SDL_UpdateRect在双缓冲屏幕上的精确时序和效果如何？
使用双缓冲屏幕和Simple DirectMedia Layer，调用SDL_UpdateRect 在位图传输多个图像后调用一次，或者在位图传输每个单独的图像后调用一次在调用 SDL_Flip 之前？换句话说，SDL_UpdateRect 会导致屏幕立即更新，或者它只是告诉简单 DirectMedia 层在屏幕翻转时必须更新哪些区域？它通常应该如何与双缓冲屏幕一起使用？
作为参考，以下是 SDL_UpdateRect 的描述。
确保给定区域在给定屏幕上更新。这 矩形必须限制在屏幕边界内（无裁剪 完成）。
如果“x”、“y”、“w”和“h”均为 0 ,
SDL_UpdateRect将更新 整个屏幕。
Using a double-buffered screen with the Simple DirectMedia Layer, is it more efficient to call SDL_UpdateRect once after blitting multiple images or to call it once after blitting each individual image before calling SDL_Flip? In other words, will SDL_UpdateRect cause the screen to be updated immediately, or does it simply tell the Simple DirectMedia Layer which areas must be updated when the screen is flipped? How should it typically be used with a double-buffered screen?
For reference, here is the description of SDL_UpdateRect.
Makes sure the given area is updated on the given screen. The
rectangle must be confined within the screen boundaries (no clipping
is done).If 'x', 'y', 'w' and 'h' are all 0,
SDL_UpdateRectwill update the
entire screen.
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是的，
SDL_UpdateRect立即更新屏幕（或矩形）。不需要联合使用
SDL_UpdateRect和SDL_Flip，它们做同样的事情但方式不同。区别在于，
SDL_UpdateRect只能更新部分屏幕（通过将像素从表面复制到屏幕来工作），而SDL_Flip则刷新整个屏幕（通过翻转来工作）缓冲区）。因此，如果您使用双缓冲屏幕，则无需调用
SDL_UpdateRect，只需在所有 blits 之后调用SDL_Flip即可。http://www.libsdl.org/docs/html/sdlsetvideomode.html
不要忘记，双缓冲仅适用于
SDL_HWSURFACE和SDL_FULLSCREEN视频模式。Yes,
SDL_UpdateRectupdate screen (or rect) immediately.No need to use the
SDL_UpdateRectandSDL_Flipjointly, they do the same things but different ways.The difference is that
SDL_UpdateRectcan update only part of the screen (and work by copying pixels from your surface to screen), andSDL_Fliprefresh the entire screen (and works by flip buffers).So, if you use double-buffered screen no need to call
SDL_UpdateRect, just callSDL_Flipafter all blits.http://www.libsdl.org/docs/html/sdlsetvideomode.html
And don't forget that double buffering works only with
SDL_HWSURFACEandSDL_FULLSCREENvideo mode.