Post your mapgen questions here (modding or engine)

[burli]

I found my mountains. This screenshot isn't half of that. It is gigantic.

And the magic parameter is lunarity. If I set it to 3 I get this beautiful surface



If you want to visit this place, here is the map_meta.txt

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Code: Select all

chunksize = 5
mg_biome_np_heat = {
   flags = defaults
   lacunarity = 2
   octaves = 3
   offset = 50
   persistence = 0.5
   scale = 50
   seed = 5349
   spread = (750,750,750)
}
mg_biome_np_heat_blend = {
   flags = defaults
   lacunarity = 2
   octaves = 2
   offset = 0
   persistence = 1
   scale = 1.5
   seed = 13
   spread = (8,8,8)
}
mg_biome_np_humidity = {
   flags = defaults
   lacunarity = 2
   octaves = 3
   offset = 50
   persistence = 0.5
   scale = 50
   seed = 842
   spread = (750,750,750)
}
mg_biome_np_humidity_blend = {
   flags = defaults
   lacunarity = 2
   octaves = 2
   offset = 0
   persistence = 1
   scale = 1.5
   seed = 90003
   spread = (8,8,8)
}
mg_flags = trees, nocaves, nodungeons, noflat, light, decorations
mg_name = v7
mgv7_cave_width = 0.2
mgv7_np_cave1 = {
   flags = defaults
   lacunarity = 2
   octaves = 3
   offset = 0
   persistence = 0.5
   scale = 12
   seed = 52534
   spread = (61,61,61)
}
mgv7_np_cave2 = {
   flags = defaults
   lacunarity = 2
   octaves = 3
   offset = 0
   persistence = 0.5
   scale = 12
   seed = 10325
   spread = (67,67,67)
}
mgv7_np_filler_depth = {
   flags = defaults
   lacunarity = 2
   octaves = 3
   offset = 0
   persistence = 0.7
   scale = 1.2
   seed = 261
   spread = (150,150,150)
}
mgv7_np_height_select = {
   flags = defaults
   lacunarity = 2
   octaves = 5
   offset = 1
   persistence = 0.6
   scale = 4
   seed = 7244
   spread = (600,600,600)
}
mgv7_np_mount_height = {
   flags = defaults
   lacunarity = 2
   octaves = 3
   offset = 256
   persistence = 0.6
   scale = 112
   seed = 72449
   spread = (1000,1000,1000)
}
mgv7_np_mountain = {
   flags = eased
   lacunarity = 3
   octaves = 5
   offset = -0.6
   persistence = 0.3
   scale = 1.4
   seed = 5333
   spread = (250,350,250)
}
mgv7_np_ridge = {
   flags = defaults
   lacunarity = 2
   octaves = 4
   offset = 0
   persistence = 0.75
   scale = 1
   seed = 6467
   spread = (100,100,100)
}
mgv7_np_ridge_uwater = {
   flags = defaults
   lacunarity = 2
   octaves = 5
   offset = 0
   persistence = 0.6
   scale = 1
   seed = 85039
   spread = (1000,1000,1000)
}
mgv7_np_terrain_alt = {
   flags = defaults
   lacunarity = 2
   octaves = 5
   offset = 0
   persistence = 0.6
   scale = 10
   seed = 5934
   spread = (600,600,600)
}
mgv7_np_terrain_base = {
   flags = defaults
   lacunarity = 2
   octaves = 5
   offset = 0
   persistence = 0.6
   scale = 10
   seed = 82341
   spread = (600,600,600)
}
mgv7_np_terrain_persist = {
   flags = defaults
   lacunarity = 2
   octaves = 3
   offset = 0.6
   persistence = 0.6
   scale = 0.1
   seed = 539
   spread = (2000,2000,2000)
}
mgv7_spflags = mountains, ridges
seed = 10451164194390179830
water_level = 1
[end_of_params]


[burli]

Another question. I want to make realistic lakes/ponds. Any idea how to make them?

[paramat]

> Now most mountains have a gentle smoothed side an a totally insane side

The insane sections are caused by rivers, anything above the river is cut away with 3D noise.

It's lacunarity not lunarity :] this is the ratio of the scales of variation of adjacent octaves.
Standard lacunarity is 2.0, where each additional octave creates variation on a scale 1/2 that of the previous octave (which is why they're called octaves, it's analogous to musical octaves which is a doubling of frequency).

Lacunarity 3.0 means that if the 'spread' (the scale of variation of octave 1) is 900 nodes, then the 2nd octave creates variation on a scale of 300 nodes, the 3rd octave 100 nodes etc. It's a way to get a wider range of detail with the same number of octaves. it also has a different character.

[ozkur]

where could i get this?

