diff options
Diffstat (limited to 'src/utils.c')
| -rw-r--r-- | src/utils.c | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/src/utils.c b/src/utils.c index 38855671..fa239f90 100644 --- a/src/utils.c +++ b/src/utils.c @@ -122,3 +122,37 @@ int sign(double a) if ( a > 0 ) return +1; return 0; } + + +void mapping_rotate(double x, double y, double z, + double *ddx, double *ddy, double *ddz, + double omega, double tilt) +{ + double nx, ny, nz; + double x_temp, y_temp, z_temp; + + /* First: rotate image clockwise until tilt axis is aligned + * horizontally. */ + nx = x*cos(omega) + y*sin(omega); + ny = -x*sin(omega) + y*cos(omega); + nz = z; + + /* Now, tilt about the x-axis ANTICLOCKWISE around +x, i.e. the + * "wrong" way. This is because the crystal is rotated in the + * experiment, not the Ewald sphere. */ + x_temp = nx; y_temp = ny; z_temp = nz; + nx = x_temp; + ny = cos(tilt)*y_temp + sin(tilt)*z_temp; + nz = -sin(tilt)*y_temp + cos(tilt)*z_temp; + + /* Finally, reverse the omega rotation to restore the location of the + * image in 3D space */ + x_temp = nx; y_temp = ny; z_temp = nz; + nx = x_temp*cos(-omega) + y_temp*sin(-omega); + ny = -x_temp*sin(-omega) + y_temp*cos(-omega); + nz = z_temp; + + *ddx = nx; + *ddy = ny; + *ddz = nz; +} |