做一个循环“慢下来”

Question

我正在使用 OpenGL 用 C++ 制作塔防游戏。当尝试使用 Windows.H 中的“睡眠”功能时，它会导致我的 OpenGL 窗口打开我输入睡眠的任何值的总时间，然后打开窗口。有什么建议？

#include <GLFW/glfw3.h>
#include <iostream>
#include <Windows.h>


void enemy(int num) //Written By Ryan
{
     switch (num)
     {
     case 1: glBegin(GL_TRIANGLES); //Position 3
          glColor3ub(255, 0, 0);
          glVertex2f(0.25, 0.9);
          glVertex2f(0.1, 0.6);
          glVertex2f(0.4, 0.6);
          glEnd();
          break;
     case 2: glBegin(GL_TRIANGLES); //Position 6
          glColor3ub(255, 0, 0);
          glVertex2f(0.25, 0.4);
          glVertex2f(0.1, 0.1);
          glVertex2f(0.4, 0.1);
          glEnd();
          break;
     case 3: glBegin(GL_TRIANGLES); //Position 7
          glColor3ub(255, 0, 0);
          glVertex2f(-0.25, 0.4);
          glVertex2f(-0.4, 0.1);
          glVertex2f(-0.1, 0.1);
          glEnd();
          break;
     case 4: glBegin(GL_TRIANGLES); //Position 10
          glColor3ub(255, 0, 0);
          glVertex2f(-0.25, -0.1);
          glVertex2f(-0.4, -0.4);
          glVertex2f(-0.1, -0.4);
          glEnd();
          break;
     case 5: glBegin(GL_TRIANGLES); //Position 14
          glColor3ub(255, 0, 0);
          glVertex2f(-0.25, -0.6);
          glVertex2f(-0.4, -0.9);
          glVertex2f(-0.1, -0.9);
          glEnd();
          break;
     }
}

void map()
{
     glColor3ub(0, 128, 0); // set color green

          //Position 1
     glBegin(GL_QUADS);
     glVertex3f(-1.0f, 1.0f, 0.0f); //top left       
     glVertex3f(-1.0f, 0.5f, 0.0f);//bottom left
     glVertex3f(-0.5f, 0.5f, 0.0f); //bottom right        
     glVertex3f(-0.5f, 1.0f, 0.0f); //top right
     glEnd();

     //Position 2
     glBegin(GL_QUADS);
     glVertex3f(-1.0f, 1.0f, 0.0f); //top left       
     glVertex3f(-0.5f, 0.5f, 0.0f);//bottom left
     glVertex3f(0.0f, 0.5f, 0.0f); //bottom right        
     glVertex3f(0.0f, 1.0f, 0.0f); //top right
     glEnd();

     //Position 3
     glColor3ub(139, 69, 19); // set color brown
     glBegin(GL_QUADS);
     glVertex3f(0.0f, 1.0f, 0.0f); //top left       
     glVertex3f(0.0f, 0.5f, 0.0f);//bottom left
     glVertex3f(0.5f, 0.5f, 0.0f); //bottom right        
     glVertex3f(0.5f, 1.0f, 0.0f); //top right
     glEnd();

     //Position 4
     glColor3ub(0, 128, 0); // set color green
     glBegin(GL_QUADS);
     glVertex3f(0.5f, 1.0f, 0.0f); //top left       
     glVertex3f(0.5f, 0.5f, 0.0f);//bottom left
     glVertex3f(1.0f, 0.5f, 0.0f); //bottom right        
     glVertex3f(1.0f, 1.0f, 0.0f); //top right
     glEnd();

     //Position 5
     glBegin(GL_QUADS);
     glVertex3f(-1.0f, .5f, 0.0f); //top left       
     glVertex3f(-1.0f, 0.0f, 0.0f);//bottom left
     glVertex3f(-0.5f, 0.0f, 0.0f); //bottom right        
     glVertex3f(-0.5f, 0.5f, 0.0f); //top right
     glEnd();

     //Position 6
     glColor3ub(139, 69, 19); // set color brown
     glBegin(GL_QUADS);
     glVertex3f(-0.5f, 0.5f, 0.0f); //top left       
     glVertex3f(-0.5f, 0.0f, 0.0f);//bottom left
     glVertex3f(0.0f, 0.0f, 0.0f); //bottom right        
     glVertex3f(0.0f, 0.5f, 0.0f); //top right
     glEnd();

     //Position 7
     glBegin(GL_QUADS);
     glVertex3f(0.0f, 0.5f, 0.0f); //top left       
     glVertex3f(0.0f, 0.0f, 0.0f);//bottom left
     glVertex3f(0.5f, 0.0f, 0.0f); //bottom right        
     glVertex3f(0.5f, 0.5f, 0.0f); //top right
     glEnd();

     //Position 8
     glColor3ub(0, 128, 0); // set color green
     glBegin(GL_QUADS);
     glVertex3f(0.5f, 0.5f, 0.0f); //top left       
     glVertex3f(0.5f, 0.0f, 0.0f);//bottom left
     glVertex3f(1.0f, 0.0f, 0.0f); //bottom right        
     glVertex3f(1.0f, 0.5f, 0.0f); //top right
     glEnd();

     //Position 9
     glBegin(GL_QUADS);
     glVertex3f(-1.0f, 0.0f, 0.0f); //top left       
     glVertex3f(-1.0f, -0.5f, 0.0f);//bottom left
     glVertex3f(-0.5f, -0.5f, 0.0f); //bottom right        
     glVertex3f(-0.5f, 0.0f, 0.0f); //top right
     glEnd();

