## 6.2.6. VIEW OPTION, [V]

next, previous Section / Table of Contents / Index [V] This option allows you to define viewing directions, magnifications, and projections used in the graphics output and is, except for option [V], identical to the view option of the BALSAC/CLUSTER session, see Sec. 6.3.4. The view option menu V reads ========== VIEW OPTIONS ====================================== [V]iew(miller) = ( vh, vk, vl / vq ) [T]heta,(dtheta) = theta ( dtheta ) [P]hi,(dphi) = phi ( dphi ) [R]ot,(drot) = rot ( drot ) [M]agnf,(dmagnf) = magnf ( dmagnf ) [Q]persp,(dpersp) = persp ( dpersp ) [F]ocus = nfoc ( xfoc yfoc zfoc ) [S]hift (pixels) = sx , sy [A]ll [W]orkb [D]ispla {[X]plot} [?,]esc ======================================================== 26 == giving values of all view parameters and option keys described below. If BALSAC is started from scratch the plot option "[X]plot" of this menu is not available and will not be shown. BALSAC allows two alternative methods to define viewing directions in the lattice section, (a) by direction indices (vh, vk, vl ) or (vl, vm, vn, vq) described by (real-valued) Miller indices (option [V]), (b) by viewing angles theta, phi with respect to the coordinate system of the lattice planes (options [T], [P]). Direction indices (vh, vk, vl) shown in submenu V are defined with respect to the reciprocal lattice basis (G1, G2, G3) also used to characterize the lattice planes. Here the viewing direction points along vector v with v = vh*G1 + vk*G2 + vl*G3. Thus, integer-valued indices (vh,vk,vl) correspond to Miller indexed crystal directions. For crystal lattices where Miller indices are based on the simple cubic reciprocal lattice, see Sec. 6.2.1, the direction indices (vh,vk,vl) is also defined with respect to the simple cubic reciprocal lattice. Further, if the 4-index notation of lattice plane directions is chosen for hexagonal lattices, see Sec. 6.2.1, the direction indices have to be provided also in 4-index notation as (vl,vm,vn,vq) and the viewing direction points along vector v with v = vl*G1 - vn*G2 + vq*G3. Indices (vh,vk,vl) or (vl,vm,vn,vq) will be always renormalized internally such that the absolute value of the smallest non-vanishing index equals 1. Viewing angles theta, phi shown in submenu V are taken with respect to a cartesian coordinate system of the lattice planes with its origin at the section focus, see below, where the x axis points along R1' (first lattice plane periodicity vector, see Sec. 5.1) and the z axis points along the lattice plane normal vector. In this system, the unit vector of the viewing direction is defined by p = ( sin(theta)*cos(phi), sin(theta)*sin(phi), cos(theta) ) with theta giving the polar and phi giving the azimuthal angle. Since direction indices and viewing angles are equivalent definitions of the viewing direction they will be converted internally before shown in submenu V. The screen rotation angle rot shown in submenu V allows for an additional rotation of the plot about the viewing direction to achieve special effects. The magnification factor magnf shown in submenu V allows for enlargement (magnf > 1) or reduction (magnf < 1) of the actual plot size where magnf = 1 corresponds to plots where the lattice section fills the screen. The perspective parameter persp shown in submenu V defines both the projection mode and the perspective factor. Here persp = 0 or persp > 999 results in a parallel projection of the lattice section in plots while persp > 0 values lead to central projection with persp giving the distance of the viewer from the section focus in multiples of the section radius, see Sec. 5.1. The section focus shown in submenu V is defined by absolute cartesian coordinates (xfoc, yfoc, zfoc) as well as by an index nfoc where for nfoc = 0 the viewing focus coincides with the section center, nfoc > 0 the viewing focus coincides with the center of atom no. nfoc, nfoc = -1 a free definition of the focus by (xfoc, yfoc, zfoc) was given. The plot shift (sx,sy) shown in submenu V defines a rigid shift (in pixel units) of the plot which may be needed to center certain locations of a lattice section visually. In submenu V all viewing angles (theta, phi, rot), the magnification (magnf), and the perspective parameter (persp) are listed together with incremental values (dtheta, dphi, drot, dmagnf, dpersp) which are used with the fast plot option, see below. > [V] selected from submenu V allows you to redefine the viewing direction by direction indices based on reciprocal lattice vectors, see above. The prompt Input Miller view VH,VK,VL : asks for three (real valued) indices vh, vk, vl after which BALSAC returns to submenu V. If 4-index notation of lattice plane directions is chosen in hexagonal lattices, see Sec. 6.2.3, the above prompt is replaced by Input Miller view VL,VM,VN,VQ : requiring four (real valued) indices vl, vm, vn, vq. Dummy input "/" will leave the present definition unchanged in both cases. > [T] selected from submenu V allows you to redefine the polar angle of the viewing direction, see above. The prompt Input polar angle + increment THETA,DTHETA : asks for two numbers defining the polar angle theta and its increment dtheta (used with the fast plot option) after which BALSAC returns to submenu V. Dummy input "/" will leave the present definition unchanged. Angle theta will be rescaled to lie inside the range [0, 180]. > [P] selected from submenu V allows you to redefine the azimuthal angle of the viewing direction, see above. The prompt Input azimuthal angle + increment PHI,DPHI : asks for two numbers defining the azimuthal angle phi and its increment dphi (used with the fast plot option) after which BALSAC returns to submenu V. Dummy input "/" will leave the present definition unchanged. Angle phi will be rescaled to lie inside the range (-360, 360). > [R] selected