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981e0d367c
Konrad This kind of blending is rather quite useful and in my opinion should be available for all renderers. I do need it myself, but since I didn't want to use a custom blending mode which is supported only by certain renderers (e.g. not in software which is quite important for me) I did write implementation of SDL_BLENDMODE_MUL for all renderers altogether. SDL_BLENDMODE_MUL implements following equation: dstRGB = (srcRGB * dstRGB) + (dstRGB * (1-srcA)) dstA = (srcA * dstA) + (dstA * (1-srcA)) Background: https://i.imgur.com/UsYhydP.png Blended texture: https://i.imgur.com/0juXQcV.png Result for SDL_BLENDMODE_MOD: https://i.imgur.com/wgNSgUl.png Result for SDL_BLENDMODE_MUL: https://i.imgur.com/Veokzim.png I think I did cover all possibilities within included patch, but I didn't write any tests for SDL_BLENDMODE_MUL, so it would be lovely if someone could do it.
124 lines
5.2 KiB
C
124 lines
5.2 KiB
C
/*
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Simple DirectMedia Layer
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Copyright (C) 1997-2019 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 = (srcA * dstA) + (dstA * (1-srcA)) */
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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 D3D11 */
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SDL_BLENDOPERATION_MAXIMUM = 0x5 /**< max(dst, src) : supported by 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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* \brief Create a custom blend mode, which may or may not be supported by a given renderer
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*
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* \param srcColorFactor source color factor
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* \param dstColorFactor destination color factor
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* \param colorOperation color operation
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* \param srcAlphaFactor source alpha factor
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* \param dstAlphaFactor destination alpha factor
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* \param alphaOperation alpha operation
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*
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* The result of the blend mode operation will be:
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* dstRGB = dstRGB * dstColorFactor colorOperation srcRGB * srcColorFactor
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* and
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* dstA = dstA * dstAlphaFactor alphaOperation srcA * srcAlphaFactor
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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: */
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