CODEWITHSUNDEEP
swiftsprite-kit2d-gamesskaction
Vetuka
Vetuka

Reputation: 1651

How to move SpriteNode by its angle?

I am trying to create a small game where SpriteNode (aka Player) moves up vertically on constant speed. I want to use its angle for steering left or right. However, I am not able to move the Player properly using its angle.

Thank you for your time.

Here is the partial code I wrote:

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    if let touch = touches.first {
            let location = touch.previousLocation(in: self)
        if location.x < self.size.width / 2 && location.y < self.size.height / 2 {
            // Turn Left
            print("TURNING LEFT")
            turn(left: true)
         } else if location.x >= self.size.width / 2 && location.y < self.size.height / 2 {
            // Turn Right
            print("TURNING RIGHT")
            turn(left: false)
         } else if location.y > self.size.height / 2 {
            // Go Up
            print("GOING UP!")
            move()
         }
    }
}

func turn(left: Bool) {
    if left {
        // Turn Left
        let turnAction = SKAction.rotate(byAngle: 0.1, duration: 0.05)
        let repeatAction = SKAction.repeatForever(turnAction)
        player?.run(repeatAction)
    } else {
        // Turn Right
        let turnAction = SKAction.rotate(byAngle: -0.1, duration: 0.05)
        let repeatAction = SKAction.repeatForever(turnAction)
        player?.run(repeatAction)
    }
}

func move() {
    // Move Up
    let moveAction = SKAction.moveBy(x: 0, y: 15, duration: 0.5)
    let repeatAction = SKAction.repeatForever(moveAction)
    player?.run(repeatAction)
}

Upvotes: 2

Views: 210

Answers (2)

Vetuka
Vetuka

Reputation: 1651

Thanks to @makertech81 link, I was able to write below code which works:

func move() {
    // Move Up
    let playerXPos = sin((player?.zRotation)!) * -playerSpeed
    let moveAction = SKAction.moveBy(x: playerXPos, y: playerSpeed, duration: 0.5)
    let repeatAction = SKAction.repeatForever(moveAction)
    player?.run(repeatAction)
}

Basically, because I know the angle through zRotation and also I know how much Player will move toward Y, I was able to calculate its sin (which is X value). Therefore, moveAction will be properly calculated toward its destination.

Hope it helps.

Upvotes: 0

makertech81
makertech81

Reputation: 928

Using Trigonometry you can determine the sprite's x and y speed in either direction create an angle for the sprite to point towards. A great article that sums up how to do this can be found here.

If you simply wish to literally rotate the sprite it can be done by creating an SKAction for the rotation and running the action on the node.

// Create an action, duration can be changed from 0 so the user can see a smooth transition otherwise change will be instant.
SKAction *rotation = [SKAction rotateByAngle: M_PI/4.0 duration:0]; 
//Simply run the action.
[myNode runAction: rotation];

Upvotes: 1

Related Questions