     //Position 10
     glColor3ub(139, 69, 19); // set color brown
     glBegin(GL_QUADS);
     glVertex3f(-0.5f, 0.0f, 0.0f); //top left       
     glVertex3f(-0.5f, -0.5f, 0.0f);//bottom left
     glVertex3f(0.0f, -0.5f, 0.0f); //bottom right        
     glVertex3f(0.0f, 0.0f, 0.0f); //top right
     glEnd();

     //Position 11
     glColor3ub(0, 128, 0); // set color green
     glBegin(GL_QUADS);
     glVertex3f(0.0f, 0.0f, 0.0f); //top left       
     glVertex3f(0.0f, -0.5f, 0.0f);//bottom left
     glVertex3f(0.5f, -0.5f, 0.0f); //bottom right        
     glVertex3f(0.5f, 0.0f, 0.0f); //top right
     glEnd();

     //Position 12
     glBegin(GL_QUADS);
     glVertex3f(0.5f, 0.0f, 0.0f); //top left       
     glVertex3f(0.5f, -0.5f, 0.0f);//bottom left
     glVertex3f(1.0f, -0.5f, 0.0f); //bottom right        
     glVertex3f(1.0f, 0.0f, 0.0f); //top right
     glEnd();

     //Position 13
     glBegin(GL_QUADS);
     glVertex3f(-1.0f, -0.5f, 0.0f); //top left       
     glVertex3f(-1.0f, -1.0f, 0.0f);//bottom left
     glVertex3f(-0.5f, -1.0f, 0.0f); //bottom right        
     glVertex3f(-0.5f, -0.5f, 0.0f); //top right
     glEnd();

     //Position 14
     glColor3ub(139, 69, 19); // set color brown
     glBegin(GL_QUADS);
     glVertex3f(-0.5f, -0.5f, 0.0f); //top left       
     glVertex3f(-0.5f, -1.0f, 0.0f);//bottom left
     glVertex3f(-0.0f, -1.0f, 0.0f); //bottom right        
     glVertex3f(-0.0f, -0.5f, 0.0f); //top right
     glEnd();

     //Position 15
     glColor3ub(0, 128, 0); // set color green
     glBegin(GL_QUADS);
     glVertex3f(0.0f, -0.5f, 0.0f); //top left       
     glVertex3f(0.0f, -1.0f, 0.0f);//bottom left
     glVertex3f(0.5f, -1.0f, 0.0f); //bottom right        
     glVertex3f(0.5f, -0.5f, 0.0f); //top right
     glEnd();

     //Position 16
     glBegin(GL_QUADS);
     glVertex3f(0.5f, -0.5f, 0.0f); //top left       
     glVertex3f(0.5f, -1.0f, 0.0f);//bottom left
     glVertex3f(1.0f, -1.0f, 0.0f); //bottom right        
     glVertex3f(1.0f, -0.5f, 0.0f); //top right
     glEnd();
}


int main(void)
{
     GLFWwindow* window;

     /* Initialize the library */
     if (!glfwInit())
          return -1;

     /* Create a windowed mode window and its OpenGL context */
     window = glfwCreateWindow(1000, 1000, "Aloha Tower Defence", NULL, NULL);
     if (!window)
     {
          glfwTerminate();
          return -1;
     }

     /* Make the window's context current */

     glfwMakeContextCurrent(window);


     if (glewInit() != GLEW_OK)
          std::cout << "Error!" << std::endl;

     std::cout << glGetString(GL_VERSION) << std::endl;

     /* Loop until the user closes the window */
     while (!glfwWindowShouldClose(window))
     {
          /* Render here */
          //'The' Loop
          for (int x = 0; x <= 5; x++)
          {

               // glClear(GL_COLOR_BUFFER_BIT);
               map();
               enemy(x);
               Sleep(100);
          }


               // glClear(GL_COLOR_BUFFER_BIT);



          /* Swap front and back buffers */
          glfwSwapBuffers(window);

          map();


          /* Poll for and process events */
          glfwPollEvents();


     }

     glfwTerminate();
     return 0;
}

所以上面导致窗口静置 100 毫秒（* 5 因为循环值）然后它打开窗口并在 x 值 5 处显示 Enemy。我想看到敌人“移动”下来板从 x 值 1-5

Answer 1

您必须使用应用程序循环。添加变量x并在循环中递增变量：

int x = 0;

/* Loop until the user closes the window */
while (!glfwWindowShouldClose(window))
{
    /* Render here */
    //'The' Loop

    glClear(GL_COLOR_BUFFER_BIT);
    map();
    enemy(x);
    if (x < 5)
        x += 1;

    /* Swap front and back buffers */
    glfwSwapBuffers(window);

    /* Poll for and process events */
    glfwPollEvents();

    Sleep(100);
}

您可以使用glfwGetTime 代替Sleep，它以秒为单位检索时间，因为glfw 已初始化：

int x = 0;
double startTime = glfwGetTime();

/* Loop until the user closes the window */
while (!glfwWindowShouldClose(window))
{
    double currentTime = glfwGetTime();

    /* Render here */
    //'The' Loop

    glClear(GL_COLOR_BUFFER_BIT);
    map();
    enemy(x);
    if (x < 5 && (currentTime - startTime) > x * 0.1)
        x += 1;

    /* Swap front and back buffers */
    glfwSwapBuffers(window);

    /* Poll for and process events */
    glfwPollEvents();
}