1 /* 2 Simple DirectMedia Layer 3 Copyright (C) 1997-2021 Sam Lantinga <slouken@libsdl.org> 4 5 This software is provided 'as-is', without any express or implied 6 warranty. In no event will the authors be held liable for any damages 7 arising from the use of this software. 8 9 Permission is granted to anyone to use this software for any purpose, 10 including commercial applications, and to alter it and redistribute it 11 freely, subject to the following restrictions: 12 13 1. The origin of this software must not be misrepresented; you must not 14 claim that you wrote the original software. If you use this software 15 in a product, an acknowledgment in the product documentation would be 16 appreciated but is not required. 17 2. Altered source versions must be plainly marked as such, and must not be 18 misrepresented as being the original software. 19 3. This notice may not be removed or altered from any source distribution. 20 */ 21 22 /** 23 * \file SDL_blendmode.h 24 * 25 * Header file declaring the SDL_BlendMode enumeration 26 */ 27 28 #ifndef SDL_blendmode_h_ 29 #define SDL_blendmode_h_ 30 31 #include "begin_code.h" 32 /* Set up for C function definitions, even when using C++ */ 33 #ifdef __cplusplus 34 extern "C" { 35 #endif 36 37 /** 38 * \brief The blend mode used in SDL_RenderCopy() and drawing operations. 39 */ 40 typedef enum 41 { 42 SDL_BLENDMODE_NONE = 0x00000000, /**< no blending 43 dstRGBA = srcRGBA */ 44 SDL_BLENDMODE_BLEND = 0x00000001, /**< alpha blending 45 dstRGB = (srcRGB * srcA) + (dstRGB * (1-srcA)) 46 dstA = srcA + (dstA * (1-srcA)) */ 47 SDL_BLENDMODE_ADD = 0x00000002, /**< additive blending 48 dstRGB = (srcRGB * srcA) + dstRGB 49 dstA = dstA */ 50 SDL_BLENDMODE_MOD = 0x00000004, /**< color modulate 51 dstRGB = srcRGB * dstRGB 52 dstA = dstA */ 53 SDL_BLENDMODE_MUL = 0x00000008, /**< color multiply 54 dstRGB = (srcRGB * dstRGB) + (dstRGB * (1-srcA)) 55 dstA = (srcA * dstA) + (dstA * (1-srcA)) */ 56 SDL_BLENDMODE_INVALID = 0x7FFFFFFF 57 58 /* Additional custom blend modes can be returned by SDL_ComposeCustomBlendMode() */ 59 60 } SDL_BlendMode; 61 62 /** 63 * \brief The blend operation used when combining source and destination pixel components 64 */ 65 typedef enum 66 { 67 SDL_BLENDOPERATION_ADD = 0x1, /**< dst + src: supported by all renderers */ 68 SDL_BLENDOPERATION_SUBTRACT = 0x2, /**< dst - src : supported by D3D9, D3D11, OpenGL, OpenGLES */ 69 SDL_BLENDOPERATION_REV_SUBTRACT = 0x3, /**< src - dst : supported by D3D9, D3D11, OpenGL, OpenGLES */ 70 SDL_BLENDOPERATION_MINIMUM = 0x4, /**< min(dst, src) : supported by D3D11 */ 71 SDL_BLENDOPERATION_MAXIMUM = 0x5 /**< max(dst, src) : supported by D3D11 */ 72 73 } SDL_BlendOperation; 74 75 /** 76 * \brief The normalized factor used to multiply pixel components 77 */ 78 typedef enum 79 { 80 SDL_BLENDFACTOR_ZERO = 0x1, /**< 0, 0, 0, 0 */ 81 SDL_BLENDFACTOR_ONE = 0x2, /**< 1, 1, 1, 1 */ 82 SDL_BLENDFACTOR_SRC_COLOR = 0x3, /**< srcR, srcG, srcB, srcA */ 83 SDL_BLENDFACTOR_ONE_MINUS_SRC_COLOR = 0x4, /**< 1-srcR, 1-srcG, 1-srcB, 1-srcA */ 84 SDL_BLENDFACTOR_SRC_ALPHA = 0x5, /**< srcA, srcA, srcA, srcA */ 85 SDL_BLENDFACTOR_ONE_MINUS_SRC_ALPHA = 0x6, /**< 1-srcA, 1-srcA, 1-srcA, 1-srcA */ 86 SDL_BLENDFACTOR_DST_COLOR = 0x7, /**< dstR, dstG, dstB, dstA */ 87 SDL_BLENDFACTOR_ONE_MINUS_DST_COLOR = 0x8, /**< 1-dstR, 1-dstG, 1-dstB, 1-dstA */ 88 SDL_BLENDFACTOR_DST_ALPHA = 0x9, /**< dstA, dstA, dstA, dstA */ 89 SDL_BLENDFACTOR_ONE_MINUS_DST_ALPHA = 0xA /**< 1-dstA, 1-dstA, 1-dstA, 1-dstA */ 90 91 } SDL_BlendFactor; 92 93 /** 94 * Compose a custom blend mode for renderers. 95 * 96 * The functions SDL_SetRenderDrawBlendMode and SDL_SetTextureBlendMode accept 97 * the SDL_BlendMode returned by this function if the renderer supports it. 98 * 99 * A blend mode controls how the pixels from a drawing operation (source) get 100 * combined with the pixels from the render target (destination). First, the 101 * components of the source and destination pixels get multiplied with their 102 * blend factors. Then, the blend operation takes the two products and 103 * calculates the result that will get stored in the render target. 