Jump to content
  • Advertisement
Sign in to follow this  
DirectXFreak

Emissive Mapping?

This topic is 4596 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

Hey, I was watching the Unreal 3 video, and I noticed an effect they are doing, which involves parts of the texture being emissively lit. Here's a screeny: Free Image Hosting at www.ImageShack.us So, Is this done with some sort of grayscale emissive map? Thanks

Share this post


Link to post
Share on other sites
Advertisement
In my engine the artists have an option to use an "illumination" map.

Normally you do:
Pixel = Albedo * Light

In it's simplest form you can use the illumination map to remove any light contribution using:
Pixel = Albedo * Light * (1 - Illumination) + Albedo * Illumination

It's sometimes desireble to render certain stuff without and light contribution and with the forumla above you've only got to set the illumination value to 1.

I've took it a step further though, basically doing:
RealIllum = Illumination * 8
Blend = Min(1, RealIllum)
Pixel = Albedo * Light * (1 - Blend) + Albedo * RealIllum

If the value for a pixel in the illumination map is between zero and 1/8, the final pixel color blends from the normal lit pixel to strictly using albedo, once it goes beyond 1/8 it becomes brighter and brighter, at most 8x albedo.
I'm using HDR so this will cause a nice glowing effect if set bright enought.
Ofcourse you can choose a different value than 8.

I dunno how Unreal3 does it.

Share this post


Link to post
Share on other sites
Sign in to follow this  

  • Advertisement
×

Important Information

By using GameDev.net, you agree to our community Guidelines, Terms of Use, and Privacy Policy.

We are the game development community.

Whether you are an indie, hobbyist, AAA developer, or just trying to learn, GameDev.net is the place for you to learn, share, and connect with the games industry. Learn more About Us or sign up!

Sign me up!