move from_film function into tools

2 files changed, 37 insertions, 1 deletions

diff --git a/chroma/camera.py b/chroma/camera.py
index 80fc8f6..dd00a17 100644
--- a/chroma/camera.py
+++ b/chroma/camera.py
@@ -15,7 +15,7 @@ from pycuda import gpuarray as ga
 from chroma.geometry import Mesh, Solid, Geometry, vacuum
 from chroma.transform import rotate, make_rotation_matrix
 from chroma.sample import uniform_sphere
-from chroma.project import from_film
+from chroma.tools import from_film
 from chroma import make
 from chroma import gpu
 from chroma.loader import create_geometry_from_obj
diff --git a/chroma/tools.py b/chroma/tools.py
index 3a930c1..c62fe62 100644
--- a/chroma/tools.py
+++ b/chroma/tools.py
@@ -3,6 +3,7 @@ import time
 import datetime
 import sys
 import math
+from chroma.transform import normalize
 
 def count_nonzero(array):
     '''Return the number of nonzero elements in this array'''
@@ -190,3 +191,38 @@ def argsort_direction(dir):
         morton |= (theta & 1 << i) << (i) | \
                   (phi & 1 << i) << (i+1)
     return np.argsort(morton)
+
+def from_film(position=(0,0,0), axis1=(0,0,1), axis2=(1,0,0), size=(800,600),
+              width=35.0, focal_length=18.0):
+    """Project rays from a piece of film whose focal point is located at
+    `position`. `axis1` and `axis2` specify the vectors pointing along the
+    length and height of the film respectively.
+    """
+
+    height = width*(size[1]/float(size[0]))
+
+    axis1 = normalize(axis1)
+    axis2 = normalize(axis2)
+
+    dx0 = width/size[0]
+    dx1 = height/size[1]
+
+    # for i in range(size[0]):
+    #     for j in range(size[1]):
+    #         grid[i*size[1]+j] = axis1*dx1*j - axis2*dx0*i
+
+    x = np.arange(size[0])
+    y = np.arange(size[1])
+
+    yy, xx = np.meshgrid(y,x)
+
+    n = size[0]*size[1]
+
+    grid = -np.tile(axis2, (n,1))*xx.ravel()[:,np.newaxis]*dx0 + \
+        np.tile(axis1, (n,1))*yy.ravel()[:,np.newaxis]*dx1
+
+    grid += axis2*width/2 - axis1*height/2
+    grid -= np.cross(axis1,axis2)*focal_length
+
+    return np.tile(position,(n,1)), normalize(-grid)
+