Grains: added grain reconstruction rotation function

Signed-off-by: Nicola Vigano <nicola.vigano@esrf.fr>

4_grains/gtGrainRotateStructure.m

+function [structure, proj] = gtGrainRotateStructure(structure, proj, type,  parameters, rot_tensor_angle, rot_axis)
+    if (any([size(rot_tensor_angle, 1), size(rot_tensor_angle, 2)] == 1))
+        rot_angle = rot_tensor_angle;
+        if (~exist('rot_axis', 'var'))
+            rot_axis = [0 0 1];
+        end
+        rot_tensor = eye(3);
+        for ii = 1:numel(rot_angle)
+            rotcomp = gtMathsRotationMatrixComp(rot_axis(ii, :)', 'col');
+            rot_tensor = gtMathsRotationTensor(rot_angle(ii), rotcomp) * rot_tensor;
+        end
+    else
+        rot_tensor = rot_tensor_angle;
+    end
+
+    structure.intensity = gtRotateVolume(structure.intensity, rot_tensor);
+
+    switch (upper(type))
+        case 'ODF6D'
+            dmvol = structure.voxels_avg_R_vectors;
+            dmvol(:, :, :, 1) = gtRotateVolume(dmvol(:, :, :, 1), rot_tensor);
+            dmvol(:, :, :, 2) = gtRotateVolume(dmvol(:, :, :, 2), rot_tensor);
+            dmvol(:, :, :, 3) = gtRotateVolume(dmvol(:, :, :, 3), rot_tensor);
+            structure.voxels_avg_R_vectors = dmvol;
+        case 'VOL3D'
+    end
+
+    proj.centerpix = proj.centerpix * rot_tensor;
+
+    structure.shift = gtFwdSimComputeVolumeShifts(proj, parameters, size(structure.intensity));
+end