Move CCSprite based on users touch - Cocos2d - ios

Question

I have an object that I wish to move 50 pixels in the direction the the touch event occurs. It is a fixed CCSprite called _eyeObject.
I know I need to use
- (void)touchBegan:(UITouch *)touches withEvent:(UIEvent *)event {
CGPoint touchLocation = [touches locationInNode:self];
//Not sure what to do now
}
How would I calculate the CCSprite to move 50 pixels towards the users touch? Then move back to the original position when the touch ends?
A starting point would be great....I don't need to know how to animate or anything, just the calculation.

Answer 1

Whenever a touch happens you want to move 50 pixels in that direction you can do (based on your desire to do it based on a statically positioned eye object sprite):
- (void)touchBegan:(UITouch *)touch withEvent:(UIEvent *)event
{
CGPoint touchPos = [touch locationInNode:self];
CGPoint delta = ccpSub(touchPos, self.eyeObject.position);
float moveAmount = 50.0f;
CGPoint moveVec;
if (delta.x > 0.0f)
{
moveVec.x = moveAmount;
}
else
{
moveVec.x = -moveAmount;
}
if (delta.y > 0.0f)
{
moveVec.y = moveAmount;
}
else
{
moveVec.y = -moveAmount;
}
self.spriteStartPosition = self.sprite.position;
self.sprite.position = ccpAdd(self.sprite.position, moveVec);
}
- (void)touchEnded:(UITouch *)touch withEvent:(UIEvent *)event
{
self.sprite.position = self.spriteStartPosition;
}
If the object you are moving IS that eyeObject then it would be:
- (void)touchBegan:(UITouch *)touch withEvent:(UIEvent *)event
{
CGPoint touchPos = [touch locationInNode:self];
CGPoint delta = ccpSub(touchPos, self.eyeObject.position);
float moveAmount = 50.0f;
CGPoint moveVec;
if (delta.x > 0.0f)
{
moveVec.x = moveAmount;
}
else
{
moveVec.x = -moveAmount;
}
if (delta.y > 0.0f)
{
moveVec.y = moveAmount;
}
else
{
moveVec.y = -moveAmount;
}
self.eyeObjStartPosition = self.eyeObject.position;
self.eyeObject.position = ccpAdd(self.eyeObject.position, moveVec);
}
- (void)touchEnded:(UITouch *)touch withEvent:(UIEvent *)event
{
self.eyeObject.position = self.eyeObjStartPosition;
}
To move in general if the static object was representing a joystick or gamepad (would do the same in touch began so I'd separate this into its own method):
- (void)touchMoved:(UITouch *)touch withEvent:(UIEvent *)event
{
CGPoint touchPos = [touch locationInNode:self];
CGPoint delta = ccpSub(touchPos, self.dPad.position);
float moveAmount = 50.0f;
if (delta.x > 0.0f)
{
self.sprite.position.x += moveAmount;
}
else
{
self.sprite.position.x -= moveAmount;
}
if (delta.y > 0.0f)
{
self.sprite.position.y += moveAmount;
}
else
{
self.sprite.position.y -= moveAmount;
}
}

Answer 2

Here's a simple solution - get the unit vector between the two points, multiply it by 50, and add it to the current position. AKA this:
- (void)touchBegan:(UITouch *)touches withEvent:(UIEvent *)event {
CGPoint touchLocation = [touches locationInNode:self];
//Not sure what to do now
CGPoint destinationVector = ccpSub(touchPos, self.eyeObject.position);
CGPoint movementVector = ccpNormalize(destinationVector);
movementVector = ccpMult(movementVector, 50);
[_eyeObject runAction:[CCActionMoveTo actionWithDuration:1.0 position:ccpAdd(_eyeObject, movementVector)]];
}
If you want to have it move back on touchEnded, just save the position in a variable before you move it the first time, and send it back to that spot on touchEnded.