• 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
TheResolute

2D lighting through blend states

5 posts in this topic

Hello there,

I want to create a lighting system for my 2D game using D3D11
Blend states seem like the way to go
The lighting one that I would expect to work would look like this:
SrcBlend = SRC_COLOR (output from pixel shader that shaded the light map, so this would be the light map)
DestBlend = DEST_COLOR (the existing game scene that was rendered and looks completely lit up and normal without this lighting process)
BlendOp = SUBTRACT (subtracts the light map from the existing scene)

Here's my theoretical process:
Render game scene normally
Set the OM's blend state
Draw the lighting map

The theory for the blend and lighting map is that the blend takes the existing rendered scene and subtracts the inverse of the lighting map from it
Lighting would be white on the map, and darkness black
This should result in the RGB values of the already rendered scene (s) going through this equation with the light map (l): s.R - 1 - l.R, s.G - 1 - l.G, s.B - 1 - l.B. A lit pixel would have 0 subtracted from it, leaving it its natural color and a dark pixel would have 1 subtracted from it, leaving it black

My issue is that no matter what I've tried, I cannot configure a blend state that achieves this effect
Is there something I don't understand about the blend state itself or when it is incurred?

Thanks for any help
0

Share this post


Link to post
Share on other sites
Wouldn't you just want to multiply the light map value with the existing color in the render target? To do this, you want to use D3D11_BLEND_DEST for SrcBlend and D3D11_BLEND_ZERO for DestBlend (with ADD as the blend op). Edited by MJP
0

Share this post


Link to post
Share on other sites
I think the problem is that you are subtracting a light value, but you are subtracting that from what you are assuming to be a fully lit texture. What you are subtracting is only the light portion, without any consideration of the material being lit. So I think with those blend states, you would have to sample the fully lit texture from your render target, then apply the light map to that value in your shader, then output the value to be blended with the fully lit render target. This should produce what you are trying to do.

Of course, I think what Matt said is the easier way to do this - just use a multiplication to zero to get the lighting effect.
0

Share this post


Link to post
Share on other sites
That confirms that I lack a fundamental understanding of exactly how blend states work
Does the ADD operation just add the corresponding RGB values of each pixel in both the blend source and blend destination together?
A comprehensive explanation of what exactly the blend state operations and blend source values do would be excellent, thank you in advance
0

Share this post


Link to post
Share on other sites
It works like this:
[code]
FinalColor = SrcColor * SrcBlend (BlendOp) DstColor * DstBlend
[/code]

So you what you originally specified would give you this:
[code]
FinalColor = SrcColor * SrcColor - DstColor * DstColor
[/code]

The values I gave you will do this:
[code]
FinalColor = SrcColor * DstColor + DstColor * 0
[/code] Edited by MJP
1

Share this post


Link to post
Share on other sites
Microsoft did not document certain aspects of DirectX very well, apparently this was one of them
That is an absolutely brilliant explanation, it made a world of difference
And no one else offered it, not the DX documentation or even a Google search for "D3D11 blend state"

I am good to go now, knowing that tiny piece that the blend state [i]multiplies [/i]those things by their corresponding assignments
I was under the impression that those BlendSrc and BlendDest values [i]were the data themselves [/i]XD

Thank you so much for you help, I really appreciate it
0

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