Name
lok — Lookup operation
Syntax
Single lookup transitions:
lok [xy | xz | yx | yz | zx | zy] ;# Indicates which two coordinate axes to use.
lok value hi workspacename ;# Lookup transition
Lookup handling if input value is outside lookup curve
lok ... nol nolookupvalue | ext ;# setting nolookupvalue or extrapolation
Lookup transitions for active dataset:
lok [xy | xz | yx | yz | zx | zy] hi workspacename ;# Lookup transition
Multiple lookup transitions:
lok up | pml | wlc | wel | mlp | mlc ;# See separate documentation
Description
A lookup curve is a way of transforming a point trough a curve. In Geocap all curves have xyz-coordinates. Default lookup is between the y and x coordinates. The functionality of lookup curves are collected under the lok command. The system operates with single and multiple lookup curves.
A lookup curve is a curve in a plane. An input entry on one axes goes parallel with the other axes until it hits the curve. The lookup value is found by going parallel with the first axes down to the second axes.
Arguments single lookup transitions
lok [xy | xz | yx | yz | zx | zy]
Indicates which two coordinate axes to use as entry and exit of the lookup operation.
lok value hi workspacename
The lookup curve is in workspacename. Input value is value. The result is saved in @lookup. To assign it to a variable: set lup [gvar lookup]
Arguments for lookup transitions on active data
lok [xy | xz | yx | yz | zx | zy]
Indicates which two coordinate axes to use as entry and exit of the lookup operation.
lok [xy | xz | yx | yz | zx | zy] hi workspacename [nol no_lookup_value | nol keep | rem | ext] [dlo]
dlo - Display lookup curve.
nol no_lookup_value - Use no_lookup_value outside lookup range.
nol keep - Keep values outside lookup range.
rem - Remove values outside lookup range.
ext - Extrapolate values outside lookup range.
Arguments multiple lookup transitions
A set of lookup curves are spread across a horizon. A grid node can be converted using a blend of lookup curves in the node's neighbourhood.
See separate documentation.
Examples
Ex.1: Lookup transitions
# Lookup curves vie def ;# reset viewport ret 10 ;# return start window spe bgc whi ;# specify background color to white sta 0 0 0 ;# stack x y z coordinates sta 20 40 0 ;# stack x y z coordinates sta 100 100 0 ;# stack x y z coordinates rea ter ;# read 3 stacked points cur lin sav nodraw ;# spline curve, save and no draw poi num 0 ;# display point number 0 pot ;# tube the polygon mhi mm ;# move lookup curve high to mm col bla ;# color black dra win ;# draw window frame d2 ;# set in 2d mode axe adhx 15 tic ;# draw axes with tic marks and tune vertical x placement sta 20 60 25 ;# stack x y z coordinates sta 30 40 60 ;# stack x y z coordinates sta 60 80 80 ;# stack x y z coordinates rea ter ;# read 3 stacked points set xx [gvar xwin] ;# set xwin value in tcl syntax set yy [gvar ywin] ;# set ywin value in tcl syntax mhi pp ;# move pointset high to pp swi xzy ;# switch y and z sca x 0 ;# x values are scaled to 0 tra $xx 0 0 ;# shift x values by xx sca z 0 ;# z values are scaled to 0 add 50 ;# add 50 col yel ;# yellow color poi val fol yco ;# display y coordinate values mlo pp ;# move low from pp lok yx hi mm dlo ;# perform lookup transition mhi ll ;# move high the new pointset col red ;# color red mlo ll ;# move low the transformed pointset swi zyx ;# switch x and z sca y 0 ;# y values are scaled to 0 tra 0 $yy 0 ;# shift y values by yy sca z 0 ;# z values are scaled to 0 add 50 ;# add 50 col tur ;# color turqoise poi val fol xco ;# display x coordinate values
The above example produces this image.
Lookup transitions for three points