[TumeniNodes]

Okay paramat, here are the results of my tinkering so far : )
I'm loving this. I need to tweak the river-bank setting yet.
I still think adding ridges to mgflat would be great... if the ridges used the same simplistic setting for sloping and width, could be ummmmm... mg V8? :P

Anyway, here are some results






just a little fun with this one :D

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Code: Select all

mg_flags = notrees, nocaves, nodungeons, noflat, light, nodecorations

mgv7_np_height_select = {
   flags = defaults
   lacunarity = 2
   octaves = 5
   offset = 1
   persistence = 0.6
   scale = 4
   seed = 7244
   spread = (600,600,600)
}
mgv7_np_mount_height = {
   flags = defaults
   lacunarity = 1
   octaves = 2
   offset = 120
   persistence = 0.3
   scale = 60
   seed = 72449
   spread = (1000,1000,1000)
}
mgv7_np_mountain = {
   flags = eased
   lacunarity = 2
   octaves = 4
   offset = -0.3
   persistence = 0.4
   scale = 1
   seed = 5333
   spread = (250,350,250)
}
mgv7_np_ridge = {
   flags = defaults
   lacunarity = 2
   octaves = 4
   offset = 0
   persistence = 0.75
   scale = 1
   seed = 6467
   spread = (100,100,100)
}
mgv7_np_ridge_uwater = {
   flags = defaults
   lacunarity = 2
   octaves = 5
   offset = 0
   persistence = 0.6
   scale = 1
   seed = 85039
   spread = (1000,1000,1000)
}
mgv7_np_terrain_alt = {
   flags = defaults
   lacunarity = 2
   octaves = 5
   offset = -23
   persistence = 0.6
   scale = 11
   seed = 5934
   spread = (600,600,600)
}
mgv7_np_terrain_base = {
   flags = eased
   lacunarity = 1
   octaves = 2
   offset = 24
   persistence = 0.6
   scale = 0
   seed = 82341
   spread = (600,600,600)
}
mgv7_np_terrain_persist = {
   flags = defaults
   lacunarity = 2
   octaves = 3
   offset = 0.6
   persistence = 0.6
   scale = 0
   seed = 539
   spread = (2000,2000,2000)
}
mgv7_spflags = mountains, ridges
seed = 5623940581441649840
water_level = 1
[end_of_params]

[paramat]

TumeniNodes,

My noise for seabed (terrain alt) may be a little too deep at a centre value (offset) of y = -23.

For less steep coast/beach divide the offset and scale of height_select by the same amount, for example:

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Code: Select all

mgv7_np_height_select = {
   flags = defaults
   lacunarity = 2
   octaves = 5
   offset = 0.5
   persistence = 0.6
   scale = 2
   seed = 7244
   spread = (600,600,600)
}

scale must remain 4 * offset though to keep your preferred ration of lakes to land.

[paramat]

burli,

Realistic in what way? Size, shape or decorations? Remember it's impossible to decide in code if a body of water is part of a large ocean or part of a small pool.

[paramat]

ozkur,

Get what?

[paramat]

burli,

> Can you briefly explain the parameters so that i can tinker around?

For mgv7:

2D noises:

terrain_base/alt:
These 2D noises define terrain height for everything except mountains.
Each noise defines a smooth rolling surface, it is the 'height select' noise that then selects which terrain is used at a point.
Confusingly, 'base' is the high terrain at the top of cliffs and 'alt' is the typically lower terrain that creates the seabed, beaches and low hills.
If cliff terrain is below lower terrain then low terrain is used. Cliff terrain is the more rare terrain by default and you can see it rising up out of the lower terrain.

height_select:
This switches between terrains as the noise valuse crosses the range 0 to 1. Boosting the 'scale' boosts cliff steepness. 'offset' controls what proportion of terrain is cliff terrain.

terrain_persist:
Controls the persistence value (terrain roughness) of 'terrain_base' and 'terrain_alt'. 0.6 is a medium-rough value, 0.4 is smoother.

ridge_uwater:
This creates the large scale course of the river, 'spread' is the overall scale of the river pattern, 'persist' is the twistyness of the river, 'octaves' the number of levels of detail in the river course structure.

mount_height:
Controls and varies typical mountain height in nodes over large distances.

3D noises:

mountain:
The actual 3D noise creating mountain terrain, can be 'eased' in the flags for smoother noise.
The relation of 'offset' to 'scale' controls what proportion of world is covered by mountain, for example 'offset = 0' means half the world will be mountain.
Boosting 'scale' to high numbers creates insanely tall mountains and many floatlands up to y = 31000.

ridge:
The actual 3D noise creating the rough cliff surfaces either side of rivers, river channels will cut through any terrain above up to world top.

