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Large 3D terrain generator



Plugin information

Author Aaron
Description An experimental plugin for water flow modelling.
Download link atRainMaker-bin.zip [107kB]
Last updated 6th of August 2012.
DLL version
Dependencies L3DT Pro v11.11 or later

Using atRainMaker

Before we start I should point out that this calculation is rather intensive (read: slow), so as your first try with this plugin I recommend something unambitious, like a 512×512 map.

Anyway, on to the calculation. The plugin splits the calculation into three parts:

  1. Calculation of the rain flow maps.
  2. Filtering/processing of the rain flow maps.
  3. Overlaying the flow maps onto the water map.

This plugin has no user-interface, so each stage requires us to enter some simple scripts, which I've listed below.

Quick example script

Download this script file, and put it in your L3DT script folder at:

Win 7 / Vista C:\Users\[your username]\L3DT\Resources\[version]\Scripts
Win XP / 2000 C:\Documents and Settings\[your username]\L3DT\resources\[version]\Scripts


  • Start L3DT
  • Load your map project
  • Select the 'Scripts→More scripts…' menu item
  • Select the 'RainPluginTest' item from the list.

This will generate the rain depth mask using some default settings, which you can change by editing the script file ('Scripts→Edit script').

Calculating rain flow maps

Select the 'Scripts→New script' menu option, and enter the following code:

calc.WM.rain <GetMap "HF"> <GetMap "WM"> 1 100 1 1 1

The function arguments for this script call are:

Name Type Default value Description
pHF hvar <GetMap “HF”> The heightfield handle. Using the GetMap function to retrieve the project's heightfield.
pWM hvar <GetMap “WM>” The water map handle. Using the GetMap function to retrieve the project's water map.
SampleRate int 1 Normally this is 1, but if you want to speed-up the calculation (at the expense of some detail), set this to 2 or 4.
nCycles int 100 The number of iterations of the calculation. Normally this should be several hundred.
WaterLevel float 1 The initial water level, which normally should be about 1 (units of metres, of course). Must be positive.
EvapRate float 1 The evaporation rate. Normally this should be ~ the same as the initial water level. Must be positive.
CalcFlags uint 1 Described below.

The CalcFlags argument is a bitfield combination, the values of which have the following meanings:

Value Meaning
1 Calculate the average depth map.
2 Calculate the flow map.
3 = 1+2
4 Calculate the maximum depth map.
5 = 1+4
6 = 2+4
7 = 1+2+4
8+ undefined

After you click OK in the script dialog, the plugin will start its calculation. Once the calculation is complete, you will now have a new maps in your project called 'Rain-avgdepth'. You can view this using the 'View→Show map' menu option, and you should see something like this:


Filtering the flow maps

Before we can apply the rain depth map to the water map, we must first do some processing. There are in fact a large number of different scaling and manipulation options you can apply, but in this case I'm going to do one simple thing: subtract the initial flood depth (1m). To do this, I enter the following script:

calc.HF.ShiftMap <GetMap "Rain-avgdepth"> -1 true

Applying the flow maps to the water map

The final step is to bake the rain depth map onto the water map. To do this, use the following script:

calc.WM.ApplyOverlayMax <GetMap "HF"> <GetMap "WM"> <GetMap "Rain-avgdepth"> true

The map is now ready to be viewed in the main window, or in Sapphire.

If you don't like the result, you can undo using the 'Edit→Undo' menu option.

Putting it all together

If you want to do all that processing back-to-back and automagically, select 'Scripts→New script' in the menu and enter the following script:

calc.WM.rain <GetMap "HF"> <GetMap "WM"> 1 100 1 1 1
calc.HF.ShiftMap <GetMap "Rain-avgdepth"> -1 true
calc.WM.ApplyOverlayMax <GetMap "HF"> <GetMap "WM"> <GetMap "Rain-avgdepth"> true

Import / Export


To export the rain depth map, select the 'File→Export→Export map…' menu item, select the 'Rain-avgdepth' map, and export the map in whichever format you like.


To re-import the rain depth map, use the 'File→Import→New map layer' menu item.

To do list

There are many things still to do, but the most obvious one are:

  • Integration with L3DT's internal calculation manager.
  • Split the calculation into tiles and run it through the multithreaded tile calc manager (as used for normals/light/texture map calcs).
  • Calculate sediment removal and accumulation maps (use for erosion).

Change log

2012/08/06 — Added parameter validation, better logging, and proper support for virtual mosaic maps.

2012/07/30 — Updated example scripts for current release version of ZeoScript language.

2012/01/11 — Recompiled for API version 11.09.

2009/08/11 — Removed code for rendering in Sapphire, added 'cancel' button in progress box, updated backup behaviour, and updated scripts.

2007/08/02 — Uploaded.

plugins/calc/atrainmaker.txt · Last modified: 2017/08/31 05:34 (external edit)
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