• 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
JoryRFerrell

Determining which order to add vert neighbors in prep for Newells Method/Normal Calculation.

0 posts in this topic

I am attempting to find the neighbors for each vert in an object. By finding all the neighbors, adding them to a index in a consistent clockwise/counter-clockwise order, I can then calculate the normals via Newell's Method. But, I have a problem. When I run this with a cube as a test object, I get Half the normals moving in the correct direction (normals facing out of object), and the other half facing inwards. The problem is the order in which the verts are added. I can't figure out how to consistently find which verts to  add to the list of neighbors according to the neighbors position.

 

    for face in faces:

        if vert_ID+1 in face:

            if total_Neighbors == 3:

                if face.index(vert_ID+1) == 0:

                    # print "Located: 0"
                    if vertices[face[1]-1] not in neighbors:
                        neighbors[1] = vertices[face[1]-1]
                    if vertices[face[3]-1] not in neighbors:
                        neighbors[2] = vertices[face[3]-1]

                elif face.index(vert_ID+1) == 1:

                    # print "Located: 1"
                    if vertices[face[0]-1] not in neighbors:
                        neighbors[0] = vertices[face[0]-1]
                    if vertices[face[2]-1] not in neighbors:
                        neighbors[1] = vertices[face[2]-1]

                elif face.index(vert_ID+1) == 2:

                    # print "Located: 2"
                    if vertices[face[1]-1] not in neighbors:
                        neighbors[0] = vertices[face[1]-1]
                    if vertices[face[3]-1] not in neighbors:
                        neighbors[2] = vertices[face[3]-1]

                elif face.index(vert_ID+1) == 3:
                    # print "Located: 3"
                    if vertices[face[0]-1] not in neighbors:
                        neighbors[0] = vertices[face[0]-1]
                    if vertices[face[2]-1] not in neighbors:
                        neighbors[1] = vertices[face[2]-1]

For every vert in an object, I iterate through all the faces, checking to see if the vert is contained in the face. If so, I grab the address/index value of the verts position in the face. For every possible position the vert can be in (in a cube, there are obviously 4 possible places it can be...), I add the two verts, which would logically be connected to it, after checking to make sure each is not going to be written over a value already in the list of neighbors (If a value besides zero already occupies the spot, my algor. doesn't overwrite it. I ran into some issues when I did.).

 

I create the neighbors list and initialize it with values (so I can assign rather than append, which created problems with my partic. algorithm).

If the vert is in position 1 (or index value "0") I assign the two neighbors to specific spots in the neighbors list. The order and spot they occupy is important since newells method is non-commutative (the two possible results being complete opposite vectors), meaning I need to ensure all neighbors are added as either clockwise, or counter-clockwise.

 

The following is a line for each vertice, followed by the list of neighbors.

 Neighbors:
(-1.0, -1.0, 1.0)   [(-1.0, -1.0, -1.0), (1.0, -1.0, 1.0), (-1.0, 1.0, 1.0)]

(-1.0, -1.0, -1.0)   [(-1.0, -1.0, 1.0), (1.0, -1.0, -1.0), (-1.0, 1.0, -1.0)]

(1.0, -1.0, -1.0)   [(1.0, 1.0, -1.0), (1.0, -1.0, 1.0), (-1.0, -1.0, -1.0)]

(1.0, -1.0, 1.0)   [(-1.0, -1.0, 1.0), (1.0, 1.0, 1.0), (1.0, -1.0, -1.0)]

(-1.0, 1.0, 1.0)   [(-1.0, -1.0, 1.0), (1.0, 1.0, 1.0), (-1.0, 1.0, -1.0)]

(-1.0, 1.0, -1.0)   [(-1.0, -1.0, -1.0), (1.0, 1.0, -1.0), (-1.0, 1.0, 1.0)]

(1.0, 1.0, -1.0)   [(-1.0, 1.0, -1.0), (1.0, 1.0, 1.0), (1.0, -1.0, -1.0)]

(1.0, 1.0, 1.0)   [(1.0, 1.0, -1.0), (1.0, -1.0, 1.0), (-1.0, 1.0, 1.0)]


 



 

Then the output:

    Normals: 
(-2.0, -2.0,  2.0)
( 2.0,  2.0,  2.0)#<- reversed. Should be (-2.0, -2.0, -2.0)
( 2.0, -2.0, -2.0)
(-2.0,  2.0, -2.0)#<- reversed. Should be (2.0, -2.0, 2.0)
(-2.0,  2.0,  2.0)
( 2.0, -2.0,  2.0)#<- reversed. Should be (-2.0, 2.0, -2.0)
( 2.0,  2.0, -2.0)
(-2.0, -2.0, -2.0)#<- reversed. Should be (2.0, 2.0, 2.0)

And yes...I have not normalized these, so they are a length of 2. I already have a func for normalizing the values, I just didn't use it. tongue.png

Anyway's, has anyone seen examples of this problem or see any solutions for dealing with it? I have the bulk of this written, but it's useless if every other normal is pointing INTO the object.... tongue.png

 

I don't need the algorithm in any particular language or anything, you can even help with pseudocode. I'm not picky.

Thanks in advance. smile.png

Edited by JoryRFerrell
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