(This is the documentation for SDL3, which is the current stable version. SDL2 was the previous version!)

SDL_SetSurfaceAlphaMod

Set an additional alpha value used in blit operations.

Header File

Defined in <SDL3/SDL_surface.h>

Syntax

bool SDL_SetSurfaceAlphaMod(SDL_Surface *surface, Uint8 alpha);

Function Parameters

SDL_Surface *	surface	the SDL_Surface structure to update.
Uint8	alpha	the alpha value multiplied into blit operations.

Return Value

(bool) Returns true on success or false 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 3.1.3.

See Also

• SDL_GetSurfaceAlphaMod
• SDL_SetSurfaceColorMod

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CategoryAPI, CategoryAPIFunction, CategorySurface

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