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/*
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  Simple DirectMedia Layer
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  Copyright (C) 1997-2023 Sam Lantinga <slouken@libsdl.org>
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  This software is provided 'as-is', without any express or implied
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  warranty.  In no event will the authors be held liable for any damages
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  arising from the use of this software.
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  Permission is granted to anyone to use this software for any purpose,
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  including commercial applications, and to alter it and redistribute it
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  freely, subject to the following restrictions:
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  1. The origin of this software must not be misrepresented; you must not
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     claim that you wrote the original software. If you use this software
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     in a product, an acknowledgment in the product documentation would be
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     appreciated but is not required.
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  2. Altered source versions must be plainly marked as such, and must not be
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     misrepresented as being the original software.
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  3. This notice may not be removed or altered from any source distribution.
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*/
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/**
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 *  \file SDL_blendmode.h
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 *
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 *  Header file declaring the SDL_BlendMode enumeration
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 */
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#ifndef SDL_blendmode_h_
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#define SDL_blendmode_h_
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#include "begin_code.h"
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/* Set up for C function definitions, even when using C++ */
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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 *  \brief The blend mode used in SDL_RenderCopy() and drawing operations.
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 */
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typedef enum
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{
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    SDL_BLENDMODE_NONE = 0x00000000,     /**< no blending
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                                              dstRGBA = srcRGBA */
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    SDL_BLENDMODE_BLEND = 0x00000001,    /**< alpha blending
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                                              dstRGB = (srcRGB * srcA) + (dstRGB * (1-srcA))
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                                              dstA = srcA + (dstA * (1-srcA)) */
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    SDL_BLENDMODE_ADD = 0x00000002,      /**< additive blending
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                                              dstRGB = (srcRGB * srcA) + dstRGB
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                                              dstA = dstA */
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    SDL_BLENDMODE_MOD = 0x00000004,      /**< color modulate
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                                              dstRGB = srcRGB * dstRGB
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                                              dstA = dstA */
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    SDL_BLENDMODE_MUL = 0x00000008,      /**< color multiply
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                                              dstRGB = (srcRGB * dstRGB) + (dstRGB * (1-srcA))
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                                              dstA = dstA */
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    SDL_BLENDMODE_INVALID = 0x7FFFFFFF
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    /* Additional custom blend modes can be returned by SDL_ComposeCustomBlendMode() */
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} SDL_BlendMode;
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/**
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 *  \brief The blend operation used when combining source and destination pixel components
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 */
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typedef enum
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{
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    SDL_BLENDOPERATION_ADD              = 0x1,  /**< dst + src: supported by all renderers */
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    SDL_BLENDOPERATION_SUBTRACT         = 0x2,  /**< dst - src : supported by D3D9, D3D11, OpenGL, OpenGLES */
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    SDL_BLENDOPERATION_REV_SUBTRACT     = 0x3,  /**< src - dst : supported by D3D9, D3D11, OpenGL, OpenGLES */
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    SDL_BLENDOPERATION_MINIMUM          = 0x4,  /**< min(dst, src) : supported by D3D9, D3D11 */
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    SDL_BLENDOPERATION_MAXIMUM          = 0x5   /**< max(dst, src) : supported by D3D9, D3D11 */
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} SDL_BlendOperation;
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/**
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 *  \brief The normalized factor used to multiply pixel components
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 */
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typedef enum
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{
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    SDL_BLENDFACTOR_ZERO                = 0x1,  /**< 0, 0, 0, 0 */
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    SDL_BLENDFACTOR_ONE                 = 0x2,  /**< 1, 1, 1, 1 */
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    SDL_BLENDFACTOR_SRC_COLOR           = 0x3,  /**< srcR, srcG, srcB, srcA */
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    SDL_BLENDFACTOR_ONE_MINUS_SRC_COLOR = 0x4,  /**< 1-srcR, 1-srcG, 1-srcB, 1-srcA */
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    SDL_BLENDFACTOR_SRC_ALPHA           = 0x5,  /**< srcA, srcA, srcA, srcA */
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    SDL_BLENDFACTOR_ONE_MINUS_SRC_ALPHA = 0x6,  /**< 1-srcA, 1-srcA, 1-srcA, 1-srcA */
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    SDL_BLENDFACTOR_DST_COLOR           = 0x7,  /**< dstR, dstG, dstB, dstA */
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    SDL_BLENDFACTOR_ONE_MINUS_DST_COLOR = 0x8,  /**< 1-dstR, 1-dstG, 1-dstB, 1-dstA */
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    SDL_BLENDFACTOR_DST_ALPHA           = 0x9,  /**< dstA, dstA, dstA, dstA */
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    SDL_BLENDFACTOR_ONE_MINUS_DST_ALPHA = 0xA   /**< 1-dstA, 1-dstA, 1-dstA, 1-dstA */
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} SDL_BlendFactor;
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/**
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 * Compose a custom blend mode for renderers.
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 *
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 * The functions SDL_SetRenderDrawBlendMode and SDL_SetTextureBlendMode accept
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 * the SDL_BlendMode returned by this function if the renderer supports it.
