feat(editor): preview terrain

[dderevjanik]

[Johannes-callidus]

This looks really good.
I just have two requests.
First one is to implement the preview for custom earthkek as well.
Second one is to make the stone preview look more like they'll do when placed. That means they should also have the bigger stone images and should change their image when they are near cliffs.
I know second one is a bit more difficult but I'm sure you can do it.

[crudelios]

I'm not sure the bigger stone images are possible because they depend on the surrounding rocks and may require a full recalculation of a broader part of the map.

[Johannes-callidus]

It doesn't have to be exact.
We can just not calculate the surrounding stones in at all. But depending on the brush size the rocks inside the brush which is also what I thought of with custom earthkeks.

[crudelios]

Fair enough, that's likely doable

[dderevjanik]

It's better than before, but still not perfect. I'd rather avoid adding unnecessary complexity just to perfect the preview

[crudelios]

Coding style changes

[crudelios]

Suggested change

	else if (ring >= 1) image_id += 8;
	if (ring >= 3) {
	image_id += 24;
	} else if (ring >= 2) {
	image_id += 16;
	} else if (ring >= 1) {
	image_id += 8;
	}

Coding guideline: always use braces.

[crudelios]

Suggested change

	if (ring >= 2) image_id += 8;
	else if (ring >= 1) image_id += 4;
	if (ring >= 2) {
	image_id += 8;
	} else if (ring >= 1) {
	image_id += 4;
	}

[crudelios]

Suggested change

	if (ring >= 1) image_id += 29;
	else image_id += 24;
	if (ring >= 1) {
	image_id += 29;
	} else {
	image_id += 24;
	}