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Scroll Back: The Theory and Practice of Cameras in Side-Scrollers

This post discusses the background and evolution of camera use in 2D games. It provides numerous examples from the classic coin-ops to contemporary indie games, and offers techniques, terminology and practical solutions applicable in your own game.

This is a modified version of a talk I gave at the Independent Games Summit, GDC 2015. It contains some background information on 2D scrolling, along with plenty of classic gaming nostalgia. I hope you find it useful and enjoyable!

 

The original post can be found here.

 

Scroll Back

The Theory and Practice of Cameras in Side-Scrollers
By Itay Keren, owner of studio Untamecreator of upcoming game Mushroom 11

 

Table of Contents

 

Overview

Scrolling

Neural Background

Attention, Interaction and Comfort

Scrolling Nostalgia

Follow The Action

Curb Camera Motion

Snapping

Smoothing

Framing

Direction

Multi-focal Camera

Manual Control

Camera Shake

Custom-Made Camera

Mushroom 11

Glossary

Overview

  

 

Working on my game Mushroom 11, I was faced with many different design and technology challenges. I wasn’t expecting to find references to issues like dynamically changing shapes or vertex animation, but I was quite surprised that camera work, a subject with more than 30 years of history in games, was hardly discussed.

 

I decided to start a journey through the history of 2D gaming, documenting their challenges, approaches and how the evolution of their solutions. Also, since there’s a lack of proper terminology for the many different solutions, I started gathering and categorizing them into groups, providing my own glossary, if only for my personal reference.

Scrolling

Scrolling or Panning refers to any attempt to display a scene that is larger than what fits in a single screen. There are many potential challenges with scrolling, like choosing what the player needs to see, what we as designers would like the player to focus on, and how to do it in a way that’s fluid and comfortable for the player.

While I’m going to focus on 2D camera systems, many of these general concepts apply to 3D as well.

Neural Background

Before we examine these games, let’s touch on the neural background of scrolling so we can understand our vision and perception better. By doing this we can understand how scrolling can go wrong.

 

 

The fovea-centralis is the receptor inside our eyeball responsible for sharp and detailed central vision. The second and third receptor belts, the parafovea and perifovea, excel in reducing images and motions to patterns allowing changes to be quickly recognized, including recognizing familiar alarming shapes and changes in motion speed or direction.

 

This visual input uses the fast track straight to the Amygdala, allowing an alert response while the Visual Cortex is deciphering the input. Training your brain, especially by tying the shift in peripheral vision to the controls, proves useful over time.

 

The Vestibular system located in our inner ear, is responsible for maintaining balance and providing spatial orientation. The signals it sends allow the body to maintain its balance, while keeping visual focus on specific details.

 

When some people, like me, try to read in a car, the acceleration combined with the lack of visual corresponding feedback, can lead to nausea and vertigo.

The opposite is also true: as the Perifovea quickly picks up a change in the background, it expects a corresponding feedback from the Vestibular system. When there is none (as you’re sitting firmly in front of your computer), the result can be the same.

 

So, conflicting sensory signals (Visual vs. Vestibular) may lead to discomfort and nausea, and though it’s worse in 3D (especially VR), it is still very much in effect in 2D games.

Attention, Interaction and Comfort

To help understanding the problems in scrolling, I’ve categorized its elements into three major challenges:

 

image

Attention: Use the camera to provide sufficient game info and feedback (what the player needs to see)

 

Interaction: Provide clear player control on what’s displayed, make background changes predictable and tightly bound to controls (what the player wants to see)

 

Comfort: Ease and contextualize background changes (how to reconcile those needs smoothly and comfortably)

Scrolling Nostalgia

 

So let’s start our journey back to the 1980s, when designers were inventing completely new design schemes while overcoming technical limitations that are hard to imagine 30 years later.

 

You’ll also notice references to several leading indie games, mostly from the last 10 years or so, which tend to always to display the innovation, attention and care that can be expected from independent artists, and camera work is certainly no different.

Follow The Action
Keep attention on your control subject

Starting with the basics. Generally speaking, your player has authority over the main character. This dictates that the attention should be directed at that character by closely following it with the camera.

 

In the early 80s, scrolling was a difficult task, and the developer had to face limitations such as CPU, memory capacity and segmentation. Even with those challenges, some great side-scrollers were released, gracefully overcoming these limitations. However, in many cases the motion was understandably simplistic or low-resolution.

 

It’s remarkable that back in 1980, a game like Rally-X was able to overcome technology limitations and present a true dual axis camera. It uses the default position-locking mechanism, keeping the car in focus at all times and the camera motion completely predictable.

 

Rally-X © 1980 Namco

position-locking - camera is locked to the player’s position

 

 

 

 

 

 

 

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