def canUseFloatTextures(nvals=1):
"""Returns ``True`` if this GL environment supports floating
point textures, ``False`` otherwise. The test is based on the
availability of the ``ARB_texture_float`` extension.
:arg nvals: Number of values per voxel
:returns: A tuple containing:
- ``True`` if floating point textures are supported,
``False`` otherwise
- The base texture format to use (``None`` if floating
point textures are not supported)
- The internal texture format to use (``None`` if
floating point textures are not supported)
"""
# We need the texture_float extension. The
# texture_rg extension just provides some
# nicer/more modern data types, but is not
# necessary.
floatSupported = glexts.hasExtension('GL_ARB_texture_float')
rgSupported = glexts.hasExtension('GL_ARB_texture_rg')
if not floatSupported:
return False, None, None
if rgSupported:
if nvals == 1: baseFmt = gl.GL_RED
elif nvals == 3: baseFmt = gl.GL_RGB
elif nvals == 4: baseFmt = gl.GL_RGBA
if nvals == 1: intFmt = gl.GL_R32F
elif nvals == 3: intFmt = gl.GL_RGB32F
elif nvals == 4: intFmt = gl.GL_RGBA32F
return True, baseFmt, intFmt
else:
if nvals == 1: baseFmt = gl.GL_LUMINANCE
elif nvals == 3: baseFmt = gl.GL_RGB
elif nvals == 4: baseFmt = gl.GL_RGBA
if nvals == 1: intFmt = arbtf.GL_LUMINANCE32F_ARB
elif nvals == 3: intFmt = gl.GL_RGB32F
elif nvals == 4: intFmt = gl.GL_RGBA32F
return True, baseFmt, intFmt
def oneChannelFormat(dtype):
"""Determines suitable one-channel base and internal texture formats
to use for the given ``numpy`` data type.
:return: A tuple containing:
- the base texture format to use
- the internal texture format to use
.. note:: This is used by the :func:`getTextureType` function. The
returned formats may be ignored for floating point data
types, depending on whether floating point textures are
supported - see :func:`canUseFloatTextures`.
"""
# Make sure we have a numpy dtype
# *instance*, and not a class.
dtype = _makeInstance(dtype)
floatSupported = glexts.hasExtension('GL_ARB_texture_float')
rgSupported = glexts.hasExtension('GL_ARB_texture_rg')
nbits = dtype.itemsize * 8
if rgSupported:
if nbits == 8: return gl.GL_RED, gl.GL_R8
else: return gl.GL_RED, gl.GL_R16
# GL_RED does not exist in old OpenGLs -
# we have to use luminance instead.
else:
if nbits == 8:
return gl.GL_LUMINANCE, gl.GL_LUMINANCE8
# But GL_LUMINANCE is deprecated in GL 3.x,
# and some more recent GL drivers seem to
# have trouble displaying GL_LUMINANCE16
# textures - displayting them at what seems
# to be a down-sampled (e.g. using a 4 bit
# storage format) version of the data. So we
# store the data as floating point if we can.
elif floatSupported:
return gl.GL_LUMINANCE, arbtf.GL_LUMINANCE16F_ARB
# Hopefully float textures are supported
# on recent GL drivers which don't support
# LUMINANCE_16
else:
return gl.GL_LUMINANCE, gl.GL_LUMINANCE16
def queryExtensions(*args):
from OpenGL import extensions
class Extensions(object):
pass
result = Extensions()
_logger.info("Extensions:")
for name in args:
value = extensions.hasExtension(name)
setattr(result, name, value)
_logger.info("%s: %s", name, value)
return result