Could someone please provide working GDL code for a POLY2 command that gives a half circle? I just can't figure out the correct syntax for the POLY2 commands and it's driving me crazy!
Acording the GDL manual, POLY2 does not implement
additional status codes but POLY2_ does unless you have
a resol statement earlier in the script set to eight or less.
Peter Devlin
Okay, you got me on semantics... in any case, I'll just answer my own post:
FILL circ_fill ! fill setting
POLY2_ 6, 3,
0,0,1, ! node
-bcirc,0,1, ! node
1,90,800, ! set tangent (see Additional Status Codes)
bcirc,-180,2000, ! tangential arc by radius and angle
bcirc,0,1, ! node
0,0,1 ! repeat first node
Where "bcirc" is a dimension defined in the parameters. The result of the POLY2_ above give a half circle fill of radius "bcirc".
FILL circ_fill
POLY2_ 3,1+2+4,
bcirc,0,1,
0,1,801,
-bcirc,0,1001
In your examples, you have used 15 for the status-values. This works, but is normally used for 3D-commands. In 2D status is defined with 0 or 1, what you should use.
To use a 4 in the mask (1+2+4) makes the last point superfluously.
@genarch
In your working example is the tangent IMHO not proper done, because it shouldn't have an x component. You have some needless points too.
It works proper like this:
In your examples, you have used 15 for the status-values. This works, but is normally used for 3D-commands. In 2D status is defined with 0 or 1, what you should use.
I know Frank but ....
what seems an error can become an advantage.
Put bcirc,0,15,
0,0,915,
bcirc,180,4015,
bcirc,0,-1
That's right, but you set unused bits of the status, which might become in coming GDL-Versions a meaning. Maybe such old objects will not work proper anymore. It might be conservative, but I try to use the exact syntax.
I try to solve it like this:
IF GLOB_CONTEXT=2 THEN msk=1 ELSE msk=15
PUT bcirc,0,msk,
0,0,900+msk,
bcirc,180,4000+msk,
bcirc,0,-1
