[openvrml-develop] Transparency

[Damian M. <da...@er...>]

This has been open for over a year.  I'd like to close it.

There are two issues with transparency, one associated with materials and
one with images that have transparent parts.  Apparently neither work.

I have looked at the bug page and it doesn't give me much of a hint except
to say that with z-buffers it is a problem.

In 'ViewerOpenGL::insertTexture', it mentioned

	// Enable blending if needed
  	if (d_blend && (nc == 2 || nc == 4))
    		glEnable(GL_BLEND);

Don't we need an extra

	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

or does the one in ViewerOpenGL::initialize cover us forever.  There is a
glDisable(GL_BLEND) in ViewerOpenGL::redraw() and I thought that this
clobbered the glBlendFunc().  I am a long way away from being an OpenGL
guru.

Heaven only knows what to do with Material transparency.

Can anybody direct me to where there are some simple files to try this
out?  And/or any theory that might be useful especially in the context of
OpenVRML and its usage in the context of OpenGL.

Thanks - Damian (McGuckin)

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