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.TH SDL_SetSurfaceAlphaMod 3 "SDL 3.1.0" "SDL" "SDL3 FUNCTIONS"
.SH NAME
SDL_SetSurfaceAlphaMod \- Set an additional alpha value used in blit operations\[char46]
.SH SYNOPSIS
.nf
.B #include \(dqSDL3/SDL.h\(dq
.PP
.BI "int SDL_SetSurfaceAlphaMod(SDL_Surface *surface, Uint8 alpha);
.fi
.SH DESCRIPTION
When this surface is blitted, during the blit operation the source alpha
value is modulated by this alpha value according to the following formula:
.BR srcA = srcA * (alpha / 255)

.SH FUNCTION PARAMETERS
.TP
.I surface
the 
.BR SDL_Surface
 structure to update
.TP
.I alpha
the alpha value multiplied into blit operations
.SH RETURN VALUE
Returns 0 on success or a negative error code on failure; call

.BR SDL_GetError
() for more information\[char46]

.SH AVAILABILITY
This function is available since SDL 3\[char46]0\[char46]0\[char46]

.SH SEE ALSO
.BR SDL_GetSurfaceAlphaMod (3),
.BR SDL_SetSurfaceColorMod (3)