DragonRuby Game Toolkit - Camera Shake (https://www.youtube.com/watch?v=-i1ILZsIqbU&ab_channel=AmirRajan)

main.rb

def calc_camera
  if player_charging?
    if player_charge_percentage < 0.2
      state.camera.trauma += 0.005
    elsif player_charge_percentage < 0.5
      state.camera.trauma += 0.01
    elsif player_charge_percentage < 0.8
      state.camera.trauma += 0.02
    else
      state.camera.trauma += 0.04
    end
  end

  if state.camera.trauma < 0.3
    state.camera.x_offset = 0
    state.camera.y_offset = 0
    state.camera.angle    = 0
  else
    next_camera_angle = 180.0 / 20.0 * state.camera.trauma**2
    next_offset       = 100.0 * state.camera.trauma**2

    state.camera.angle = state.camera.angle > 0 ?
                         next_camera_angle * -1 :
                         next_camera_angle

    state.camera.x_offset = rand >= 0.5 ?
                            next_offset * rand :
                            next_offset * rand * -1

    state.camera.y_offset = rand >= 0.5 ?
                            next_offset * rand :
                            next_offset * rand * -1

    state.camera.trauma *= 0.95
  end
end