Real world terrain (mapgen idea)

[rubenwardy]

You don't touch the settings, you just have to request an insecure environment. It means that your mod and your mod only can access insecure functions like require(). The alternative is having an external program download it, but that's more complicated for the end user than requesting an environment. Then again, they'd need to use luarocks to get luasockets...

Note that the method I use is synchronous, I haven't found out how to make it asynchronous yet. cURL may solve this.

[bobomb]

You don't touch the settings, you just have to request an insecure environment. It means that your mod and your mod only can access insecure functions like require(). The alternative is having an external program download it, but that's more complicated for the end user than requesting an environment. Then again, they'd need to use luarocks to get luasockets....

that's what I meant. just considering minimizing the barriers to entry. but if it needs to be done one way or another then all my concerns are moot.

I will read your code as soon as I finish this: http://www.gantless.com/programs/macklem.pdf

[stu]

i have posted this mod as a work in progress: https://forum.minetest.net/viewtopic.php?f=9&t=12666

I really like what you've done with this, it's an idea I've been toying with myself for quite some time.
What I would really love to do someday is make a custom version that would generate maps on the fly from google (or wherever) and not be limited by size in any direction, only changes to the landscape would ever be saved. Of course this would require a complete rework of the engine and database so may be best done from scratch rather than trying to modify minetest.

[bobomb]

i always thought that it was only changes to the landscape that were saved but that obviously is not the case because you can change mapgens and all that has been generated up to that point stays the same as it was. That makes the most sense to me now.
anyway, i have been messing around with treating the landscape as a complex number plane and generating the mandelbrot set, here are some early results:





and here is a simple addition of two sine waves:

Your phone or window isn't wide enough to display the code box. If it's a phone, try rotating it to landscape mode.

Code: Select all

function get_pixel2(x,z)
   -- code from https://processing.org/examples/mandelbrot.html
   local maxiterations = 100
   -- Now we test, as we iterate z = z^2 + cm does z tend towards infinity?
    local a = x/500
    local b = z/500
    local n = 0
    while n < maxiterations do
      local aa = a * a
      local bb = b * b
      local twoab = 2.0 * a * b
      a = aa - bb + x/500
      b = twoab + z/500
      -- Infinty in our finite world is simple, let's just consider it 16
      if aa + bb > 16.0 then
        break  -- Bail
      end
      n = n+1
    end

    -- We color each pixel based on how long it takes to get to infinity
    -- If we never got there, let's pick the color black
    if n == maxiterations then
      return -1
    else
      -- Gosh, we could make fancy colors here if we wanted
     return n
    end
   
   
end

[bobomb]

might be a way to get elevation data from a URL request: http://open.mapquestapi.com/elevation/

calculating Aspect using a 3x3 moving window: http://resources.arcgis.com/en/help/main/10.1/index.html#/How_Aspect_works/009z000000vp000000/

calculating Slope using a 3x3 moving window: http://resources.arcgis.com/en/help/main/10.1/index.html#/How_Slope_works/009z000000vz000000/

might be useful for a calculation for vegetation...

[bobomb]

proof of concept for land-cover tiffs.
Here is a greyscale overlay for the same dimensions as the elevation graphic, which indicates water.


result:



obviously no effort has been made to fit the river to the actual terrain, but with different grey-ranges this could be used to handle roads and vegetation cover as well... if indexed color is too complicated, then simply different ranges of grey will be used. maybe I can find a lua image lib that will handle 16-bit grey for elevations, as well as maybe PNG layers for things like ores, roads/rivers.

[bobomb]

proof of concept:
different grey-range encoding for roads:

[bobomb]

Then I have no idea where the mapgen sets the final surface height.

This is still an issue for post-mapgen stuff. not really for this mod but is there an easy way to get the surface height? i found this https://github.com/minetest/minetest/pull/640 Otherwise does anyone know of a nice lua get_surface function?

[Sokomine]

Otherwise does anyone know of a nice lua get_surface function?

Some mapgens provide a useful heightmap in register_on_generated; but that's about it.

[paramat]

is there an easy way to get the surface height?

Before the corresponding mapchunk generates? immediately after the corresponding mapchunk generates? or anytime after the corresponding mapchunk generates?
Also remember there will be multiple surface heights if floating islands or overhangs are present, as in mgv5 and mgv7.

[bobomb]

is there an easy way to get the surface height?

Before the corresponding mapchunk generates? immediately after the corresponding mapchunk generates? or anytime after the corresponding mapchunk generates?
Also remember there will be multiple surface heights if floating islands or overhangs are present, as in mgv5 and mgv7.

yes i have to account for caves and overhangs. i am talking long after the map has generated. I am using a function as per: https://forum.minetest.net/viewtopic.php?f=47&t=4668&start=2050#p185714

at time of map generating you can get the heightmap, is that correct? if so, is there a way to do a "delete blocks" but not actually delete blocks, but just rerun the mapgen to the point where I can get this heightmap? not writing to the map at all?

this is for a surface analysis mod I am working on https://forum.minetest.net/viewtopic.php?f=9&t=12928 which I might try to use to handle biomes, water bodies, etc in this realterrain mod.

