From 8188b0697751d7c7ec6fe3069d0fceb50ebd0c9e Mon Sep 17 00:00:00 2001
From: Willem Jan Palenstijn <Willem.Jan.Palenstijn@cwi.nl>
Date: Thu, 2 Oct 2014 13:42:42 +0200
Subject: Improve cuda 2d header comments

---
 cuda/2d/algo.h |  7 +++++++
 cuda/2d/dims.h | 19 ++++++++++++++++++-
 2 files changed, 25 insertions(+), 1 deletion(-)

(limited to 'cuda/2d')

diff --git a/cuda/2d/algo.h b/cuda/2d/algo.h
index 96195a3..9f2aa00 100644
--- a/cuda/2d/algo.h
+++ b/cuda/2d/algo.h
@@ -74,6 +74,13 @@ public:
 	// instead of calling setBuffers, you can also call allocateBuffers
 	// to let ReconAlgo manage its own GPU memory
 	virtual bool allocateBuffers();
+
+	// copy data to GPU. This must be called after allocateBuffers.
+	// pfSinogram, pfReconstruction, pfVolMask, pfSinoMask are the
+	// sinogram, reconstruction, volume mask and sinogram mask in system RAM,
+	// respectively. The corresponding pitch variables give the pitches
+	// of these buffers, measured in floats.
+	// The sinogram is multiplied by fSinogramScale after uploading it.
 	virtual bool copyDataToGPU(const float* pfSinogram, unsigned int iSinogramPitch, float fSinogramScale,
 	                           const float* pfReconstruction, unsigned int iReconstructionPitch,
 	                           const float* pfVolMask, unsigned int iVolMaskPitch,
diff --git a/cuda/2d/dims.h b/cuda/2d/dims.h
index df349f7..3978eab 100644
--- a/cuda/2d/dims.h
+++ b/cuda/2d/dims.h
@@ -44,12 +44,29 @@ struct SFanProjection {
 
 
 struct SDimensions {
+	// Width, height of reconstruction volume
 	unsigned int iVolWidth;
 	unsigned int iVolHeight;
+
+	// Number of projection angles
 	unsigned int iProjAngles;
+
+	// Number of detector pixels
 	unsigned int iProjDets;
-	float fDetScale; // size of detector compared to volume pixels
+
+	// size of detector compared to volume pixels
+	float fDetScale;
+
+	// in FP, number of rays to trace per detector pixel.
+	// This should usually be set to 1.
+	// If fDetScale > 1, this should be set to an integer of roughly
+	// the same size as fDetScale.
 	unsigned int iRaysPerDet;
+
+	// in BP, square root of number of rays to trace per volume pixel
+	// This should usually be set to 1.
+	// If fDetScale < 1, this should be set to an integer of roughly
+	// the same size as 1 / fDetScale.
 	unsigned int iRaysPerPixelDim;
 };
 
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