Hydra (Hyperbolic Drawings) is an interpreted programming language that can be used to draw geometric objects in two-dimensional hyperbolic space.
Hydra is written in C++ and compiles to a single executable that can be used to interpret Hydra code or work with a REPL.
Compiling Hydra requires gflags (at least for now) and glog.
Once the required libraries are installed and you checked out the code from this repository, Hydra can be compiled using
make release
which creates the executable hydra in the bin directory.
Hydra can be used in two ways. First, you can create a file containing Hydra code, e.g. mycode.hydra, and interpret it using
./bin/hydra mycode.hydra
On the other hand, Hydra comes equipped with a REPL mode, which is accessed by calling ./bin/hydra without passing a file. Once started, you can then enter Hydra code line by line. The REPL environment can be exited by entering quit.
A detailed explanation of how to use Hydra can be found in the Getting Started section of the wiki.
The following Hydra code generates 100 hyperbolic lines where each line starts where the last line ended.
// Define the maximum radial coordinate for a point.
var R = 10.0
// Define the variable that holds the starting point of each line.
// The initial value is the origin of the plane.
var point_1 = Pol(r: 0.0, phi: 0.0)
// Iterate 100 times...
for i in [0, 1, 99] {
// Define the second point of the current line by choosing
// radius and angular coordinate uniformly at random.
var point_2 = Pol(r: random(from: 0.0, to: R), phi: random(from: 0.0, to: 2.0 * M_PI))
// Draw the line.
line(from: point_1, to: point_2)
// The next line starts where the last line ended.
point_1 = point_2
}
// Save the drawn lines to a file.
save(file: "random_lines.ipe")The result may look something like this
