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1
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1 /*
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2 Simple DirectMedia Layer
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3 Copyright (C) 1997-2025 Sam Lantinga <slouken@libsdl.org>
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4
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5 This software is provided 'as-is', without any express or implied
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6 warranty. In no event will the authors be held liable for any damages
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7 arising from the use of this software.
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8
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9 Permission is granted to anyone to use this software for any purpose,
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10 including commercial applications, and to alter it and redistribute it
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11 freely, subject to the following restrictions:
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12
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13 1. The origin of this software must not be misrepresented; you must not
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14 claim that you wrote the original software. If you use this software
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15 in a product, an acknowledgment in the product documentation would be
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16 appreciated but is not required.
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17 2. Altered source versions must be plainly marked as such, and must not be
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18 misrepresented as being the original software.
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19 3. This notice may not be removed or altered from any source distribution.
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20 */
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21
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22 /**
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23 * # CategoryBlendmode
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24 *
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25 * Blend modes decide how two colors will mix together. There are both
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26 * standard modes for basic needs and a means to create custom modes,
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27 * dictating what sort of math to do on what color components.
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28 */
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29
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30 #ifndef SDL_blendmode_h_
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31 #define SDL_blendmode_h_
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32
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33 #include <SDL3/SDL_stdinc.h>
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34
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35 #include <SDL3/SDL_begin_code.h>
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36 /* Set up for C function definitions, even when using C++ */
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37 #ifdef __cplusplus
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38 extern "C" {
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39 #endif
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40
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41 /**
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42 * A set of blend modes used in drawing operations.
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43 *
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44 * These predefined blend modes are supported everywhere.
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45 *
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46 * Additional values may be obtained from SDL_ComposeCustomBlendMode.
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47 *
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48 * \since This datatype is available since SDL 3.2.0.
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49 *
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50 * \sa SDL_ComposeCustomBlendMode
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51 */
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52 typedef Uint32 SDL_BlendMode;
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53
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54 #define SDL_BLENDMODE_NONE 0x00000000u /**< no blending: dstRGBA = srcRGBA */
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55 #define SDL_BLENDMODE_BLEND 0x00000001u /**< alpha blending: dstRGB = (srcRGB * srcA) + (dstRGB * (1-srcA)), dstA = srcA + (dstA * (1-srcA)) */
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56 #define SDL_BLENDMODE_BLEND_PREMULTIPLIED 0x00000010u /**< pre-multiplied alpha blending: dstRGBA = srcRGBA + (dstRGBA * (1-srcA)) */
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57 #define SDL_BLENDMODE_ADD 0x00000002u /**< additive blending: dstRGB = (srcRGB * srcA) + dstRGB, dstA = dstA */
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58 #define SDL_BLENDMODE_ADD_PREMULTIPLIED 0x00000020u /**< pre-multiplied additive blending: dstRGB = srcRGB + dstRGB, dstA = dstA */
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59 #define SDL_BLENDMODE_MOD 0x00000004u /**< color modulate: dstRGB = srcRGB * dstRGB, dstA = dstA */
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60 #define SDL_BLENDMODE_MUL 0x00000008u /**< color multiply: dstRGB = (srcRGB * dstRGB) + (dstRGB * (1-srcA)), dstA = dstA */
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61 #define SDL_BLENDMODE_INVALID 0x7FFFFFFFu
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62
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63 /**
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64 * The blend operation used when combining source and destination pixel
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65 * components.
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66 *
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67 * \since This enum is available since SDL 3.2.0.
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68 */
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69 typedef enum SDL_BlendOperation
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70 {
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71 SDL_BLENDOPERATION_ADD = 0x1, /**< dst + src: supported by all renderers */
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72 SDL_BLENDOPERATION_SUBTRACT = 0x2, /**< src - dst : supported by D3D, OpenGL, OpenGLES, and Vulkan */
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73 SDL_BLENDOPERATION_REV_SUBTRACT = 0x3, /**< dst - src : supported by D3D, OpenGL, OpenGLES, and Vulkan */
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74 SDL_BLENDOPERATION_MINIMUM = 0x4, /**< min(dst, src) : supported by D3D, OpenGL, OpenGLES, and Vulkan */
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75 SDL_BLENDOPERATION_MAXIMUM = 0x5 /**< max(dst, src) : supported by D3D, OpenGL, OpenGLES, and Vulkan */
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76 } SDL_BlendOperation;
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77
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78 /**
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79 * The normalized factor used to multiply pixel components.
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80 *
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81 * The blend factors are multiplied with the pixels from a drawing operation
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82 * (src) and the pixels from the render target (dst) before the blend
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83 * operation. The comma-separated factors listed above are always applied in
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84 * the component order red, green, blue, and alpha.
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85 *
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86 * \since This enum is available since SDL 3.2.0.
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87 */
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88 typedef enum SDL_BlendFactor
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89 {
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90 SDL_BLENDFACTOR_ZERO = 0x1, /**< 0, 0, 0, 0 */
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91 SDL_BLENDFACTOR_ONE = 0x2, /**< 1, 1, 1, 1 */
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92 SDL_BLENDFACTOR_SRC_COLOR = 0x3, /**< srcR, srcG, srcB, srcA */
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93 SDL_BLENDFACTOR_ONE_MINUS_SRC_COLOR = 0x4, /**< 1-srcR, 1-srcG, 1-srcB, 1-srcA */
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94 SDL_BLENDFACTOR_SRC_ALPHA = 0x5, /**< srcA, srcA, srcA, srcA */
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95 SDL_BLENDFACTOR_ONE_MINUS_SRC_ALPHA = 0x6, /**< 1-srcA, 1-srcA, 1-srcA, 1-srcA */
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96 SDL_BLENDFACTOR_DST_COLOR = 0x7, /**< dstR, dstG, dstB, dstA */
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97 SDL_BLENDFACTOR_ONE_MINUS_DST_COLOR = 0x8, /**< 1-dstR, 1-dstG, 1-dstB, 1-dstA */
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98 SDL_BLENDFACTOR_DST_ALPHA = 0x9, /**< dstA, dstA, dstA, dstA */
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99 SDL_BLENDFACTOR_ONE_MINUS_DST_ALPHA = 0xA /**< 1-dstA, 1-dstA, 1-dstA, 1-dstA */
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100 } SDL_BlendFactor;
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101
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102 /**
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103 * Compose a custom blend mode for renderers.
