Question

I’m currently trying to make a basic platformer with XNA and I’m wondering how to create a “jumping effect.” I currently have basic keyboard input which allows for sideways movement, but I would like my sprite to slowly progress into a jump rather than instantly teleporting there (right now I have something like Rectangle.Y += 40 every time I jump, making the sprite instantly appear there). Does anyone have any insight?

Answer 1

I’m not totally across how to implement this in XNA/C#, but in Flash games I’ve made I just added a vertical velocity property. I’ll try write everything as C# as I can..

Example; create the velocity property:

float verticalVelocity = 0;

Vertical velocity should be constantly reduced (by gravity). Set up a gravity property somewhere accessible from your player:

float Gravity = 2.5;

And in your update() method for the player, increment the verticalVelocity by Gravity. Also increment the Y position of your player by the verticalVelocity. This will simulate falling:

verticalVelocity += Gravity;
Position.Y += verticalVelocity; // this may be -= in XNA, not sure where the y axis beings

When you hit a surface, the velocity should be reset to 0.

And finally, to jump, simply subtract a given value from verticalVelocity:

public void Jump(float height)
{
    // Only jump if standing on a surface.
    if(verticalVelocity == 0)
        verticalVelocity -= height;
}