[PD] pix_blob y-value: bug?

cgc cgc at humboldtblvd.com
Wed Mar 17 04:17:54 CET 2004

On Mar 16, 2004, at 5:11 PM, Max Neupert wrote:

> The y-value of the pix_blob symbol seems to be inverted
> (it gives out data from 1-0 instead of from 0-1,
> meaning 0.7 instead of 0.3).
> Is that a bug?

It's more like a discrepancy between the QT pixmap and OpenGL 
coordinate space.  We deal with pixels starting at the top left at 
(0,0) and work to say (720,480) whereas GL has a 0,0,0 origin and 
positive coordinates move up and right.  So, should pix_blob report the 
'center' of an image in relation to the original pixmap or related to 
the GL coordinate space?  It currently does the former as it doesn't 
deliver -1..1 which would be more correct for the 3D world.


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