Smooth movement. (SOLVED)

[Murii]

The key idea of smooth movement is to change velocity gradually not in jumps.

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player.xvel = player.xvel * (1 - math.min(dt*player.friction, 1))

First, ignore the math.min and look at that:

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player.xvel = player.xvel * (1 - dt*player.friction)

this can be expanded and you get:

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player.xvel = player.xvel - player.xvel * dt * player.friction

That means that the player's x-velocity is changed by (player.xvel*dt*player.friction). This term defines how fast the player slows down. You can see, that if the player is very fast, then he slows down fast. If he is slow (player.xvel almost zero) then the slowing down is slow.

This piece of code:

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player.xvel = player.xvel * (1 - dt*player.friction)

is not equal to :

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player.xvel = player.xvel - player.xvel * dt * player.friction

but instead if you note the result of

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1 - dt*player.friction

with "y" :

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 player.xvel = player.xvel * y 

.

So this means that the final result is going to be totally different micha

[pgimeno]

This piece of code:

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player.xvel = player.xvel * (1 - dt*player.friction)

is not equal to :

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player.xvel = player.xvel - player.xvel * dt * player.friction

It is. Due to distributive law, A*(B+C) equals (A*B)+(A*C), and similarly A*(B-C) equals (A*B)-(A*C). Here A=player.xvel, B=1, C=dt*player.friction. Therefore:

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player.xvel*(1 - dt*player.friction) = (player.xvel*1) - (player.xvel*dt*player.friction)
___________  _   __________________     ___________ _     ___________ __________________
     A       B           C                   A      B          A               C

which is the same as Micha said.

There can be differences in the results between the two formulas due to floating point precision, but we would be talking about differences in the 20th significant digit or so.