[gameprogrammer] Re: newb openGL q: positioning multiple objects

Hi Ethan,

Check out line 223...
     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

This will blank the screen each time...

You should call this once before you begin rendering your scene...

It looks like you are rendering multiple cubes but clearing the buffer
before each one.

Hope this helps.

Rich



2009/7/5 Ethan Grammatikidis <eekee57@xxxxxxxxxxx>:
> On Sun, 5 Jul 2009 02:47:55 +0100
> Ethan Grammatikidis <eekee57@xxxxxxxxxxx> wrote:
>
>> Hi, I'm just starting out with OpenGL on a Linux box. I've been working 
>> through an old O'Rielly tutorial creating a spinning cube,[1] and thought I 
>> could modify the program to display multiple cubes, but no matter what I do 
>> I only get one or zero cubes.
>>
>> [1] 
>> http://www.oreillynet.com/pub/a/network/2000/06/23/magazine/opengl_build.html?page=2
>>
>> It's GLUT-based with a cbRenderScene() callback which originally contained 
>> all the drawing code for the cube and the HUD-like text. I rearranged 
>> cbRenderScene() so that it calls my functions, do_objects() and do_hud(). 
>> do_objects calls obj_spinning_cube() twice, passing different positions each 
>> time. obj_spinning_cube() passes this position (a struct with x, y, z) to 
>> glTranslatef() immediately after calling glLoadIdentity().
>>
>> I only see one spinning cube, corresponding to the second call to 
>> obj_spinning_cube(). I can see the first cube if I disable that second call. 
>> I wonder if I'm misunderstanding glLoadIdentity()?
>
> I forgot to link my code:
>
> http://sprunge.us/NZNc?c
>
> and a 3-line header (position struct):
>
> http://sprunge.us/VGDc?c
>
> --
> Ethan Grammatikidis
>
> Those who are slower at parsing information must
> necessarily be faster at problem-solving.
>
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