Rotate background texture?

SDL Development
#1

Hi

I have a background texture 2048x2048 that I render with:
SDL_RenderCopyEx(renderer, texture,&SrcR,&DestR,mangle,NULL,SDL_FLIP_NONE);

Where the window size is 512x512.

The problem is that even though the background is rotating, I get artifacts in the corners where the texture isn’t updated.

Tried changing SrcR and DestR to all sorts of values, but I never get the artifacts gone completely.

How do I set it up so the background is rotated without artifacts?

#2

With SrcR as NULL (or 2048x2048) and DestR as 724x724 (or larger) - large enough for the rotated texture always to fill the window whatever the angle - I wouldn’t have expected any artefacts. Can you confirm that you still see them even with those values?

#3

The only Dest I got working is:

DestR.x = -256;
DestR.y = -256;
DestR.w = 1024;
DestR.h = 1024;

with dest =
DestR.x = 0;
DestR.y = 0;
DestR.w = 768;
DestR.h = 768;

I still get artifacts in one corner

#4

That rectangle isn’t centred. Try:

DestR.w = 724;
DestR.h = 724;
DestR.x = -106;
DestR.y = -106;

You need to ensure that the destination rectangle is centred in your window, so in general:

DestR.x = (WindowWidth - DestR.w) / 2;
DestR.y = (WindowHeight - DestR.h) / 2;
#5

Ahh yes, this works perfectly :slight_smile: