benl23x5/gloss

Painless 2D vector graphics, animations and simulations.

gloss

Gloss hides the pain of drawing simple vector graphics behind a nice data type and a few display functions.

• Home page and bug tracker are on a separate site.

Example

Getting something on the screen is as easy as:

import Graphics.Gloss
main = display (InWindow "Nice Window" (200, 200) (10, 10)) white (Circle 80)

Explore and run the example projects using stack:

$ stack setup
$ stack build
$ stack exec gloss-boids

Usage

Once the window is open you can use the following:

• Quit

  • esc-key

• Move Viewport

  • arrow keys
  • left-click drag

• Zoom Viewport

  • page up/down-keys
  • control-left-click drag
  • right-click drag
  • mouse wheel

• Rotate Viewport

  • home/end-keys
  • alt-left-click drag

• Reset Viewport

  • 'r'-key

More

• Animations and simulations can be constructed similarly using the 'animate' and 'simulate' functions
• Games with user input can be constructed with the 'play' function.
• See the gloss-examples package for more.

PULL REQUESTS

As Gloss is now fairly stable, I typically make releases only when there is a new GHC version. If you have added a new feature or fixed a bug, and want your pull request merged sooner than that, then send email to benl AT ouroborus.net. I don't pay attention to github notifications, but am happy to receive emails from people. If you have changed any internal functionality then please test that all the gloss-examples still work before submitting your pull request.

If you just want to bump a dependency version then get a Hackage trustee to edit the package information directly on Hackage. You don't need to raise a pull request here.

gloss's Issues

GLFW backend - Holding down a key results in repeated Up events

GLFW repeatedly sends GLFW.KeyState'Repeating when button is held down - https://www.glfw.org/docs/3.3/input_guide.html#input_key.

It gets mapped to Up here:

gloss/gloss/Graphics/Gloss/Internals/Interface/Backend/GLFW.hs

Line 348 in af1301a

= do let keystate = keystateglfw == GLFW.KeyState'Pressed

gloss/gloss/Graphics/Gloss/Internals/Interface/Backend/GLFW.hs

Line 352 in af1301a

let keystate' = if keystate then Down else Up

GLFW.KeyState'Repeating should be just ignored and mapping should be GLFW.KeyState'Pressed to Down and GLFW.KeyState'Released to UP

Option to turn off character key modifier clever-ness

Holding a modifier key often also changes the character Gloss reports.

Say that I want to perform a certain operation when the L key is pressed, and thus pattern match on EventKey (Char 'l') Down _ _. If I then desire a slight modification in behaviour when the Shift key is pressed, I find that this branch isn't hit at all, since the character is L rather than l.

This behaviour is easy enough to work around, but can be quite annoying, and is fundamentally non-compositional. It would be great if there were an option to always report the same character as when no modifiers are held.

cannot build gloss-examples with ghc 9.4.7

Looks like gloss-examples has a dependency on repa which cannot be built with newer versions of base (following the project website's instructions and using cabal).

Here is the issue: haskell-repa/repa#26

There is a PR open for repa to address this: haskell-repa/repa#27

gloss doesn't work on wayland/swaywm *without xwayland

Hello! I've recently started figuring out gloss and was working on a project in xmonad. A couple days ago I switched over to swaywm to check it out, however I got an error ( freeglut (gloss-stuff): failed to open display '' ) whenever I tried to do stack run. Going back to xmonad it runs just fine, same for xfce. Has anyone else encountered this? I'm willing to try another wayland-based de and see if this problem is swaywm-specific or wayland-broad.

running gloss in `ghci`: closing the window with ESC produces "too many hs-exit()s"

I want to use gloss with ghci (either stack repl or cabal repl. The gloss window opens nicely but when I close it, it also closes ghci. In an old but report I saw that the gloss window can be closed with ESC which returns control then to ghci. When I try this I get:

<interactive>: interrupted
<interactive>: warning: too many hs_exit()s

and ghci is closed.

I saw some discussion about running gloss with some flags (??), but could not find a comprehesible and likely up-to-date instruction. What is the correct procedure to run gloss graphics in ghci and how to interact with the windows (especially how to close them without closing ghci ?
Thank you!

I work with ghc 8.10.7 and gloss 1.13.2.1 (lts-18.28