Learning Gravity, Basic Physics, and Camera Controls: An Angry Birds-like Game, Part I - Learn GameSalad for iOS: Game Development for iPhone, iPad, and HTML5 - page 167

Create a new rule named ''Touch.'' The condition will be ''Actor receives
event''''touch'' is ''pressed.'' This will detect that the actor is touched.
Drag and drop a Constrain Attribute into the rule and
changeProjectile.Position.X to game.InitialProjectX + min(game.MaxPower,
magnitude( game.Mouse.Position.X - game.InitialProjectX,
game.Mouse.Position.Y -- game.InitialProjectY) * cos(
vectorToAngle(game.Mouse.Position.X - game.InitialProjectX,
game.Mouse.Position.Y -- game.InitialProjectY)).
Going back to Figure 6-11,
 X2 is Projectile.Position.X
 X1 is game.InitialProjectX
 c is
min(game.MaxPower,magnitude(game.Mouse.Position.X -
game.InitialProjectX, game.Mouse.Position.Y --
game.InitialProjectY))
 alpha is vectorToAngle(game.Mouse.Position.X -
game.InitialProjectX, game.Mouse.Position.Y --
game.InitialProjectY)
Drag and drop a Constrain Attribute into the rule and change
Projectile.Position.Y to game.InitialProjectY + min(game.MaxPower ,
magnitude(game.Mouse.Position.X - game.InitialProjectX,
game.Mouse.Position.Y -- game.InitialProjectY) *
sin(vectorToAngle(game.Mouse.Position.X - game.InitialProjectX,
game.Mouse.Position.Y -- game.InitialProjectY)).
Going back to Figure 6-11,
 Y2 is Projectile.Position.Y
 Y1 is game.InitialProjectY
 c is
min(game.MaxPower,magnitude(game.Mouse.Position.X -
game.InitialProjectX, game.Mouse.Position.Y --
game.InitialProjectY))
 alpha is vectorToAngle(game.Mouse.Position.X -
game.InitialProjectX, game.Mouse.Position.Y --
game.InitialProjectY
The rule is shown in Figure 6-12.