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zoomSurface problem

Started by pnroach Aug 18, 2005 at 4:46 PM 2 replies 700+ views

Original Post

Aug 18, 2005 at 4:46 PM

i tried using zoomSurface to scale my texture and it did scale it but the resulting surface lost its transparent background. i used SDL_image library to load image (png format). SDL_Surface* temp ; temp = zoomSurface(texture, scale_x, scale_y, 1); Why is transparency lost? Suggestions?

ender7771

Aug 18, 2005 at 11:43 PM

Maybe it looses transparency because the function (I am not familiar with it) returns a new surface, so you have to set the transparency again for it.

Or maybe when it zooms it does anti-aliasing and changes your color that you want transparent a little bit and so instead of like 0x00ff00 its 0x11dd11 and it looks a like but really isnt.

But I dont know anything about the peculiars of zoomSurface.

clayasaurus

Aug 23, 2005 at 10:58 PM

You have to treat colors 0 though 16777215 as transparent, because when you use rotozoom, the colors are messed around a bit but the transparent range displacement seems limited to this range.

Rob Loach

Aug 24, 2005 at 10:21 AM

You'll have to fiddle with the colour key when blitting the zoomSurface. Try changing the colour key on the source surface to black before rotating, try changing the colour key to purple on the final surface, fiddle around with it and you'll eventually get it.

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