Drawing line starting from SKSpriteNode_01.pos - ending at SKSpriteNode_02.pos (and adding particles)

Question

Hi All I am wondering what is the best approach to draw a particlesystem line between two sprites (which updates if the sprite positions moved nudged/gravity etc)

Ive tried this way (ps sorry for my newbie code ><) drawing the line starting from obj01 - ending at obj02 that is working so far but I im not sure how to update the line coordinates if the sprites move for example

the other problem related probably because the pathToDraw is not updated the particle system seems to drift off So I know I need to update it (if someone could write a sudo code/idea of where I would expect to init the path to draw, where to remove etc that would really be very helpful in figuring out)

with thanks N :)

-(void)drawLineFromObj2:(EnemyClass*)obj03 to:(EnemyClass*)obj04
{
    if (UFO02IsDead == NO && UFO03IsDead == NO)
    {
        if (ufo_02ReadyToLink == YES && ufo_03ReadyToLink == YES) {
            NSLog(@"Line from Obj2 to obj03");

           // **CreateLine**

    lineNode02.path = pathToDraw;
    lineNode02 = [SKShapeNode node];
    CGMutablePathRef pathToDraw = CGPathCreateMutable();
    CGPathMoveToPoint(pathToDraw, NULL, obj03.position.x, obj03.position.y);
    CGPathAddLineToPoint(pathToDraw, NULL, obj04.position.x, obj04.position.y);
    lineNode02.path = pathToDraw;

    //Add Particles
    NSString *myParticlePath = [[NSBundle mainBundle] pathForResource:@"ForceField" ofType:@"sks"];
    SKEmitterNode *myParticle = [NSKeyedUnarchiver unarchiveObjectWithFile:myParticlePath];
    [self addChild:myParticle];

//get particles to drop by adding physics? 
(this no effect the particles don't follow the line and don't seem

attached to it, and if the sprites move they dot change position either)

//myParticle.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:self.frame.size];
//myParticle.physicsBody.affectedByGravity = YES;
//myParticle.physicsBody.allowsRotation = NO;

pathToDraw myParticle uses SKAction followPath:pathToDraw

How to update pathToDraw to draw smooth lines and remove last line properly

 SKAction *followTrack =
 [SKAction followPath:pathToDraw asOffset:NO orientToPath:YES duration:.5];
 SKAction *forever = [SKAction repeatActionForever:followTrack];
 myParticle.particleAction = forever;

 lineNode02.name = @"lineNode";
 [self addChild:lineNode02];

//is there a way to link the movement with the crystal positions and   animate the line length and angle (is there another way of doing this)


 //stops line being redrawn (but how to update when sprite is  moved, and how to delete the old lines?)
  ufo_03ReadyToLink = NO;


            }

        }
    }

StackBuddy StackBuddy · Accepted Answer · 2015-08-11T13:32:34

Fixed it by moving the function down into -(void)update

created an action block

SKAction *remove = [SKAction removeFromParent];
    SKAction* blockAction = [SKAction runBlock:^
    {
        [self DrawLine]; //draws new line every update
        //then removes line
    }];
    [self runAction:[SKAction sequence:@[blockAction,remove]]];

also used a texture rather than a particle but this is how I attached it

//Add Particles
NSString *myParticlePath = 
[[NSBundle mainBundle] pathForResource:@"ForceField" ofType:@"sks"];
myParticle = [NSKeyedUnarchiver unarchiveObjectWithFile:myParticlePath];
[self addChild:myParticle];

SKAction *followTrack =
[SKAction followPath:pathToDraw asOffset:NO orientToPath:YES duration:.5];
SKAction *forever = [SKAction repeatActionForever:followTrack];
myParticle.particleAction = forever;

lineNode01.name = @"lineNode";
[self addChild:lineNode01];

Hope it helps someone else :)

Drawing line starting from SKSpriteNode_01.pos - ending at SKSpriteNode_02.pos (and adding particles)

1 Answers