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 *
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 * A blend mode controls how the pixels from a drawing operation (source) get
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 * combined with the pixels from the render target (destination). First, the
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 * components of the source and destination pixels get multiplied with their
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 * blend factors. Then, the blend operation takes the two products and
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 * calculates the result that will get stored in the render target.
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 *
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 * Expressed in pseudocode, it would look like this:
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 *
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 * ```c
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 * dstRGB = colorOperation(srcRGB * srcColorFactor, dstRGB * dstColorFactor);
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 * dstA = alphaOperation(srcA * srcAlphaFactor, dstA * dstAlphaFactor);
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 * ```
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 *
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 * Where the functions `colorOperation(src, dst)` and `alphaOperation(src,
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 * dst)` can return one of the following:
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 *
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 * - `src + dst`
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 * - `src - dst`
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 * - `dst - src`
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 * - `min(src, dst)`
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 * - `max(src, dst)`
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 *
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 * The red, green, and blue components are always multiplied with the first,
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 * second, and third components of the SDL_BlendFactor, respectively. The
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 * fourth component is not used.
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 *
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 * The alpha component is always multiplied with the fourth component of the
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 * SDL_BlendFactor. The other components are not used in the alpha
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 * calculation.
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 *
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 * Support for these blend modes varies for each renderer. To check if a
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 * specific SDL_BlendMode is supported, create a renderer and pass it to
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 * either SDL_SetRenderDrawBlendMode or SDL_SetTextureBlendMode. They will
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 * return with an error if the blend mode is not supported.
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 *
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 * This list describes the support of custom blend modes for each renderer in
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 * SDL 2.0.6. All renderers support the four blend modes listed in the
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 * SDL_BlendMode enumeration.
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 *
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 * - **direct3d**: Supports all operations with all factors. However, some
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 *   factors produce unexpected results with `SDL_BLENDOPERATION_MINIMUM` and
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 *   `SDL_BLENDOPERATION_MAXIMUM`.
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 * - **direct3d11**: Same as Direct3D 9.
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 * - **opengl**: Supports the `SDL_BLENDOPERATION_ADD` operation with all
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 *   factors. OpenGL versions 1.1, 1.2, and 1.3 do not work correctly with SDL
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 *   2.0.6.
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 * - **opengles**: Supports the `SDL_BLENDOPERATION_ADD` operation with all
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 *   factors. Color and alpha factors need to be the same. OpenGL ES 1
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 *   implementation specific: May also support `SDL_BLENDOPERATION_SUBTRACT`
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 *   and `SDL_BLENDOPERATION_REV_SUBTRACT`. May support color and alpha
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 *   operations being different from each other. May support color and alpha
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 *   factors being different from each other.
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 * - **opengles2**: Supports the `SDL_BLENDOPERATION_ADD`,
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 *   `SDL_BLENDOPERATION_SUBTRACT`, `SDL_BLENDOPERATION_REV_SUBTRACT`
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 *   operations with all factors.
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 * - **psp**: No custom blend mode support.
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 * - **software**: No custom blend mode support.
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 *
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 * Some renderers do not provide an alpha component for the default render
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 * target. The `SDL_BLENDFACTOR_DST_ALPHA` and
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 * `SDL_BLENDFACTOR_ONE_MINUS_DST_ALPHA` factors do not have an effect in this
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 * case.
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 *
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 * \param srcColorFactor the SDL_BlendFactor applied to the red, green, and
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 *                       blue components of the source pixels
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 * \param dstColorFactor the SDL_BlendFactor applied to the red, green, and
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 *                       blue components of the destination pixels
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 * \param colorOperation the SDL_BlendOperation used to combine the red,
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 *                       green, and blue components of the source and
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 *                       destination pixels
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 * \param srcAlphaFactor the SDL_BlendFactor applied to the alpha component of
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 *                       the source pixels
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 * \param dstAlphaFactor the SDL_BlendFactor applied to the alpha component of
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 *                       the destination pixels
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 * \param alphaOperation the SDL_BlendOperation used to combine the alpha
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 *                       component of the source and destination pixels
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 * \returns an SDL_BlendMode that represents the chosen factors and
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 *          operations.
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 *
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 * \since This function is available since SDL 2.0.6.
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 *
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 * \sa SDL_SetRenderDrawBlendMode
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 * \sa SDL_GetRenderDrawBlendMode
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 * \sa SDL_SetTextureBlendMode
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 * \sa SDL_GetTextureBlendMode
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 */
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extern DECLSPEC SDL_BlendMode SDLCALL SDL_ComposeCustomBlendMode(SDL_BlendFactor srcColorFactor,
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                                                                 SDL_BlendFactor dstColorFactor,
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                                                                 SDL_BlendOperation colorOperation,
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                                                                 SDL_BlendFactor srcAlphaFactor,
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                                                                 SDL_BlendFactor dstAlphaFactor,
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                                                                 SDL_BlendOperation alphaOperation);
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/* Ends C function definitions when using C++ */
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#ifdef __cplusplus
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}
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#endif
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#include "close_code.h"
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#endif /* SDL_blendmode_h_ */
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/* vi: set ts=4 sw=4 expandtab: */