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104 *
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105 * The functions SDL_SetRenderDrawBlendMode and SDL_SetTextureBlendMode accept
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106 * the SDL_BlendMode returned by this function if the renderer supports it.
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107 *
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108 * A blend mode controls how the pixels from a drawing operation (source) get
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109 * combined with the pixels from the render target (destination). First, the
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110 * components of the source and destination pixels get multiplied with their
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111 * blend factors. Then, the blend operation takes the two products and
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112 * calculates the result that will get stored in the render target.
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113 *
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114 * Expressed in pseudocode, it would look like this:
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115 *
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116 * ```c
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117 * dstRGB = colorOperation(srcRGB * srcColorFactor, dstRGB * dstColorFactor);
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118 * dstA = alphaOperation(srcA * srcAlphaFactor, dstA * dstAlphaFactor);
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119 * ```
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120 *
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121 * Where the functions `colorOperation(src, dst)` and `alphaOperation(src,
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122 * dst)` can return one of the following:
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123 *
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124 * - `src + dst`
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125 * - `src - dst`
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126 * - `dst - src`
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127 * - `min(src, dst)`
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128 * - `max(src, dst)`
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129 *
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130 * The red, green, and blue components are always multiplied with the first,
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131 * second, and third components of the SDL_BlendFactor, respectively. The
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132 * fourth component is not used.
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133 *
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134 * The alpha component is always multiplied with the fourth component of the
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135 * SDL_BlendFactor. The other components are not used in the alpha
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136 * calculation.
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137 *
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138 * Support for these blend modes varies for each renderer. To check if a
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139 * specific SDL_BlendMode is supported, create a renderer and pass it to
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140 * either SDL_SetRenderDrawBlendMode or SDL_SetTextureBlendMode. They will
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141 * return with an error if the blend mode is not supported.
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142 *
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143 * This list describes the support of custom blend modes for each renderer.
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144 * All renderers support the four blend modes listed in the SDL_BlendMode
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145 * enumeration.
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146 *
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147 * - **direct3d**: Supports all operations with all factors. However, some
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148 * factors produce unexpected results with `SDL_BLENDOPERATION_MINIMUM` and
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149 * `SDL_BLENDOPERATION_MAXIMUM`.
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150 * - **direct3d11**: Same as Direct3D 9.
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151 * - **opengl**: Supports the `SDL_BLENDOPERATION_ADD` operation with all
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152 * factors. OpenGL versions 1.1, 1.2, and 1.3 do not work correctly here.
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153 * - **opengles2**: Supports the `SDL_BLENDOPERATION_ADD`,
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154 * `SDL_BLENDOPERATION_SUBTRACT`, `SDL_BLENDOPERATION_REV_SUBTRACT`
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155 * operations with all factors.
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156 * - **psp**: No custom blend mode support.
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157 * - **software**: No custom blend mode support.
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158 *
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159 * Some renderers do not provide an alpha component for the default render
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160 * target. The `SDL_BLENDFACTOR_DST_ALPHA` and
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161 * `SDL_BLENDFACTOR_ONE_MINUS_DST_ALPHA` factors do not have an effect in this
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162 * case.
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163 *
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164 * \param srcColorFactor the SDL_BlendFactor applied to the red, green, and
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165 * blue components of the source pixels.
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166 * \param dstColorFactor the SDL_BlendFactor applied to the red, green, and
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167 * blue components of the destination pixels.
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168 * \param colorOperation the SDL_BlendOperation used to combine the red,
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169 * green, and blue components of the source and
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170 * destination pixels.
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171 * \param srcAlphaFactor the SDL_BlendFactor applied to the alpha component of
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172 * the source pixels.
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173 * \param dstAlphaFactor the SDL_BlendFactor applied to the alpha component of
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174 * the destination pixels.
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175 * \param alphaOperation the SDL_BlendOperation used to combine the alpha
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176 * component of the source and destination pixels.
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177 * \returns an SDL_BlendMode that represents the chosen factors and
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178 * operations.
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179 *
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180 * \threadsafety It is safe to call this function from any thread.
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181 *
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182 * \since This function is available since SDL 3.2.0.
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183 *
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184 * \sa SDL_SetRenderDrawBlendMode
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185 * \sa SDL_GetRenderDrawBlendMode
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186 * \sa SDL_SetTextureBlendMode
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187 * \sa SDL_GetTextureBlendMode
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188 */
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189 extern SDL_DECLSPEC SDL_BlendMode SDLCALL SDL_ComposeCustomBlendMode(SDL_BlendFactor srcColorFactor,
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190 SDL_BlendFactor dstColorFactor,
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191 SDL_BlendOperation colorOperation,
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192 SDL_BlendFactor srcAlphaFactor,
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193 SDL_BlendFactor dstAlphaFactor,
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194 SDL_BlendOperation alphaOperation);
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195
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196 /* Ends C function definitions when using C++ */
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197 #ifdef __cplusplus
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198 }
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199 #endif
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200 #include <SDL3/SDL_close_code.h>
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201
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202 #endif /* SDL_blendmode_h_ */
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