Fix a regression that was causing failure of categorical test.

[joa-quim]

Also document -Qt option that was missing since its creation.

[Esteban82]

How can I test this?

I tried this script but I got this error:

grdview [ERROR]: Categorical data (as implied by CPT) cannot be interpolated and require -T or just -Qm.

Full script:

gmt begin ex05_3d png
 	gmt makecpt -Ccategorical -T0/4/1 -F+cOceanic,Land,Lakes,Islands,Ponds
	gmt grdview @earth_mask -JM15c -JZ4c -B -Bz0.5 -BSEwnZ -N-1+gwhite -RUY -p120/30 -C -Qt
gmt end

[joa-quim]

I tested it with a bit of the categorical.sh test.

[Esteban82]

That works but it is a bit different. It doesn't plot use -JZ or -p.

# Finally plot as texture image -Qt100
gmt grdview tt.nc -Ctt.cpt -JU31/2.75 -B5g5 -BWSne+t"-Qt100" -Qt100i -JZ4c -J

[joa-quim]

That's a different issue (and it lacks -R to use the -JZ)

[Esteban82]

That's a different issue (and it lacks -R to use the -JZ)

This is the full script I am using:

gmt begin ex05_3d png
 	gmt makecpt -Ccategorical -T0/4/1 -F+cOceanic,Land,Lakes,Islands,Ponds
	gmt grdview @earth_relief -G@earth_mask -JM15c -JZ5c -B -Bza -BSEwnZ -N-500+gwhite -R-58/-54/-36/-32/-500/500 -p120/30 -C -Qt100i
gmt end

First, I am not completely sure that I fully understand what the -Qt option is intended for.

Second, using the script above, I was able to generate the figure shown below by adding || Ctrl->Q.special to this line in grdview.c:

gmt/src/grdview.c

Line 1076 in 8d53ecb

if (P->categorical && !(Ctrl->Q.mode == GRDVIEW_MESH || Ctrl->T.active)) {

Without this modification, I got the previous error:

grdview [ERROR]: Categorical data (as implied by CPT) cannot be interpolated and require -T or just -Qm.

Do you want me to modify the grdview.c file?

[joa-quim]

Better not. That is a different issue. Open a new one.

[Esteban82]

Ok. I will make another PR.

[joa-quim]

But better wait till I update the copyright year