How can I implement a revealing light beam?

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In SEARCHLIGHT, you control a ray of light that illuminates incoming enemies that are otherwise invisible in the night sky. Here is an illustration:

How would I go about doing this, preferably in Unity? I imagine this is less about lighting and more about shaders, but I'm not sure on details. The fact that I know very little about coding shaders makes it worse.

If it is about shaders, what are the specifics? Is there a stretched quad that moves with said shader applied to it, or perhaps is using the Line Renderer a better option?

As a beginner, may I try to achieve a similar effect, or should I leave it for when I'm better?

(P.S.: The game was made in Unity. Here is its itch.io page.)

edited 6 hours ago

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up vote
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In SEARCHLIGHT, you control a ray of light that illuminates incoming enemies that are otherwise invisible in the night sky. Here is an illustration:

If it is about shaders, what are the specifics? Is there a stretched quad that moves with said shader applied to it, or perhaps is using the Line Renderer a better option?

As a beginner, may I try to achieve a similar effect, or should I leave it for when I'm better?

(P.S.: The game was made in Unity. Here is its itch.io page.)

edited 6 hours ago

DMGregoryâ™¦

53k1198150

asked 10 hours ago

Demetre Saghliani

212

New contributor

add a commentÂ |Â

up vote
4
down vote

favorite

In SEARCHLIGHT, you control a ray of light that illuminates incoming enemies that are otherwise invisible in the night sky. Here is an illustration:

If it is about shaders, what are the specifics? Is there a stretched quad that moves with said shader applied to it, or perhaps is using the Line Renderer a better option?

As a beginner, may I try to achieve a similar effect, or should I leave it for when I'm better?

(P.S.: The game was made in Unity. Here is its itch.io page.)

edited 6 hours ago

DMGregoryâ™¦

53k1198150

asked 10 hours ago

Demetre Saghliani

212

New contributor

In SEARCHLIGHT, you control a ray of light that illuminates incoming enemies that are otherwise invisible in the night sky. Here is an illustration:

If it is about shaders, what are the specifics? Is there a stretched quad that moves with said shader applied to it, or perhaps is using the Line Renderer a better option?

As a beginner, may I try to achieve a similar effect, or should I leave it for when I'm better?

(P.S.: The game was made in Unity. Here is its itch.io page.)

unity 2d shaders lighting

edited 6 hours ago

DMGregoryâ™¦

53k1198150

asked 10 hours ago

Demetre Saghliani

212

New contributor

edited 6 hours ago

DMGregoryâ™¦

53k1198150

asked 10 hours ago

Demetre Saghliani

212

New contributor

edited 6 hours ago

DMGregoryâ™¦

53k1198150

edited 6 hours ago

DMGregoryâ™¦

53k1198150

edited 6 hours ago

DMGregoryâ™¦

53k1198150

asked 10 hours ago

Demetre Saghliani

212

New contributor

asked 10 hours ago

Demetre Saghliani

212

asked 10 hours ago

Demetre Saghliani

212

New contributor

Demetre Saghliani is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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One way to implement an effect like this is with the stencil buffer.

This is an extra few bits the renderer keeps around for every pixel in a render target, that you can use for scratch notes about what you've drawn there or are allowed to draw later.

You can create a new shader using one of Unity's built-in templates, and add some stencil operations to the top of the SubShader or Pass section:

Stencil 
 Ref 1
 Comp always
 Pass replace

This says "write a 1 into the stencil buffer, no matter what was there before" - put this on the shader/material that you use to render your light beam quad, and it will mark all the on-screen pixels it's touched.

Then, for objects that should only show up inside the light beam, use:

Stencil 
 Ref 1
 Comp equal

This checks to see if the magic number 1 got written into this pixel previously (ie. is this pixel illuminated by the light beam?) - if not, the shader aborts rendering this pixel of the object, neatly clipping it to just the illuminated region of your screen.

Make sure your objects that read the stencil information render later in the queues than the objects that write it, so the information is ready for them when they look for it.

answered 6 hours ago

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up vote
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One way to implement an effect like this is with the stencil buffer.

This is an extra few bits the renderer keeps around for every pixel in a render target, that you can use for scratch notes about what you've drawn there or are allowed to draw later.

You can create a new shader using one of Unity's built-in templates, and add some stencil operations to the top of the SubShader or Pass section:

Stencil 
 Ref 1
 Comp always
 Pass replace

Then, for objects that should only show up inside the light beam, use:

Stencil 
 Ref 1
 Comp equal

Make sure your objects that read the stencil information render later in the queues than the objects that write it, so the information is ready for them when they look for it.

answered 6 hours ago

DMGregoryâ™¦

53k1198150

add a commentÂ |Â

up vote
5
down vote

One way to implement an effect like this is with the stencil buffer.

This is an extra few bits the renderer keeps around for every pixel in a render target, that you can use for scratch notes about what you've drawn there or are allowed to draw later.

You can create a new shader using one of Unity's built-in templates, and add some stencil operations to the top of the SubShader or Pass section:

Stencil 
 Ref 1
 Comp always
 Pass replace

Then, for objects that should only show up inside the light beam, use:

Stencil 
 Ref 1
 Comp equal

Make sure your objects that read the stencil information render later in the queues than the objects that write it, so the information is ready for them when they look for it.

answered 6 hours ago

DMGregoryâ™¦

53k1198150

add a commentÂ |Â

up vote
5
down vote

One way to implement an effect like this is with the stencil buffer.

This is an extra few bits the renderer keeps around for every pixel in a render target, that you can use for scratch notes about what you've drawn there or are allowed to draw later.

You can create a new shader using one of Unity's built-in templates, and add some stencil operations to the top of the SubShader or Pass section:

Stencil 
 Ref 1
 Comp always
 Pass replace

Then, for objects that should only show up inside the light beam, use:

Stencil 
 Ref 1
 Comp equal

Make sure your objects that read the stencil information render later in the queues than the objects that write it, so the information is ready for them when they look for it.

answered 6 hours ago

DMGregoryâ™¦

53k1198150

One way to implement an effect like this is with the stencil buffer.

This is an extra few bits the renderer keeps around for every pixel in a render target, that you can use for scratch notes about what you've drawn there or are allowed to draw later.

You can create a new shader using one of Unity's built-in templates, and add some stencil operations to the top of the SubShader or Pass section:

Stencil 
 Ref 1
 Comp always
 Pass replace

Then, for objects that should only show up inside the light beam, use:

Stencil 
 Ref 1
 Comp equal

Make sure your objects that read the stencil information render later in the queues than the objects that write it, so the information is ready for them when they look for it.

answered 6 hours ago

DMGregoryâ™¦

53k1198150

answered 6 hours ago

DMGregoryâ™¦

53k1198150

answered 6 hours ago

DMGregoryâ™¦

53k1198150

answered 6 hours ago

DMGregoryâ™¦

53k1198150

add a commentÂ |Â

Demetre Saghliani is a new contributor. Be nice, and check out our Code of Conduct.

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