• 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

Choosing normal when ordering counter clockwise

1 post in this topic

Hello all,

I'm having trouble choosing the normal vector to order my triangle vertexes.

So I have the 3 points that define a plane, I did the subtraction - got 2 vectors, did cross product got the normal.
My problem now is I don't understand how to choose between the ordering I get and the opposite to make sure I define a surface that is from above, just like a terrain.

Some psedo-code to explain better:
[source lang="java"]private boolean isCounterClock(Vector3f p1, Vector3f p2, Vector3f p3) {
Vector3f a1 = p1.subtract(p2);
Vector3f a2 = p3.subtract(p2);
Vector3f normal = a2.crossLocal(a1).normalizeLocal();
// the normal vector for the downwards face must always have negative y
if (normal.y < = 0f) {
return true;
else {
return false;

What am I doing wrong?

Share this post

Link to post
Share on other sites
I usually order my vectors so they are in sequence (e.g. p2-p1, and p3-p2), but what you have looks like it will work too. What's the problem exactly?

Note that you are describing the specific case when the triangle is being viewed from the +ve y axis. In the general case you would [b]dot[/b] the normal with the vector that points toward the viewer (which in this case is (0, 1, 0)), and test if the dot product is +ve or not.

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