adding polynomial2d scale and test (#128)

Author: djkapner

renderapi/transform/leaf/polynomial_models.py

@@ -89,6 +89,16 @@ def order(self):
         no_coeffs = len(self.params.ravel())
         return int((abs(np.sqrt(4 * no_coeffs + 1)) - 3) / 2)
 
+    @property
+    def scale(self):
+        """tuple of scale for x, y"""
+        if self.order > 0:
+            scale = (self.params[0, 1], self.params[1, 2])
+        else:
+            # translation only has no scale impact
+            scale = (1.0, 1.0)
+        return scale
+
     @property
     def dataString(self):
         """dataString of polynomial"""

test/test_transform.py

@@ -167,6 +167,18 @@ def test_invert_Affine():
     assert(np.allclose(am.concatenate(Iam).M, np.eye(3)))
 
 
+def test_polynomial_scale():
+    p = np.transpose(np.array([[0, 0]]))
+    t = renderapi.transform.Polynomial2DTransform(params=p)
+    assert(t.order==0)
+    assert(t.scale==(1.0, 1.0))
+    
+    p = np.transpose(np.array([[0, 0], [1.1, 0], [0, 0.9]]))
+    t = renderapi.transform.Polynomial2DTransform(params=p)
+    assert(t.order==1)
+    assert(t.scale==(1.1, 0.9))
+
+
 def test_Polynomial_estimation(use_numpy=False):
     if use_numpy:
         try: