C++小游戏tankwar之界面绘制的详细过程

下面是“C++小游戏tankwar之界面绘制的详细过程”的完整攻略。

界面绘制的流程

1. 初始化SDL

在使用SDL进行图形绘制前，需要进行SDL库的初始化。调用SDL_Init函数即可进行初始化。同时还需要对SDL图形界面进行设置，包括窗口大小、窗口名称等。

SDL_Init(SDL_INIT_VIDEO);
SDL_Window* window = SDL_CreateWindow("TankWar", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, SCREEN_WIDTH, SCREEN_HEIGHT, SDL_WINDOW_SHOWN);
SDL_Renderer* renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);

1. 加载图片素材

将需要用到的图片素材加载进内存中，方便后面渲染到屏幕上。调用SDL_LoadBMP函数可将位图文件加载进SDL_Surface数据结构中。

SDL_Surface* playerImg = SDL_LoadBMP("player.bmp");

1. 将图片素材渲染到屏幕上

调用SDL_RenderCopy函数将图片素材渲染到屏幕上。该函数需要传递三个参数，分别是SDL_Renderer对象、SDL_Texture对象和SDL_Rect对象。其中，SDL_Texture对象可以通过调用SDL_CreateTextureFromSurface函数将SDL_Surface对象转化为。

SDL_Texture* playerTexture = SDL_CreateTextureFromSurface(renderer, playerImg);
SDL_Rect playerPos = {100, 100, PLAYER_WIDTH, PLAYER_HEIGHT};
SDL_RenderCopy(renderer, playerTexture, NULL, &playerPos);

1. 绘制文本

在屏幕上绘制文本需要用到TTF库。与SDL初始化类似，需要对TTF库进行初始化。然后调用TTF_OpenFont函数打开需要使用的字体文件，然后再调用TTF_RenderUTF8_Solid函数即可将需要显示的文字渲染进SDL_Surface上，最后再将SDL_Surface渲染到屏幕上即可。

TTF_Init();
TTF_Font* font = TTF_OpenFont("Heavy.ttf", 20);
SDL_Color white = {255, 255, 255};
SDL_Surface* surfaceMessage = TTF_RenderUTF8_Solid(font, "Game Over!", white);
SDL_Rect messageRect = {200, 200, surfaceMessage->w, surfaceMessage->h};
SDL_Texture* message = SDL_CreateTextureFromSurface(renderer, surfaceMessage);
SDL_RenderCopy(renderer, message, NULL, &messageRect);

示例

下面分别给出路径为./images/的图片素材绘制及TTF字体绘制的示例代码：

图片素材绘制示例代码

SDL_Surface* playerImg = SDL_LoadBMP("./images/player.bmp");
SDL_Texture* playerTexture = SDL_CreateTextureFromSurface(renderer, playerImg);
SDL_Rect playerPos = {100, 100, PLAYER_WIDTH, PLAYER_HEIGHT};
SDL_RenderCopy(renderer, playerTexture, NULL, &playerPos);

TTF字体绘制示例代码

TTF_Init();
TTF_Font* font = TTF_OpenFont("./fonts/Heavy.ttf", 20);
SDL_Color white = {255, 255, 255};
SDL_Surface* surfaceMessage = TTF_RenderUTF8_Solid(font, "Game Over!", white);
SDL_Rect messageRect = {200, 200, surfaceMessage->w, surfaceMessage->h};
SDL_Texture* message = SDL_CreateTextureFromSurface(renderer, surfaceMessage);
SDL_RenderCopy(renderer, message, NULL, &messageRect);