Displays the voxels and the control points.

def render(self, **kwargs):
        """ Displays the voxels and the control points. """
        # Calling parent function
        super(VisVoxel, self).render(**kwargs)

        # Initialize variables
        legend_proxy = []
        legend_names = []

        # Start plotting of the surface and the control points grid
        fig = plt.figure(figsize=self.vconf.figure_size, dpi=self.vconf.figure_dpi)
        ax = Axes3D(fig)

        # Start plotting
        for plot in self._plots:
            # Plot control points
            if plot['type'] == 'ctrlpts' and self.vconf.display_ctrlpts:
                pts = np.array(plot['ptsarr'], dtype=self.vconf.dtype)
                ax.scatter(pts[:, 0], pts[:, 1], pts[:, 2], color=plot['color'], marker='^', s=20, depthshade=True)
                plot_proxy = mpl.lines.Line2D([0], [0], linestyle='none', color=plot['color'], marker='^')
                legend_proxy.append(plot_proxy)
                legend_names.append(plot['name'])

            # Plot evaluated points
            if plot['type'] == 'evalpts' and self.vconf.display_evalpts:
                faces = np.array(plot['ptsarr'][1], dtype=self.vconf.dtype)
                filled = np.array(plot['ptsarr'][2], dtype=self.vconf.dtype)
                # Find filled voxels
                faces_filled = np.concatenate(faces[filled == 1.0])
                # Create a single Poly3DCollection object
                pc3d = Poly3DCollection(faces_filled, facecolors=plot['color'], edgecolors='k')
                ax.add_collection3d(pc3d)
                # Set axis limits
                gf_min = np.amin(faces_filled, axis=(0, 1))
                gf_max = np.amax(faces_filled, axis=(0, 1))
                ax.set_xlim([gf_min[0], gf_max[0]])
                ax.set_ylim([gf_min[1], gf_max[1]])
                ax.set_zlim([gf_min[2], gf_max[2]])
                # Legend
                plot_proxy = mpl.lines.Line2D([0], [0], linestyle='none', color=plot['color'], marker='o')
                legend_proxy.append(plot_proxy)
                legend_names.append(plot['name'])

            # Plot bounding box
            if plot['type'] == 'bbox' and self.vconf.display_bbox:
                ax.plot(pts[:, 0], pts[:, 1], pts[:, 2], color=plot['color'], linestyle='--')
                plot_proxy = mpl.lines.Line2D([0], [0], linestyle='--', color=plot['color'])
                legend_proxy.append(plot_proxy)
                legend_names.append(plot['name'])

            # Plot extras
            if plot['type'] == 'extras':
                ax.plot(pts[:, 0], pts[:, 1], pts[:, 2],
                        color=plot['color'][0], linestyle='-', linewidth=plot['color'][1])
                plot_proxy = mpl.lines.Line2D([0], [0], linestyle='-', color=plot['color'][0])
                legend_proxy.append(plot_proxy)
                legend_names.append(plot['name'])

        # Add legend to 3D plot, @ref: https://stackoverflow.com/a/20505720
        if self.vconf.display_legend:
            ax.legend(legend_proxy, legend_names, numpoints=1)

        # Remove axes
        if not self.vconf.display_axes:
            plt.axis('off')

        # Set axes equal
        if self.vconf.axes_equal:
            self.vconf.set_axes_equal(ax)

        # Axis labels
        if self.vconf.display_labels:
            ax.set_xlabel('x')
            ax.set_ylabel('y')
            ax.set_zlabel('z')

        # Process keyword arguments
        fig_filename = kwargs.get('fig_save_as', None)
        fig_display = kwargs.get('display_plot', True)

        # Display the plot
        if fig_display:
            plt.show()
        else:
            fig_filename = self.vconf.figure_image_filename if fig_filename is None else fig_filename

        # Save the figure
        self.vconf.save_figure_as(fig, fig_filename)

        # Return the figure object
        return fig