Added option to have an arbitrarily oriented cutting plane

glue_vispy_viewers/volume/shaders.py

@@ -80,6 +80,10 @@ def indent(text, prefix):
 varying vec4 v_nearpos;
 varying vec4 v_farpos;
 
+// A cutting plane defined as ax + by + cz + d = 0 where the vector below is (a, b, c)
+uniform vec3 u_cutting_plane_abc;
+uniform float u_cutting_plane_d;
+
 // uniforms for lighting. Hard coded until we figure out how to do lights
 const vec4 u_ambient = vec4(0.2, 0.4, 0.2, 1.0);
 const vec4 u_diffuse = vec4(0.8, 0.2, 0.2, 1.0);
@@ -121,6 +125,10 @@ def indent(text, prefix):
     distance = max(distance, min((-0.5 - v_position.z) / view_ray.z,
                             (u_shape.z - 0.5 - v_position.z) / view_ray.z));
 
+    // Compute distance to cutting plane
+    float cutting_distance = -(dot(v_position, u_cutting_plane_abc) + u_cutting_plane_d) / dot(view_ray, u_cutting_plane_abc);
+    distance = max(distance, cutting_distance);
+
     // Now we have the starting position on the front surface
     vec3 front = v_position + view_ray * distance;
 

glue_vispy_viewers/volume/viewer_state.py

@@ -15,6 +15,8 @@ class Vispy3DVolumeViewerState(Vispy3DViewerState):
                                                          'which defines the coordinate frame in '
                                                          'which the images are shown')
 
+    cutting_plane = CallbackProperty(None)
+
     def __init__(self, **kwargs):
 
         super(Vispy3DVolumeViewerState, self).__init__()

glue_vispy_viewers/volume/volume_viewer.py

@@ -45,6 +45,13 @@ def setup_widget_and_callbacks(self):
         self.state.add_callback('resolution', self._update_resolution)
         self._update_resolution()
 
+        self.state.add_callback('cutting_plane', self._update_cutting_plane)
+        self._update_cutting_plane()
+
+    def _update_cutting_plane(self, *args):
+        self._vispy_widget._multivol.set_cutting_plane(self.state.cutting_plane)
+        self._vispy_widget.canvas.update()
+
     def _update_clip(self, force=False):
         if hasattr(self._vispy_widget, '_multivol'):
             if (self.state.clip_data or force):

glue_vispy_viewers/volume/volume_visual.py

@@ -101,6 +101,9 @@ def __init__(self, n_volume_max=16, emulate_texture=False, bgcolor='white', reso
         self.shared_program['u_clip_min'] = [0, 0, 0]
         self.shared_program['u_clip_max'] = [1, 1, 1]
 
+        # Set initial cutting plane
+        self.set_cutting_plane(None)
+
         # Set up texture vertices - note that these variables are required by
         # the parent VolumeVisual class.
 
@@ -201,6 +204,14 @@ def set_multiply(self, label, label_other):
         self.volumes[label]['multiply'] = label_other
         self._update_shader()
 
+    def set_cutting_plane(self, parameters):
+        if parameters is None:
+            self.shared_program['u_cutting_plane_abc'] = [0, 0, 1]
+            self.shared_program['u_cutting_plane_d'] = -10000.
+        else:
+            self.shared_program['u_cutting_plane_abc'] = list(parameters[:3])
+            self.shared_program['u_cutting_plane_d'] = float(parameters[3])
+
     # The following methods don't require any changes to the shader code, so we
     # don't update the shader after setting the OpenGL variables.
 
@@ -388,10 +399,7 @@ def draw(self):
         if not any(self.enabled):
             return
         else:
-            try:
-                super(MultiVolumeVisual, self).draw()
-            except Exception:
-                pass
+            super(MultiVolumeVisual, self).draw()
 
 
 MultiVolume = create_visual_node(MultiVolumeVisual)