Question

I am making a game. I would like to have a joystick that moves the character around the screen. Kinda like a video game controller. Any help would be greatly appreciated! Thanks!

Here is what I am currently using, guys. From looking at it, I don’t think that it generates an input:

-(id) init
{


if( (self=[super initWithColor:ccc4(255,255,255,255)] )) {
    self.isTouchEnabled = YES;

    SneakyJoystickSkinnedBase *leftJoy = [[[SneakyJoystickSkinnedBase alloc] init] autorelease];
    leftJoy.position = ccp(72,72);
    leftJoy.backgroundSprite = [CCSprite spriteWithFile:@"dpad.png"];
    leftJoy.thumbSprite = [CCSprite spriteWithFile:@"joystick.png"];
    leftJoy.joystick = [[SneakyJoystick alloc] initWithRect:CGRectMake(0,0,128,128)];
    leftJoyStick = [leftJoy.joystick retain];
    [self addChild:leftJoy];

    [[CCDirector sharedDirector] setAnimationInterval:1.0f/60.0f];

}
return self;

}

Answer 1

You can get direction and speed from the vector produced by the joystick. Usually, joystick input generates normalized 2d position whose x and y values are between -1 and 1. For example, Up is (0, 1.0), Right is (0, 1.0), Left is (-1.0, 0) and Down is (0, -1.0). Once you have this input vector, you can get the two values.

direction = normalize( input_vector );
speed = length( input_vector ) * SCALE_CONSTANT; 
// SCALE_CONSTANT is a custom value to get a  real speed. 

1. Set your character’s look-at vector (it is a normalized vector representing character’s current direction) to direction. If you want to rotate the character smoothly, do interpolation from the current look-at vector to direction in your update.

2. Update your character’s position with the speed

   new_position = current_position + look-at * speed * time;

You can see there are two movements, rotating and forwarding. People usually set two different speed constants to control them. You can also do one at a time like rotating first and then forwarding. Good Luck! 🙂

[UPDATE]

Well, if you don’t want to rotate it, you can just do step 2 with “direction” instead of “look-at”. Also, you can produce “input vector” by subtracting the center position of the joystick from the actual movement (I assume this is a position from the joystick) and then, normalize it.