Emissive decal node

Comments

• TSasha Smith Posts: 27,312

  May 2016

  I have been trying to do light emissive shaders with not much luck in iRay.   I want to know too.
• Oso3D Posts: 15,089

  May 2016

  ... Well, huh. I was going to roll my eyes, but... crud, it looks like emission DOESN'T work on decals.

  That's weird.

   
• ItsTraveler Posts: 184

  May 2016

  This is just technical speculation, but It may be one of those things that would require a custom shader network.
  ​I wish I had more time to experiment with stuff like this. Because..... an Emissive decal would be awesome!
• Oso3D Posts: 15,089

  May 2016

  I could make a custom shader, but first we have to find out exactly WHY it doesn't work. It might be something intentionally blocked off, or... something.

   
• Tobor Posts: 2,300

  May 2016 edited May 2016

  I think the reason is related to why there is a decal feature to begin with, and how it was intended to be used. At least one (major) use case is in product mockups, and internationalizing the labels on them, or experimenting with variations as part of marketing development of a commercial product.

  Rather than set up scenes with textures for each label, the decal node allows for very quick and easy scene database swaps (something not really doable with D|S at the moment), allowing for programmatic rendering -- in fact, you could render these interactively based on user input, such as what you might create on a Web site for allowing user-customizing of a product. Decals are independent scene database elements, so they likely do not process through the renderer the same as the standard MDL surfaces do.

  As background, the Iray programmer's docs say this.:

  Decals are a first-class scene database element that allows you to place decals, such as stickers and labels, on objects in the scene, give them full MDL materials on their own, place them in space and selectively enable or disable them. The placement of decals on objects is physically based insofar as they can be placed on either side of a surface, they can overlap each other, and you can see through transparent decals and see other decals below it.

  And notes these limitations:

  Materials on decals have a few restrictions:

  • Materials are always thin-walled on decals.
  • Front and back-side can have different surface properties. For example a label on a glass bottle can have the logo printed on the front-side while the back-side has a plain white paper surface.
  • Decals support cutout opacity and transmissive materials.
  • Emission is not supported.
  • Normal maps are supported.
  • Displacements are not supported.
  • Volume properties are not supported, except that the IOR value is used in valid thin-walled surface material effects, like in the Fresnel-driven selection between reflection and transmission in the combined specular BSDF.

  Post edited by Tobor on May 2016