• 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

UV mirror issues with normalmap , using nonprecomputed tangent space calculating

2 posts in this topic

Hi,I'm trying to do normalmap using directx9.After reading [url="http://www.shaderx5.com/TOC.html"]2.6 Normal Mapping without Pre-Computed Tangents by Christian Schueler[/url] ,I deside to use this.
[source lang="cpp"]float3x3 ComputeTangentFrame(float3 N,float3 p,float2 uv)
float3 dp1 = ddx(p);
float3 dp2 = ddy(p);
float2 duv1 = ddx(uv);
float2 duv2 = ddy(uv);

float3x3 M = float3x3(dp1,dp2,cross(dp1,dp2));
float2x3 inversetransposeM =
float3 T = mul(float2(duv1.x,duv2.x),inversetransposeM);
float3 B = mul(float2(duv1.y,duv2.y),inversetransposeM);
return float3x3(normalize(T),normalize(B),N);
It seems good and simple,but soon I get punished at little seams with UV mirrors.The whole model looks right under light,but at those seams,normal gets wrong and light reflect in unproper way,so a sudden change or miss lighting on surface appears.I think this is because when current pixel is shared by different triangles with different directions of UV,the ddx and ddy instruction will get wrong answers.
So,I use
[source lang="cpp"]float r = (dot(cross(T,B),N)<0.0f) ? -1.0f : 1.0f;[/source]
to judge whether UV was mirrored.Then I realized I can't change tangent or binormal or normal,for most part of the mesh already seems right.On the other hand,I cannot know whether it's U mirror or V mirror.It's hard to tell the right direction of two axes(tangent and binormal) when you only know one axes(Normal).The author do not give futher information.
Btw,because I'm using dx9,so I can't split vertexes in shader.
So I want to know is there a possible way to solve this problem?Thanks for any reply :)

Share this post

Link to post
Share on other sites
The problem at mirrored seams is, that the tangentspace changes the handness at the mirrored faces (=> dot(cross(T,B),N)<0.0f is a way to determine this). When using shared vertices you only save one tangent space, so one face will use the wrong one often resulting in [i]inverted [/i]lighting. The solution is quite simple, just duplicate the vertices when you detect a change in the handness of the tanget space much like you would duplicate a vertex when the uv coords change. Edited by Ashaman73

Share this post

Link to post
Share on other sites
Thanks for replying my problem.
Things are not the way I thought.The problem is not about UV seams at all,but the UV directions.The truth is I was using directx sampling texture directions to calculate my Binormal,that is having a V direction from top to down.But I haven't check my resources.They are bulit in Maya,which have a down-to-top V direction.So it's OK with color and fails correct normal mapping.Without my artist,I could never know this.[img]http://public.gamedev.net//public/style_emoticons/default/smile.png[/img]

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