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写在前面： 

1.本篇文章将解决 freeglut.h 和 glut.h两个库在VS2019下的配置问题，并解决三个OpenGL课本上的三个问题：

利用OpenGL实现折线和矩形的橡皮筋绘制技术，并采用右键菜单实现功能的选择。

利用OpenGL，分别用点和折线模式实现正弦和余弦曲线的绘制。 
利用OpenGL程序绘制实线、虚线和点画线。

此外，还将绘制一个三角形。

代码参考：

问题一代码：
 

#include "freegult.h"
int iPointNum = 0;
int iMode = 0;
int x1 = 0, y1 = 0, x2 = 0, y2 = 0;int width = 500, height = 500;void MousePlot(GLint button, GLint action, GLint xMouse, GLint yMouse) {if (button == GLUT_LEFT_BUTTON && action == GLUT_DOWN) {if (iPointNum == 0 || iPointNum == 2) {iPointNum = 1;x1 = xMouse;y1 = height - yMouse;} else {iPointNum = 2;x2 = xMouse;y2 = height - yMouse;glutPostRedisplay();}}
}void PassiveMouseMove(GLint xMouse, GLint yMouse) {if (iPointNum == 1) {x2 = xMouse;y2 = height - yMouse;glutPostRedisplay();}
}void ProcessMenu(int value) {iMode = value;x1 = 0;y1 = 0;x2 = 0;y2 = 0;glutPostRedisplay();
}void processNormalKeys(unsigned char key, int x, int y) {switch (key) {case 99:iMode = 0;iPointNum = 0;break;case 27:exit(0);}glutPostRedisplay();
}void myinit(void) {glClearColor(1.0, 1.0, 1.0, 1.0);glutCreateMenu(ProcessMenu);glutAddMenuEntry("line", 1);glutAddMenuEntry("broken_line", 2);glutAddMenuEntry("rectangle", 3);glutAttachMenu(GLUT_RIGHT_BUTTON);
}void myReshape(GLsizei w, GLsizei h) {width = w;height = h;glViewport(0, 0, w, h);glMatrixMode(GL_PROJECTION);glLoadIdentity();gluOrtho2D(0.0, width, 0.0, height);
}void display(void) {glClear(GL_COLOR_BUFFER_BIT);glColor3f(1.0, 0.0, 0.0);if (iMode == 1) {glBegin(GL_LINES);glVertex2i(x1, y1);glVertex2i(x2, y2);glEnd();} else if (iMode == 2) {glBegin(GL_LINE_STRIP);glVertex2i(x1, y1);glVertex2i(x2, y1);glVertex2i(x2, y2);glEnd();} else if (iMode == 3) {glBegin(GL_LINE_LOOP);glVertex2i(x1, y1);glVertex2i(x2, y1);glVertex2i(x2, y2);glVertex2i(x1, y2);glEnd();}glutSwapBuffers();
}int main(int argc, char* argv[]) {glutInit(&argc, argv);glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA);glutInitWindowSize(500, 500);glutInitWindowPosition(100, 100);glutCreateWindow("luoxiaoc");myinit();glutKeyboardFunc(processNormalKeys);glutMouseFunc(MousePlot);glutPassiveMotionFunc(PassiveMouseMove);glutReshapeFunc(myReshape);glutDisplayFunc(display);glutMainLoop();return 0;
}

