Gravity and lag

[Nixola]

If the dt is too high, the moving object could pass through other objects in only one frame, without the collision being detected. Updating the world more times with smaller dt helps to prevent it

[Puzzlem00n]

If the dt is too high, the moving object could pass through other objects in only one frame, without the collision being detected. Updating the world more times with smaller dt helps to prevent it

I get that, I was the one who linked that answer on this thread earlier. I just don't understand why

Code: Select all

function love.update(dt)
    local physics_dt = dt
    while physics_dt > 0 do
        physics_update(math.min(0.1, physics_dt))
        physics_dt = physics_dt - 0.1
    end
end

Is better than

Code: Select all

function love.update(dt)
    dt = math.min(0.1, dt)
    ......
end

I don't understand in part because I don't get what that first code block is even doing. While loops are sort of foreign to me (as far as I can tell, they do the same thing as if statements). Sorry, should've been clearer before.

[Nixola]

The former will repeat the update many times every frame with small dts, the latter will update only once per frame, decreasing dt if it's too highso slowing the game if the framerate is low


Anyway, the whiles are like ifs, but they "freeze" everything else until their condition is false. Example:

Code: Select all

a = 90
while a > 0 do
   a = a - <
   print(a)
end

I'll try a (bad!) example that uses IFs to do the same thing:

Code: Select all

a = 90
while = function()
   a = a - 1
   if a > 0 then
      while()
   end
end

I don't think I explained it well, do you understand what I mean?

[Puzzlem00n]

Well, that clears up while statements. I guess that code then is allowing everything to update at the amount it should, but not all at once to account for things moving through others. Now that I get it, I see it's actually pretty clever.

Thanks a lot, Nixola!