[burli]

Paramat, thanks for the explanation of the noises. That clarify some things

burli,

Realistic in what way? Size, shape or decorations? Remember it's impossible to decide in code if a body of water is part of a large ocean or part of a small pool.

It is, if lakes are above sea level. But I know that this isn't easy. I found an article where they place randomly water sources to the map and use A* to search for rivers and lakes

[paramat]

Here's my attempt at pools filling natural depressions in core mapgens, can sometimes be slow.
https://forum.minetest.net/viewtopic.php?f=11&t=8400

[burli]

"Remove the trees". Same thing with caves, because mods only run after everything is done.

[burli]

The VoxelManip is fast. The carve loop for caves, tunnels, the stone biomes and some ore generation only needs ~40ms, but ...

reading the data needs, ~25ms, writing the data takes around 40ms and, most worse, noise generation. I need currently 5 3d noises. They need together 150-160ms. Each chunk needs an average of ~250ms

So 16% is generation, 26% is data read/write and 58% is noise

How can this be improved?

[burli]

The heightmap is only valid in mapchunks at water level. Mapchunks above may only contain -31000, but not
always.

I overwrite the chunks with heightmap -31000 with obsidian glass. This is the result



Is this a bug or a feature?

[paramat]

Yes the highlandpools mod needs work.

5 3D noises is heavy usage, heavier than any core mapgen. A 3D noise is roughy 80 times heavier than 2D noise and occupies a lot of Lua memory. An improvement is noise code optimisation wich hmmmm has mentioned might be possible for 3D noise. You can help by using less octaves in 3D noise.

In core mapgen the heightmap is created by searching down each column in a mapchunk for terrain, if no terrain is found in a column the value is -31000. The heightmap works in all mapchunks not just y = -32 to 47.

[burli]

5 3D noises is heavy usage, heavier than any core mapgen

Well, 2 noises for tunnels, one noise for caves, one for "stone biomes" and one for ore generation. It is a huge 3d space. And of course it takes 80 times more because in a chunk there are 80 2d noises

In core mapgen the heightmap is created by searching down each column in a mapchunk for terrain, if no terrain is found in a column the value is -31000. The heightmap works in all mapchunks not just y = -32 to 47.

I will check that again, but in this case on the screenshot there was terrain in a chunk with a heightmap value of -31000.

And mapchunks below -32 always return -33, -114 (I guess) and so on

[burli]

5 3d noises is heavy usage? I count 6 ;-)

https://github.com/paramat/intersecting ... r/init.lua

[burli]

What does the option flat/noflat in mg v5 mean?

[paramat]

Some of my mods are insanely heavy users of 3D noise, 'riverdev' has 10 which is far too much for a lua mod.

'flat', 'noflat' only affects mgv6, it is now a 'mgv6_spflag' (mgv6 specific) but was left in 'mgflags' for a while for backwards compatibility. However the flat flag has just now been removed from 'mgflags' to clean up the mess.

> I will check that again, but in this case on the screenshot there was terrain in a chunk with a heightmap value of -31000.

Yes some columns in that mapchunk will have -31000 because terrain was not found in those columns. However the heightmap does work because that is where decorations are placed and they are placed correctly.

[burli]

I have lines of sand at chunk borders. Has this something to do with this mudflow? How can I remove this?

[procedural_map]

Using Lua, how do I procedurally generate a map? I copy-pasted some examples from wiki into init.lua but they don't work (don't create map or something like this)

For example (I might use not proper minetest's names)
1)
y = 1 => sand
y < 1 => rock
y > 1 => air
2) Then let's say every 3rd block in x- and z- coordinate will be dirt (y = 1; z, x = 3, 6, 9, 12, ...)

[paramat]

burli,

This is a lua mapgen? Operating in singlenode mapgen or adding to another? Can you link to your code?
The sand is probably the seabed sand from the defined biomes, this does appear sometimes in core mapgens down to y = -112 and is caused by overgeneration of large caves.

[paramat]

procedural_map,

You create a lua mapgen using the lua voxel manipulator, an example simple mapgen is here https://github.com/paramat/noise23

[BrunoMine]

What is the best way to check if an area is generated a plain?

[paramat]

You mean detect a grassland biome?

[BrunoMine]

Yes, I do not want to create decorative items. I want to create structures such as villages.

[paramat]

So you're looking for a fairly flat area too?

[BrunoMine]

Yes, exacly.

[BrunoMine]

Here's an example. This looks like a smooth behavior of the perlin noise.

[paramat]

Easiest way is to use the 'mapgen object heightmap' and scan it for a small height variation.
For biome hopefully soon we will have a 'get biome at point' API (hmmmm intends to write it), until then you'll have to use the mapgen's heat- and humidity- (and in mgv6 tree-) noises and check for values that result in grassland.