Transparent materials are typically rendered using alpha blending, you can set that up with the code below.

GraphicsDevice.RenderState.AlphaBlendEnable = true;GraphicsDevice.RenderState.SourceBlend = Blend.SourceAlpha;GraphicsDevice.RenderState.DestinationBlend = Blend.InverseSourceAlpha;// render transparent meshpart hereGraphicsDevice.RenderState.AlphaBlendEnable = false;

However, rendering transparent materials isn't quite as straightforward as you might think. Because of depth buffering, if you render your transparent material before you render the stuff that's behind it, it won't be there. The device doesn't care if an object is transparent (with alphablending, alphatesting is another matter), so it'll mark the pixels as 'taken' in the depth buffer and discard any pixels rendered behind it. A bit of googling should provide you with more in depth info.

There are basically two ways around this, sorting materials so you render the transparent ones last or disabling zbuffer writes when rendering transparent materials. Disabling the zbuffer writes is only useful if you don't care the transparent material gets overwritten (common with grass and foilage), so I'm afraid you're going to have to do some sorting. For a single mesh though, this is just a matter of figuring out the MeshPart index which uses the transparent material and rendering that after you've looped over the opaque parts.

There you go, I hope this makes some sense [smile]