This is new wiki software and old wiki content. It's a work in progress!
Here's the explanation.
Be gentle, report bugs, leave feedback on pages, or just edit them yourself! Thanks!

SDL Wiki

Draft

THIS PAGE IS A WORK IN PROGRESS ... Please make edits to this page to improve it!

SDL_ComposeCustomBlendMode

Compose a custom blend mode for renderers.

Syntax

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

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.

Remarks

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:

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 in SDL 2.0.6. All renderers support the four blend modes listed in the SDL_BlendMode enumeration.

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.

Version

This function is available in SDL 2.0.6.

Code Examples

You can add your code example here
SDL_SetRenderDrawBlendMode
SDL_GetRenderDrawBlendMode
SDL_SetTextureBlendMode
SDL_GetTextureBlendMode

CategoryAPI, CategoryRender, CategoryDraft


[ edit | delete | history | feedback | raw ]

[ front page | index | search | recent changes | git repo | offline html ]

All wiki content is licensed under Creative Commons Attribution 4.0 International (CC BY 4.0).
Wiki powered by ghwikipp.