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Art Gallery Competition

Scenario Week at UCL-CS (Spring 2016)

This project contains all the sources of the scenario week dedicated to solving the Art Gallery Problem.

It also provides, as a part of the development, the source of the framework for generation of random polygons with specific "features" and QuickCheck-style testing of geometric procedures. For more examples, check the test files (for instance, src/test/scala/ucl/scenario/geometry/VisibilityCheckerTests.scala) and the section Generating random polygons below.

The overall experience of organising the competition and using the testing framework is described in the ICFP'16 experience report Growing and Shrinking Polygons for Random Testing of Computational Geometry Algorithms.


Some relevant reading includes the following books, papers and links:

Description of the scenario for the participants and slides

See the folder docs.

Mathematical background

Scala programming and related frameworks

Requirements and building

Requirements: sbt (version >0.13.0), JDK 1.8.

To compile and test, execute

sbt test 

To run the visualizer, execute

sbt "runMain ucl.scenario.geometry.runners.ArtGalleryPainter filepath"

where filepath points to a test file, e.g.,

sbt "runMain ucl.scenario.geometry.runners.ArtGalleryPainter ./src/test/resources/testdata/lshaped.agp"

If the set of guards (blue dots) doesn't cover the whole gallery with their visibility areas (yellow), a counterexample position will be located (red dot).

Check ucl.scenario.geometry.ArtGalleryPainter object for details.

AGP test file format

The files are formatted as follows:

comma-separated list of polygon vertices in a counter-clockwise order
comma-separated list of guards

In the counter-clockwise order the polygon stays on the left while walking its the boundary. For instance:

(0, 0), (5, 0), (5, 2), (4, 1), (1, 1), (0, 2)
(0, 2), (5, 2)

The following extended format allows to input the auxiliary triangulation:

(0, 0), (5, 0), (5, 2), (4, 1), (1, 1), (0, 2)
(0, 2), (5, 2)

More examples can be found in ./src/test/resources/testdata/.

Running the scenario server

To run the server with the simple test scenario project locally (located in ./instances/test), run the following command from terminal:

sbt "runMain ucl.scenario.server.Boot ./instances/test"

You can change some parameters of the scenario (e.g., host address or port) by modifying the config file in the root of the folder instance, passed as an argument to Boot.

To check the stub page, navigate to (or the host you put in the config file).

You can add your email address by changing some of the emails files of the test instances. For example, you can add your email into ./instances/test/teams/albatros, therefore getting all notifications for the albatros team to your email address.

You can find some examples of good and bad solutions for different teams for this specific test scenario instance in the folders ./resources/test_scenarios/test/solutions.

Bootstrapping a new scenario instance

All necessary instances of the scenario are already create, but if you want to create a new one, run

sbt "runMain ucl.scenario.util.SetupScenario <filepath> <scnearioname>"

where filepath will be the root folder of your scenario, for instance

sbt "runMain ucl.scenario.util.SetupScenario ./instances myscenario"

This will create team accounts, default task files and confing file.

Generating random polygons

In order to generate series of different random polygons, run one of the following scripts:

For rectilinear polygons:

sbt "runMain ucl.scenario.geometry.runners.RectilinearPolygonGenerator"

For triangular-like polygons:

sbt "runMain ucl.scenario.geometry.runners.TriangularPolygonGenerator"

For quasi-convex polygons:

sbt "runMain ucl.scenario.geometry.runners.QuasiConvexPolygonGenerator"

For totally random polygons:

sbt "runMain ucl.scenario.geometry.runners.CrazyPolygonGenerator"

You can also run them in the form

sbt "runMain ucl.scenario.geometry.runners.X path num"

Where X is the corresponding class name (one of the four above), path is the desired output file path and num is a number of polygons generated. If path is absent, the default file with extension .pol will be put to the project root folder.

Use the visualiser described above in order to render polygons.

Checking solutions for the Art Gallery problem

Run from the command line:

sbt "runMain ucl.scenario.geometry.runners.CheckVisibility inputPath"

where inputPath is a path to your file with solutions to the Guards problem, formated as follows:

polygon_number: polygon_vertices ; guards

For instance, you can try it on the problem file from Part 2 as follows:

sbt "runMain ucl.scenario.geometry.runners.CheckVisibility ./resources/tasks/check/check.pol"