Daisyworld [1] is a computer simulation of a hypothetical world orbiting around a star whose radiant energy slowly varies with time.
Its original version was introduced by James Lovelock and Andrew Watson as a toy model to show how living creatures (biotas) and the environment they populate evolve as an interconnected system, one affecting the other.
The only living beings populating Daisyworld are (indeed) daises, that (in the simplest model) exist in two varieties: white- and black- petaled. White-daisies mostly reflect light, while black-daisies mostly absorb light.
The light absorbed or reflected (albedo) by daisies, contributes to the variation of the temperature of a local patch of land, or to the overall Daisyworld average temperature, respectively.
The simulation tracks the two daisy populations and the Daisyworld average temperature as the sun luminosity varies.
Several variants of the toy model were developed over the years (e.g. deterministic, as the one described above, or stochastic - some examples can be found in [2] and [3]).
In this simulation the world is represented by a matrix of cells that can either be barren or populated by one of two types of daisy (black or white).
The temperature of the patches of land are determined by the albedo of their surface, different for black and white daisy and barren land, and the solar luminosity.
The temperature of a patch of land influences the temperature of the neighbouring terrain.
The flowers age with the ticks of the simulation and die out when they reach a specific age, turning their patch of land barren.
The live flowers spread to the neighbouring land based on seeding probability dependent on their local temperature.
The CMakeLists.txt file makes it easy to compile and run the code:
cmake -S . -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build
build/daisyworld
Alternatively you can manually run the compilation with something like:
g++ main.cpp daisy.cpp world.cpp
[1] Watson, A.J.; Lovelock, J.E (1983). "Biological homeostasis of the global environment: the parable of Daisyworld". Tellus. 35B (4): 286–9.
[2] An Online Daisyworld simulator with many options, which includes and document both deterministic and stochastic evolution models.
[3] A NetLogo version of a stochastic Daisyworld model.