Godot Platformer - Throwing projectiles - How to make it land in a certain point
Please I need your help to figure this out.
I have this formula that I have been trying to apply to my project.
I use the GoDot engine to create a 2D platformer game with projectiles.
static public Vector2 calculate_arc_velocity(Vector2 point_a, Vector2 point_b, float arc_height,float up_gravity=30, float? down_gravity=null)
{
if(down_gravity==null)
down_gravity=up_gravity;
Vector2 velocity = new Vector2();
Vector2 displacement = point_b-point_a;
//GD.Print(displacement);
if(displacement.y>arc_height)
{
var time_up = Mathf.Sqrt(-2F*(float)arc_height/(float)up_gravity);
var time_down = Mathf.Sqrt(2F*((float)displacement.y-(float)arc_height)/(float)down_gravity);
velocity.y = -Mathf.Sqrt(-2F*(float)up_gravity*(float)arc_height);
velocity.x = (float)displacement.x/(float)time_up+(float)time_down;
}
return velocity;
}
}
public void launch(Node2D start, Node2D target, float direction)
{
Vector2 startpos = start.GlobalPosition;
targetpos = target.GlobalPosition;
float up_gravity= (target.GlobalPosition.y-start.GlobalPosition.y)/2;
float arc_heigh = (target.GlobalPosition.y-start.GlobalPosition.y)-50;
//velocity = throw_velocity*new Vector2(direction,1);
//Vector2 arc_height = target.GlobalPosition-start.GlobalPosition;
velocity = PhysicsHelper.calculate_arc_velocity(startpos,targetpos,arc_heigh,-arc_heigh);
//velocity =throw_velocity+velocity;
GD.Print(arc_heigh);
GD.Print(up_gravity);
velocity/=2;
}
The calculate_arc_velocity should do the job I think but the 'launch' method is just really messy.
My up_gravity and arc_heigh is just a desperate attempt to make it work. I started to mess with that because I couldn't make it work when I started to move the mouse up.
I greatly appreciate your help with this.
Replies
you want to move the projectile from point a to point b
Do you need to calculate the velocity and arc that it follows or do you already have some of tha information?
public void launch(Node2D start, Node2D target, float direction) { Vector2 startpos = start.GlobalPosition; targetpos = target.GlobalPosition; //float up_gravity= (target.GlobalPosition.y-start.GlobalPosition.y)/2; float arc_height = target.Position.y; float gravity = Globals.GRAVITY; if(arc_height>0) { gravity = Globals.GRAVITY/3; arc_height *=-1; } //GD.Print(arc_height); //GD.Print(target.Position.x); //float arc_height = 100; //velocity = throw_velocity*new Vector2(direction,1); //Vector2 arc_height = target.GlobalPosition-start.GlobalPosition; velocity = PhysicsHelper.calculate_arc_velocity(startpos,targetpos,arc_height,gravity); GD.Print(velocity); //velocity.x = 100; //velocity.y = -100; //velocity =throw_velocity+velocity; // GD.Print(arc_height); // GD.Print(up_gravity); //velocity/=2;