问题二代码：
 

#include <GL/freeglut.h>
#include <math.h>
#define PI 3.1416int winWidth = 500, winHeight = 500;void myinit(void) {glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
}void myReshape(int w, int h) {winWidth = w;winHeight = h;glViewport(0, 0, w, h);glMatrixMode(GL_PROJECTION);glLoadIdentity();gluOrtho2D(0.0, w, 0.0, h);
}void display(void) {glClear(GL_COLOR_BUFFER_BIT);glColor3f(0.0, 1.0, 0.0);glBegin(GL_LINES);glVertex2f(0, 250.0);glVertex2f(500.0, 250.0);glVertex2f(250.0, 0);glVertex2f(250.0, 500.0);glEnd();glColor3f(1.0, 0.0, 0.0);glTranslatef(250, 250, 0);glBegin(GL_POINTS);for (float x = -PI; x < PI; x += 2 * PI / 180) {float y = sin(x);glVertex2f(50 * x, 50 * y);}glEnd();glBegin(GL_LINE_STRIP);for (float x = -PI; x < PI; x += 2 * PI / 180) {float y = sin(x);glVertex2f(50 * x, 50 * y);}glEnd();glBegin(GL_POINTS);for (float x = -PI; x < PI; x += 2 * PI / 180) {float y = cos(x);glVertex2f(50 * x, 50 * y);}glEnd();glBegin(GL_LINE_STRIP);for (float x = -PI; x < PI; x += 2 * PI / 180) {float y = cos(x);glVertex2f(50 * x, 50 * y);}glEnd();glutSwapBuffers();
}int main(int argc, char* argv[]) {glutInit(&argc, argv);glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA);glutInitWindowSize(500, 500);glutInitWindowPosition(100, 100);glutCreateWindow("");myinit();glutReshapeFunc(myReshape);glutDisplayFunc(display);glutMainLoop();return 0;
}

【注】display函数中四个画线函数每次运行一个即可； 

问题三代码：
 

#include "glut.h"void init() {glClearColor(1.0, 1.0, 1.0, 1.0);glColor3f(0.0, 0.0, 0.0);glLineWidth(2.0);
}void display() {glClear(GL_COLOR_BUFFER_BIT);glBegin(GL_LINES);glVertex2f(-0.9, 0.8);glVertex2f(0.9, 0.8);glEnd();glEnable(GL_LINE_STIPPLE);glLineStipple(1, 0x00FF);glBegin(GL_LINES);glVertex2f(-0.9, 0.5);glVertex2f(0.9, 0.5);glEnd();glDisable(GL_LINE_STIPPLE);glEnable(GL_LINE_STIPPLE);glLineStipple(1, 0x1C47);glBegin(GL_LINES);glVertex2f(-0.9, 0.2);glVertex2f(0.9, 0.2);glEnd();glDisable(GL_LINE_STIPPLE);glFlush();
}int main(int argc, char** argv) {glutInit(&argc, argv);glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);glutInitWindowSize(800, 600);glutInitWindowPosition(100, 100);glutCreateWindow("Line Styles in OpenGL");init();glutDisplayFunc(display);glutMainLoop();return 0;
}

三角形代码：
 

#include "freeglut.h"const GLsizei windowWidth = 800;
const GLsizei windowHeight = 800;// This function renders the scene using OpenGL.
void RenderScene() {// Clear the frame buffer by setting it to the clear color.glClear(GL_COLOR_BUFFER_BIT);// Select the Modelview Matrix and reset it to its default state.glMatrixMode(GL_MODELVIEW);glLoadIdentity();// Draw the triangle.glBegin(GL_TRIANGLES);glColor3f(1.0, 0.0, 0.0); // redglVertex2f(0.0, 1.0);glColor3f(0.0, 1.0, 0.0); // greenglVertex2f(1.0, -1.0);glColor3f(0.0, 0.0, 1.0); // blueglVertex2f(-1.0, -1.0);glEnd();// Flush the graphic buffers &// swap them (double buffering).glFlush();glutSwapBuffers();
}// This is the entry point of the program.
int main(int argc, char* argv[]) {// Initialize GLUT.glutInit(&argc, argv);// Set the display mode to use double buffering.// GLUT_SINGLE will came flichering.glutInitDisplayMode(GLUT_DOUBLE);// Create a window with the title "Hello OpenGL".int windowID = glutCreateWindow("Hello OpenGL");glutReshapeWindow(windowWidth, windowHeight);// Set the display function to render the scene.glutDisplayFunc(RenderScene);// Set the clear color to white.glClearColor(1.0, 1.0, 1.0, 1.0);// Transfer control over to GLUT.glutMainLoop();// This code is never reached.return 0;
}

参考链接：

三角形代码：三角形绘制；

环境配置：先看（从头看到精准空降的这里），然后退出来把这个视频看完安装库。

问题一参考；

问题二参考；