refactor arcball

Author: monkstone

3DSketches/test_arcball.py

@@ -7,6 +7,9 @@
 ArcBall class uses Quaternions class for efficient calculation of rotation, hold down x, y or z
 keys to constrain rotation to that plane otherwise drag mouse for smooth rotation
 """
+X = 0
+Y= 1
+Z = 2
 
 def setup():
     size(600, 600)
@@ -18,11 +21,17 @@ def draw():
     background(0xff66c0ff)
     translate(width/2.0, height/2.0, -height/4.0)
     defineLights()
-    w,  x,  y,  z = arcball.update()
-    rotate(w,  x,  y,  z)
+    update()
     lights()
     stroke(0)
     cube(arcball.radius)
+    
+def update():
+    """
+    wrap arcball update and rotation as a local function
+    """
+    theta,  x,  y,  z = arcball.update()
+    rotate(theta,  x,  y,  z)    
 
 def mousePressed():
     arcball.mousePressed(mouse.x, mouse.y)
@@ -46,13 +55,16 @@ def keyPressed():
     of rotation by holding down key corresponding to axis
     """
     if (key.char == 'x'):
-        arcball.selectAxis(0)
+        arcball.selectAxis(X)
     if (key.char == 'y'):
-        arcball.selectAxis(1)
+        arcball.selectAxis(Y)
     if (key.char == 'z'):
-        arcball.selectAxis(2)
+        arcball.selectAxis(Z)
 
 def keyReleased():
+    """
+    Release axis constraint
+    """
     arcball.selectAxis(-1)
 
 def cube(sz):

3DSketches/util/arcball.py

@@ -23,13 +23,14 @@ def __init__(self, cx, cy, radius):
 
     def selectAxis(self,  axis):
         """
-        call this from sketch (typically keyPressed() to constrain rotation to one axis)
+        call this from sketch (typically in keyPressed() to constrain rotation to one axis)
+        valid input 0, 1, 2 or -1
         """
         self.axis = axis
 
-    def mouseToSphere(self, x, y):
+    def __mouse2sphere(self, x, y):
         """
-        Map mouse to ArcBall (sphere)
+        private map mouse to ArcBall (sphere)
         """
         v = PVector()
         v.x = (x - self.center_x) / self.radius
@@ -39,24 +40,27 @@ def mouseToSphere(self, x, y):
             v.normalize()
         else:
             v.z = sqrt(1.0 - mag)
-        return  v  if (self.axis == -1) else (self.constrainVector(v, self.axisSet[self.axis]))
+        return  v  if (self.axis == -1) else (self.__constrain(v, self.axisSet[self.axis]))
 
     def mousePressed(self, x, y):
         """
         pass in mouse.x and mouse.y parameters from sketch
         """
-        self.v_down = self.mouseToSphere(x, y)
+        self.v_down = self.__mouse2sphere(x, y)
         self.q_down.copy(self.q_now)
         self.q_drag.reset()
 
     def mouseDragged(self, x, y):
         """
         pass in mouse.x and mouse.y parameters from sketch
         """
-        self.v_drag = self.mouseToSphere(x, y)
+        self.v_drag = self.__mouse2sphere(x, y)
         self.q_drag.set(PVector.dot(self.v_down, self.v_drag), self.v_down.cross(self.v_drag))
 
-    def constrainVector(self, vector, axis):
+    def __constrain(self, vector, axis):
+        """
+        private constrain (used to constrain axis)
+        """
         res = PVector.sub(vector, PVector.mult(axis, PVector.dot(axis, vector)))
         res.normalize()
         return res
@@ -66,11 +70,11 @@ def update(self):
         Call this function in the sketch draw loop to get rotation matrix as an array 
         """
         self.q_now = Quaternion.mult(self.q_drag, self.q_down)
-        return self.quat2Matrix(self.q_now)
+        return self.__quat2matrix(self.q_now)
 
-    def quat2Matrix(self,  q) :
+    def __quat2matrix(self,  q) :
         """
-        Return matrix as array
+        private return matrix as array
         """
         rot = q.getValue()
         return rot