On Thu, Apr 1, 2010 at 5:54 AM, Scott <scottymcdoo@gmail.com> wrote:

Hello!

I have a problem when trying to run some code found on this tutorial page:

http://public.beuth-hochschule.de/~panitz/hopengl/skript.html

The demo is called "LightCube." The problem seems to have to do with the following line (which I've commented out in the provided source):

depthFunc $= Just Less

Uncommenting the line gives a Segmentation Fault when I run the executable generated by:

ghc --make -package GLUT -o LightCube LightCube.hs

Does anyone else have this problem? Here is the necessary code:

LightCube

import Graphics.Rendering.OpenGL
import Graphics.UI.GLUT as GLUT

import Cube

main = do
(progName,_) <- getArgsAndInitialize

-- depthFunc $= Just Less

createWindow progName

lighting $= Enabled
position (Light 0) $= Vertex4 1 0.4 0.8 1
light (Light 0) $= Enabled

displayCallback $= display
mainLoop

display = do
clear [ColorBuffer]
rotate 40 (Vector3 1 1 (1::GLfloat))
cube 0.5
loadIdentity
flush

Cube

module Cube where

import Graphics.Rendering.OpenGL
import Graphics.UI.GLUT as GLUT

import PointsForRendering

cube l = renderAs Quads corners
where
   corners =
    [(l,0,l),(0,0,l),(0,l,l),(l,l,l)
    ,(l,l,l),(l,l,0),(l,0,0),(l,0,l)
    ,(0,0,0),(l,0,0),(l,0,l),(0,0,l)
    ,(l,l,0),(0,l,0),(0,0,0),(l,0,0)
    ,(0,l,l),(l,l,l),(l,l,0),(0,l,0)
    ,(0,l,l),(0,l,0),(0,0,0),(0,0,l)
    ]

PointsForRendering

module PointsForRendering where
import Graphics.UI.GLUT
import Graphics.Rendering.OpenGL

renderInWindow displayFunction = do
(progName,_) <- getArgsAndInitialize
createWindow progName
displayCallback $= displayFunction
mainLoop

displayPoints points primitiveShape = do
renderAs primitiveShape points
flush

renderAs figure ps = renderPrimitive figure$makeVertexes ps

makeVertexes = mapM_ (\(x,y,z)->vertex$Vertex3 x y z)

mainFor primitiveShape
= renderInWindow (displayMyPoints primitiveShape)

displayMyPoints primitiveShape = do
clear [ColorBuffer]
currentColor $= Color4 1 1 0 1
displayPoints myPoints primitiveShape

myPoints
= [(0.2,-0.4,0::GLfloat)
   ,(0.46,-0.26,0)
   ,(0.6,0,0)
   ,(0.6,0.2,0)
   ,(0.46,0.46,0)
   ,(0.2,0.6,0)
   ,(0.0,0.6,0)
   ,(-0.26,0.46,0)
   ,(-0.4,0.2,0)
   ,(-0.4,0,0)
   ,(-0.26,-0.26,0)
   ,(0,-0.4,0)
   ]