It may seem odd now to use a handheld gaming device that doesn't have a touch screen. The 3DS, Playstation Vita, the iPhone/iPad, and all droid phones now feature touch displays. Yet when Nintendo first announced the DS with its odd dual-screen-single-touch design the gaming industry had trouble seeing the point. It's been over six years since the launch of the DS and the legitimacy of the touch screen has been proven.
Reach Out And Touch
The touch screen is an analog 2D input and display combination where the visuals on the screen can have a direct, one-to-one relationship with the touch sensitive areas. As long as you have screen to touch you have potential interactivity. Before I go into detail, there are three types of touch controls that I want to focus on; touch pads, touch screens, and multi-touch screens.
Touch pads are touch sensitive areas that have no display. The degree of sensitivity varies. Sometimes styli are used. Other times, just fingers. The Guitar Hero 4 guitar controller features a touch pad. With it players could play by pressing on the sections like buttons or by sliding their fingers up and down. Most laptops feature a touch pad to control the pointer. And the Playstation Vita will innovate by featuring a rear touch pad that is the same size as the screen display on front.
Touch screens are displays that are sensitive to touch. In this case the screens are pressure sensitive so a stylus or a finger will work. However, the resistive screen technology is limited to accurately tracking one touch input at a time. The Nintendo DS, 3DS, and upcoming Wii U all feature touch screen with stylus control. Using the pencil like a stylus draws on one's fine motor skills from writing or drawing. With pixel fidelity stylus control uses the muscles of multiple fingers, your wrist, and your arm. Such controls would be quite a dexterity barrier if we weren't already trained. There is, without a doubt, no input device that gives players a higher level of 2D analog control and precision. One downside to stylus control is how the player's hand and stylus can obscure the view of the screen.
Popularized by the success of the iPhone, capacitive touch screens are commonly referred to as multi-touch screens. Capacitive touch screens react to anything that conducts electricity. So a plastic stylus doesn't work on these screens. Instead, special capacitive styli can be used though they are not widespread. With the norm being finger tip interactions a few issues emerge. A finger tends to obscure much more of the screen than a stylus. The finger has less fine control than a stylus. And it's more difficult to tell where exactly a finger touches the screen because of how large and soft it is. Though the multi-touch technology allows for more complex actions like pinch zoom, more fingers on the screen obscures even more of the view.
Regardless of the type of touch screen, the biggest limitation developers face is dealing with the lack of tactile feedback. Though one can feel when a stylus or a finger makes contact with the touch screen, when interacting with virtual elements there is no tactile differentiation if you miss. It all feels the same. Fortunately, good audio and visual feedback can help make up for the lacking tactile feedback. When interacting with or manipulating a touch screen element the player tends to focus on the visual object. After this point if the object moves or the context changes the player can react accordingly. It's when players are encouraged or required to look at a location other than where they are touching that the chances of missing the target increase. With traditional gaming controllers players quickly learn to feel their away around the controller so they can focus on the game screen. The more complex the game and inputs (like multi-touch) the more players will have to focus on inputting. Yet, if the virtual buttons are in the same place relative to the screen, muscle memory can help.
Regardless of input device limitations we can always design smarter. Design (the software part) is the most flexible part of game design. A few years ago I wrote a post on the great design features for the DS that utilize the touch screen. I suggest taking a look here. The following are a few examples I want to highlight.
Triggers Down
The trigger is basically an analog button. Or perhaps it's like a button and a lever in one. Still one dimensional, a trigger has a much wider range than just on and off. To clarify, a trigger must have a springy push back (the button like quality) and a wide range of sensitivity. While most console controllers have triggers the Wii Nunchuck and Wii U controller do not. More examples include the Wii Balance Board, which is made up of 4 triggers like a D-pad for your feet. The Guitar Hero/Rock Band drum pedals are also triggers. Similar examples that can't quite be categorized as triggers are the DJ Hero controller turn table, the Arcanoid paddel, some racing wheels, and the mouse wheel.
The hardest part about designing mechanics that utilize the analog trigger is coming up with fitting ideas. As I've explained, buttons are great for turning things on and off (binary 1D). And because countless mechanical and electronic devices are activated by buttons, in video games buttons cover a wide array of creative possibilities. Analog sticks are great for controlling actions like motion especially in 2D. Simply point in the direction you want to move and the game actions generally follow suit. But how many things in real life operate by a pedal (analog 1D)? The easy answer and possibly the only answer are motor vehicles. The bottom line is that a trigger is a specialized input device best used for controlling variable continuous actions that deactivate once you release the pressure. There aren't many functions and devices that need this.
After racking my brain and reading through a few NeoGaf threads, I couldn't come up with many mechanics that work best (or even work well) with an analog trigger outside of racing/acceleration mechanics. Here are the examples I found.
I believe most developers simply design trigger mechanics as if triggers are buttons. With such mechanics, developers have to be mindful of the "deadzone" design like analog stick mechanics. For me, the actions mapped to the triggers in Street Fighter 4 for the PS3 are too sensitive. And for Brawl, because light shielding was removed, players have to press all the way to the button at the bottom of the triggers to activate a shield or air dodge. This means when I hit the trigger like a button, my timing gets off. Adjusting to mismatches like these between software and hardware design takes a bit of time. After all, the mismatch exist because of a clash between long established learned and intuited behavior.
In part 4 we'll cover pointing devices from mice to Wiimotes. We'll also tackle microphones as inpute devices.