Hey all,

Coming at you with another Quick Blog Tutorial on black light in Blender Render! Here is the result:


I don't know how many know that you can actually do this in Blender, but I only found out while writing the book. GOD wanted me informed about where the textures apply and how to make them visible, but for this specifically, HE hadn't given me any practical application apart from possible caustics on stationary objects, like the walls in a pool room, which I haven't tried yet.

This is the first real practical use HE's given me for it, so I hope it proves useful to you all!

Light receiving object:
> Basically, add an object (the one that is to receive the light)
> Add a new material
> Make it any color except white or black (black mutes the effect and white washes it out)
> Make sure Ambient light is set to 1 in the Shading section, not Shadow, but Shading
> Enable receiving of transparent shadows in the Shadow section
> Add a new texture, leave it on Color Influence and enable Emit Influence to make sure it is the right size and correctly mapped
> Disable both Color and Emit influence and make sure that only Ambient influence is on and on 1
Feel free to adjust the contrast of your texture with the ramp option.

Black light:
> Add a cylinder or a plane
> Form it to be elongated
> Add a new blue or purple material to it
> Set it's Emit to ~150 (depends on the scale of your light and scene)
> Add around it a box to help block some of the light from the viewer
> Parent (Ctrl+P) the light to the box so that when the box moves, the light stays with it
> Position it fairly close to the surface that will react to it

World:
> Ambient occlusion only allowed if on Multiply
> No environment lighting, because it makes the texture show, like the black light would.
> Indirect Lighting (IL) has to be turned on (make it's error possibility as low as you are willing to wait for a render, because as you can tell in the animation, IL is very error prone. As many bounces as you'd like.
> There has to be a falloff in the IL though. I set mine to 10, but you have to adjust it according to your scene size
> World lighting has to be very low, as though someone switched the light off

Sun:
> You can add a sun lamp on a very low setting or pastel blue just to show some of the objects in the scene

Some things to take into account:
- The ambient light influence does not allow for color. Which means you can't let it glow red if the object is blue, unless you use compositing and object or material indexing (haven't done something like that yet).
- The ambient light influence only enables you to block out ambient light, not bring more into the scene.
- It can be tied only to a single material, like in the example. It's not like a textured lamp

I hope you liked this one! Share it and have fun with it!

Thank YOU!!!!!!!!