NAME

       SDL_ComposeCustomBlendMode - Compose a custom blend mode for renderers.

SYNOPSIS

       #include <SDL3/SDL_blendmode.h>

       SDL_BlendMode SDL_ComposeCustomBlendMode(SDL_BlendFactor srcColorFactor,
                                            SDL_BlendFactor dstColorFactor,
                                            SDL_BlendOperation colorOperation,
                                            SDL_BlendFactor srcAlphaFactor,
                                            SDL_BlendFactor dstAlphaFactor,
                                            SDL_BlendOperation alphaOperation);

DESCRIPTION

       The functions SDL_SetRenderDrawBlendMode and SDL_SetTextureBlendMode accept the SDL_BlendMode returned by
       this function if the renderer supports it.

       A  blend mode controls how the pixels from a drawing operation (source) get combined with the pixels from
       the render target (destination).  First,  the  components  of  the  source  and  destination  pixels  get
       multiplied  with their blend factors. Then, the blend operation takes the two products and calculates the
       result that will get stored in the render target.

       Expressed in pseudocode, it would look like this:

              dstRGB = colorOperation(srcRGB * srcColorFactor, dstRGB * dstColorFactor);
              dstA = alphaOperation(srcA * srcAlphaFactor, dstA * dstAlphaFactor);

       Where the functions  colorOperation(src,  dst)  and  alphaOperation(src,  dst)  can  return  one  of  the
       following:

       • src + dst

       • src - dst

       • dst - src

       • min(src, dst)

       • max(src, dst)

       The red, green, and blue components are always multiplied with the first, second, and third components of
       the SDL_BlendFactor, respectively. The fourth component is not used.

       The  alpha  component  is  always multiplied with the fourth component of the SDL_BlendFactor.  The other
       components are not used in the alpha calculation.

       Support for these blend modes varies  for  each  renderer.  To  check  if  a  specific  SDL_BlendMode  is
       supported, create a renderer and pass it to either SDL_SetRenderDrawBlendMode or SDL_SetTextureBlendMode.
       They will return with an error if the blend mode is not supported.

       This  list  describes the support of custom blend modes for each renderer. All renderers support the four
       blend modes listed in the SDL_BlendMode enumeration.

       • direct3d: Supports all operations with all factors. However, some factors  produce  unexpected  results
       with SDL_BLENDOPERATION_MINIMUM and SDL_BLENDOPERATION_MAXIMUM.

       • direct3d11: Same as Direct3D 9.

       •  opengl:  Supports the SDL_BLENDOPERATION_ADD operation with all factors. OpenGL versions 1.1, 1.2, and
       1.3 do not work correctly here.

       •      opengles2:      Supports      the       SDL_BLENDOPERATION_ADD,       SDL_BLENDOPERATION_SUBTRACT,
       SDL_BLENDOPERATION_REV_SUBTRACT operations with all factors.

       • psp: No custom blend mode support.

       • software: No custom blend mode support.

       Some   renderers   do   not   provide   an   alpha   component   for   the  default  render  target.  The
       SDL_BLENDFACTOR_DST_ALPHA and SDL_BLENDFACTOR_ONE_MINUS_DST_ALPHA factors do not have an effect  in  this
       case.

FUNCTION PARAMETERS

       srcColorFactor
              the SDL_BlendFactor applied to the red, green, and blue components of the source pixels.

       dstColorFactor
              the SDL_BlendFactor applied to the red, green, and blue components of the destination pixels.

       colorOperation
              the  SDL_BlendOperation  used  to  combine  the  red, green, and blue components of the source and
              destination pixels.

       srcAlphaFactor
              the SDL_BlendFactor applied to the alpha component of the source pixels.

       dstAlphaFactor
              the SDL_BlendFactor applied to the alpha component of the destination pixels.

       alphaOperation
              the SDL_BlendOperation used to combine the alpha component of the source and destination pixels.

RETURN VALUE

       Returns an SDL_BlendMode that represents the chosen factors and operations.

THREAD SAFETY

       It is safe to call this function from any thread.

AVAILABILITY

       This function is available since SDL 3.2.0.

SEE ALSO

       SDL_SetRenderDrawBlendMode(3),         SDL_GetRenderDrawBlendMode(3),         SDL_SetTextureBlendMode(3),
       SDL_GetTextureBlendMode(3)

Simple Directmedia Layer                           SDL 3.2.26                      SDL_ComposeCustomBlendMode(3)