以下是使用C++做一颗会跳动的爱心实例的完整攻略:
1. 准备工作
在开始编写代码之前,我们需要以下准备工作:
- 安装 C++ 编译器:可以选择 GCC(GNU Compiler Collection)或者 Visual Studio。
- 选择一个图形库:常见的可选项有 OpenGL、DirectX、SDL、SFML 等。这里我们选择使用 SDL2 图形库,因为 SDL2 是跨平台的,可以在 Windows、Linux、MacOS 等系统上运行。
2. 编写代码
2.1. 初始化 SDL2
首先,需要在代码中引入 SDL2 相关的头文件:
#include <SDL2/SDL.h>
初始化 SDL2:
SDL_Init(SDL_INIT_VIDEO);
创建窗口:
SDL_Window* window = SDL_CreateWindow("Heartbeat", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 640, 480, SDL_WINDOW_SHOWN);
创建渲染器:
SDL_Renderer* renderer = SDL_CreateRenderer(window, -1, 0);
2.2. 绘制爱心
创建一个函数,用来绘制爱心:
void drawHeart(SDL_Renderer* renderer, int x, int y, int size)
{
// 绘制左半边的心形
SDL_SetRenderDrawColor(renderer, 255, 0, 0, 255);
SDL_RenderDrawLine(renderer, x, y, x-size/2, y-size/2);
SDL_RenderDrawLine(renderer, x, y, x-size/2, y+size/2);
SDL_RenderDrawLine(renderer, x-size/2, y-size/2, x-size, y-size/2);
SDL_RenderDrawLine(renderer, x-size/2, y+size/2, x-size, y+size/2);
SDL_RenderDrawLine(renderer, x-size, y+size/2, x-size, y-size/2);
// 绘制右半边的心形
SDL_RenderDrawLine(renderer, x, y, x+size/2, y-size/2);
SDL_RenderDrawLine(renderer, x, y, x+size/2, y+size/2);
SDL_RenderDrawLine(renderer, x+size/2, y-size/2, x+size, y-size/2);
SDL_RenderDrawLine(renderer, x+size/2, y+size/2, x+size, y+size/2);
SDL_RenderDrawLine(renderer, x+size, y+size/2, x+size, y-size/2);
}
在主函数中,调用上面的函数,绘制出多个爱心:
int main(int argc, char* argv[])
{
SDL_Init(SDL_INIT_VIDEO);
SDL_Window* window = SDL_CreateWindow("Heartbeat", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 640, 480, SDL_WINDOW_SHOWN);
SDL_Renderer* renderer = SDL_CreateRenderer(window, -1, 0);
int size = 100;
int x = 320;
int y = 240;
while (true) {
SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255);
SDL_RenderClear(renderer);
drawHeart(renderer, x, y, size);
size += 2; // 心形大小逐渐增大
x -= 1; // 心形位置往左移动
y -= 1; // 心形位置往上移动
SDL_RenderPresent(renderer);
SDL_Delay(10);
}
SDL_DestroyRenderer(renderer);
SDL_DestroyWindow(window);
SDL_Quit();
return 0;
}
3. 示例说明
下面以两个示例说明使用 C++ 绘制爱心的过程:
3.1. 示例1
我想要绘制一个将心形放到窗口中心的爱心,并且这个爱心要逐渐变大、跳动起来。
首先,我们需要确定心形的起始大小和位置。在这个例子中,heartSize=100,x=320,y=240。
绘制心形的函数可以参考上面代码中的 drawHeart 段代码,我们可以将其复制到主函数的循环中,像这样:
void drawHeart(SDL_Renderer* renderer, int x, int y, int size)
{
// 绘制左半边的心形
SDL_SetRenderDrawColor(renderer, 255, 0, 0, 255);
SDL_RenderDrawLine(renderer, x, y, x-size/2, y-size/2);
SDL_RenderDrawLine(renderer, x, y, x-size/2, y+size/2);
SDL_RenderDrawLine(renderer, x-size/2, y-size/2, x-size, y-size/2);
SDL_RenderDrawLine(renderer, x-size/2, y+size/2, x-size, y+size/2);
SDL_RenderDrawLine(renderer, x-size, y+size/2, x-size, y-size/2);
// 绘制右半边的心形
SDL_RenderDrawLine(renderer, x, y, x+size/2, y-size/2);
