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-rw-r--r--src/diffraction.c11
1 files changed, 5 insertions, 6 deletions
diff --git a/src/diffraction.c b/src/diffraction.c
index 6df00164..bcfee476 100644
--- a/src/diffraction.c
+++ b/src/diffraction.c
@@ -141,7 +141,7 @@ struct rvec get_q(struct image *image, unsigned int xs, unsigned int ys,
unsigned int sampling, float *ttp, float k)
{
struct rvec q;
- float twothetax, twothetay, twotheta, r;
+ float twotheta, r, az;
float rx = 0.0;
float ry = 0.0;
int p;
@@ -164,14 +164,13 @@ struct rvec get_q(struct image *image, unsigned int xs, unsigned int ys,
/* Calculate q-vector for this sub-pixel */
r = sqrt(pow(rx, 2.0) + pow(ry, 2.0));
- twothetax = atan2(rx, image->det.panels[p].clen);
- twothetay = atan2(ry, image->det.panels[p].clen);
- twotheta = atan2(r, image->det.panels[p].clen);
+ twotheta = atan2(r, image->det.panels[p].clen);
+ az = atan2(ry, rx);
if ( ttp != NULL ) *ttp = twotheta;
- q.u = k * sin(twothetax);
- q.v = k * sin(twothetay);
+ q.u = k * sin(twotheta)*cos(az);
+ q.v = k * sin(twotheta)*sin(az);
q.w = k - k * cos(twotheta);
return quat_rot(q, image->orientation);