Updating the jump in game
- by Luka Tiger
I am making a Java game and I want my game to run the same on any FPS so I'm using time delta between each update. This is the update method of the Player:
public void update(long timeDelta) {
//speed is the movement speed of a player on X axis
//timeDelta is expressed in nano seconds so I'm dividing it with 1000000000 to express it in seconds
if (Input.keyDown(37))
this.velocityX -= speed * (timeDelta / 1000000000.0);
if (Input.keyDown(39))
this.velocityX += speed * (timeDelta / 1000000000.0);
if(Input.keyPressed(38)) {
this.velocityY -= 6;
}
velocityY += g * (timeDelta/1000000000.0); //applying gravity
move(velocityX, velocityY); /*this is method which moves a player
according to velocityX and velocityY,
and checking the collision
*/
this.velocityX = 0.0;
}
The strange thing is that when I have unlimited FPS (and update number) my player is jumping about 10 blocks. It jumps even higher when the FPS is increasing. If I limit FPS it is jumping 4 blocks. (BLOCK: 32x32) I have just realized that the problem is this:
if(Input.keyPressed(38)) {
this.velocityY -= 6;
}
I add -6 to velocityY which increases player's Y proportionally to the update number and not to the time.
But I don't know how to fix this.
