[Yt-svn] yt: Fixes to PerspectiveCamera, adding docstrings for new expand...

[hg at spacepope.org]

hg Repository: yt
details:   yt/rev/4225edfc20da
changeset: 3615:4225edfc20da
user:      Sam Skillman <sam.skillman at gmail.com>
date:
Thu Dec 16 12:44:52 2010 -0700
description:
Fixes to PerspectiveCamera, adding docstrings for new expand_factor parameter in the PerspectiveCamera.

diffstat:

 yt/visualization/volume_rendering/camera.py |  21 +++++++++++++++------
 1 files changed, 15 insertions(+), 6 deletions(-)

diffs (60 lines):

diff -r a86466a42810 -r 4225edfc20da yt/visualization/volume_rendering/camera.py
--- a/yt/visualization/volume_rendering/camera.py	Tue Dec 14 12:52:54 2010 -0800
+++ b/yt/visualization/volume_rendering/camera.py	Thu Dec 16 12:44:52 2010 -0700
@@ -45,7 +45,7 @@
                  log_fields = None,
                  sub_samples = 5, pf = None,
                  use_kd=True, l_max=None, no_ghost=False,
-                 tree_type='domain'):
+                 tree_type='domain',expand_factor=1.0):
         r"""A viewpoint into a volume, for volume rendering.
 
         The camera represents the eye of an observer, which will be used to
@@ -132,6 +132,12 @@
             prone to longer data IO times.  If all the data can fit in
             memory on each cpu, this can be the fastest option for
             multiple ray casts on the same dataset.
+        expand_factor: float, optional
+            A parameter to be used with the PerspectiveCamera.
+            Controls how much larger a volume to render, which is
+            currently difficult to gauge for the PerspectiveCamera.
+            For full box renders, values in the 2.0-3.0 range seem to
+            produce desirable results. Default: 1.0
 
         Examples
         --------
@@ -174,6 +180,7 @@
         self.width = width
         self.center = center
         self.steady_north = steady_north
+        self.expand_factor = expand_factor
         # This seems to be necessary for now.  Not sure what goes wrong when not true.
         if north_vector is not None: self.steady_north=True
         self.north_vector = north_vector
@@ -499,9 +506,12 @@
         # We should move away from pre-generation of vectors like this and into
         # the usage of on-the-fly generation in the VolumeIntegrator module
         # We might have a different width and back_center
-        px = na.linspace(-self.width[0]/2.0, self.width[0]/2.0,
+        dl = (self.back_center - self.front_center)
+        self.front_center += dl
+        self.back_center -= dl
+        px = self.expand_factor*na.linspace(-self.width[0]/2.0, self.width[0]/2.0,
                          self.resolution[0])[:,None]
-        py = na.linspace(-self.width[1]/2.0, self.width[1]/2.0,
+        py = self.expand_factor*na.linspace(-self.width[1]/2.0, self.width[1]/2.0,
                          self.resolution[1])[None,:]
         inv_mat = self.inv_mat
         bc = self.back_center
@@ -514,9 +524,8 @@
         
         # We are likely adding on an odd cutting condition here
         vectors = self.front_center - positions
-        n = vectors * vectors
-        n = na.sum(n, axis=2)**0.5
-        vectors /= n[:,:,None]
+        positions = self.front_center - 2.0*(((self.back_center-self.front_center)**2).sum())**0.5*vectors
+        vectors = (self.front_center - positions)
         print vectors.shape, vectors.dtype, vectors.flags
 
         vector_plane = VectorPlane(positions, vectors,