From a32bb5180d19a67b976be5d6622cfa4620883657 Mon Sep 17 00:00:00 2001
From: Paul McCarthy <pauld.mccarthy@gmail.com>
Date: Tue, 20 May 2014 15:00:12 +0100
Subject: [PATCH] Comment updates
---
fsl/fslview/slicecanvas.py | 37 +++++++++++++++++++------------------
1 file changed, 19 insertions(+), 18 deletions(-)
diff --git a/fsl/fslview/slicecanvas.py b/fsl/fslview/slicecanvas.py
index 4af3d6c9a..7bf785693 100644
--- a/fsl/fslview/slicecanvas.py
+++ b/fsl/fslview/slicecanvas.py
@@ -27,24 +27,24 @@ import fsl.data.fslimage as fslimage
class GLImageData(object):
"""
A GLImageData object encapsulates the OpenGL information necessary
- to render an image.
+ to render 2D slices of a 3D image.
- A slice from one image is rendered using three buffers and one
- texture. The first buffer, the 'geometry buffer' simply contains four
- vertices, which define the geometry of a single voxel (using triangle
- strips).
-
- The second buffer, the 'position buffer', contains the location of every
- voxel in one slice of the image (these locations are identical for every
- slice of the image, so we can re-use the location information for every
- slice). The four vertices for each voxel (from the geometry buffer, above)
- are offset by the voxel position, which is read from this position buffer.
-
- The third buffer, the 'image buffer' contains the image data itself,
- scaled to lie between 0 and 255. It is used to calculate voxel colours.
-
- Finally, the texture, the 'colour buffer', is used to store a lookup table
- containing colours.
+ A slice from one image is rendered using four buffers and two textures.
+
+ The first buffer, the 'geometry buffer' simply contains the 3D
+ coordinates (single precision floating point) of four vertices, which
+ define the geometry of a single voxel (using triangle strips).
+
+ The remaining buffers contain the X, Y, and Z coordinates of the voxels
+ in the slice to be displayed. These coordinates are stored as single
+ precision floating points, and used both to position a voxel, and to
+ look up its value in the 3D data texture (see below).
+
+ The image data itself is stored as a 3D texture, with each voxel value
+ stored as a single unsigned byte in the range 0-255.
+
+ Finally, a 1D texture is used is used to store a lookup table containing
+ an RGBA8 colour map, to colour each voxel according to its value.
"""
def __init__(self, image, canvas):
@@ -201,6 +201,7 @@ class GLImageData(object):
return imageBuffer
+
def updateColourBuffer(self):
"""
Regenerates the colour buffer used to colour image voxels.
@@ -235,7 +236,7 @@ class GLImageData(object):
colourmap = display.cmap(newRange)
# The colour data is stored on
- # the GPU as 8 bit rgb triplets
+ # the GPU as 8 bit rgba tuples
colourmap = np.floor(colourmap * 255)
colourmap = np.array(colourmap, dtype=np.uint8)
colourmap = colourmap.ravel(order='C')
--
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