Moving skspritenode with Game Controller (ThumbStick) Swift

Question

I try to build 2d - top down game, and I have player(skspritenode) and I want to move him when I use the thumbstick. I use this code:

gamepad its GCExtendedGamepad

if gamepad.leftThumbstick.xAxis.value > 0.1 || gamepad.leftThumbstick.xAxis.value < -0.1 || gamepad.leftThumbstick.yAxis.value > 0.1 || gamepad.leftThumbstick.yAxis.value < -0.1
{
    self.player.moveAndRotate(gamepad.leftThumbstick.xAxis.value, yValue: gamepad.leftThumbstick.yAxis.value)
}

moveAndRotate - function

func moveAndRotate(xValue: Float, yValue: Float)
{
    zRotation = CGFloat(-atan2(xValue, yValue))

    physicsBody!.velocity = CGVectorMake(0, 0)
    physicsBody!.applyImpulse(CGVectorMake(CGFloat(xValue) * moveSpeed, CGFloat(yValue) * moveSpeed))
}

But, when player moves by diagonal, his speed faster than normal speed. Can anyone help me?

Answer 1

I am sure that your trig functions is backwards

Here is snippet of code I use in a game to move diagonally.

let angle: CGFloat = atan2f(dest.y - self.position.y, dest.x - self.position.x)

The y value comes before the x value

Quoted from Raywenderlich.com

For this specific problem, instead of using atan(), it is simplier to use the function atan2(), which takes the x and y components as separate parameters, and correctly determines the overall rotation angle.

angle = atan2(opposite, adjacent)

let angle = atan2(playerVelocity.dy, playerVelocity.dx)
playerSprite.zRotation = angle

Notice that the Y-coordinate goes first. A common mistake is to write atan(x, y), but that’s the wrong way around. Remember the first parameter is the opposite side, and in this case the Y coordinate lies opposite the angle you’re trying to measure.

new I was able to recreate your issue, but by changing the code to the below I was able to have diagonal move a the same speed as up and down

if ((!isDPad && dirPad.up.value > 0.2) || (isDPad && dirPad.up.pressed == true)) { self.upValue = 1 //upValue = gamepad.leftThumbstick.up.value }

    if ((!isDPad && dirPad.down.value > 0.2) || (isDPad && dirPad.down.pressed == true)) {
        self.downValue = 1
    }

    if ((!isDPad && dirPad.right.value > 0.2) || (isDPad && dirPad.right.pressed == true)) {
        self.rightValue = 1
    }

    if ((!isDPad && dirPad.left.value > 0.2) || (isDPad && dirPad.left.pressed == true)) {
        self.leftValue = 1
    }

    let speed: Float = 300.0
    let xValue = self.rightValue - self.leftValue
    let yValue = self.upValue - self.downValue

    let length = hypotf(xValue, yValue)

    var moveDirection: CGVector?

    if length > 0.0 {
        let inverseLength = 1 / length
        moveDirection = CGVector(dx: CGFloat(xValue * inverseLength * speed), dy: CGFloat(yValue * inverseLength * speed))
    }
    else {
        moveDirection = CGVector(dx: 0, dy: 0)
    }

    testObject.physicsBody!.velocity = CGVectorMake(0, 0)
    testObject.physicsBody!.applyImpulse(direction)