[paramat]

Re-running mapgen just to get the heightmap is not recommended.
Yes use a column search for walkable, but use a 'non mapgen object' lua voxelmanip instead of 'get node' for speed. The voxelmanip could be a tall single column or cover a certain area to create a heghtmap.

[Ryster]

Hello,

subscribing/following/poking this thread with great interest!

@bobomb and @paramat .. really good stuff, and it's exactly why I am here.. for the generation of real-world landscape. I understand most people see this as a game, and are interested in mines, caves ores etc, but it can be so much more than that! I am here purely as a researcher, wanting to be able to replicate and edit the real-world for use as a visual aid in the cognitive understanding of the landscape around us. People cant collaborate in real time using google-earth, and it's honestly not as accurate up-close as a voxel-based terrain is, especially in remote regions.

There are excellent 3D rendering engines on the market, some proprietary and some open source, but vector-based world generators are complex and require a lot of technical knowledge. While I possess such knowledge, a vast majority of researchers in social and earth-sciences do not. Enabling them to be able to use a relatively easier system, based on a voxel mapgen world, will help within the methodologies of research and add another dimension to comprehensive understanding.

Scale, of course, is a central theme in landscapes. As mentioned before there is a plethora of freely available land use/ land cover (LU/LC) and elevation data, often at 30m resolution. This may be redundant, but for elevation, the most common format, and one that most others can be converted to is a 16bit GeoTIFF. As we are not really interested in the Geo part, lets say TIFF. For LU/LC that can be 8bit anything, GIF, PNG, BMP etc...

It's a very simple process to resample the resolution up to 1m... presenting us with a raster data set based on a 1:1 scale. From there, we can further resample by powers of 10 to deci, centi and milimeter scale (divide x,y by 10 and multiple z by 10 etc). This would be useful for recreating small spaces in the real world, in macroscopic scale... all within the spatial limits of Minetest.

I can do this in Minecraft with relative ease using the World Painter program, but that pesky 256 limit is quite bothersome. My personal study area has a delta z of 600 meters, so I'm forced to a 1:3 ratio, or a 3m square voxel. It's decent but I really want a 1:1 and/or 100:1 capability

I see you all have already accomplished this to some degree and I'm going to being playing around with it. I wish I had time to help code but my studies take up all my free time at the moment. :) I'm also more interested in the proof of concept and beta functionality, less about robustness and optimization. if it takes 2 days to generate on my octo-core system because you are using a brute force method to prove it works, I'm ok with that.

:)
thanks again for all your work on this subject!

[bobomb]

this mod has its own thread now: viewtopic.php?f=9&t=12666

[afflatus]

Minetest's coordinates span from like -32k to +32k in each dimension I believe, which if you consider a scale of 1m per node would only give you a 64km square area to play with.

I'm glad someone else is as dyslexic with maths as I am. I always work strictly to a voxel being a cubic metre, because my brain can't manage scaling. I'd convinced myself that the total playing surface was about 100 square miles. Of course, that's rubbish. I just worked it out as 1600 square miles (4096 km2). Could someone who doesn't suffer from dyscalculia confirm the real value?

[Gael de Sailly]

That's right. 64² = 4096.
In fact, the maximal distance is not 32 km but 31, so the length of the world is 62 km. 62² = 3844 km² = 1484 square miles.

[Samson1]

I think the hole map-gen idea for Minetest is rubbish, the worlds are to flat or to hilly, there are no mountains or lakes or underground streams or rivers or...


all the rain mods have never been finished or they are so full of bugs they don't work. There's no snow, no rain.


Minecraft's rain works properly, Minecraft's Redstone is programmed correctly and works a treat. measecons make the hole game lag like anything, so do the weather mods.

It's great to see people actually making Minetest a better place then Minecraft for once...

My argument is, how on earth can anything in MT be better then MC when most of the developers don't know what there talking about when it comes to knowing how Minecraft works in-game when they have never played it.

[Gael de Sailly]

I think the hole map-gen idea for Minetest is rubbish, the worlds are to flat or to hilly, there are no mountains or lakes or underground streams or rivers or...

That's the reason why mapgen is one of the main concerns of MT. And if you only know mapgen v6, try the others. v6 works well but is not beautiful (for me).

+ Offtopic

My argument is, how on earth can anything in MT be better then MC when most of the developers don't know what there talking about when it comes to knowing how Minecraft works in-game when they have never played it.

The aim of the game isn't to copy Minecraft.
You want Minecraft? Play Minecraft.

all the rain mods have never been finished or they are so full of bugs they don't work. There's no snow, no rain.


Minecraft's rain works properly, Minecraft's Redstone is programmed correctly and works a treat. measecons make the hole game lag like anything, so do the weather mods.

MT's API is not made for that. The problem is not on the mods side, but on the core side. And, technically, the weather mods have nothing related to mapgen.

General discussion about MT/MC have they forum topics.