Re: [Glsdk-devel] Geometry generation

[Branan R. <br...@gm...>]

I have to agree with Jason on this one. If the user wants custom
geometry, they need to learn how to deal with drawing it. For the sake
of tutorials, we just need objects to show off transformations and
shaders with. An opaque format reduces the risk of abuse not only by
newbies, but also by people coding SDK examples.

One thing that does need to be clear is how vertex attributes map to
the arrays generated by the shape function. Something like:

Attrib 0 is the position (vec4)
Attrib 1 is the normal (vec3)
Attrib 2 is the texcoord (vec2)

That way shaders can always get the correct variables. I think I'll
add preprocessor defines for this - GLS_POSITION_ATTRIBUTE,
GLS_NORMAL_ATTRIBUTE, and GLS_TEXCOORD_ATTRIBUTE, so that there are no
magic numbers floating around.

On Sat, Aug 23, 2008 at 8:00 PM, Jason McKesson <ko...@gm...> wrote:
> Stefanos A. wrote:
>> If I understand correctly, what we actually need is a way to generate
>> geometry for the tutorials. Which means we just need the
>> vertex/texcoord/normal/element arrays.
>>
>> While it's good to have functions that *generate* this data, is it really
>> a good idea to hide the *drawing* part behind a glsDrawShape function?
>> Maybe it would be better to simply return these four arrays and handle the
>> drawing inside the tutorial?
>>
>> Just trying to understand the focus of the shape functions. What do you
>> say?
>>
> Well, the problem with any form of generation of that type is this:
> where are you going to put it? You can't put it into a user-supplied
> buffer object because it might be too big (and having a query for the
> size makes creating them very complex). And if you have it create the
> buffer, how do you communicate the data format to the user?
>
> Basically, we want these things to be as simple as possible for the user
> to use. This isn't production code, so flexibility is not a concern. We
> want them to be able to go:
>
> //initialize GL/create window.
> GLSshape myBox = glsCreateShapeBox(params);
>
> while(true)
> {
>  //setup context.
>  glsShapeDraw(myBox);
> }
>
> glsDestroyShape(param);
>
> The goal being that you can't make that fail. The user can't do
> something wrong. And it's immediately obvious how it works.
>
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