c++ - 如何在 opengl c++ 中使用多线程添加几个弹跳球

Question

我是 OpenGL 的新手。我有一个简单的程序，可以让我有一次弹跳球。你知道我如何调整代码让两个或更多球弹跳(使用多线程)吗？如果发生碰撞，我还应该让球相互反弹。这是我的一个弹跳球的代码。

/*
 * GL07BouncingBall.cpp: A ball bouncing inside the window
 */
#include <string>
#include <iostream>
#include <thread>
using namespace std;

#include <windows.h>  // for MS Windows
#include <GL/glut.h>  // GLUT, includes glu.h and gl.h
#include <Math.h>     // Needed for sin, cos
#define PI 3.14159265f

// Global variables
char title[] = "Bouncing Ball (2D)";  // Windowed mode's title
int windowWidth  = 640;     // Windowed mode's width
int windowHeight = 480;     // Windowed mode's height
int windowPosX   = 50;      // Windowed mode's top-left corner x
int windowPosY   = 50;      // Windowed mode's top-left corner y

GLfloat ballRadius = 0.2f;   // Radius of the bouncing ball
GLfloat ballX = 0.0f;         // Ball's center (x, y) position
GLfloat ballY = 0.0f;
GLfloat ballXMax, ballXMin, ballYMax, ballYMin; // Ball's center (x, y) bounds
GLfloat xSpeed = 0.02f;      // Ball's speed in x and y directions
GLfloat ySpeed = 0.007f;
int refreshMillis = 30;      // Refresh period in milliseconds

// Projection clipping area
GLdouble clipAreaXLeft, clipAreaXRight, clipAreaYBottom, clipAreaYTop;

/* Initialize OpenGL Graphics */
void initGL() {
   glClearColor(0.0, 0.0, 0.0, 1.0); // Set background (clear) color to black
}

/* Callback handler for window re-paint event */
void display() {
   glClear(GL_COLOR_BUFFER_BIT);  // Clear the color buffer
   glMatrixMode(GL_MODELVIEW);    // To operate on the model-view matrix
   glLoadIdentity();              // Reset model-view matrix

   glTranslatef(ballX, ballY, 0.0f);  // Translate to (xPos, yPos)
   // Use triangular segments to form a circle
   glBegin(GL_TRIANGLE_FAN);
      glColor3f(0.0f, 0.0f, 1.0f);  // Blue
      glVertex2f(0.0f, 0.0f);       // Center of circle
      int numSegments = 100;
      GLfloat angle;
      for (int i = 0; i <= numSegments; i++) { // Last vertex same as first vertex
         angle = i * 2.0f * PI / numSegments;  // 360 deg for all segments
         glVertex2f(cos(angle) * ballRadius, sin(angle) * ballRadius);
      }
   glEnd();

   glutSwapBuffers();  // Swap front and back buffers (of double buffered mode)

   // Animation Control - compute the location for the next refresh
   ballX += xSpeed;
   ballY += ySpeed;
   // Check if the ball exceeds the edges
   if (ballX > ballXMax) {
      ballX = ballXMax;
      xSpeed = -xSpeed;
   } else if (ballX < ballXMin) {
      ballX = ballXMin;
      xSpeed = -xSpeed;
   }
   if (ballY > ballYMax) {
      ballY = ballYMax;
      ySpeed = -ySpeed;
   } else if (ballY < ballYMin) {
      ballY = ballYMin;
      ySpeed = -ySpeed;
   }
}

/* Call back when the windows is re-sized */
void reshape(GLsizei width, GLsizei height) {
   // Compute aspect ratio of the new window
   if (height == 0) height = 1;                // To prevent divide by 0
   GLfloat aspect = (GLfloat)width / (GLfloat)height;

   // Set the viewport to cover the new window
   glViewport(0, 0, width, height);

