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+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2022 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+/**
+ *  \file SDL_blendmode.h
+ *
+ *  Header file declaring the SDL_BlendMode enumeration
+ */
+
+#ifndef SDL_blendmode_h_
+#define SDL_blendmode_h_
+
+#include "begin_code.h"
+/* Set up for C function definitions, even when using C++ */
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ *  \brief The blend mode used in SDL_RenderCopy() and drawing operations.
+ */
+typedef enum
+{
+    SDL_BLENDMODE_NONE = 0x00000000,     /**< no blending
+                                              dstRGBA = srcRGBA */
+    SDL_BLENDMODE_BLEND = 0x00000001,    /**< alpha blending
+                                              dstRGB = (srcRGB * srcA) + (dstRGB * (1-srcA))
+                                              dstA = srcA + (dstA * (1-srcA)) */
+    SDL_BLENDMODE_ADD = 0x00000002,      /**< additive blending
+                                              dstRGB = (srcRGB * srcA) + dstRGB
+                                              dstA = dstA */
+    SDL_BLENDMODE_MOD = 0x00000004,      /**< color modulate
+                                              dstRGB = srcRGB * dstRGB
+                                              dstA = dstA */
+    SDL_BLENDMODE_MUL = 0x00000008,      /**< color multiply
+                                              dstRGB = (srcRGB * dstRGB) + (dstRGB * (1-srcA))
+                                              dstA = (srcA * dstA) + (dstA * (1-srcA)) */
+    SDL_BLENDMODE_INVALID = 0x7FFFFFFF
+
+    /* Additional custom blend modes can be returned by SDL_ComposeCustomBlendMode() */
+
+} SDL_BlendMode;
+
+/**
+ *  \brief The blend operation used when combining source and destination pixel components
+ */
+typedef enum
+{
+    SDL_BLENDOPERATION_ADD              = 0x1,  /**< dst + src: supported by all renderers */
+    SDL_BLENDOPERATION_SUBTRACT         = 0x2,  /**< dst - src : supported by D3D9, D3D11, OpenGL, OpenGLES */
+    SDL_BLENDOPERATION_REV_SUBTRACT     = 0x3,  /**< src - dst : supported by D3D9, D3D11, OpenGL, OpenGLES */
+    SDL_BLENDOPERATION_MINIMUM          = 0x4,  /**< min(dst, src) : supported by D3D11 */
+    SDL_BLENDOPERATION_MAXIMUM          = 0x5   /**< max(dst, src) : supported by D3D11 */
+
+} SDL_BlendOperation;
+
+/**
+ *  \brief The normalized factor used to multiply pixel components
+ */
+typedef enum
+{
+    SDL_BLENDFACTOR_ZERO                = 0x1,  /**< 0, 0, 0, 0 */
+    SDL_BLENDFACTOR_ONE                 = 0x2,  /**< 1, 1, 1, 1 */
+    SDL_BLENDFACTOR_SRC_COLOR           = 0x3,  /**< srcR, srcG, srcB, srcA */
+    SDL_BLENDFACTOR_ONE_MINUS_SRC_COLOR = 0x4,  /**< 1-srcR, 1-srcG, 1-srcB, 1-srcA */
+    SDL_BLENDFACTOR_SRC_ALPHA           = 0x5,  /**< srcA, srcA, srcA, srcA */
+    SDL_BLENDFACTOR_ONE_MINUS_SRC_ALPHA = 0x6,  /**< 1-srcA, 1-srcA, 1-srcA, 1-srcA */
+    SDL_BLENDFACTOR_DST_COLOR           = 0x7,  /**< dstR, dstG, dstB, dstA */
+    SDL_BLENDFACTOR_ONE_MINUS_DST_COLOR = 0x8,  /**< 1-dstR, 1-dstG, 1-dstB, 1-dstA */
+    SDL_BLENDFACTOR_DST_ALPHA           = 0x9,  /**< dstA, dstA, dstA, dstA */
+    SDL_BLENDFACTOR_ONE_MINUS_DST_ALPHA = 0xA   /**< 1-dstA, 1-dstA, 1-dstA, 1-dstA */
+
+} SDL_BlendFactor;
+
+/**
+ * Compose a custom blend mode for renderers.
+ *
+ * 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:
+ *
+ * ```c
+ * 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 in
+ * SDL 2.0.6. All renderers support the four blend modes listed in the
+ * SDL_BlendMode enumeration.
+ *
+ * - **direct3d**: Supports `SDL_BLENDOPERATION_ADD` with all factors.
+ * - **direct3d11**: Supports all operations with all factors. However, some
+ *   factors produce unexpected results with `SDL_BLENDOPERATION_MINIMUM` and
+ *   `SDL_BLENDOPERATION_MAXIMUM`.
+ * - **opengl**: Supports the `SDL_BLENDOPERATION_ADD` operation with all
+ *   factors. OpenGL versions 1.1, 1.2, and 1.3 do not work correctly with SDL
+ *   2.0.6.
+ * - **opengles**: Supports the `SDL_BLENDOPERATION_ADD` operation with all
+ *   factors. Color and alpha factors need to be the same. OpenGL ES 1
+ *   implementation specific: May also support `SDL_BLENDOPERATION_SUBTRACT`
+ *   and `SDL_BLENDOPERATION_REV_SUBTRACT`. May support color and alpha
+ *   operations being different from each other. May support color and alpha
+ *   factors being different from each other.
+ * - **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.
+ *
+ * \param srcColorFactor the SDL_BlendFactor applied to the red, green, and
+ *                       blue components of the source pixels
+ * \param dstColorFactor the SDL_BlendFactor applied to the red, green, and
+ *                       blue components of the destination pixels
+ * \param colorOperation the SDL_BlendOperation used to combine the red,
+ *                       green, and blue components of the source and
+ *                       destination pixels
+ * \param srcAlphaFactor the SDL_BlendFactor applied to the alpha component of
+ *                       the source pixels
+ * \param dstAlphaFactor the SDL_BlendFactor applied to the alpha component of
+ *                       the destination pixels
+ * \param alphaOperation the SDL_BlendOperation used to combine the alpha
+ *                       component of the source and destination pixels
+ * \returns an SDL_BlendMode that represents the chosen factors and
+ *          operations.
+ *
+ * \since This function is available since SDL 2.0.6.
+ *
+ * \sa SDL_SetRenderDrawBlendMode
+ * \sa SDL_GetRenderDrawBlendMode
+ * \sa SDL_SetTextureBlendMode
+ * \sa SDL_GetTextureBlendMode
+ */
+extern DECLSPEC SDL_BlendMode SDLCALL SDL_ComposeCustomBlendMode(SDL_BlendFactor srcColorFactor,
+                                                                 SDL_BlendFactor dstColorFactor,
+                                                                 SDL_BlendOperation colorOperation,
+                                                                 SDL_BlendFactor srcAlphaFactor,
+                                                                 SDL_BlendFactor dstAlphaFactor,
+                                                                 SDL_BlendOperation alphaOperation);
+
+/* Ends C function definitions when using C++ */
+#ifdef __cplusplus
+}
+#endif
+#include "close_code.h"
+
+#endif /* SDL_blendmode_h_ */
+
+/* vi: set ts=4 sw=4 expandtab: */