Height and passability

[alre]

As I already wrote once in a different thread, I'd like to create a random map where height and reliefs have an important role, but I need answer to some important questions:

• how can one access the heightmap from random map generation?
• how is passability computed from heightmap?
• how does that relate to height rendering in game?
• how can one apply a specific texture to impassable terrains?

An answer to one of these questions alone, is better than nothing.

[Stan`]

19 minutes ago, alre said:

how is passability computed from heightmap?

By computing the slope. eg. if the slope is too steep then your terrain is impassable

20 minutes ago, alre said:

how can one apply a specific texture to impassable terrains?

I believe there are a bunch of functions in the rmgen code to tell you that.

21 minutes ago, alre said:

how can one access the heightmap from random map generation?

See binaries/data/mods/public/maps/random/jebel_barkal.js#L347

You can also do

const heightmapHellas = convertHeightmap1Dto2D(Engine.LoadHeightmapImage("maps/random/hellas.png"));

 

 

As a general note you can look at how other maps are made https://github.com/0ad/0ad/blob/f314b5b9d2be852a4d25f4b9ef40ab4acf4f2002/binaries/data/mods/public/maps/random/belgian_uplands.js

[Feldfeld]

4 hours ago, alre said:

how can one access the heightmap from random map generation?

g_Map.height[x][y] could be what you want

4 hours ago, alre said:

how can one apply a specific texture to impassable terrains?

Depending on what you want, adding a PassableMapAreaConstraint, or a SlopeConstraint to your painter could be a solution.
If you want an example for SlopeConstraint check the map in the thread you linked.

[alre]

PassableMapAreaConstraint doesn't work at all for me. I mean, it selects all tiles as they all were passable.

Edited August 22, 2021 by alre

[Feldfeld]

Did you try SlopeConstraint? What exactly, in your case is defined as not passable?

If, for example, you want to select not only the flank of the mountain but the top where the slope becomes small again, in order to paint it, then you can try (SlopeConstraint or HeightConstraint), or you can also try floodfilling (https://code.wildfiregames.com/D2828) if you want to check the area reachable starting from a specific point in the map.

[Ceres]

Apart from the technical aspects, you might want to consider the topic "fairness". I mention it because some such maps have comments pointing out that they might not be fair for all players, depending on where they start.

[alre]

23 minutes ago, Feldfeld said:

Did you try SlopeConstraint? What exactly, in your case is defined as not passable?

If, for example, you want to select not only the flank of the mountain but the top where the slope becomes small again, in order to paint it, then you can try (SlopeConstraint or HeightConstraint), or you can also try floodfilling (https://code.wildfiregames.com/D2828) if you want to check the area reachable starting from a specific point in the map.

the problem with SlopeConstraint is that it seems to work when TILE_CENTERED_HEIGTH_MAP = true, but it doesn't quite reflect passability (for units to walk on them) if TILE_CENTERED_HEIGTH_MAP = false. this is more like a mishap than a deal breaker, but it's a pity that PassableMapAreaConstraint doesn't work.

besides, I'd like to ruefully notice that none of this is documented anywhere, so I still have a very rough understanding of how the heightmap is rendered, or what's the role of tiles in the pathfinder in general, like what's the true maximum passable slope, and how is it computed.

[Stan`]

Nothing here ? https://trac.wildfiregames.com/wiki/Rmgen_Library

Would be nice to expand it

Ping @FeXoR

[alre]

Related: note that Ngorongoro map uses SlopeConstraint to paint cliffs, and unfortunately they don't quite fit to unpassable areas:

I tried to change the value of TILE_CENTERED_HEIGTH_MAP for that map, but it seems it actually doesn't make any difference.

I gave up on making my map.

[alre]

I realised what's the problem with Ngorongoro map: heightmap gets modified by player placement, after cliffs are painted. SlopeConstraint may be working after all.