semi transparent - sdl

[legendarysnake]

how i render a semi transmarent image using sdl?
i want this effect:
https://www.google.com.br/search?q=rpg+maker+xp+netplay&client=firefox-a&hs=uPS&rls=org.mozilla:pt-BR:official&channel=sb&source=lnms&tbm=isch&sa=X&ei=Zz25U_vWDeimsQTf34CABQ&sqi=2&ved=0CAcQ_AUoAg&biw=1348&bih=604

[Peter87]

You could create an image that have transparency and then load and use it like any other image.

Another way is to set an alpha value on the whole image inside the code.

_{SDL 1.2}
http://sdl.beuc.net/sdl.wiki/SDL_SetAlpha

_{SDL 2}
https://wiki.libsdl.org/SDL_SetSurfaceAlphaMod
https://wiki.libsdl.org/SDL_SetTextureAlphaMod