SDL_RenderDrawLine(renderer, x, y, x+size/2, y+size/2);
SDL_RenderDrawLine(renderer, x+size/2, y-size/2, x+size, y-size/2);
SDL_RenderDrawLine(renderer, x+size/2, y+size/2, x+size, y+size/2);
SDL_RenderDrawLine(renderer, x+size, y+size/2, x+size, y-size/2);
}
int main()
{
SDL_Init(SDL_INIT_VIDEO); // 初始化
SDL_Window* window = SDL_CreateWindow("Heartbeat", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 640, 480, SDL_WINDOW_SHOWN); // 创建窗口
SDL_Renderer* renderer = SDL_CreateRenderer(window, -1, 0); // 创建渲染器
int heartSize = 100; // 球的大小
int x = 320; // 球的水平位置
int y = 240; // 球的竖直位置
while (true) {
SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255); // 清空画面为白色
SDL_RenderClear(renderer);
drawHeart(renderer, x, y, heartSize);
heartSize += 2; // 球的大小逐渐增大
x -= 1; // 球的水平位置往左移动
y -= 1; // 球的竖直位置往上移动
SDL_RenderPresent(renderer); // 更新画面
SDL_Delay(10); // 延时10毫秒
}
SDL_DestroyRenderer(renderer); // 销毁渲染器
SDL_DestroyWindow(window); // 销毁窗口
SDL_Quit();
return 0;
}
3.2. 示例2
有时我们希望爱心不断跳动,这就需要在循环中计算心形的大小、位置和颜色。
以下代码实现了一个不断跳动的红色爱心:
include
void drawHeart(SDL_Renderer* renderer, int x, int y, int size)
{
// 绘制左半边的心形
SDL_SetRenderDrawColor(renderer, 255, 0, 0, 255);
SDL_RenderDrawLine(renderer, x, y, x-size/2, y-size/2);
SDL_RenderDrawLine(renderer, x, y, x-size/2, y+size/2);
SDL_RenderDrawLine(renderer, x-size/2, y-size/2, x-size, y-size/2);
SDL_RenderDrawLine(renderer, x-size/2, y+size/2, x-size, y+size/2);
SDL_RenderDrawLine(renderer, x-size, y+size/2, x-size, y-size/2);
// 绘制右半边的心形
SDL_RenderDrawLine(renderer, x, y, x+size/2, y-size/2);
SDL_RenderDrawLine(renderer, x, y, x+size/2, y+size/2);
SDL_RenderDrawLine(renderer, x+size/2, y-size/2, x+size, y-size/2);
SDL_RenderDrawLine(renderer, x+size/2, y+size/2, x+size, y+size/2);
SDL_RenderDrawLine(renderer, x+size, y+size/2, x+size, y-size/2);
}
int main(int argc, char* argv[])
{
SDL_Init(SDL_INIT_VIDEO);
SDL_Window* window = SDL_CreateWindow("Heartbeat", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 640, 480, SDL_WINDOW_SHOWN);
SDL_Renderer* renderer = SDL_CreateRenderer(window, -1, 0);
int size = 100;
int x = 320;
int y = 240;
int r = 255;
int g = 0;
int b = 0;
while (true) {
SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255);
SDL_RenderClear(renderer);
drawHeart(renderer, x, y, size);
size += 2;
x -= 1;
y -= 1;
r -= 1;
g += 1;
SDL_SetRenderDrawColor(renderer, r, g, b, 255); // 爱心的颜色逐渐变化
if (x+size/2 <= 0) { // 如果爱心离开了窗口左侧,就重新回到窗口右侧
x = 640+size/2;
}
SDL_RenderPresent(renderer);
SDL_Delay(10);
}
SDL_DestroyRenderer(renderer);
SDL_DestroyWindow(window);
SDL_Quit();
return 0;
}
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