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Hi, could some one point me to right direction on how to do this kind of predicted trajectory?

Hey, I'm trying to make a basketball game with predicted trajectory and I am having trouble with the trajectory. chargeBall: function(Pointer, x, y) { // If the button is down we charge the ball. if( Pointer.isDown && !isBallMoving ) { // Clear the graphics, set the style and draw the line from the ball to the Pointer. trajectoryGraphics.clear(); trajectoryGraphics.lineStyle( 2, '0xCCCCCC' ); trajectoryGraphics.moveTo( ball.x, ball.y ); trajectoryGraphics.lineTo( x, y ); // Calculate the velocity variables for the ball body to use in launchBall. launchVelocity.x = ( ball.x - x ) * 5; launchVelocity.y = ( ball.y - y ) * 5; // Make the line narrower. trajectoryGraphics.lineStyle( 1, '0xCCCCCC' ); // Lets make 11 segmented trajectory line. For every segment get the point and draw a small square. for( var i = 0; i < 15; i++ ) { var trajectoryPoint = this.getTrajectoryPoint( ball.x, ball.y, launchVelocity.x, launchVelocity.y, i ); trajectoryGraphics.drawRect( trajectoryPoint.x, trajectoryPoint.y, 2, 2 ); } } }, launchBall: function() { if( !isBallMoving ) { // Clear the graphics if the ball has been launched. trajectoryGraphics.clear(); // Set the ball velocity. ball.body.velocity.x = launchVelocity.x; ball.body.velocity.y = launchVelocity.y; // Flag the ball as moving. isBallMoving = true; // Set the ball physics to enabled. ball.body.data.gravityScale = 1; ball.body.data.collisionResponse = true; // Create a new ball after 4 seconds. this.time.events.add( Phaser.Timer.SECOND * 4, this.createNewBall, this ); } }, getTrajectoryPoint: function( startX, startY, velocityX, velocityY, n ) { var t = 1 / 60; var stepVelocityX = t * this.physics.p2.pxm(-velocityX); var stepVelocityY = t * this.physics.p2.pxm(-velocityY); var stepGravityX = t * t * this.physics.p2.pxm(-this.physics.p2.gravity.x); var stepGravityY = t * t * this.physics.p2.pxm(-this.physics.p2.gravity.y); startX = this.physics.p2.pxm(-startX); startY = this.physics.p2.pxm(-startY); var tpx = startX + n * stepVelocityX + 0.05 * (n * n * n) * stepGravityX; var tpy = startY + n * stepVelocityY + 0.05 * (n * n * n) * stepGravityY; tpx = this.physics.p2.mpx(-tpx); tpy = this.physics.p2.mpx(-tpy); return { x: tpx, y: tpy }; } The code is from Phaser Box2D physics example I think, but I am using the P2 physics system. It works. Kind of. The trajectory is wrong. I am absolutely not sure but I think it has got to do something with the ball physics body. I'd love it if you'd take a quick look and tell me if I'm doing something very wrong.