Is it possible to create a torus-/ring-shaped light? If so, how?

Question

As the title says. I've been searching Google, but I can't get my head around it. Thanks in advance!

Answer 1

Best Answer

Answer by Fattie · Jun 03, 2012 at 04:43 PM

It sounds like what you want is not "A LIGHT FITTING" (like "a chandelier")

What you want is like "SOME LIGHT FALLING ON STUFF"

In other words if I pointed a spotlight on a floor, that would be a "circle of light" on the floor -- what you want is a "donut of light"

Is that correct?

If so, I have your answer. You have to learn about "Projectors"

If you look at blob shadows, that is exactly what a projector is.

In your project, look around for the free standard assets that unity gives you.

Add a projector, blob shadow. In fact, ther eis indeed one that is a "shadow" (it's dark) and there is one that is a "light blob" .... which is exactly what you are asking for, I believe.

the only difference is you want a particular shape (a donut) rather than just a circle.

From here, you will have to do the work to figure out how to make it your own custom shape! I hope, that helps!

FTR earlier answer,

Just use a "self-illuminated shader"

http://unity3d.com/support/documentation/Components/Built-in%20Shader%20Guide.html http://unity3d.com/support/documentation/Components/shader-SelfIllumFamily

4 Show 2 · Share

Thevet · Jun 03, 2012 at 04:51 PM 0

Share

Then looking into projectors it is. Thank you very much.

Wolfram · Jun 03, 2012 at 06:48 PM 2

Share

Nice catch, none of us understood what he was trying to do ^^

Actually, for light sources, there is already a Unity feature dedicated to this, called "Light Cookie". It's an alpha texture that's applied directly to the light source, so there's no need to fiddle around with Projectors: http://unity3d.com/support/documentation/Components/class-Light.html

Answer 2

Answer by Mortoc · Jun 03, 2012 at 01:29 PM

If you don't need the light to move in the scene, make a mesh torus, give it a light emitting material and bake it with the lightmapper. If you do need the light to change in the scene, give it a point light in the middle. An area based light is too complicated to run at runtime (at the very least without some complicated shader-fu)

2 Show 1 · Share

Thevet · Jun 03, 2012 at 04:36 PM 0

Share

My light is supposed to expand around the player, but also travel across any mesh it touches, much like Prototype 2's ping function. Would a similar approach work for this? Sorry for the unclear question.

Answer 3

alt text

Is this what you want? If so, you can add a circle cookie to the point light 2D, that makes a ring light. The cookie is a texture I generated with R script.

 library(png)
 
 N = 128
 Nhalf = N/2
 InnerRadius = 8
 OuterRadius = 32
 
 
 tab <- array(0, c(N, N, 2))
 
 f <- function(i, j) {
   return(clamp((sqrt((i - Nhalf + 0.5)^2 + (j - Nhalf + 0.5)^2) - InnerRadius)/OuterRadius, lower=0, upper=1))
 }
 
 for(x in (1:N)){
   for(y in (1:N)){
     tab[x, y, 1] = f(x, y)
     tab[x, y, 2] = 1 - f(x, y)
   }
 }
 
 png::writePNG(image = tab, target="C:\\Users\\YOUR_USER_HERE\\Desktop\\image.png")

Set N to be the size of your sprite, then InnerRadius to be the radius of the no-light ring in the center, and OuterRadius where unity's point light takes full effect. Both in pixels as well., alt text

Is what you want something like this? If so, it can be achieved in 2D by using a Point Light with a cookie. The cookie will be a grayscale image with alpha, which I generated via an R script.

Here is the following R code. You want N to be the size of your sprite, and InnerRadius and OuterRadius also in pixels. Try a few different values until you find one to your liking.

 library(png)
 
 N = 128
 Nhalf = N/2
 InnerRadius = 8
 OuterRadius = 32
 
 
 tab <- array(0, c(N, N, 2))
 
 f <- function(i, j) {
   return(clamp((sqrt((i - Nhalf + 0.5)^2 + (j - Nhalf + 0.5)^2) - InnerRadius)/OuterRadius, lower=0, upper=1))
 }
 
 for(x in (1:N)){
   for(y in (1:N)){
     tab[x, y, 1] = f(x, y)
     tab[x, y, 2] = 1 - f(x, y)
   }
 }
 
 png::writePNG(image = tab, target="C:\\PATH\\TO\\SOMETHING\\image.png")

Also make sure the png package is installed: install.packages(png)

Not really sure how you'd achieve the same thing in 3d.

Is it possible to create a torus-/ring-shaped light? If so, how?

3 Replies

Your answer

Welcome to Unity Answers

Follow this Question

Related Questions