[Solved] Player moves faster to the left :*(

[Pirate]

I'm running into some problems with my fixed time step and calculating negative movement.

When the player pushes the left key mMovement = -1; right key mMovement = 1;

my problem is that when moving left "-1" the player goes faster then if they were going right "1";


main loop

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float deltaTime = App.GetFrameTime();

mainPlayer.Update(deltaTime);
otherPlayer.Update(deltaTime);



player update

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// Player pushes Left then mMovement is "-1" right mMovement is "1"

mVelocity.x += mMovement * 2000 * ElapsedTime;
mVelocity.x = clamp(mVelocity.x, -100, 100);

// Apply velocity.
mPosition.x += mVelocity.x * ElapsedTime;

mSprite.SetPosition((int)mPosition.x, 600);



0_o I'm sure it's something very simple, but I just can't seem to figure it out.

when I breakpoint it,  the velocity seems to be clamped at the proper positive or negative number so it's something with

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mPosition.x += mVelocity.x * ElapsedTime;


[Nexus]

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mVelocity.x += mMovement * 2000 * ElapsedTimeShouldn't it be = instead of +=? Do you work with immediate movement or acceleration?

[Pirate]

if I remove the + I lose the ability to go right.

hrmm, but then left seems to be the proper speed :{

[Nexus]

if I remove the + I lose the ability to go right.

No, you don't. You needn't change the velocity relatively to the former velocity (unless you work with acceleration).

The velocity (let's call it vx) is either positive or negative, depending on the sign of mMovement.
Then you write x += vx * dt; which adds the velocity to the position. If the velocity is positive, the object moves right; if negative, it moves left.

[Pirate]

I must of really messed something up somewhere then.
What you are saying makes perfect sense.

just for some reason It won't move right :{

[Nexus]

Reduce your code to a minimal and complete example, omitting all details irrelevant to the problem.

[Pirate]

changing mMovement from = 1; to = 2;  seemed to fix it.
I have no idea why.

But now left (-1) and right (2) have the same speeds :*(

I made this change after stripping everything down, and It still wouldn't go right.

and if I make changes to "2000" in the velocity formula it breaks right movement again.

[Pirate]

Well I figured it out.


I was storing mVelocity.x and .y as integers :*( switched it to float and everything is all good now.

[tntexplosivesltd]

So, the truncation of integers was your problem then? As in, if it was 2.5, it would be 2 as an int.

[Pirate]

yes since the ElapsedTime was a fraction It was messing up the formula.