绘制一个矩形、三角形、三个点和三条直线,并且由直线组成新的三角形
编写程序:在一个黑色的窗口中央画一个矩形、三角形和三个点。第一幅图是示范程序的结果,添加代码,在原有结果基础上添加三条直线组成新的三角形(如第二幅图所示)
代码如下所示:
#include "stdafx.h"
#include <GL/glut.h>
void Display(void)
{
glClearColor(0, 0, 0, 0);//图形的背景颜色
glClear(GL_COLOR_BUFFER_BIT);
glColor3f(1, 1, 1);//三角形后边的正方形的颜色
glRectf(-0.5, -0.5, 0.5, 0.5);//绘制正方形
//绘制一个彩色的三角形
glBegin(GL_TRIANGLES);
glColor3f(1, 0, 0);//控制颜色
glVertex2f(0, 1);//控制线条
glColor3f(0, 1, 0);
glVertex2f(0.8, -0.5);
glColor3f(0, 0, 1);
glVertex2f(-0.8, -0.5);
glEnd();
glPointSize(3);//添加三个彩色的点
glBegin(GL_POINTS);
glColor3f(1, 0, 0);
glVertex2f(-0.4, -0.4);
glColor3f(0, 1, 0);
glVertex2f(0, 0);
glColor3f(0, 0, 1);
glVertex2f(0.4, 0.4);
glEnd();
//向彩色三角形内部添加三条白线构成一个三角形
glBegin(GL_LINES);
glColor3f(1, 1, 1);
glVertex3f(0.4, 0.25, 0);
glColor3f(1, 1, 1);
glVertex3f(-0.4, 0.25, 0);
glEnd();
glBegin(GL_LINES);
glColor3f(1, 1, 1);
glVertex3f(-0.4, 0.25, 0);
glColor3f(1, 1, 1);
glVertex3f(0, -0.5, 0);
glEnd();
glBegin(GL_LINES);
glColor3f(1, 1, 1);
glVertex3f(0.4, 0.25, 0);
glColor3f(1, 1, 1);
glVertex3f(0, -0.5, 0);
glEnd();
glFlush();
}
int main(int argc, char *argv[])
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE);
glutInitWindowPosition(100, 100);
glutInitWindowSize(400, 400);
glutCreateWindow("Hello Opengl!");
glutDisplayFunc(Display);
glutMainLoop();
return 0;
}