1、利用第三节课的代码先显示这张图片：修改了代码的图片路径和显示位置，见下图红色标记。运行结果如图。
2、现在只需添加两行代码即可实现texture透明度。见下图红色标记。
4、第13行：SDL_SetTextureAlphaMode是渲染texture时设置它的透明俣觊鄄幼度。参数：255/2是一半透明，它取值范围：0~255，另外255是不透明，0是全透明。
6、代码：#include<SDL2/SDL.h>#include<SDL2/SDL_imag髫潋啜缅e.h>intmain(intargc,char**argv){SDL_Init(SDL_INIT_VIDEO);SDL_Window*window=SDL_CreateWindow("调节texture透明度",SDL_WINDOWPOS_CENTERED,SDL_WINDOWPOS_CENTERED,720,1280,SDL_WINDOW_SHOWN);SDL_Renderer*renderer=SDL_CreateRenderer(window,-1,SDL_RENDERER_ACCELERATED);SDL_RenderClear(renderer);SDL_Surface*surface=IMG_Load("./resource/circle.png");SDL_Rectbox={150,400,surface->w,surface->h};SDL_Texture*texture=SDL_CreateTextureFromSurface(renderer,surface);SDL_SetTextureBlendMode(texture,SDL_BLENDMODE_BLEND);SDL_SetTextureAlphaMod(texture,255/2);SDL_RenderCopy(renderer,texture,NULL,&box);SDL_RenderPresent(renderer);SDL_Delay(6000);SDL_FreeSurface(surface);SDL_DestroyTexture(texture);SDL_DestroyRenderer(renderer);SDL_DestroyWindow(window);SDL_Quit();}
