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How do I?: Change particles velocity wihtout change its direction

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    • CommentAuthordfdiaza
    • CommentTimeNov 6th 2012
     
    This is my second day using Flint and I have a doubt.
    I have some particles moving inside a BoundingBox, but I need to have a Slider control, so I can change the particles velocity without change their directions.
    I don't have idea how to achieve it. Can you help me please?

    Regards,
    Diego

    Here is the current code with the particles inside a BoundingBox

    import org.flintparticles.common.counters.*;
    import org.flintparticles.common.displayObjects.RadialDot;
    import org.flintparticles.common.initializers.*;
    import org.flintparticles.twoD.actions.*;
    import org.flintparticles.twoD.emitters.Emitter2D;
    import org.flintparticles.twoD.initializers.*;
    import org.flintparticles.twoD.renderers.*;
    import org.flintparticles.twoD.zones.*;

    var emitter:Emitter2D = new Emitter2D();
    emitter.counter = new Blast( 10 );
    var renderer:DisplayObjectRenderer = new DisplayObjectRenderer();
    renderer.addEmitter( emitter );
    addChild( renderer );






    var moleculeGroup:InitializerGroup = new InitializerGroup();
    moleculeGroup.addInitializer(new ImageClass(Asteroide) );

    var bounds:Rectangle = new Asteroide().getBounds(this);
    moleculeGroup.addInitializer(
    new CollisionRadiusInit(
    Math.max(bounds.width,
    bounds.height)/2)
    );


    moleculeGroup.addInitializer(new Position( new RectangleZone( 150,150,300,300) ));
    moleculeGroup.addInitializer(new Velocity( new PointZone( new Point( 100,100 ))));


    emitter.addInitializer(moleculeGroup);
    emitter.addAction( new Move() );
    emitter.addAction(new Collide(1));
    emitter.addAction(new BoundingBox(150,150,300,300))



    emitter.start();

    //TODO:
    function changeSpeed()
    {
    how can I change the speed for all the particles from my emitter?
    }
    • CommentAuthordfdiaza
    • CommentTimeNov 6th 2012
     
    Never mind. I don't know if this is the correct way to achieve this, but I found a solution.

    for(var i=0;i<emitter.particles.length;i++)
    {
    var p:Particle2D = Particle2D( emitter.particles[i] );
    var loc:Point = new Point(velocity,velocity) // A point zone with my desired velocity.
    if( p.rotation == 0 )
    {
    p.velX = loc.x;
    p.velY = loc.y;
    }
    else
    {
    var sin:Number = Math.sin( p.rotation );
    var cos:Number = Math.cos( p.rotation );
    p.velX = cos * loc.x - sin * loc.y;
    p.velY = cos * loc.y + sin * loc.x;
    }
    }

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