[GEM-dev] frambuffer does change the scene perspective

marius schebella marius.schebella at gmail.com
Sun May 25 15:30:58 CEST 2008


cyrille henry wrote:
> here is a patch that explain this problem.

hi cyrille,

I think you are right, gemframebuffer should not affect the main window. 
Not sure why nobody noticed that before...
but besides from that, I am not sure, how gemframebuffer should behave, 
if it should adjust to the world perspec or not. since framebuffer is 
ignoring the view, maybe it should also ignore the perspec? (and accept 
individual frustum message instead, and individual view?).

I posted a question about ortho some days ago, and would like to know if 
this is related? (when using ortho in non square windows everything is 
distorted, too).

marius.

> 
> cyrille
> 
> cyrille henry a écrit :
>> hello,
>> when using a framebuffer in a patch, the perspective of the main 
>> windows is change to (-1, 1) in X and Y.
>> So it's no more possible to use custom perspective (sending the 
>> perspec message to gemwin is useless).
>> moreover, the perspective used lead to distorted images when the 
>> gemwin is not square.
>>
>> fixing this is quite easy, but will break all patch using frambuffer 
>> with a not square gem windows.
>> so, i'm wondering if i should commit the fix.
>>
>> the fix is mainly to replace line 145 of gemframebuffer.cpp  :
>> glFrustum(-1,1,-1,1,1,25);
>>
>> with :
>>   float xDivy = (float)GemMan::m_w / (float)GemMan::m_h;
>>
>>   glFrustum(GemMan::m_perspect[0] * xDivy, GemMan::m_perspect[1] * 
>> xDivy,    // left, right
>>             GemMan::m_perspect[2], GemMan::m_perspect[3],            
>> // bottom, top
>>             GemMan::m_perspect[4], GemMan::m_perspect[5]);            
>> // front, back
>>
>> but it need to add #include "Base/GemMan.h"
>>
>> and to move  static int       m_w;                  static int       
>> m_h;  from private to public in GemMan.h
>>
>> should i commit this?
>>
>> cyrille
>>
>>               
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>>
>>
> 
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