SimpleErosion

Simple C++ implementatoin of particle-based hydraulic erosion on a square grid.

Rendered using homebrew engine, written in C++ using OpenGL3 with control using DearImGUI.

Link to Blog!

Compiling

Use the makefile to compile the binary:

make all

Dependencies

Erosion System:
- gcc (compilation)
- glm (vectors)
- libnoise (noise initialization)

Renderer:
- SDL2 (core, image, ttf)
- OpenGL3
- GLEW
- Boost (System, Filesystem)
- ImGUI (included as binaries in the project, no install required)

Usage

Launch the simulation using the binary:

./erosion

Controls

Mouse and Keyboard Inputs:

- Toggle Control Panel: ESC
- Toggle Pause: P **NOTE: PAUSED BY DEFAULT**
- Change Camera Vertical Angle: Up / Down
- Change Camera Zoom and Rotation: Scroll
- Move Camera Vertically: Space / C

Panel

A control panel is included with DearImGUI. There are three tabs: Map, Erosion and Renderer

Map:
  - Reinitialize the Heightmap using a random seed (i.e. perlin noise)
  - Change the map-scaling and remesh! This affects the PHYSICAL height of the map and therefore erosion characteristics!
  
Erosion (Note: Default settings produced the graphics in the blog post and in this repo):
  - Erosion Cycles: Number of cycles remaining to do
  - Stepsize: Number of cycles to do in a batch before updating the image
  - Run / Stop Erosion: Run or pause the cycles! (Note: After clicking run, unpause simulation)
  - Parameters: Erosion physical parameters.
    - Timestep: Integration timestep. Higher = More erosion, but the relative parameter scales stay the same
    - Minimum Volume: Volume below which a droplet is killed
    - Density: Density of droplet, to give their inertia
    - Deposition Rate: Rate of approach to equilibrium sediment capacity
    - Evaporation Rate: Volume loss factor every timestep
    - Friction: Speed loss factor every timestep
    
Renderer:
  - Steepness: Angle at which you transition from flat to steep color
  - Flat / Steep Color: Shader colors
  - Light Strength: ...
  - Auto-Rotate / Rate: If you want the map to turn (made this for cinematics)
  

Screenshots

Example erosion process.

Sample of 10 results, only the results shown here.

A before after comparison of 10 OTHER samples.

Source

If you are interested in the erosion simulation, read the world.h and world.cpp files. This is where all the erosion code takes place. To see how this integrates into the actual project, read erosion.cpp. Everything else is just to make the results renderable in OpenGL3.

The renderer / engine is taken from another project of mine, but I stripped it down to the bare necessities for this project. If you are interested in rendering your own heightmap using OpenGL3, you should study the view.h and view.cpp files. These are the engine master files.

Otherwise some of the details are explained on my blog!

License

MIT License

See my website for a more detailed copyright notice.