from submenu V allows you to redefine the screen rotation angle, see above. The prompt Input rotation angle + increment ROT,DROT : asks for two numbers defining the screen rotation angle rot and its increment drot (used with the fast plot option) after which BALSAC returns to submenu V. Dummy input "/" will leave the present definition unchanged. Angle rot will be rescaled to lie inside the range (-360, 360). > [M] selected from submenu V allows you to redefine the magnification used to display lattice sections. The prompt Input magnification + increment MAGNF,DMAGNF : asks for two numbers defining the magnification factor magnf and its increment dmagnf (used with the fast plot option) after which BALSAC returns to submenu V. Here magnf > 1 leads to enlargement and magnf < 1 to reduction of the actual plot size while magnf = 1 corresponds to plots where the lattice section fills the screen. Dummy input "/" will leave the present definition unchanged. > [Q] selected from submenu V allows you to redefine the perspective parameter used to display lattice sections in central projection geometry. The prompt Input perspective + increment PERSP,DPERSP : asks for two numbers defining the perspective parameter persp and its increment dpersp (used with the fast plot option) after which BALSAC returns to submenu V. Here persp = 0 or persp > 999 results in a parallel projection of the lattice section in plots while persp > 0 values lead to central projection with persp giving the distance of the viewer from the section focus in multiples of the section radius, see Sec. 5.1. Dummy input "/" will leave the present definition unchanged. > [F] selected from submenu V allows you to redefine the section focus (xfoc, yfoc, zfoc) used to display lattice sections in central projection geometry. The prompt Focus center NC,X,Y,Z ("nc,0,0,0"=atom, "-1,x,y,z"=abs, "0,0,0,0"=avg) : asks for four numbers, nfoc (integer), xfoc, yfoc, zfoc (real), defining the section focus where three different definitions can be used. For nfoc > 0 values xfoc, yfoc, zfoc are ignored and the focus is assumed to coincide with the center of atom no. nfoc, nfoc = 0 the focus is assumed to coincide with the section center (center of the rectangular block, see Sec. 6.2.4), nfoc = -1 the focus is assumed to be given by absolute cartesian coordinates xfoc, yfoc, zfoc of the lattice section. After complete input BALSAC returns to submenu V. Dummy input "/" will leave the present definition unchanged. Note that the graphic analysis option offers a focus definition which is much more intuitive and faster, see Sec. 6.3.12. > [S] selected from submenu V allows you to set a rigid shift to move the plot on the screen. The prompt Input plot shift SHPIXX,SHPIXY : asks for two numbers defining the x and y coordinates sx, sy (in pixel units) of the plot shift after which BALSAC returns to submenu V. Here sx = sy = 0 defines the default where plots of lattice sections will be centered such that the image of the section center coincides with the screen center. Values sx > 0 will shift to the right, sx < 0 will shift to the left, sy > 0 will shift downwards, sy < 0 will shift upwards, Dummy input "/" will leave the present definition unchanged. Note that the graphic analysis option offers a plot shift definition which is much more intuitive and faster, see Sec. 6.3.12. > [A] selected from submenu V allows you to set the most important view parameters (without increments) in one step. The prompt Input THETA,PHI,ROT,MAGNF,PERSP : asks for five numbers defining the polar and azimuthal view angles, theta, phi, the screen rotation angle rot, the magnification factor magnf, and the perspective parameter persp after which BALSAC returns to submenu V. Here incremental values previously defined (or default values) will be used. Dummy input "/" will leave the present definition unchanged. > [W] selected from submenu V moves to the color/shading workbench switching to graphics mode (DOS) or opening a graphics window (Unix). This allows you to change all basic and paint colors as well as ball shading angles in a very intuitive way using the mouse or a graphics pointer. Further details are given in Sec. 6.2.15.2. > [D] selected from submenu V shows up to 10 lines of the most recent output generated by the graphic analysis option, see Sec. 6.2.14.2, by ============ Latest Graphics Output ================== 1: Xyz,R,Id( n1)= x y z rad nuc ... ====================================================== This allows you to look up and use numerical output from the analysis for input within submenu V. After the listing BALSAC returns to submenu V. > [X] selected from submenu V (if available) plots the lattice section (switching to graphics mode (DOS) or opening a graphics window (Unix)) or lists its atom coordinates depending on the plot/list mode defined in the graphics option, see Sec. 6.2.7. > [,] selected from submenu V returns to the BALSAC/LATTICE main option menu, see Sec. 6.2.0. The view parameters theta, phi, rot, magnf, and persp (and other option parameters) can be varied outside the view option menu immediately after a plot has been completed (or interrupted and finished incomplete by selecting [,]). The available option keys are shown in a menu line at the bottom of the screen (graphics/text window (Unix)) and are explained in detail in Sec. 6.2.9. NOTE that view parameters theta, phi, rot, magnf, and persp can also be changed quasi-continuously by mouse dragging inside the plot screen or window after a plot has been completed. This requires the mouse menu option to be - active for the BALSAC DOS version (if needed press [@] to toggle mouse option key). - inactive for the BALSAC Unix version (if needed L-click "Menu off" button inside menu window). For further details see Secs. 3.3.8, 6.2.9. next, previous Section / Table of Contents / Index