• 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

Real-time day-night cycles in Assassins Creed

2 posts in this topic

Hi Guys,

     I'm an animator, and I'm trying to wrap my head around real-time day-night cycles, and how they are executed in games such as Assassin's Creed.  Obviously the day-night cycle changes aren't rendered, animated frames (which is how I do things).  So how is it done?  Some sort of scripting?




Share this post

Link to post
Share on other sites

The more complex ones are definitely scripted. There are many ways to approach this.


Usually, the simplest thing to do is have two skyspheres, one with a night sky texture and the other with a day sky texture. To switch between day and night, you adjust the transparency of the spheres to fade from one to the other. The spheres need to rotate slowly, depending on what time it is, so the sky appears to move. I can imagine this still being achieved using only one animated object, but most of the time the rotation and fading is scripted rather than animated.


This can be combined with a light source positioned at the sun, which also needs to have its colours and brightness adjusted according to what time it is. For example, the sun would be mostly white with a tint of yellow during most of the day, and be bright orange/red during sunset and sun rise. The moon probably also uses a light source, which would be a deep blue colour during most of the night, and transition into white during "moonset" and "moonrise".


Some games combine fog to help with the transition.

Edited by TheComet

Share this post

Link to post
Share on other sites

There are a ton of ways render sky and transitions. But basically boil down to different procedural generation techniques vs blending baked skies.


Though blending two skydomes works, like TheComet said; most implementations procedural generate the sky (Google "atmospheric scattering").


Since you come from an art background, I'm just going to say it's a lot of math stuff behind it, having a cool blue sky with a sun in it.

Perhaps of interest to you is that the game will usually have a set of key settings for each time of day (i.e. sun power, sun colour, and optionally different mie & rayleigh scattering parameters although that is cheating/artistic-license since technically those two params should remain unchanged regardless of time of day) and blend (interpolate) the parameters based on the current in-game time.


Atmospheric scattering doesn't cover clouds, so clouds are rendered separately: could be as a extra layer(s) of noise textures, using baked skyboxes, using oriented sprites, or using volumetric techniques.

Often clouds are rendered with a special shader to do some math to be coloured by the sun while still looking real.


In simple words, it's really technical stuff; but there is no one unique way. I was just reading yesterday slides from CryTek (starting page 108) where they were telling they tried 3 different cloud rendering techniques until they were happy (and they didn't end entirely happy).




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