[PyOpenGL-Users] PyOpengGL glHistogram()

[Ant S. <an...@ce...>]

Hi

I've been looking at the documentation for PyOpenGL and it certainly seems
to contain pages on the ARB imaging extension that allows image histogram
generation. However, I've not been able to make this work, nor have I been
able to find out definitively whether another package, like glewpy, provides
these functions. 

So far, I have introduced the following into a PyOpenGL / WxPython canvas:

from OpenGL.GL.ARB import imaging 

def OnPaint:
	# some code here ...

	glHistogram(GL_HISTOGRAM, 4, GL_RGB, GL_FALSE)
	glEnable(GL_HISTOGRAM)
	self.OnDraw()
	# glGetHistogram() definitely doesn't work, that's why it's
commented below!
	#glGetHistogram(GL_HISTOGRAM, GL_FALSE, GL_RGB,  GL_UNSIGNED_BYTE,
self.HistValues)

	if glIsEnabled(GL_HISTOGRAM):
		print "True"
	else:
		print "False"

	# some more code here ...

I can enable GL_HISTOGRAM, I guess because this is only setting a bool(?),
but when I try to actually call the function glHistogram(), I get the
following traceback:

Traceback (most recent call last):
  File "..\glHistogramTest.py", line 97, in OnPaint
    glHistogram(GL_HISTOGRAM, 4, GL_RGB, GL_FALSE)
  File "..\Python25\lib\site-packages\OpenGL\platform\baseplatform.py", line
252, in __call__
    if self.extension and self.load():
  File "..\Python25\lib\site-packages\OpenGL\platform\baseplatform.py", line
234, in load
    func = functionTypeFor( self.DLL )(
NameError: global name 'functionTypeFor' is not defined

If anyone knows whether these functions are indeed supported (or not) and
how, or if anyone has successfully used other modules that implement them,
then I would much appreciate knowing about it.

Many thanks.

Ant