thanks Alex,
I didnt know it was faster with 0-255. Considering Nathan's argument
"most of the color system's I've ever encountered have used 0-255 for
rgb values" and your benchmarks, I am convinced that 0-255 is a best
convention.


On 26 mar, 19:50, "Alex Holkner" <[EMAIL PROTECTED]> wrote:
> On 3/27/08, Thomas Woelz <[EMAIL PROTECTED]> wrote:
>
>
>
> >  Responding Nathan,
> >  pyglet 1.1 uses 0-255 colors for instance in the new text module (like
> >  text.Label)
> >  I also prefer reading 0-1 colors so I am still using 0-1 and using a
> >  conversion function:
> >  def to_rgb(a_gl_color):
> >     return tuple([int(x * 255) for x in a_gl_color])
> >  Maybe thats not a good idea, since it involves 2 conversions, since
> >  pyglet will probably have to convert it back to float for OpenGL to
> >  draw it right?
>
> The graphics module, like OpenGL, allows colors to be set with any
> data type (0-1, 0-255, 0-65536, etc, ..).  Internally, all current
> video drivers use the 0-255 range.  To convert to this from a Python
> 0-1 float requires first a double->float conversion (by ctypes, as
> Python uses doubles internally), followed by a float->int
> scale+conversion (by the video driver).
>
> Seeing as the choice to use 0-1 seemed fairly arbitrary to me (only
> glClearColor enforces it in OpenGL, from memory), the text and sprite
> modules (which use pyglet.graphics for rendering) were designed to use
> the most efficient format.  My benchmarks showed that there was a
> small but measurable difference.
>
> Alex.
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