Sprite rotation in SDL?

Just rotate them ahead of time using Photoshop/GIMP/whatever.

Or use SDL_gfx

Definitely use the SDL_gfx library. You can use the function

rotozoomSurface(SDL_Surface* surface, double zoom, double angle, int smooth)

to easily rotate and zoom in on your sprites.

Thanks guys, this is exactly what I'm looking for. I want in-game rotation. Just a couple more question:

How do I get the spaceship to go in the direction it's facing when I press the up arrow?

How do I get the bullets to move in that direction when I press the fire button?

thx again!

Quote:

Original post by Gameteen Thanks guys, this is exactly what I'm looking for. I want in-game rotation. Just a couple more question: How do I get the spaceship to go in the direction it's facing when I press the up arrow? How do I get the bullets to move in that direction when I press the fire button? thx again!

Think back to your trigonomtery.

on up increase angle, on down decrease angle.

on fire shoot bullet at cosine of angle * velocity and sine of angle * velocity.

Don't use rotozoomSurface in realtime. It's extremely slow and if you call it a bunch of times in your main loop, your framerate will drop quite fast. It would be a better idea to cache the rotation and then use it when needed. This will dramatically speed up the framerate an ensure you don't loose any frames.

This was a huge issue I had with Blastoids and I ended up implementing a low detail and high detail graphic settings for the user so that they can choose to allow or disallow realtime rotations on objects that don't need them.

Quote:

Original post by Rob Loach Don't use rotozoomSurface in realtime. It's extremely slow and if you call it a bunch of times in your main loop, your framerate will drop quite fast. It would be a better idea to cache the rotation and then use it when needed. This will dramatically speed up the framerate an ensure you don't loose any frames. This was a huge issue I had with Blastoids and I ended up implementing a low detail and high detail graphic settings for the user so that they can choose to allow or disallow realtime rotations on objects that don't need them.

Yes, do precache the surfaces... But just so you know, that would use a lot of memory because you might end up having 359 surfaces for 360 degrees (considering you can use the 0 degrees one for a 360 degrees one)... Which means creating 359 surfaces and then using pixel-access (slow-also) to rotate... What you can do is, to have approximate degreess... For example, rotate in 4 directions and estimate the angle... Or maybe 8 to make it a little more realistic... Just a few tips..

@Rob - So you are using the rotations in real-time? That seems incredibly fast.... (on my pc, atleast; which isn't exactly "fast")

Awesome! Alright, now I have to stop messing around and actually do it! sigh....... Thx!