Projectile not starting at correct point? - ios

Question

I'm making a simple iOS game where the goal is to have an angel in the middle of the screen shoot arrows at monsters coming at him from all sides. When the user taps the screen, I want an arrow to travel from the angel in the direction of the tap. But when I tap the screen, it travels from the corner of the screen, not the middle. Here's my code:
#import "MyScene.h"
static inline CGPoint rwAdd(CGPoint a, CGPoint b)
{
return CGPointMake(a.x + b.x, a.y + b.y);
}
static inline CGPoint rwSub(CGPoint a, CGPoint b)
{
return CGPointMake(a.x - b.x, a.y - b.y);
}
static inline CGPoint rwMult(CGPoint a, float b)
{
return CGPointMake(a.x * b, a.y * b);
}
static inline float rwLength(CGPoint a)
{
return sqrtf(a.x * a.x + a.y * a.y);
}
static inline CGPoint rwNormalize(CGPoint a)
{
float length = rwLength(a);
return CGPointMake(a.x / length, a.y / length);
}
#implementation MyScene
- (id) initWithSize: (CGSize) size
{
if (self = [super initWithSize:size])
{
self.backgroundColor = [SKColor colorWithRed: 1.0 green: 1.0 blue: 1.0 alpha: 1.0];
SKSpriteNode *angel = [SKSpriteNode spriteNodeWithImageNamed: #"Angel"];
angel.position = CGPointMake(CGRectGetMidX(self.frame), CGRectGetMidY(self.frame));
angel.xScale = 0.25;
angel.yScale = 0.25;
[self addChild: angel];
}
return self;
}
- (void) touchesBegan: (NSSet *) touches withEvent: (UIEvent *) event
{
UITouch * touch = [touches anyObject];
CGPoint location = [touch locationInNode: self];
SKSpriteNode *arrow = [SKSpriteNode spriteNodeWithImageNamed: #"Arrow"];
arrow.xScale = 0.25;
arrow.yScale = 0.25;
SKNode *angel = [self childNodeWithName: #"Angel"];
arrow.position = angel.position;
CGPoint offset = rwSub(location, arrow.position);
[self addChild: arrow];
CGPoint direction = rwNormalize(offset);
CGPoint shootAmount = rwMult(direction, 500);
CGPoint realDest = rwAdd(shootAmount, arrow.position);
float velocity = 480.0/1.0;
float realMoveDuration = self.size.width / velocity;
SKAction *actionMove = [SKAction moveTo: realDest duration: realMoveDuration];
SKAction *actionMoveDone = [SKAction removeFromParent];
[arrow runAction: [SKAction sequence: #[actionMove, actionMoveDone]]];
}
#end
Suggestions? Thanks.

Answer 1

Make the following modifications:
#implementation MyScene
{
SKSpriteNode *angel; // <- add this
}
- (void) touchesBegan: (NSSet *) touches withEvent: (UIEvent *) event
{
UITouch * touch = [touches anyObject];
CGPoint location = [touch locationInNode: self];
SKSpriteNode *arrow = [SKSpriteNode spriteNodeWithImageNamed: #"Arrow"];
arrow.xScale = 0.25;
arrow.yScale = 0.25;
//SKNode *angel = [self childNodeWithName: #"Angel"]; // <- delete this
arrow.position = angel.position;
CGPoint offset = rwSub(location, arrow.position);
[self addChild: arrow];
CGPoint direction = rwNormalize(offset);
CGPoint shootAmount = rwMult(direction, 500);
CGPoint realDest = rwAdd(shootAmount, arrow.position);
float velocity = 480.0/1.0;
float realMoveDuration = self.size.width / velocity;
SKAction *actionMove = [SKAction moveTo: realDest duration: realMoveDuration];
SKAction *actionMoveDone = [SKAction removeFromParent];
[arrow runAction: [SKAction sequence: #[actionMove, actionMoveDone]]];
}