View Full Version : Edge fading & transparency problems

02-06-2012, 08:12 AM
Not sure this would be the correct forum, but...

I have a request from a client to do a rendering of a diving helmet that fades from a photo-real render on one side into a transparent wireframe on the other.

I'm figuring the easiest way to do this is to have two versions of the model rendering, one for the real helmet, one for the wireframe.

I'm having two problems I can't seem to figure out...

Firstly, I've popped a gradient onto the transparency channel keyed by distance to the Y axis, which is a pain but working, however, it seems to be generating a spherical fading from the object's axis, but I need a straight up left to right fade. I could do this with an image map, but I'm keen on doing it in a way that i can then spin the objects to get the desired angle.

Secondly, I can find no way to have an object's edges fade. The wireframe version is set to 99.9% object dissolve, so i can't see the surfaces, but the edges always render completely.

I am losing some hair over this...

I'm on Xp using LightWave 9.5.

Any advice / tips appreciated...

02-06-2012, 01:57 PM
If you have After Effects or an editing app, it might be easier to render the full render and the wireframe render separately and do the transition in post. You could also render a custom wipe to use as the alpha/matte/mask in post by making your object solid white and your gradient solid black.

Are you using a gradient node or a gradient layer? If it's the layer system, I'd add a Null object to the scene and set the gradient to "Y Distance to Object" and select the null object. If you're in the Node editor you can check out this thread for the solution: http://forums.newtek.com/showthread.php?t=125605&highlight=gradient (set the Vector Scalar node to Y position)

02-06-2012, 02:03 PM
I don't know if this is what you want?

One texture is your normal surface.
The other shows your wires.

Switch between the two. If you make your range from the null quite large it will look pretty flat.


02-07-2012, 05:42 AM
XswampyX That's pretty much bang on, except, I need the helmet's normal surface to fade rather than end abruptly. The same with the wireframe - there needs to be an overlap between the two...

I'd probably do the sharp edge as you've done by using a boolean to split the helmet along a seam and do each half as separate layers, which is almost certainly a horribly lame way of doing things.

02-07-2012, 05:49 AM

I'm using a gradient layer set to the Y distance to object, the object being a null (I have also tried an invisible plane to no avail), but each time I try it, the null seems to generate a spherical effect, rather than a neat planar fade.

At this time I have no after effects bundles. I'm somewhat time-poor for experimenting in this area, unfortunately.

02-07-2012, 10:50 PM
Can you post an image of the problem? Are you using a wide angle camera lens?

02-08-2012, 07:08 AM
Think so, ought to be below.

I can generate a 2D image which works, but I'd much rather have the fading at an angle to camera, rather than straight on (so you look into a concave section of the helmet) , and ideally be able to rotate the helmet so that the area that is 'metal' (and obviously, also the wires) would move when the helmet rotates, so that as it spins bits of it fade out of wireframe and into metal.

The attached is set to adjust the transparency of the metal surface by Y distance to a null object. The object is 1 meter in width, with the gradient set at 100% visible to around 120 mm, then sloped to 0% at about 700 mm.

Thanks so much for helping, I'm 100% self taught and suspect I may be entirely missing whole sections of how LW actually works, so I am almost certainly using a foolish methodology to do something that pros will find comical :-)

02-11-2012, 05:26 PM
I put together a video that might help with the gradient set up.


02-12-2012, 08:10 AM
That's very cool. From this I have got, mainly, that I absolutely need to take a few days off and go learn the node editor (I've never touched it).

Any thoughts on getting the wireframe object to similarly fade? The trouble seems to be (I'm assuming, really) that the edges when rendering don't have a surface, per se (at least in 9.5) so there's nothing to attach a gradient to...

Thanks again!

02-13-2012, 12:00 AM
It looks like you're using the edges settings in the object panel. There's a check box on the surface settings for rendering wireframes on the surface. You'd probably want to use the surface version instead of the object edges version.

I haven't tried it, so I don't know if it'll work.