104 * 105 * Expressed in pseudocode, it would look like this: 106 * 107 * ```c 108 * dstRGB = colorOperation(srcRGB * srcColorFactor, dstRGB * dstColorFactor); 109 * dstA = alphaOperation(srcA * srcAlphaFactor, dstA * dstAlphaFactor); 110 * ``` 111 * 112 * Where the functions `colorOperation(src, dst)` and `alphaOperation(src, 113 * dst)` can return one of the following: 114 * 115 * - `src + dst` 116 * - `src - dst` 117 * - `dst - src` 118 * - `min(src, dst)` 119 * - `max(src, dst)` 120 * 121 * The red, green, and blue components are always multiplied with the first, 122 * second, and third components of the SDL_BlendFactor, respectively. The 123 * fourth component is not used. 124 * 125 * The alpha component is always multiplied with the fourth component of the 126 * SDL_BlendFactor. The other components are not used in the alpha 127 * calculation. 128 * 129 * Support for these blend modes varies for each renderer. To check if a 130 * specific SDL_BlendMode is supported, create a renderer and pass it to 131 * either SDL_SetRenderDrawBlendMode or SDL_SetTextureBlendMode. They will 132 * return with an error if the blend mode is not supported. 133 * 134 * This list describes the support of custom blend modes for each renderer in 135 * SDL 2.0.6. All renderers support the four blend modes listed in the 136 * SDL_BlendMode enumeration. 137 * 138 * - **direct3d**: Supports `SDL_BLENDOPERATION_ADD` with all factors. 139 * - **direct3d11**: Supports all operations with all factors. However, some 140 * factors produce unexpected results with `SDL_BLENDOPERATION_MINIMUM` and 141 * `SDL_BLENDOPERATION_MAXIMUM`. 142 * - **opengl**: Supports the `SDL_BLENDOPERATION_ADD` operation with all 143 * factors. OpenGL versions 1.1, 1.2, and 1.3 do not work correctly with SDL 144 * 2.0.6. 145 * - **opengles**: Supports the `SDL_BLENDOPERATION_ADD` operation with all 146 * factors. Color and alpha factors need to be the same. OpenGL ES 1 147 * implementation specific: May also support `SDL_BLENDOPERATION_SUBTRACT` 148 * and `SDL_BLENDOPERATION_REV_SUBTRACT`. May support color and alpha 149 * operations being different from each other. May support color and alpha 150 * factors being different from each other. 151 * - **opengles2**: Supports the `SDL_BLENDOPERATION_ADD`, 152 * `SDL_BLENDOPERATION_SUBTRACT`, `SDL_BLENDOPERATION_REV_SUBTRACT` 153 * operations with all factors. 154 * - **psp**: No custom blend mode support. 155 * - **software**: No custom blend mode support. 156 * 157 * Some renderers do not provide an alpha component for the default render 158 * target. The `SDL_BLENDFACTOR_DST_ALPHA` and 159 * `SDL_BLENDFACTOR_ONE_MINUS_DST_ALPHA` factors do not have an effect in this 160 * case. 161 * 162 * \param srcColorFactor the SDL_BlendFactor applied to the red, green, and 163 * blue components of the source pixels 164 * \param dstColorFactor the SDL_BlendFactor applied to the red, green, and 165 * blue components of the destination pixels 166 * \param colorOperation the SDL_BlendOperation used to combine the red, 167 * green, and blue components of the source and 168 * destination pixels 169 * \param srcAlphaFactor the SDL_BlendFactor applied to the alpha component of 170 * the source pixels 171 * \param dstAlphaFactor the SDL_BlendFactor applied to the alpha component of 172 * the destination pixels 173 * \param alphaOperation the SDL_BlendOperation used to combine the alpha 174 * component of the source and destination pixels 175 * \returns an SDL_BlendMode that represents the chosen factors and 176 * operations. 177 * 178 * \since This function is available in SDL 2.0.6. 179 * 180 * \sa SDL_SetRenderDrawBlendMode 181 * \sa SDL_GetRenderDrawBlendMode 182 * \sa SDL_SetTextureBlendMode 183 * \sa SDL_GetTextureBlendMode 184 */ 185 extern DECLSPEC SDL_BlendMode SDLCALL SDL_ComposeCustomBlendMode(SDL_BlendFactor srcColorFactor, 186 SDL_BlendFactor dstColorFactor, 187 SDL_BlendOperation colorOperation, 188 SDL_BlendFactor srcAlphaFactor, 189 SDL_BlendFactor dstAlphaFactor, 190 SDL_BlendOperation alphaOperation); 191 192 /* Ends C function definitions when using C++ */ 193 #ifdef __cplusplus 194 } 195 #endif 196 #include "close_code.h" 197 198 #endif /* SDL_blendmode_h_ */ 199 200 /* vi: set ts=4 sw=4 expandtab: */ 201