[PD] flip image in glsl

Cyrille Henry ch at chnry.net
Mon Apr 8 10:05:22 CEST 2013


when using rectangular texturing, coordinate goes from 0 to image pixel size.
when using "rectangle 0" mode, pixel coordinate goes from 0 to 1. (sometimes 1 is for the power of 2 bigger than the image pixel size)

so, in rectangular mode, use pixetl_size - image coordinate to flip the image.
and 1 - image coordinate in non rectangle mode.

Image can be fliped because the "fliped" flag is not used on the shader.


Le 08/04/2013 09:24, Patrice Colet a écrit :
> Hello,
>   how is it possible to flip upside down an image in glsl example 05.multitexture
> I tried to implement this in fragment program:
> http://stackoverflow.com/questions/9857089/flip-upside-down-vertex-shader-gles
> but it doesn't work. The only thing I can do is changing texture scale and position, but I couldn't do it with negative values
> like it would be done in pix_coordinates.
> In fact when I use pix_multiimage before pix_texture, the image gets flipped, I don't know why...
> Colet Patrice
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