FIX: project -G use angular unit

[Dengda98]

Hi, GMT!

I found that gmt project -G<dist> uses wrong interval when <dist> appending angular unit d|m|e. For example,

$ gmt project -C125/33 -E146/46 -G1d -Q | head -n3
125     33      0
125.000007565   33.0000063736   0.001
125.00001513    33.0000127473   0.002

looks like there's a strange 1e-3 scale. I checked project.c, and I guess maybe we need to add an if statement here, to check whether -G use angular unit.

gmt/src/project.c

Lines 847 to 848 in 640f1e6

	if (Ctrl->Q.active && Ctrl->G.unit != 'k' && !Ctrl->G.number)
	Ctrl->G.inc *= 0.001 / GMT->current.map.dist[GMT_MAP_DIST].scale; /* Now in km */

So I imitate some lines for -Z,

gmt/src/project.c

Lines 783 to 793 in 640f1e6

	if (Ctrl->Z.mode && Ctrl->Z.unit != 'k') { /* Degenerate ellipse with diameter given in units */
	if (gmt_init_distaz (GMT, Ctrl->Z.unit, Ctrl->Z.mode, GMT_MAP_DIST) == GMT_NOT_A_VALID_TYPE)
	Return (GMT_NOT_A_VALID_TYPE);
	if (GMT->current.map.dist[GMT_MAP_DIST].arc) { /* Got angular measures, convert to km */
	Ctrl->Z.minor *= (GMT->current.proj.KM_PR_DEG / GMT->current.map.dist[GMT_MAP_DIST].scale); /* Now in km */
	Ctrl->Z.major *= (GMT->current.proj.KM_PR_DEG / GMT->current.map.dist[GMT_MAP_DIST].scale); /* Now in km */
	}
	else {
	Ctrl->Z.minor /= (GMT->current.map.dist[GMT_MAP_DIST].scale * METERS_IN_A_KM); /* Now in km */
	Ctrl->Z.major /= (GMT->current.map.dist[GMT_MAP_DIST].scale * METERS_IN_A_KM); /* Now in km */
	}

I add an if statement for -G,

if (Ctrl->Q.active && Ctrl->G.unit != 'k' && !Ctrl->G.number){
	if (GMT->current.map.dist[GMT_MAP_DIST].arc) {
		Ctrl->G.inc *= (GMT->current.proj.KM_PR_DEG / GMT->current.map.dist[GMT_MAP_DIST].scale); /* Now in km */
	}
	else {
		Ctrl->G.inc /= METERS_IN_A_KM * GMT->current.map.dist[GMT_MAP_DIST].scale;	/* Now in km */
	}
}

After recompiling, I test it with same command, the result seems fine.

$ gmt project -C125/33 -E146/46 -G1d -Q | head -n3
125     33      0
125.848042113   33.705854159    111.195051975
126.710079013   34.4058180505   222.39010395

[welcome]

💖 Thanks for opening this pull request! 💖

Please make sure you read our Contributing Guide and abide by our Code of Conduct.

A few things to keep in mind:

• If you need help writing tests, take a look at the existing ones for inspiration. If you don't know where to start, let us know and we'll walk you through it.
• All new features should be documented. It helps to write the comments below for your functions describing the it, all arguments, and return types before writing the code. This will help you think about your code design and results in better code.
• We are grateful that you put in the effort to do this! 🎉

[joa-quim]

Thanks for finding this and even more for providing a fix.

[welcome]

🎉🎉🎉 Congrats on merging your first pull request and welcome to the team! 🎉🎉🎉

We hope that this was a good experience for you. Let us know if there is any way that the contributing process could be improved.