GH in Rhino Viewport display preview issue

I'm not sure if this is normal or not, but my Grasshopper preview in Rhino displays as a X-ray type display style, with some weird clipping going on. I have the document materials set without transparency, as well as custom previews on all solid geometry and surfaces. Its really difficult to see whats going on and would like the geometry to appear solid. Thanks for any help.

Edit: I have Rhino SR9 and Grasshopper V 0.8.0066

Replies to This Discussion

Permalink Reply by Andrew Heumann on February 23, 2012 at 9:41am

I've had this problem as well. The only thing I can suggest is that meshing your geometry before you feed it to a custom preview component will sometimes correct the strange clipping issues. Here's an image showing the same problem occurring for me.

Permalink Reply by tvett on February 23, 2012 at 10:38am

Thanks, converting to mesh makes for a quick fix, but it would be nice to see this fixed. Also any curves still show through. Maybe its better in Rhino 5?

Permalink Reply by Juan_P on February 23, 2012 at 10:43am

Hey Fnm1,

This question is out of the topic. But I noticed on your screenshot that you have the plug-in "rhino terrain" Ive tried downloading the trial thru the rhino website but it gives me error. Do you happen to know anyother source.? and is it worth it getting, Im working on my thesis and I need the terrain of my site. I know this might help.

Best,

Juan_P

Permalink Reply by tvett on February 23, 2012 at 11:37am

Did you try http://www.rhinoterrain.com/download.php? Rhino Terrain is a pretty good plugin, it can make a mesh from contours pretty fast. Also it adds the ability to import shape files with GIS spatial data. I don't know where but I have seen other methods to make terrain from contours, either through Grasshopper or a script.

Good Luck

Permalink Reply by Hannes Löschke on February 23, 2012 at 2:29pm

I ran into this problem with my own component for Rhino block instances.

I'm using the previewAware interface to show the blocks bounding box. Seems like the preview sometimes has problems updating the overall geometry bounding box for the viewport. There seems to be a front clipping plane that doesn't get updated. I just thought it was my fault in implementing something wrong. But it looks like there is something fundametally wrong.

Permalink Reply by Nathan Howe on March 5, 2013 at 9:36am

I am having the same issue. It appears to show up rather randomly. This is effecting being able to analyze the script. Happens mostly with points being scattered out in the ether. If I zoom out the points show up again where they are supposed to be but zooming in they react like oil to soap and scatter. Quite frustrating when you are working on something which you are trying to dial into.

Attachments:

Permalink Reply by David Rutten on March 5, 2013 at 9:51am

Are you overriding the ClippingBox property and returning a BoundingBox that contains all the geometry you're about to draw?

David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by Nathan Howe on March 5, 2013 at 9:58am

No. Not sure how to override the ClippingBox property. Let me know how and I will check.

Permalink Reply by David Rutten on March 5, 2013 at 10:24am

You type "override" (or "Overrides" in VB), pick the property ClippingBox from the dropdown list and implement it.

The ClippingBox property is called prior to all drawing functions and it's here that you tell Rhino how big the geometry is you're about to draw. This is important because Rhino needs to set up the OpenGL depth buffer. This depth buffer is used to determine which objects are in front of which other objects and it must be both 'deep' enough to contain all objects and 'shallow' enough to not contain too much empty space because that will reduce the quality of the depth-buffering.

So when you're going to draw a circle at the world origin of radius 10, you should make sure that the clippingbox contains this circle:

Dim clip As New BoundingBox(New Point3d(-10, -10, 0), New Point3d(10,10,0))

Furthermore, the base implementation of ClippingBox is also important, so you need to merge your own clippingbox with the box returned by the base class:

Public Overrides ReadOnly Property ClippingBox() As BoundingBox
Get

Dim localBox As New BoundingBox(-10, -10, 0, 10, 10, 0)
Dim boxBase As BoundingBox = MyBase.ClippingBox
boxBase.Union(localBox)
Return boxBase
End Get
End Property

David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by Nathan Howe on March 5, 2013 at 10:31am

All of this makes sense but I am just using common grasshopper components no VB components to be found. Not sure where to override anything.

Permalink Reply by David Rutten on March 5, 2013 at 11:25am

Ah, I thought it was a problem with custom drawn geometry. I think you're using an older version, it would be nice to know whether this still happens with the latest version as well.

David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by David Rutten on March 5, 2013 at 12:10pm

In lieu of a better solution, I added an option to the Preview section of the Canvas toolbar that enables/disables preview bumping for all Grasshopper preview (i.e. it's not a document property but an application property).

The difference of bumping vs no bumping can easily be seen when the camera is relatively close to the preview geometry:

And before you yell out in unadulterated rage about bumping being the default allow me to explain that the problem with not-bumping the preview is that Grasshopper and Rhino geometry that exist in the same place (for example referenced curves) now suffer from the flickering problem. It is no longer obvious which is obscuring the other and thus the Grasshopper geometry will no longer always be drawn on top.

I'm sure a better solution exists somewhere but at the moment I cannot think of one.

David Rutten

david@mcneel.com

Poprad, Slovakia