c++ - Movement of sprite using fixed time step -

i have loop:

sf::clock clock; sf::time timesincelastupdate = sf::time::zero; while (mwindow.isopen()) {     processevents();     timesincelastupdate += clock.restart();      while (timesincelastupdate > timeperframe)     {         timesincelastupdate -= timeperframe;         processevents();         update(timeperframe);     }     render(); } 

and in update function this:

object.speed = object.speed * timeperframe.asseconds(); 

and run method in do:

sprite.move(cos(sprite.getrotation()*pi / 180) * speed, sin(sprite.getrotation()*pi / 180) * speed); 

but problem sprite doesn't move. when don't multiply speed timeperframe.asseconds(), move. how should fix correct? , how use timeperframe variable?

object.speed = object.speed * timeperframe.asseconds(); 

this line reducing speed every frame until 0.

you need scale movement distance delta time whenever move object. try this:

float distance = speed * timeperframe.asseconds();  sprite.move(cos(sprite.getrotation()*pi / 180) * distance, sin(sprite.getrotation()*pi / 180) * distance);