Sprite rotation

Hi,

Is there any way to rotate a sprite, either by code or using the sprite editor? 

Thanks

There's no rotation function in the sprite editor (or the image editor) a the moment. But I'll look into it when I've got some time for a future release.
It is obviously impractical to try doing it in real time, but precomputing in code shouldn't be that difficult.
I would recommend doing it all in bitmap to benefit from the built-in functions and then convert to sprites at the end.
There are two approaches:

1. Using a rotation matrix to transform each pixel, something similar to this:   www.lexaloffle.com/bbs/?tid=38548
2. Using the shear method, used by many 16-bits arcade:  games:  www.ocf.berkeley.edu/~fricke/projects/is...ion_by_shearing.html

The first is probably quicker to implement but will end up very slow during generation (might be a problem if the generation is done at the start of the game).
The second should be quite fast, as it was intended for real-time hardware implementation, but is more complex to implement.
If it's just to precompute and save as a file, I'd go with the first approach. May I ask what is your use case?

Hi Franck,

Sorry, I should have been more specific. My use case is much simpler, for the moment. I am moving a ship ( I got the sprite from multi.spr) in 4 directions and I want it to have the right orientation. I use sprFlip for up/down but for left/right I need to rotate it 90º.

Since there is no support yet, I will try to rotate it in memory on start up time. Thanks for the pointers: they will be useful if I ever need something more complicated.

Best,
rosogon

I realized that given a sprite is 24x21pixels, the rotated ship would not fit. So I dedicated 10 minutes in the editor to rotate it myself, removing two lines.

Couldn't resist. I wrote a small utility to precompute sprite rotations. It computes rotations from 0 to 90 degrees, the rest is handled by using the hardware flipping. Example usage included. It will also be added to the upcoming 0.7.5 update. (edit: added screenshot)  

It works like a charm!

I think I found a nasty bug. I will create a new post for that.