Added alpha compositing scheme to Python API Plot class to highlight domains

openmc/plots.py

@@ -270,7 +270,7 @@ class Plot(object):
         Params
         ------
         geometry : openmc.Geometry
-            The geometry for which the plot is created
+            The geometry for which the plot is defined
         seed : Integral
             The random number seed used to generate the color scheme
 
@@ -284,7 +284,7 @@ class Plot(object):
         if self.color is 'mat':
             domains = geometry.get_all_materials()
         else:
-            domains = geometry.get_all_materials()
+            domains = geometry.get_all_cells()
 
         # Set the seed for the random number generator
         np.random.seed(seed)
@@ -295,9 +295,63 @@ class Plot(object):
             r = np.random.randint(0, 255)
             g = np.random.randint(0, 255)
             b = np.random.randint(0, 255)
-            self.col_spec[domain.id] = (r, g, b)
+            self.col_spec[domain] = (r, g, b)
 
 
+    def highlight_domains(self, geometry, domains, seed=1,
+                          alpha=0.5, background='grey'):
+        """Use alpha compositing to highlight one or more domains in the plot.
+
+        This routine generates a color scheme and applies alpha compositing
+        to make all domains except the highlighted ones partially transparent.
+
+        Params
+        ------
+        geometry : openmc.Geometry
+            The geometry for which the plot is defined
+        domains : Iterable of Integral
+            A collection of the domain IDs to highlight in the plot
+        seed : Integral
+            The random number seed used to generate the color scheme
+        alpha : Real in [0,1]
+            The value to apply in alpha compisiting
+        background : 3-tuple of Integral or 'white' or 'black' or 'grey'
+            The background color to apply in alpha compisiting
+
+        """
+
+        cv.check_iterable_type('domains', domains, Integral)
+        cv.check_type('alpha', alpha, Real)
+        cv.check_greater_than('alpha', alpha, 0., equality=True)
+        cv.check_less_than('alpha', alpha, 1., equality=True)
+
+        # Get a background (R,G,B) tuple to apply in alpha compositing
+        if isinstance(background, basestring):
+            if background == 'white':
+                background = (255, 255, 255)
+            elif background == 'black':
+                background = (0, 0, 0)
+            elif background == 'grey':
+                background = (160, 160, 160)
+            else:
+                msg = 'The background "{}" is not defined'.format(background)
+                raise ValueError(msg)
+
+        cv.check_iterable_type('background', background, Integral)
+
+        # Generate a color scheme
+        self.colorize(geometry, seed)
+
+        # Apply alpha compositing to the colors for all domains
+        # other than those the user wishes to highlight
+        for domain_id in self.col_spec:
+            if domain_id not in domains:
+                r, g, b = self.col_spec[domain_id]
+                r = int(((1-alpha) * background[0]) + (alpha * r))
+                g = int(((1-alpha) * background[1]) + (alpha * g))
+                b = int(((1-alpha) * background[2]) + (alpha * b))
+                self._col_spec[domain_id] = (r, g, b)
+
     def get_plot_xml(self):
         """Return XML representation of the plot