How to apply a glow texture in YafaRay?

[pouar]

I'm trying to get a texture glow effect in YafaRay. The closest I got was layering the texture on top of another texture in the same material and setting the blend mode to either Add or Screen, but the problem is that it doesn't emit any light. Setting the emit property in the material doesn't work because that will cause the glow texture itself to show up in the render and I want it to just emit light and not actually show up when rendering.

[Samo]

there are only one way in YafaRay to get textured-based light emission, in fact this is a pending issue for future versions of YafaRay. The solution is using emit control in a shiny diffuse material with a diffuse texture in Path tracing. For instance, mesh light with a texture won't take the later into account when emiting light. The feature is explained in the last part of the article below:
http://www.yafaray.org/documentation/us ... ffusecolor

The thing is that emit + texture only works as light source in path tracing. It won't work in the other integrators, including DL. However, there are other tricks you can try. For instance, an emit material plus a duplicated mesh working as a portal. However, this trick is not that good, because portal won't take into account the texture applied, unless maybe if you map the same texture on the background. The best and easiest way is using shiny diffuse emit+diffuse texture+path tracing.

[Samo]

example of blender scene below

[pouar]

I was afraid of that. I was trying to render a model of the Death Egg from Sonic The Hedgehog I got from the Source Filmmaker Workshop on Steam in Blender using YafaRay (as I like Blender way more than Source Filmmaker and I actually find it easier to use) and it uses a glow texture and a diffuse texture, and it's the glow texture that's supposed to emit light while the diffuse texture provides the color of the mesh (For example, the eyes are supposed to light up, and using the glow texture as the diffuse texture will change the appearance of the model to a solid black color for everything that doesn't light up, which is obviously not what I want)

[pouar]

Managed to work around it by using the duplicate mesh thing, but setting it as the emit material instead of a portal, then having the material of the duplicate mesh have the transparency set to 1 and the transmit filter set to 0, though for this to work I had to make the duplicate mesh slightly bigger than the original.

[pouar]

I'm an idiot. I just found out it's possible to render the 2 meshes separately, and use the emit render layer of the mesh with just the lighting with the combined render layer of the mesh with the color and combine the 2 in gimp with the emit layer set to screen.

[Samo]

an HDRI image as a texture will give you better results, if you can get one that fits your needs.

[pouar]

Just tested it and in terms of lighting there seems to be no visual difference (afaict by looking at it) between having YafaRay doing the lighting by making the 2nd mesh slightly larger, and doing the lighting in GIMP by rendering them separately and setting the blending mode to additive (other than the position of the lighting due to the mesh with the emit texture being slightly larger than the mesh with the diffuse texture). Setting the blending mode to screen instead of additive seems to make it brighter than doing it in YafaRay.