[HOpenGL] 2D textures with OpenGL and GLUT

[Elise Huard]

Definitely, I want to avoid unsafeCoerce completely.
thanks,

Elise

On 8 July 2014 12:32, Jason Dagit <dagitj at gmail.com> wrote:
>
>
>
> On Tue, Jul 8, 2014 at 9:20 AM, Elise Huard <haskell at elisehuard.be> wrote:
>>
>> I wanted to thank you, because pointing to unsafeCoerce was a nice bit
>> of serendipity.  I'll admit I thought it was nitpicking initially, but
>> I did a quick pass at cleaning things up last week after your mail
>> (not perfect, but this was a prototype so I'm not looking for pretty):
>>
>>
>> https://github.com/elisehuard/game-prototype/commit/5cf85fa60f325dbe610b5e1f017c9427e304daf6
>>
>> and that fixed the texture mapping!
>> Consider me informed on that issue :)
>
>
> Cool! By the way, the 'proper way' to convert between Double and CDouble is
> to use realToFrac:
>
> Prelude Foreign.C.Types λ> realToFrac (1 :: Double) :: CDouble
> 1.0
>
> In specific case like this (Double <-> CDouble) it should be equivalent (but
> as a user of the library you shouldn't depend on know that). In some cases
> it can be a performance hit, but that's what RULEs pragmas are for.
> Moreover, some versions of the Haskell OpenGL bindings made it so that
> GLdouble was not the same type as CDouble. So the safest way is to use
> realToFrac and depend on the library writer to provide RULEs that make it
> efficient.
>
> I hope that helps,
> Jason
>
>