• 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

Advanced collision detection technique resources

4 posts in this topic

Hello all,


I am looking for some resources or information for developing a complex collision detection\response system.  I have a swept-ellipsoid system up and running for player-world collisions but where I am running into issues is combining object-object and object world collisions.  

The real issue I am trying to resolve in the design phase is when looking at objects that could potentially stop or alter another object's motion (say some crates that can be moved, but act as "walls" when the player runs up against them.)

I imagine that I would have to do something similar to the following:

  1. Find the displacement of the object
  2. Find the earliest time that the object collides with the world (a)
  3. Find the earliest time that the object collides with ANY other object (culled in the broad phase, of course)
  4. Move the object along the displacement by the less of (a) or (b) and perform response
  5. Iterate until the displacement is entirely used

Is this correct? This seems like it will be very expensive as I will have to check each possible colliding object every iteration of the check.

Another issue: What about objects that push other objects:

Example, say a crate falls and pushes a player. I would need to move the crate until it hits the player, then do an entire collision detection run for the player as it is pushed before finishing the crate's movement. That also seems like it could get prohibitively expensive as a push may cause another push, and so on.

Most of the information I have found is to determine whether 2 object collide, which I already have a firm grasp of.  I need to expand that into a collision system with multiple objects. Any guidance is much appreciated.


Share this post

Link to post
Share on other sites

All systems I know deals collision and response object-to-object. And there are no earliest time, everything goes at curient time and collision response depends on object shape overlapping, movement directins, mass and etc...


I think if there was more complex system than it was to expensive for cpu...


Share this post

Link to post
Share on other sites

Sorry Serumas, but this is not correct. E.g Box2D has what is called a TOI solver to handle collisions in the order in which they occur. Ipion (the physics engine used in Half-Life 2 and which later was merged into Havok) had one as well. Havok also solves TOI events. I am also aware of other in-house physics engines which solve TOI events.


If you want to have a look at an example TOI solver I recommend looking at Box2D source code. Check b2World::SolveTOI()

Erin also gave a great presentation this year at the GDC how to calculate the TOI between two objects. It is an improvement of the Conservative Advancement method suggested by Mirtich.


You can find the downloads here: https://code.google.com/p/box2d/downloads/list

Edited by Dirk Gregorius

Share this post

Link to post
Share on other sites

Example, say a crate falls and pushes a player. I would need to move the crate until it hits the player, then do an entire collision detection run for the player as it is pushed before finishing the crate's movement
Major problem here.

There are three object types in real-world simulated physics for games. Static, dynamic and kinematic, player avatars often being in the third class.

Kinematics are not intended to be subject from "standard" physics and I strongly suggest you to not allow that. Don't move kinematics just because you feel like it. At the very least, you need some kind of notification system.


To solve this in an useful way, I'd ditch the academical references and just go browsing Bullet source code.


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