   // Set the aspect ratio of the clipping area to match the viewport
   glMatrixMode(GL_PROJECTION);  // To operate on the Projection matrix
   glLoadIdentity();             // Reset the projection matrix
   if (width >= height) {
      clipAreaXLeft   = -1.0 * aspect;
      clipAreaXRight  = 1.0 * aspect;
      clipAreaYBottom = -1.0;
      clipAreaYTop    = 1.0;
   } else {
      clipAreaXLeft   = -1.0;
      clipAreaXRight  = 1.0;
      clipAreaYBottom = -1.0 / aspect;
      clipAreaYTop    = 1.0 / aspect;
   }
   gluOrtho2D(clipAreaXLeft, clipAreaXRight, clipAreaYBottom, clipAreaYTop);
   ballXMin = clipAreaXLeft + ballRadius;
   ballXMax = clipAreaXRight - ballRadius;
   ballYMin = clipAreaYBottom + ballRadius;
   ballYMax = clipAreaYTop - ballRadius;
}

/* Called back when the timer expired */
void Timer(int value) {
   glutPostRedisplay();    // Post a paint request to activate display()
   glutTimerFunc(refreshMillis, Timer, 0); // subsequent timer call at milliseconds
}

/* Main function: GLUT runs as a console application starting at main() */
int main(int argc, char** argv) {
   glutInit(&argc, argv);            // Initialize GLUT
   glutInitDisplayMode(GLUT_DOUBLE); // Enable double buffered mode
   glutInitWindowSize(windowWidth, windowHeight);  // Initial window width and height
   glutInitWindowPosition(windowPosX, windowPosY); // Initial window top-left corner (x, y)
   glutCreateWindow(title);      // Create window with given title

   glutDisplayFunc(display);     // Register callback handler for window re-paint
   glutReshapeFunc(reshape);     // Register callback handler for window re-shape
   glutTimerFunc(0, Timer, 0);   // First timer call immediately
   initGL();                     // Our own OpenGL initialization
   glutMainLoop();               // Enter event-processing loop
   return 0;
}

**编辑:我已经对我的代码进行了改进。我现在创建了两个球，每个球都有自己的速度、颜色和中心。虽然，两个球保持静止。我创建球的函数定义如下:

void create(double s, GLfloat ballRadius, GLfloat ballX, GLfloat ballY, GLfloat xSpeed, GLfloat ySpeed)//, double r, double t)
{
    //ballRadius = f; 
    //xSpeed = r;
    //ySpeed = t;


    glTranslatef(ballX, ballY, 0.0f);  // Translate to (xPos, yPos)
      glBegin(GL_TRIANGLE_FAN);
      glColor3f(s, 0.0f, 1.0f);  // Blue
      glVertex2f(0.0, 0.0f);       // Center of circle
      int numSegments = 100;
      GLfloat angle;
      for (int i = 0; i <= numSegments; i++) { // Last vertex same as first vertex
         angle = i * 2.0f * PI / numSegments;  // 360 deg for all segments
         glVertex2f(cos(angle) * ballRadius, sin(angle) * ballRadius);
      }
   glEnd();

   // Animation Control - compute the location for the next refresh
   ballX += xSpeed;
   ballY += ySpeed;
   // Check if the ball exceeds the edges
   if (ballX > ballXMax) {
      ballX = ballXMax;
      xSpeed = -xSpeed;
   } else if (ballX < ballXMin) {
      ballX = ballXMin;
      xSpeed = -xSpeed;
   }
   if (ballY > ballYMax) {
      ballY = ballYMax;
      ySpeed = -ySpeed;
   } else if (ballY < ballYMin) {
      ballY = ballYMin;
      ySpeed = -ySpeed;
   }
}

我通过以下方式调用此函数:

create(1.0, 0.2f, 0.0f, 0.0f, 0.02f, 0.007f);
create(0.0, 0.1f, 0.0f, 0.0f, 0.04f, 0.014f);

两个独立的球

Answer 1

这段代码“创建”了一个圆圈

// Use triangular segments to form a circle
       glBegin(GL_TRIANGLE_FAN);
          glColor3f(0.0f, 0.0f, 1.0f);  // Blue
          glVertex2f(0.0f, 0.0f);       // Center of circle
          int numSegments = 100;
          GLfloat angle;
          for (int i = 0; i <= numSegments; i++) { // Last vertex same as first vertex
             angle = i * 2.0f * PI / numSegments;  // 360 deg for all segments
             glVertex2f(cos(angle) * ballRadius, sin(angle) * ballRadius);
          }
       glEnd();