Transparent Edges

[dgreenlaw]

Hi,

I'm a LightWave user who is making a transition to Maya. Adapting to Maya has been going smoothly but the other day I had to fall back on LightWave because I needed to render an object with transparent edges. In LightWave this is accomplished by applying an Edge_Transparency shader to a surface and then selecting the desired settings. I was told that in Maya there was no easy way to apply transparent edges to objects short of writing a MEL script for it. Is this true? If so, could somebody offer some guidance on how to do this or point me to a script already written for this effect?

Thanks in advance for any help.

D.R. Greenlaw
Encore Visual FX
Hollywood, CA

[deke-kincaid]

The closest thing you can do this by either mapping the transparency with a texture map or a ramp. There isnt a built in option for just doing the edges as transparent.

Deke

[sunil_born2win]

You can try something that worked for me : duplicate your poly object, then make a Edit Polygon -> Textures -> Normalize UVs. Then create a material, a ramp that you drag onto the transparency channel. The ramp is of UVRamp type, just keep two colors (black and white) and bring the white color entry to the top, and the black one just a bit under, so that you have a black ramp with a small white area on top in the Attr Ed. Now test and render, and you should have transparent edges. If there are uncorrect faces, you can also do a Unitize UV on the object. This method works well with four sided faces, problems can occur on triangles and five sided faces.

Hope ti helps

Alban

[dgreenlaw]

Hi,

Thanks for the tips and speedy response guys. Will give it another shot today.

Best,

D.R. Greenlaw
Encore Visual FX
Hollywood, CA

[zacktown]

It is possible that I am not completely understanding your post, but I do this all the time by:

In the hypershade window,
create your shader
create a multiply divide node,
create a samplerInfoNode,
then create a reverseNode

First connect the facing ratio attribute of the samplerInfoNode to the inputX of the reverseNode;
then, connect the outputX of the reverse node to the input1X of the multiply divide node;
then connect the outputX of the multiplyDivide node to the transparencyR,G, & B;

you could do this without the multiplyDivide node, but by adding it, you have the ability to adjust the edge transparency. I use multiply for the operation. In the input2X, I type in different values until my edge transparency is what I want.

If this totally doesn't make sense, let me know your e-mail and I will send you an example shader.

Good luck,

mike
mike@townshendproductions.com

At first this sounds like a lot of work, but after a couple of times, it becomes very routine.

[dgreenlaw]

Hi Mike,

Thanks for the detailed explanation! I haven't tried your suggestion yet so I'm not sure if it answers my question. If you could sent that sample shader to examine, I'd appreciate it very much. My e-mail is dgreenlaw@aol.com.

Here's some more info to clarify what I'm looking for. The way LightWave's Edge_Transparency shader works is that it gives the curved edges of an object a transparent fall-off, sort of the way it would look if you choked and blurred its alpha channel in a compositing program, except that the transparency follows all the edges of the geometry in 3D and not just the 2D contour of the object. This is useful for faking volumetric elements like plasma, smoke, etc., or making a character appear 'ghostly' by softening its edges.

I think this is similar to the way the Soft Edges option in Maya's Cloud Texture behaves...the transparency of the texture increases as the surface turns away from the camera.

In LightWave you can also invert the effect making the interior of an object transparent and its edges solid. This effect is nice for objects made of glass or ice.

It would be great help if I'm able to do this easily in Maya. Thanks again for your input!

Best,

D.R. Greenlaw
Encore Visual FX
Hollywood, CA

[hwy101]

I haven't tried it specifically, but it sounds like the easiest way to do this is to map a ramp to the transparency channel, the value of which is controlled by the facing ratio of a sampler info node...
Whoa, that sounds a lot more complex than it really is.
www.aliaswavefront.com has many tutorials on just how the sampler info node works.
This technique practically duplicates a Lightwave 6 method, which would be to apply a gradient to the transparency channel and select "incedence angle" to control the gradient.
Hope that helped.