This is an order problem… Transparency is nothing more than an “effect” that tricks humans into thinking they’re seeing something that is “see through”…nothing more.
The effect is achieved by blending pixel colors with other pixel colors by some percentage amount. However, if MUST make sure that certain pixels exist in a very specific order, otherwise the effect will be lost.
That being said… The way Rhino achieves the transparent effect is that it first draws ALL objects that don’t have any kind of transparent effect… It then sorts all remaining objects by distance from the camera/eye from furthest to closest (known as “The Painter’s Algorithm”). It then draws those objects and performs a blend between their pixels and the pixels that exist prior to drawing them. The end result is that some objects “appear” to be behind other objects…but all it really is, is a bunch of pixels with certain color values…there is no such thing as “transparency” to a computer.
Given that, since Rhino’s pipeline draws all “transparent based” objects last, any object that gets drawn after that will “wreck” the effect… And any transparent objects drawn before they’re supposed to, will most likely lose their transparent effect.
Sorry for being long winded here…but it’s important that you understand the “why” behind what I’m about to say next…
The only way plugins and 3rd party code can come close to getting their objects to appear transparent is to make sure that they draw their transparent objects after Rhino has completed drawing all objects…and currently the only way to do that is to make sure the drawing is done in the
PostDrawObjects() channel. If you’re drawing things in any other channel, I’m afraid “transparency” is just not going to work.
So Dale’s question is very relevant and important… What channel are you using to draw your objects? I don’t really know what is meant by “I’m drawing them in GH’s preview”… somewhere you must specify a channel(s) for your conduit…which channel(s) are you including, and which ones are drawing geometry?