open();
+#
+door = {
+	new : func {
+		d = { parents: [door] };
+		d.base = props.globals.getNode(arg[0], 1);
+		d.pos = d.base.getNode("position-norm", 1);
+		d.enabled = d.base.getNode("enabled", 1);
+		d.enabled.setBoolValue(1);
+
+		d.swingtime = arg[1];
+		pos = if (size(arg) > 2 and arg[2] != nil) { arg[2] } else { 0 };
+		d.pos.setDoubleValue(pos);
+		d.target = pos < 0.5;
+		return d;
+	},
+
+	# door.enable(bool)    -> set <property>/enabled
+	enable  : func { me.enabled.setBoolValue(arg[0]) },
+
+	# door.setpos(double)  -> set <property>/position-norm without movement
+	setpos  : func { me.pos.setValue(arg[0]); me.target = arg[0] < 0.5 },
+
+	# double door.getpos() -> return current position as double
+	getpos  : func { me.pos.getValue() },
+
+	# door.close()         -> move to closed state
+	close   : func { me.move(0) },
+
+	# door.open()          -> move to open state
+	open    : func { me.move(1) },
+
+	# door.toggle()        -> move to farther away end position
+	#                         (0 -> 1, 1 -> 0, 0.3 -> 1, 0.6 -> 0)
+	toggle  : func { me.move(me.target) },
+
+	# door.move(double)    -> move to arbitrary position
+	move    : func {
+		time = abs(me.getpos() - arg[0]) * me.swingtime;
+		interpolate(me.pos, arg[0], time);
+		me.target = !me.target;
+	},
+};
+
+