Ensure hoels of polygons have correct handedness

[PaulWessel]

Do not trust the incoming data. For polygons with holes that need to be filled, we ensure the holes have a different handedness than the parent, reversing the child if needed. Closes #3135.

[joa-quim]

OK, this works but there is some other bug from externals that probably is not looking for the -Ph option.
This paints the hole in blue

> -Gred
0  0
5  0
5  10
0  10
0  0
> -Ph -Gblue
2  1
2  3
4  3
4  1
2  1

D = gmtread("quad.dat");
plot(D, J="X12c", B="a2f1WSen", W=1, show=1)

but does not make it transparent when I remove the -Gblue from second segment header. So -Ph is in fact ignored.
It does, however, work fine when I don't read the data before hand and let GMT do it. That is, this works

plot("quad.dat", J="X12c", B="a2f1WSen", W=1, show=1)

[PaulWessel]

Maybe make a mex version of the test?

[joa-quim]

Use your Julia. Life is much easier with it

D=gmtmex('read quad.dat -Td');
gmtmex('psxy -JX12c -Ba2f1WSen -W1 -R-0.5/10.5/-0.5/10.5 > lixo.ps', D)

[PaulWessel]

OK, fine. I just installed/update julia to 1.3.1. Followed your macOS hint of addint startup.jl. Then tried ]add GMT and ERROR unexpected ].

[PaulWessel]

Am I completely missing any instructions for actuallly installing GMT.jl?.

[joa-quim]

Last version is Julia 1.4 but 1.3 is just as good.
You only have to do
] add GMT
When you type the ] the prompt immediately turns into pkg. What is your ERROR unexpected``?

[PaulWessel]

Seems like your instructions is missing some critical spaces between ] and add. Works now.

[joa-quim]

Ah, because you copy-pasted?

[PaulWessel]

Yes, but also the README.md has no space.

[PaulWessel]

Now here:
ia> D = gmtread("quad.dat");
ERROR: UndefVarError: gmtread not defined

[PaulWessel]

FYI, the adding package seems to work?

v1.3) pkg>  add GMT
   Cloning default registries into `~/.julia`
   Cloning registry from "https://github.com/JuliaRegistries/General.git"
     Added registry `General` to `~/.julia/registries/General`
 Resolving package versions...
 Installed GMT ─ v0.17.0
  Updating `~/.julia/environments/v1.3/Project.toml`
  [5752ebe1] + GMT v0.17.0
  Updating `~/.julia/environments/v1.3/Manifest.toml`
  [5752ebe1] + GMT v0.17.0
  [de0858da] + Printf 
  [4ec0a83e] + Unicode 

[joa-quim]

Ok, you should not need it but better to have the master version
] add GMT#master
And more thing, you have to do
D = gmtread("/path/to/file"); or do a cd("/path/to/file) first.
But you say gmtread is not found? Can't be. Try running the tests
] test GMT

[joa-quim]

Ah sorry, I know. It's like Python. Before using any package you have to import it. So first command per session has to be
using GMT

[PaulWessel]

D = gmtread("quad.dat");
ERROR: error compiling gmtread: error compiling #gmtread#60: error compiling gmt: could not load library "libgmt"

I put the startup.jp in config with path to my library dir and restarted.

julia
ERROR: LoadError: UndefVarError: Libdl not defined

[joa-quim]

Ok the other user that passed through this had to do
using Libdl before the push!(Libdl.DL_LOAD_PATH ...
I have to update this instructions also

[PaulWessel]

I added a call to Libdl in startup.jo before the LIB call. Same error.
Admittedly I am a Julia rookie so this is a very good test - clearly your README needs some work. I would think the average rookie would give up by now.

[PaulWessel]

OK, using Libdl works.
Plot generated.

[joa-quim]

Good. I debugged to confirm that the header is well transmitted to GMT. And mex version confirms the same thing. No hole.

[PaulWessel]

So when I debug MEX I have to load in gmtmex.c (compiled for Xcode) into Xcode, set a stop point, start matlab, connect Xcode to MATLAB processes, then run the matlab command.
What do I load into Xcode to set a stop point for Julia???

[PaulWessel]

You may need to add a "how to debug" section.

[PaulWessel]

Anyway, in the GMT io we do this:

if (gmt_parse_segment_item (GMT, S->header, "-Ph", NULL)) SH->pol_mode = GMT_IS_HOLE;

so the hidden helper structure per segment sets a flag. When gmt read returns to mablat it has the info:

ans = 

  struct with fields:

       data: [5x2 double]
       text: []
     header: '-Gred'
    comment: []
      proj4: []
        wkt: []

>> D(2)

ans = 

  struct with fields:

       data: [5x2 double]
       text: []
     header: '-Ph'
    comment: []
      proj4: []
        wkt: []

What does your Julia D data have?

[joa-quim]

Ok, dinner time here (still preparing it).
To debug from Julia you should do exactly the same but load the Julia process in Xcode. There is no equivalent in C to gmtmex so you can't debug that part with Xcode (you need VScode).

In Julia you get the same thing as in Matlab . Have a function for display that only shows first segment. To see more you do

julia> D[1]
Header: -Gred
5×2 Array{Float64,2}:
 0.0   0.0
 5.0   0.0
 5.0  10.0
 0.0  10.0
 0.0   0.0


julia> D[2]
Header: -Ph -Gblue
5×2 Array{Float64,2}:
 2.0  1.0
 2.0  3.0
 4.0  3.0
 4.0  1.0
 2.0  1.0

[PaulWessel]

As far as I can tell, when D is passed back into a matlab gmt call the header is extracted and copied into the GMT segment header so it should work - I just need to rebuild gmtmex here.

[joa-quim]

I verified that it is indeed like that from Julia, but -Ph makes no effect (tried with both -Ph -Gblue and -Ph

[joa-quim]

Don't want to try a debug from Julia?

1. Load the Julia process in XCode
2. Open a GMT source code in XCode and set a breakpoint
3. run the julia command that triggers that breakpoint

Ofc never tried in Mac but that's what I do on Windows.

[PaulWessel]

OK, it makes sense to set stop point in the GMT C in Xcode. I will see - as you know multi-tasking on this end during the day...

[joa-quim]

BTW, I updated the installing instructions so you can give a star to the project.