Re: [OpenSCAD] function syntax
Hi John,
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JohnMark wrote*
It can be done! But it's not easy.
I recommend you write and test your code in something easy like
javascript.
And then transcribe it into openSCAD compatible code.
Most functions you can code in JavaScript you can also code in OpenSCAD.
But it's super hacky.
The two tricks you need to know:
- Functions can call other functions.
- Conditionals are allowed in functions.
I also recommend two monitors for getting this job done.
One monitor I have my javascript code on that I work from.
The other monitor I have the openSCAD code I am writing
from the javascript reference.
Basically, just make a getter function for EVERY SINGLE VARAIBLE
in your original function. For simplicity, every single getter should take
the same arguments as the main function. Which, is really dirty and...
not efficient code at all. But it will make things simpler for your brain.
Oh. One last thing.
It's going to be a lot of code.
So I recommend importing it with a "use" statement.
I don't do an "include" because I usually put test-code at the bottom of
the file
and don't want that to execute in whatever file I am using it with.
And... Take the time and go slow.
Make sure your javascript (or whatever language you use)
code works perfectly. Test it!
Then carefully transcribe it into openSCAD and test the openSCAD code
with test functions as well.
This code is NOT going to be maintainable. But the good thing is, if you
are writing
mathematical functions. It doesn't need to be maintainable if you get it
100% correct.
Because, for example, the logic for how to intersect a line and a circle
will never change.
For example: Here is some of my circle-line collision code in openSCAD:
//Use conditional to split off two two different main
//Functions depending on if any edge cases were detected.
function getPNCC(pX,pY,vX,vY,cX,cY,r) =
0 < getPNCC_HasEdgeCases(pX,pY,vX,vY,cX,cY,r)
//--------------------------------------------//
? getPNCC_TheEdgeCases(pX,pY,vX,vY,cX,cY,r,
getPNCC_HasEdgeCases(pX,pY,vX,vY,cX,cY,r) //<--supply edge case to
func.
)
//--------------------------------------------//
: getPNCC_StandardCase(pX,pY,vX,vY,cX,cY,r);
//--------------------------------------------//
//DETECTION, but NOT handling, of edge cases:
//[ECD]++[ECD]++[ECD]++[ECD]++[ECD]++[ECD]++[ECD]++[ECD]++[ECD]//[|START|]
//Each edge-case detection sub-function will return 0 or a postive
//value indicating which edge case was triggered.
function getPNCC_HasEdgeCases(pX,pY,vX,vY,cX,cY,r) =
max(
//edge case #1: point at center of circle.
PNCC_EC_1(pX,pY,cX,cY), //10,000
//edge case #2: Parallel vectors, line passes through
//center-point of circle. But start is not at center of circle.
PNCC_EC_2(pX,pY,vX,vY,cX,cY,r), //2,000
//edge case #3: dist_CD > r, AKA:
//Perpendicular distance from line to center of
//circle exceeds radius of circle.
PNCC_EC_3(pX,pY,vX,vY,cX,cY,r), //300
//edge case #4: dist_CD === r, AKA: Tangency.
PNCC_EC_4(pX,pY,vX,vY,cX,cY,r) //40
);
function PNCC_EC_1(pX,pY,cX,cY)=
(
(pX==cX) && (pY==cY)
) ?
EC_01
:
0;
function PNCC_EC_2(pX,pY,vX,vY,cX,cY,r)=
(
abs(PNCC_GET_u_dot_v(pX,pY,vX,vY,cX,cY,r))
abs(PNCC_GET_prod_of_mags(pX,pY,vX,vY,cX,cY,r))
) ?
EC_02
:
0;
function PNCC_EC_3(pX,pY,vX,vY,cX,cY,r)=
(
PNCC_GET_dist_CD(pX,pY,vX,vY,cX,cY,r) > r
) ?
EC_03
:
0;
function PNCC_EC_4(pX,pY,vX,vY,cX,cY,r)=
(
PNCC_GET_dist_CD(pX,pY,vX,vY,cX,cY,r) == r
) ?
EC_04
:
0;
//[ECD]++[ECD]++[ECD]++[ECD]++[ECD]++[ECD]++[ECD]++[ECD]++[ECD]//[|END|]
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