(This is the legacy documentation for stable SDL2, the current stable version; SDL3 is the current development version.)

SDL_SetSurfaceAlphaMod

Set an additional alpha value used in blit operations.

Header File

Defined in SDL_surface.h

Syntax

int SDL_SetSurfaceAlphaMod(SDL_Surface * surface,
                           Uint8 alpha);

Function Parameters

surface the SDL_Surface structure to update
alpha the alpha value multiplied into blit operations

Return Value

Returns 0 on success or a negative error code on failure; call SDL_GetError() for more information.

Remarks

When this surface is blitted, during the blit operation the source alpha value is modulated by this alpha value according to the following formula:

srcA = srcA * (alpha / 255)

Version

This function is available since SDL 2.0.0.

See Also

CategoryAPI, CategoryAPIFunction, CategorySurface