From 4640801af015f6eb46f12d17b22f8c0767a0091e Mon Sep 17 00:00:00 2001
From: Thomas White <taw@physics.org>
Date: Thu, 5 Sep 2019 15:28:31 +0200
Subject: Allow the polarsation correction to be completely disabled

---
 libcrystfel/src/geometry.c | 6 ++++++
 libcrystfel/src/geometry.h | 4 ++++
 2 files changed, 10 insertions(+)

(limited to 'libcrystfel/src')

diff --git a/libcrystfel/src/geometry.c b/libcrystfel/src/geometry.c
index 13fcbe3b..fa896cd0 100644
--- a/libcrystfel/src/geometry.c
+++ b/libcrystfel/src/geometry.c
@@ -967,10 +967,12 @@ struct polarisation parse_polarisation(const char *text)
 	if ( strcmp(text, "none") == 0 ) {
 		p.fraction = 0.5;
 		p.angle = 0.0;
+		p.disable = 1;
 		return p;
 	}
 
 	p.fraction = 1.0;
+	p.disable = 0;
 
 	i = 0;
 	n = 0;
@@ -1027,6 +1029,10 @@ void polarisation_correction(RefList *list, UnitCell *cell,
 	double bsx, bsy, bsz;
 	double csx, csy, csz;
 
+	if ( p.disable ) {
+		return;
+	}
+
 	cell_get_reciprocal(cell, &asx, &asy, &asz,
 	                          &bsx, &bsy, &bsz,
 	                          &csx, &csy, &csz);
diff --git a/libcrystfel/src/geometry.h b/libcrystfel/src/geometry.h
index db3c0fe8..0a403a9c 100644
--- a/libcrystfel/src/geometry.h
+++ b/libcrystfel/src/geometry.h
@@ -97,8 +97,12 @@ enum gparam {
 struct polarisation
 {
 	double fraction;   /**< Polarisation fraction (0 to 1) */
+
 	double angle;      /**< Angle of electron beam, radians, clockwise from
 	                    * horizontal when looking along beam */
+
+	int disable;       /**< If set, don't even correct for the polarisation
+	                    * of the diffracted beam (1 - 0.5sin^2(2theta)) */
 };
 
 
-- 
cgit v1.2.3