[PD] pix_blob y-value: bug?
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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