i guess it's about textures (loading circle problem)

[paul.mihaita]

Hey guys. I am making an Space invaders type of game, and i want to make some power-ups.I want to make an animation for that, like an loading circle so that user can know how much time left he has to take the power-up.I know how to do that by sprites(5-6 sprites with 1/5-1/6 of circle and just display the images after a time) but i want to do it smoothly, and by that i mean to calculate the % of circle to fill based on the time i want.I guess it can be done with texture updating...but i don't know

[Ixrec]

Updating the texture directly is probably not the best idea.  I believe the "best" way of implementing this (in terms of performance and flexibility) is to draw the circle using a shader that takes a number like 1/5 as input and then only "lets through" those pixels that are in the first 1/5 of the circle.

[paul.mihaita]

and how i can do that shader? i'm new into this kind of program, i've heard about but never did it

[Ixrec]

The basics are in the tutorials: http://sfml-dev.org/tutorials/2.1/graphics-shader.php

[paul.mihaita]

so i have to learn GLSL?

[eXpl0it3r]

If you want to use shaders, then yes.

There should also be ways to achieve such an effect with triangle fans or a special implementation of circle shape.

Also this question has been asked before, search the forum a bit or even google for it, you're not the only one who wanted that.

[Laurent]

The triangle fan will be the easiest and most efficient solution, yes. More details are given in the other topic, if you can find it.