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# Positioning 2D QUAD in front of screenview

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### #1WiredCat  Members   -  Reputation: 368

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Posted 28 May 2012 - 01:14 AM

Hello i just made and postprocess effect but i need to draw it on the whole screen not only on the part of the screeen, i decided to draw it with glulookat because glortho didn't work for me:

so what i am doing: i first draw scene then i copy it to texture and draw a quad (in example 1024x768 [not pixels]) and position it at the 0,0,0 point (starting point) the center of this quad is 512,384,0 (x,y,z)

then i call gluLookAt(512.0f,384.0f,256.0f, 512.0f,384.0f,0.0f, 0.0f,1.0f,0.0f);

but the quad i see is too big - so theres a problem how can i calculate the proper distance to draw this quad on the whole screen (screen dimensions are 1024x768 pixels) and my z_near value is 0.010f

this is what i've got now, ahh and i need this quad to be quite larger because i need to see (its really a 3d grid) some different z values from it to actually see the effect lets say z = about 200 points

Peace ;d

Edited by ___, 28 May 2012 - 01:17 AM.

### #2V-man  Members   -  Reputation: 805

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Posted 28 May 2012 - 08:29 AM

Sig: http://glhlib.sourceforge.net
an open source GLU replacement library. Much more modern than GLU.
float matrix[16], inverse_matrix[16];
glhTranslatef2(matrix, 0.0, 0.0, 5.0);
glhScalef2(matrix, 1.0, 1.0, -1.0);
glhQuickInvertMatrixf2(matrix, inverse_matrix);
glUniformMatrix4fv(uniformLocation1, 1, FALSE, matrix);
glUniformMatrix4fv(uniformLocation2, 1, FALSE, inverse_matrix);

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