Ship jitters

[chris-kun]

current code here.

So basically the ship is just a bit jittery and I was wondering if there was a smoother way to do it. The only lines that matter are the three starting from 64. I was trying to compare the current point of the ship with where is was in the previous frame and move the camera according (I'm using the hump library.) Any ideas?

[BlackBulletIV]

I don't have the time to track down the jitters; although I have suspicion that it could be caused by your camera. I had trouble with the player jerking (or jittering, whatever) when using physics and a smooth moving camera. Taehl and bartbes helped me out there, so here's the code I came up with for my camera, it might help.

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camera.x = camera.x - (camera.x - (self.player.x - love.graphics.getWidth() / 2)) * dt * camera.speed
camera.y = camera.y - (camera.y - (self.player.y - love.graphics.getHeight() / 2)) * dt * camera.speed

Also, I noticed a block of code which most certainly doesn't need to be as big as it is. This is what I'm referring to:

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  do
    local px, py = playerBody:getWorldCenter()
    local pvec = vector.new(200, 200)
    local x, y = playerBody:getWorldCenter()
    local bvec = vector.new(x,y)
    local distance = pvec - bvec
    local f = 500000 / distance:len2()
    distance:normalize_inplace()
    local force = f * distance
    local fx = force.x
    local fy = force.y
    playerBody:applyForce(fx,fy)
  end

It could be shortened to this:

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do
  local distance = vector.new(200, 200) - vector.new(playerBody:getWorldCenter())
  local f = 500000 / distance:len2()
  distance:normalize_inplace()
  local force = f * distance
  playerBody:applyForce(force.x, force.y)
end

And you might not even need the do/end bit either. Anyway, hope some of that helps.

[vrld]

As BlackBulletIV wrote, you have to make the camera movement dependent on the time to get a smooth movement. So instead of

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view:translate(vector((nx-lx)*2,(ny-ly)*2))

use this:

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view:translate( vector(nx-lx, ny-ly) * 0.5 * dt )

What that does is move the camera depending with a speed depending how far away it is from the player body, so it will smoothly follow the player. The 0.5 can be changed to vary the speed of the camera movement (camera.speed in the other example).