shadows: force interocular distance to 0 for shadow cameras

panda/src/pgraphnodes/directionalLight.cxx

@@ -59,6 +59,7 @@ DirectionalLight(const string &name) :
   LightLensNode(name, new OrthographicLens()),
   _has_specular_color(false)
 {
+  _lenses[0]._lens->set_interocular_distance(0);
 }
 
 /**

panda/src/pgraphnodes/pointLight.cxx

@@ -66,21 +66,27 @@ PointLight(const string &name) :
 {
   PT(Lens) lens;
   lens = new PerspectiveLens(90, 90);
+  lens->set_interocular_distance(0);
   lens->set_view_vector(1, 0, 0, 0, -1, 0);
   set_lens(0, lens);
   lens = new PerspectiveLens(90, 90);
+  lens->set_interocular_distance(0);
   lens->set_view_vector(-1, 0, 0, 0, -1, 0);
   set_lens(1, lens);
   lens = new PerspectiveLens(90, 90);
+  lens->set_interocular_distance(0);
   lens->set_view_vector(0, 1, 0, 0, 0, 1);
   set_lens(2, lens);
   lens = new PerspectiveLens(90, 90);
+  lens->set_interocular_distance(0);
   lens->set_view_vector(0, -1, 0, 0, 0, -1);
   set_lens(3, lens);
   lens = new PerspectiveLens(90, 90);
+  lens->set_interocular_distance(0);
   lens->set_view_vector(0, 0, 1, 0, -1, 0);
   set_lens(4, lens);
   lens = new PerspectiveLens(90, 90);
+  lens->set_interocular_distance(0);
   lens->set_view_vector(0, 0, -1, 0, -1, 0);
   set_lens(5, lens);
 }

panda/src/pgraphnodes/spotlight.cxx

@@ -68,6 +68,7 @@ Spotlight(const string &name) :
   LightLensNode(name),
   _has_specular_color(false)
 {
+  _lenses[0]._lens->set_interocular_distance(0);
 }
 
 /**