Grasshopper preview isn’t working for me in rendered mode, but I can see it if I create a custom Display Mode.
In this display mode, if i select X-ray wires, all of the normal rhino objects are x-rayed. However, the preview objects do no x-ray. They (the previews) are there, but i cannot see them through an object. Is there a way to engage x-ray for grasshopper preview?
This is by design. In renderings and display modes that approximate renderings only Custom Display geometry is included.
All Grasshopper previews are drawn after the objects in Rhino are drawn. At this point the z-buffer is already set to the nearest pixel, even if that pixel is transparent. Rhino solves this issue by sorting all meshes back to front before drawing, and drawing backfaces first. Grasshopper cannot participate in this sorting because it won’t draw until afterwards, but it doesn’t even sort its own geometry. A very transparent GH preview mesh will fully occlude an opaque mesh behind it, if it is part of a component which draws first.
We can probably improve upon this in GH2, but in GH1 you are out of luck.
Thanks for the information, David.
Count me as one who would like the improvement added back to GH2. For most of my experience* in Rhino 5, grasshopper preview items appeared and xrayed appropriately. I used them in my workflow - so the change has negatively affected me. My particular preview priority would be preview points and curves. Maybe those would be easier to implement than other objects initially?
*R5/grasshopper xrays were seemingly broken by a update in the past few months and possibly connected to the changes coming in R6. Preview objects would only xray if you zoomed in extra close. The GH preview objects were always available in rendered mode in R5)
