Multiple Decals on Object

[TomDowd]

Has anyone figured out an easy way to do multiple decals on an object? I figure I can do it with geoshells, but building eight of them (one for each decal) is a pain. Any ideas?

TomD

[huakiami]

Hi TomD,

There are a lot of ways to do this, but it will vary depending on the effect you're trying to achieve. A Geo Shell can be a great method, particularly if you don't want your decals to combine with the material they're on top of. You shouldn't need to use a separate Geo Shell for each decal though - you can combine them all in the material of a single Geo Shell.

Here is an example where I put the three decals on a brick wall. The first decal is a red number 1, the second is a green number 2, and the third a blue number 3. Each decal is a colored PNG image of the number with a transparent background.

Three decals on a Geo Shell of the brick wall object.

Below is the node setup of the Geo Shell. Basically each decal PNG is loaded twice - once as an RGBA Image used for the opacity and masking and secondly as a regular RGB Image for the diffuse color. It doesn't have to be 3 decals - you could follow this pattern indefinitely for any number of decal images you want to add.

Node setup for three layered decals.

Now the render above is fine if I wanted the numbers to be three plastic signs someone hung on the wall. But what if I want it to be more like paint? Well in that case I wouldn't use a Geo Shell at all - I would just add the same decal node setup from the screenshot above to my brick wall material and use the combined RGBA nodes for the 'Amount' input of a Mix Material instead of a Geo Shell's opacity. Then I can easily use the brick AO, normal and displacement maps for both the brick material AND my decal material. Getting something like this -

No Geo Shell. Three decals added to the brick wall material and combined with its AO, Normal and Displacement maps.

Or also multiply the decal color with the brick color for an even more blended look -

Now if I wanted the decals combined instead of on top of each other we can do that too -

So it really depends exactly what you're trying to do. But in all the examples above I used that same node setup for combining the decal images. So long as your decal is an image with a transparent background or you have at least some way to mask where you want it to show you should not need to stack Geo Shells. Which is good because if you have G8F at 3 or 4 levels of subdivision and then start stacking Geo Shells on her performance tanks pretty quickly.

-Matt

[Tugpsx]

Awesome tutorial thanks for sharing.