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OpenGL

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This article is a stub. You can help by expanding it. This is a stub page for Haskell's OpenGL and GLUT bindings. It is meant as a starting point to replace the outdated and misleading documentation at the old page.

First, note that the implementation is far more up-to-date than that old page suggested (originally, it was quite useful, but the page hasn't kept up with the implementation for a long time now).

Contents

1 References

In particular, note that the examples/ directory in the GLUT repo contains lots of examples, including translations of the red book examples.

(Note: at least some of these resources appear to be missing from /packages, but there are copies at /ghc-6.8/packages.)

Both the API documentation and the examples are best studied with the original specs and the original red book examples at hand. An index of the examples from v1.1 of the red book, with screen shots, can be found here.

2 Projects using the OpenGL bindings

  • Endless Cavern, a 2D procedurally-generated exploration game.
  • Frag, a 3D first-person shooter game.
  • Monadius, a 2D scrolling arcade game.
  • Roguestar, a roguelike adventure game using 3D graphics.
  • Shu-thing, a 2D scroling arcade game.
  • Topkata, a jumping ball puzzle game.
  • PolyFunViz, a toolkit for scientific visualization (e.g. surfaces, flows, contours, volumes)
  • Raincat, a 2d puzzle game

3 HOpenGL Resources

4 OpenGL Resources

5 Getting Started

6 Additional software

  • OpenGLRaw: A 1:1 mapping of OpenGL's C API, intended as a basis for a nicer interface
  • StateVar: This package contains state variables, which are references in the IO monad, like IORefs or parts of the OpenGL state
  • ObjectName: Explicitly handled object names. This tiny package contains the class ObjectName, which corresponds to the general notion of explicitly handled identifiers for API objects, e.g. a texture object name in OpenGL or a buffer object name in OpenAL
  • GLURaw: A raw binding for the OpenGL graphics system. GLURaw is a raw Haskell binding for the GLU 1.3 OpenGL utility library. It is basically a 1:1 mapping of GLU's C API, intended as a basis for a nicer interface
  • FTGL: Portable TrueType font rendering for OpenGL using the Freetype2 library
  • GLFW: A binding for GLFW, An OpenGL Framework
  • GLUT: A binding for the OpenGL Utility Toolkit
  • graphics-drawingcombinators: A functional interface to 2D drawing in OpenGL
  • Tensor: This package contains tensor data types and their instances for some basic type classes.
  • GPipe: A functional graphics API for programmable GPUs

Somewhat related is SDL, which is also based on OpenGL:

To add sound to OpenGL applications:

  • OpenAL: A binding to the OpenAL cross-platform 3D audio API
  • ALUT: A binding for the OpenAL Utility Toolkit

A fork of HOpenGL:


7 Troubleshooting

7.1 I can't display text with renderString

It's probably because the text is displayed too big. Setting a much smaller scale factor before calling renderString should solve the problem.

scale 0.001 0.001 (0.001∷GLfloat)
renderString Roman "Test string"

7.2 Animations flicker

If you're not using DoubleBuffered display mode, turn that on. Also, you must set the display mode before creating the window you're going to be drawing in. To check if you've enabled double buffering use something like:

db <- get doubleBuffered

and set DoubleBuffered mode (before creating your windows!) like this:

initialDisplayMode $= [DoubleBuffered]
createWindow "My Window"
You will also need to call <div dir="ltr" class="mw-geshi mw-content-ltr">
swapBuffers
</div>
at the end of your draw function.

7.3 The depth buffer doesn't work (things that are closer to the camera are occluded by things that are farther from the camera)

Make sure that depthFunc is set:

depthFunc $= Just Less

Furthermore, if you're using GLFW, the following var has to be greater than zero:

get (windowParam DepthBits)

If DepthBits is 0, you probably forgot to initialize the window, like so:

openWindow size [DisplayDepthBits 16] Window

Once you enable the depth buffer, you will need to clear it before each cycle of your drawing method:

clear [ColorBuffer, DepthBuffer]

See also: The OpenGL FAQ: 12.010 How do I make depth buffering work?