Astray

A performance-portable geodesic ray tracing library.

Requirements

• CMake 3.23+
• Optional: CUDA 11.6+
• Optional: MPI 2.0+

Installation

• Clone the repository.
• Run bootstrap.[bat|sh]. This will install all dependencies except CUDA and MPI, and create the project under the ./build directory.
• Optional: Run cmake on the ./build directory.
  • Toggle ASTRAY_BUILD_APPLICATIONS for building the example applications.
  • Toggle ASTRAY_BUILD_TESTS for building the tests.
  • Toggle ASTRAY_USE_FFMPEG for video support.
  • Toggle ASTRAY_USE_MPI for MPI support. The build will ask for the location of MPI upon enabling this option.
  • Toggle ASTRAY_DEVICE_SYSTEM for CUDA/OMP/TBB support. The build will ask for the location of the respective library upon enabling this option.
  • Remember to generate or run bootstrap.bat after changes. You can ignore the cmake developer errors as long as generation is successful.

Example Usage: Rendering a Schwarzschild Black Hole

#include <astray/api.hpp>

int main(int argc, char** argv)
{
  using scalar_type   = double;
  using metric_type   = ast::metrics::schwarzschild<scalar_type>;
  using geodesic_type = ast::geodesic<scalar_type, ast::runge_kutta_4_tableau<scalar_type>>;

  ast::ray_tracer<metric_type, geodesic_type> ray_tracer;
  ray_tracer.set_image_size      ({1920, 1080});
  ray_tracer.set_lambda_step_size(0.01);
  ray_tracer.set_iterations      (1000);

  auto& transform       = ray_tracer.get_observer().get_transform();
  transform.translation = {0.0, 0.0, -10.0};
  transform.look_at      ({0.0, 0.0,   0.0});

  const auto image = ray_tracer.render_frame();
  image.save("example.png");
}

See the tests for more.

UI Application

See Astrid for a UI application built on Astray.

Future Work

• Fermi Walker transport.
• Precompute the Christoffel symbols into a 4D image.
• More tests.