Question

I’m trying to make jumping functionality in my Movement test. My character jumps and comes back down, but it’s very choppy and not smooth at all.
What happens is he juts up to his max height, then comes down smoothly.

I can spot the problem, the for loop doesn’t want to play nicely with the code. However, I don’t know how to circumvent this. Is there any way to keep the button press and have him jump up nicely?

Code:

if (leftStick.Y > 0.2f && sprite.Position.Y == position.Y || isPressed(Keys.Up) == true && sprite.Position.Y == position.Y) 
            {
                if (wasLeft == true)
                {
                    sprite.CurrentAnimation = "JumpLeft";

                }
                else if (wasLeft == false)
                {
                    sprite.CurrentAnimation = "JumpRight";
                }

                //This for loop is my issue, it works but it's jumpy and not smooth.

                for (movement.PlayerHeight = 0; movement.PlayerHeight < movement.PlayerMaxHeight; movement.PlayerJump())
                {

                    sprite.Position.Y -= movement.PlayerJump();
                }
            }
            sprite.StartAnimation();
        }
        else
        {

            leftStick = NoInput(leftStick);
        }

private Vector2 NoInput(Vector2 leftstick)
{
if (sprite.Position.Y < position.Y) //(movement.PlayerSpeed > 0) 
            {
                sprite.Position.Y += movement.PlayerHeight;
                movement.PlayerHeight -= movement.Player_Gravity;

                //sprite.Position.Y += movement.PlayerSpeed;
                //movement.PlayerSpeed -= movement.Player_Decel;
            }
            else
            {
                sprite.Position.Y = position.Y;
            }
}

Movement class:

public float PlayerMaxHeight = 15f;
public float PlayerHeight = 0;
public float Player_Gravity = 0.01f;
private const float Player_Jump = 0.35f;


public float PlayerJump()
{
    PlayerHeight += Player_Jump + Player_Gravity;
    if (PlayerHeight > PlayerMaxHeight)
    {
        PlayerHeight = PlayerMaxHeight;
    }
    return PlayerHeight;
}

Answer 1

My general approach to get a jump really quickly is to use a bleed off value to make slightly smoother looking movement. I can’t look at any code/xna right now but my first thought would be something like below.

Define variables:

float bleedOff = 1.0f;
bool jumping = false;

Input update:

if(input.JumpKey())
{
    jumping = true;
}

Jumping update:

if(jumping)
{
    //Modify our y value based on a bleedoff
    //Eventually this value will be minus so we will start falling.
    position.Y += bleedOff;
    bleedOff -= 0.03f;

    //We should probably stop falling at some point, preferably when we reach the ground.
    if(position.Y <= ground.Y)
    {
        jumping = false;
    }
}

bleedOff = MathHelper.Clamp(bleedOff, -1f, 1f);

Obviously the bleedOff value should be calculated with a bit more randomness, probably using a gravity value, to it to make it look right but this will give the illusion of acceleration/decceleration with the jump as they rise and fall.

Rising very fast to begin with and slowing down and eventually starting to fall again and that will speed up. The clamp at the bottom will be your maximum vertical velocities.

I just wrote this off the top of my head at work so apologies if it’s not quite what your looking for but I tried to keep it a bit more general. Hope it helps.