c – 仅当使用SDL_RENDERER_SOFTWARE创建渲染器时,SDL2程序才有效
作者：互联网
我用C和SDL2编写了一个程序：
>创建一个窗口
>获取窗口的表面
>为窗口创建渲染器
>将一些填充的矩形渲染到窗口上
>从窗口的表面创建纹理
>清除屏幕
>将一些实心圆圈渲染到窗口上
>从窗口的表面创建第二个纹理
>进入事件循环,每次按下一个键：
>如果当前正在显示圆圈,则使用SDL_RenderCopy()将方块纹理复制到窗口.
>否则,如果当前正在显示方块,则将圆形纹理复制到窗口.
如果使用SDL_RENDERER_SOFTWARE标志创建渲染器,则该程序可以正常工作.
如果使用SDL_RENDERER_ACCELERATED标志创建渲染器,我发现虽然我可以直接渲染到屏幕,但是如果我从窗口的表面创建了几个不同的纹理,然后尝试使用SDL_RenderCopy()将它们复制回窗口;我只看到一个黑色的窗户.
我找不到任何失败的SDL呼叫.
我想知道纹理格式和渲染器之间是否存在某些不兼容性 – 但我不确定如何跟进它.
任何帮助或建议？
我的环境是：
> Windows 10
> Visual Studio社区2015
> SDL2版本2.0.4
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其他信息和源代码：
我添加了减少的源代码来演示下面的问题.
请注意,为了减小大小,我删除了所有错误检查并将相关代码合并到一个主函数中.
我得到的是,如果我取消注释第40行,程序将按预期工作,以便我使用SDL_RENDERER_SOFTWARE标志调用SDL_CreateRenderer.
如果我取消注释任何其他SDL_CreateRenderer行(第41-43行：使用硬件加速),我会在最初渲染到屏幕时看到红色和蓝色方块.
但是当我按下按键时,而不是在红色和蓝色方块之间轻弹的窗口,我正在看一个黑色的窗口.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#include <SDL.h>
#include <SDL_image.h>
#include <stdio.h>
#include <string>
//Screen dimension constants
const int SCREEN_WIDTH = 640;
const int SCREEN_HEIGHT = 480;
int main(int argc, char* args[])
{
//The window we'll be rendering to
SDL_Window* gWindow = NULL;
//The surface contained by the window
SDL_Surface* gScreenSurface = NULL;
//And two textures, one for a red square, on for a blue square
SDL_Texture* texture_red = NULL;
SDL_Texture* texture_blue = NULL;
//The window renderer
SDL_Renderer* gRenderer = NULL;
//Initialize SDL
SDL_Init(SDL_INIT_VIDEO);
//Create window
gWindow = SDL_CreateWindow("SDL Tutorial", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, SCREEN_WIDTH, SCREEN_HEIGHT, SDL_WINDOW_SHOWN);
//Get the screen surface
gScreenSurface = SDL_GetWindowSurface(gWindow);
//Create renderer for window
gRenderer = SDL_CreateRenderer(gWindow, -1, SDL_RENDERER_SOFTWARE);
//gRenderer = SDL_CreateRenderer(gWindow, -1, SDL_RENDERER_ACCELERATED);
//gRenderer = SDL_CreateRenderer(gWindow, -1, SDL_RENDERER_PRESENTVSYNC);
//gRenderer = SDL_CreateRenderer(gWindow, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_TARGETTEXTURE);
/*###########################################################################################
# I can not figure out how to make this program work with hardware acceleration. It works #
# fine when I define the renderer using SDL_RENDERER_SOFTWARE, but doesn't display anything #
# if I define the renerer using the SDL_RENDERER_ACCELERATED flag #
###########################################################################################*/
//Initialize renderer color
SDL_SetRenderDrawColor(gRenderer, 0xFF, 0xFF, 0xFF, 0xFF);
//Clear screen
SDL_SetRenderDrawColor(gRenderer, 0xFF, 0xFF, 0xFF, 0xFF);
SDL_RenderClear(gRenderer);
//Render red filled quad
SDL_Rect fillRect = { 100, 75, 100, 100 };
SDL_SetRenderDrawColor(gRenderer, 0xFF, 0x00, 0x00, 0xFF);
SDL_RenderFillRect(gRenderer, &fillRect);
//Update the rendered image on screen
SDL_RenderPresent(gRenderer);
//Pause long enough to see it
SDL_Delay(200);
//Create texture_red texture from the screen surface
texture_red = SDL_CreateTextureFromSurface(gRenderer, gScreenSurface);
//Clear screen
SDL_SetRenderDrawColor(gRenderer, 0xFF, 0xFF, 0xFF, 0xFF);
SDL_RenderClear(gRenderer);
//Render blue filled quad
fillRect = { 225, 250, 100, 100 };
SDL_SetRenderDrawColor(gRenderer, 0x00, 0x00, 0xFF, 0xFF);
SDL_RenderFillRect(gRenderer, &fillRect);
//Update the rendered image on screen
SDL_RenderPresent(gRenderer);
//Pause long enough to see it
SDL_Delay(200);
//Create texture_red texture from the screen surface
texture_blue = SDL_CreateTextureFromSurface(gRenderer, gScreenSurface);
//Main loop flag
bool quit = false;
//Flag to keep track of which colour we're currently looking at
bool blue = true;
//Event handler
SDL_Event e;
//While application is running
while (!quit)
{
//Handle events on queue
while (SDL_PollEvent(&e) != 0)
{
//User requests quit
if (e.type == SDL_QUIT)
{
quit = true;
}
//User presses a key
else if (e.type == SDL_KEYDOWN)
{
//Select surfaces based on key press
switch (e.key.keysym.sym)
{
case SDLK_ESCAPE:
quit = true;
break;
default:
if (blue)
{
//Copy surface used to store red image onto the screen surface
SDL_RenderCopy(gRenderer, texture_red, NULL, NULL);
//Update current colour flag
blue = false;
}
else
{
//Copy surface used to store blue image onto the screen surface
SDL_RenderCopy(gRenderer, texture_blue, NULL, NULL);
//Update current colour flag
blue = true;
}
//Update the screen with recent render activity
SDL_RenderPresent(gRenderer);
break;
}
}
}
}
//Deallocate surfaces
SDL_FreeSurface(gScreenSurface);
//Destroy window
SDL_DestroyWindow(gWindow);
gWindow = NULL;
//Quit SDL subsystems
SDL_Quit();
return 0;
}
解决方法:
SDL_GetWindowSurface()header comment特别禁止将其与SDL_Renderer功能一起使用：
/**
* \brief Get the SDL surface associated with the window.
*
* \return The window's framebuffer surface, or NULL on error.
*
* A new surface will be created with the optimal format for the window,
* if necessary. This surface will be freed when the window is destroyed.
*
* \note You may not combine this with 3D or the rendering API on this window.
*
* \sa SDL_UpdateWindowSurface()
* \sa SDL_UpdateWindowSurfaceRects()
*/
extern DECLSPEC SDL_Surface * SDLCALL SDL_GetWindowSurface(SDL_Window * window);
使用SDL_RENDERER_TARGETTEXTURE& SDL_SetRenderTarget()如果要捕获SDL_Renderer输出.
您可以使用SDL_GetRendererInfo()查询兼容的纹理格式.或者只是向前推进SDL_PIXELFORMAT_ARGB8888 like testrendertarget.c does并希望最好:)
标签：sdl-2,c,sdl 来源： https://codeday.me/bug/20190928/1825607.html