• Announcements

    • khawk

      Download the Game Design and Indie Game Marketing Freebook   07/19/17

      GameDev.net and CRC Press have teamed up to bring a free ebook of content curated from top titles published by CRC Press. The freebook, Practices of Game Design & Indie Game Marketing, includes chapters from The Art of Game Design: A Book of Lenses, A Practical Guide to Indie Game Marketing, and An Architectural Approach to Level Design. The GameDev.net FreeBook is relevant to game designers, developers, and those interested in learning more about the challenges in game development. We know game development can be a tough discipline and business, so we picked several chapters from CRC Press titles that we thought would be of interest to you, the GameDev.net audience, in your journey to design, develop, and market your next game. The free ebook is available through CRC Press by clicking here. The Curated Books The Art of Game Design: A Book of Lenses, Second Edition, by Jesse Schell Presents 100+ sets of questions, or different lenses, for viewing a game’s design, encompassing diverse fields such as psychology, architecture, music, film, software engineering, theme park design, mathematics, anthropology, and more. Written by one of the world's top game designers, this book describes the deepest and most fundamental principles of game design, demonstrating how tactics used in board, card, and athletic games also work in video games. It provides practical instruction on creating world-class games that will be played again and again. View it here. A Practical Guide to Indie Game Marketing, by Joel Dreskin Marketing is an essential but too frequently overlooked or minimized component of the release plan for indie games. A Practical Guide to Indie Game Marketing provides you with the tools needed to build visibility and sell your indie games. With special focus on those developers with small budgets and limited staff and resources, this book is packed with tangible recommendations and techniques that you can put to use immediately. As a seasoned professional of the indie game arena, author Joel Dreskin gives you insight into practical, real-world experiences of marketing numerous successful games and also provides stories of the failures. View it here. An Architectural Approach to Level Design This is one of the first books to integrate architectural and spatial design theory with the field of level design. The book presents architectural techniques and theories for level designers to use in their own work. It connects architecture and level design in different ways that address the practical elements of how designers construct space and the experiential elements of how and why humans interact with this space. Throughout the text, readers learn skills for spatial layout, evoking emotion through gamespaces, and creating better levels through architectural theory. View it here. Learn more and download the ebook by clicking here. Did you know? GameDev.net and CRC Press also recently teamed up to bring GDNet+ Members up to a 20% discount on all CRC Press books. Learn more about this and other benefits here.
Sign in to follow this  
Followers 0
Nairou

Deferred lighting over-saturates the scene

5 posts in this topic

All of the deferred shading tutorials I've read use blending (glBlend) to blend the illumination of each light onto the final image. For a single light, this looks great. However, when multiple lights are in close proximity, they blend together and end up over-saturating the scene. With enough lights, all you end up seeing is the light color. However, in reality, additional lights wouldn't end up obscuring the diffuse color, you would just get a bright unlit copy of the diffuse image.

I've tried changing the blending method (GL_ONE,GL_ONE and GL_ONE,GL_ONE_MINUS_SRC_ALPHA), but the result is the same.

How can I blend the lighting passes without distorting the diffuse coloring of the scene?
0

Share this post


Link to post
Share on other sites
The colors are clamped in the range 0-1. So if you add enough eventually everything will become one. You probably want to look into high dynamic range lighting. (hdr) (unless I'm misunderstanding what you said completely)
0

Share this post


Link to post
Share on other sites
Is that how most other deferred shading games handle it? With HDR? Or do they just somehow balance the amount of light shining on any given point? I know games like Starcraft 2 use deferred shading, and you can see the glow of lights on the scene, but it never looks over-saturated from too many lights in close proximity.

Another idea I had was to apply the light attenuation to a separate render texture, then use that texture as a mask to blend all lights in the scene at once, to avoid over-saturation. But that would involve another pass and wouldn't work very well for multi-colored lights.

Is there any way to clamp the amount of light being blended in without resorting to HDR? Or am I incorrect in assuming that HDR is an expensive operation?
0

Share this post


Link to post
Share on other sites
umm yes, that's how they do it.

"but it never looks over-saturated from too many lights in close proximity"

yep, that's the point of HDR rendering.

you may tinker around with the lighting but HDR is the ultimate solution to your problem.

HDR isn't that expensive... nowadays. (if implemented properly!!!)
0

Share this post


Link to post
Share on other sites
N.B. this happens in forward renderers as well as deferred renderers. This isn't a problem of deferred VS forward renderers -- it's a problem of low-range VS HDR lighting.
e.g.given a forward-rendering pixel shader snippet like:[code]float3 result = (float3)0;
result += diffuse * nDotL0 * lightColor0;
result += diffuse * nDotL1 * lightColor1;
result += diffuse * nDotL2 * lightColor2;
return result;[/code]if diffuse was white, color0 was pink(255,192,192), color1 was grey(128,128,128) and color2 was green(0,255,0), then the end result can be as high as (383,575,320), however when you output it to an 8-bit render target it gets clamped to white (255,255,255).
If your forward renderer used HDR, then after tone-mapping you would instead end up with a greenish-whiteish colour.


[quote name='Nairou' timestamp='1329064671' post='4912282']Another idea I had was to apply the light attenuation to a separate render texture, then use that texture as a mask to blend all lights in the scene at once, to avoid over-saturation. But that would involve another pass and wouldn't work very well for multi-colored lights.[/quote]This sounds a bit like "light pre pass" ([i]or some call it "deferred lighting" instead of "deferred shading"[/i]). If you implemented this method with low-range (non-HDR) buffers, then when you place too many lights in one area, the result will look ok, but the artefact will be that your lights lose colour, because at some point they will clamp at white.
1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0