Erodr is an implementation of Hans Theobald Beyer's algorithm for simulated hydraulic erosion of landscapes. The algorithm is described in detail in his his thesis Implementation of a method for hydraulic erosion which can be found here.
This image shows a 1024x1024 heightmap after being processed inside the Erodr visualizer/live preview window.
Link to a video demo of Erodr: https://www.youtube.com/watch?v=jiTiTiV2hcU
Erodr v2.0.0 includes a built-in 3D heightmap live preview (built using Raylib). The live preview allows you to:
- Watch your heightmap transform in real time as you are running the particle simulation.
- Reload parameters from a parameter ini-file and re-run the simulation without closing the program.
- View the generated terrain using a handful of different visualizer modes (including a snow cover visualizer, gradient visualizer, pseudo coloring based on height, etc.)
The visualizer/live preview is launched by default. If you wish to run Erodr without the visualizer you can supply erodr with the --no-ui option, which makes erodr behave like in previous versions.
Erodr v2.0.0 includes more tunable parameters:
-for--initial-velocity. This option specifies the initial velocity of the particle. In previous versions of Erodr this value was implicitly set to 0. I found out that using a value closer to 1 tends to produce better looking results.-wor--initial-water. This option specifies the initial water content of the particle. In previous versions of Erodr this value was implicitly set to 1.
Erodr is now bundled with gept ([GE]neric [P]rogrammable [T]emplates). Gept is a program I developed to add some semblance of meta-programming support to C and other languages that don't have compile time execution. For Erodr, I use it to embed shader source code directly into the binary. If you wish to build gept on your own, you can get the source code here: https://github.com/henrikglass/gept
Erodr v2.0.0 does not include a musl libc build. Trying to get musl libc to work with raylib was a big pain, so I abandoned it.
If you're running on Linux and your glibc version does not match the version required by the prebuilt binary, you should be able to build Erodr yourself without any issue. The only requirement is a C compiler. Here's the simplest possible command to compile Erodr for linux (without using the makefile and without openmp support):
$ tools/gept -i src/shaders/shaders.h.template > src/shaders/shaders.h && cc -Iinclude -Llib/linux src/*.c -lraylib -lm -lpthread -ldlTo build for linux simply run make (equivalent to make linux-omp), make linux, or make linux-omp.
To build for windows (requires mingw-w64) run make windows or make windows-omp.
Targets with the -omp suffix utilize OpenMP to parallelize the algorithm and should run much faster. Keep in mind that the OpenMP implementation of Erodr hasn't been thoroughly tested. If you experience any odd issues or bugs use the standard single-threaded version.
Usage: erodr [Options]
Options:
-i,--input path to input heightmap *.pgm file (default = (null))
-o,--output path to output heightmap *.pgm file (default = output.pgm)
-p,--params path to simulation parameters *.ini file (default = (null))
-a, --ascii Use ascii encoding for output *.pgm file. (default = 0)
-n,--num-particles Number of particles to simulate (default = 70000, valid range = [-9223372036854775808, 9223372036854775807])
-t,--ttl Maximum lifetime of a particle (default = 32, valid range = [-9223372036854775808, 9223372036854775807])
-r,--radius Particle erosion radius (default = 2, valid range = [-9223372036854775808, 9223372036854775807])
-g,--gravity Gravitational constant (default = 1, valid range = [-1.7976931e+308, 1.7976931e+308])
-y,--inertia Particle inertia coefficient (default = 0.3, valid range = [-1.7976931e+308, 1.7976931e+308])
-c,--capacity Particle capacity coefficient (default = 8, valid range = [-1.7976931e+308, 1.7976931e+308])
-v,--evaporation-rate Particle evaporation rate (default = 0.02, valid range = [-1.7976931e+308, 1.7976931e+308])
-s,--erosion-coefficient Particle erosion coefficient (default = 0.7, valid range = [-1.7976931e+308, 1.7976931e+308])
-d,--deposition-coefficient Particle deposition coefficient (default = 0.3, valid range = [-1.7976931e+308, 1.7976931e+308])
-m,--minimum-slope Minimum slope (default = 0.0001, valid range = [-1.7976931e+308, 1.7976931e+308])
-f,--initial-velocity Particle initial velocity (default = 0.9, valid range = [-1.7976931e+308, 1.7976931e+308])
-w,--initial-water Particle initial water content (default = 1, valid range = [-1.7976931e+308, 1.7976931e+308])
--no-ui Don't open the UI/Visualizer (just perform the simulation and save like older versions of erodr did) (default = 0)
--help Show this message (default = 0)
--generate-completion-cmd Generate a completion command for Erodr on stdout (default = 0)
With no other specified options except the input file (-i, or --input) Erodr will launch with the default parameters.
For input and output, Erodr so far only supports grayscale heightmaps in Netpbm grayscale image format, i.e. *.pgm files.
Run Erodr on input heightmap examples/heightmap.pgm using the default simulation parameters:
$ ./erodr -i examples/heightmap.pgm
Run Erodr on input heightmap examples/heightmap provided with the simulation parameters in examples/params.ini:
$ ./erodr -i examples/heightmap.pgm -p examples/params.ini
As above, but use Earth gravity:
$ ./erodr -i examples/heightmap.pgm -p examples/params.ini -g 9.81
As above, but run Erodr without the visualizer (directly output to output.pgm):
$ ./erodr -i examples/heightmap.pgm -p examples/params.ini -g 9.81 --no-ui
This project was written entirely for fun. If anyone wants to contribute feel free to create a pull request.
The software is provided "as is".
