• 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
Florian22222

[GLSL] Question about normal mapping

8 posts in this topic

I took a look at some tutorials on the internet about how to do normal mapping and they all convert the light direction with into tangent space.

 

In my shader setup every shader has a "#define NUM_LIGHTS" and a respective array of structs for each light.

 

Every tutorial I looked at only calculated the lightDir for one light and passing it on with the "out" modifier to the fragment shader.

How would I go about passing, for example, 4 lightDirs to the fragmentShader, without creating a vec3 lightDir0; vec3 lightDir1; etc for each light?

I looked up arrays with out modifier but it seems those dont work on every card?

 

Hopefully someone can clarify this for me.

 

Have a nice day!

0

Share this post


Link to post
Share on other sites

inputs to fragment shader are varying variables issued from vertex function , and those are rather very limited, not considering GPU you use. The standard bypass of "multilights" in a shader is to establish the vertex object space position as a varying variable input to pixel shader, and subtract this position in pixel shader from light uniform you pick (being in object space). In case of a lightdirection, directional light, you just keep it as an uniform variable of pixel shader in apropriate space, and vary(interpolate) only vertex normal from vertex shader to pixel shader (along with vertex tangent/binormal, depending on wheather you do normal mapping or perpixel lightning only).

 

0

Share this post


Link to post
Share on other sites

Isn't it very unefficient making the BTN-Matrix(tangent space) in the fragment shader?

 

I used a vec3 vLightDirs[NUM_LIGHTS] to pass the light dirs in tangent space. Is this gonna cause problem on certain gpus?

Edited by IceBreaker23
0

Share this post


Link to post
Share on other sites

http://stackoverflow.com/questions/7954927/glsl-passing-a-list-of-values-to-fragment-shader

 

I am just making a theory so bare with me.

This can help, for your case I would assume that you would want to make it a uniform 1-D array. Have it so that lets say in your scene your had four lights. The first element would say  how many lights are in your current scene. You can use flow control *looks up keywords* for/while and use that number to process each light in the array. So it will pull a 4 in the first array then after that pull 3 numbers from the array to use as light vectors. Also you can store more data like light color and stuff for more effects. Only problem with this is that if the lights move/create/destroy/change in any way then you will have to update the array with a new one, which really isn't much of a problem.

0

Share this post


Link to post
Share on other sites

The method you mentioned here is to pass data from cpu to the fragment shader. 

What I want is passing multiple vec3's from vertex to fragment shader.

 

i used

out vec3 vLightDirs[4];

to pass 4 light dirs to fragment shader. I just hope that this works on every gpu

0

Share this post


Link to post
Share on other sites

The method you mentioned here is to pass data from cpu to the fragment shader. 

What I want is passing multiple vec3's from vertex to fragment shader.

 

i used

out vec3 vLightDirs[4];

to pass 4 light dirs to fragment shader. I just hope that this works on every gpu

 

Depends on what OpenGL version you use. If you use 3.0 version I believe most GPUs made after August, 2008 will work. But I hope someone will correct me if I am wrong.

0

Share this post


Link to post
Share on other sites

4 varying vec4 vectors are lowend gpus likely limit.  But in any case, you have those 2 methods available . Which one is more effective depends on amount of lights you are to shade, 4 lights are likely limit of the first method to compute less, since method 2 demands only normal+tangent+postion interpolation and moving texture normal to object space. The second method is also more effective if amount of vertices of model is bigger than its fillrate.

0

Share this post


Link to post
Share on other sites

Thanks Johnny Code for the clarification. I want to shade 4 lights.

 

4 varying vec4 vectors are lowend gpus likely limit.  But in any case, you have those 2 methods available . Which one is more effective depends on amount of lights you are to shade, 4 lights are likely limit of the first method to compute less, since method 2 demands only normal+tangent+postion interpolation and moving texture normal to object space. The second method is also more effective if amount of vertices of model is bigger than its fillrate.

 

Well it's highly unlikely that there is less fillrate than vertices, at least with the game I am making(mid-poly count with cartoony art style).

0

Share this post


Link to post
Share on other sites

you should than  pay a special attention to divisions and square roots amount in pixel function then. Remember, that compared to those, multiplications and additions you can waste as you please. Also, second method has certain precision advances toward first, since, transforming light vector to texture space will alter its length inapropriate (tangent matrix is very unlikely orthonormal, so if you compute radius based point lights, go for the second method)

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