Circular hole in circular PRISM

[Bruce]

Can someone enlighten me on the trick to create a circular hole in a circular PRISM? The usual -1 status code doesn't seem to work.

E.g., by my reading of the GDL reference guide (page 27 for AC21) the code should be:

PRISM_ 5, height,
 0, 0, 913,
radius_outer, 360, 4000,
0, 0, -1,
radius_inner,  360, 4000,
radius_inner,  360, -1

OR

PRISM_ 6, height,
 0, 0, 913,
radius_outer, 360, 4000,
0, 0, -1,
0, 0, 913,
radius_inner,  360, 4000,
0, 0, -1

But both of these return a compiling error.

[Barry Kelly · Accepted solution]

Try this.
I think the problem is you are needing to use the circle centre with the -1 mask which dosen't work with a full 360 degree circle.

Break it up into semi circles.

	PRISM_ 14, height,
		radius_outer,       0.0,      15+64, 
		0,       0.0,    900, 
		   0,          180,   4000, 
	   -radius_outer,       0.0,      15+64, 
		0,       0.0,    900, 
		   0,          180,   4000, 
		radius_outer,       0.0,     -1,

		radius_inner,       0.0,      15+64, 
		0,       0.0,    900, 
		   0,          180,   4000, 
	   -radius_inner,       0.0,      15+64, 
		0,       0.0,    900, 
		   0,          180,   4000, 
		radius_inner,       0.0,     -1

Barry.

[Bruce]

That's it Barry - thanks.

[Jochen Suehlo]

Although logically it should not, the following simplified version works as well:

PRISM_ 3, 1,
0, 0,  979,
0.2, 360, 4079,
0.1, 360, 4049

[Bruce]

I like that one too!