繪制一個矩形、三角形、三個點和三條直線,并且由直線組成新的三角形
編寫程式:在一個黑色的視窗中央畫一個矩形、三角形和三個點。第一幅圖是示範程式的結果,添加代碼,在原有結果基礎上添加三條直線組成新的三角形(如第二幅圖所示)
代碼如下所示:
#include "stdafx.h"
#include <GL/glut.h>
void Display(void)
{
glClearColor(0, 0, 0, 0);//圖形的背景顔色
glClear(GL_COLOR_BUFFER_BIT);
glColor3f(1, 1, 1);//三角形後邊的正方形的顔色
glRectf(-0.5, -0.5, 0.5, 0.5);//繪制正方形
//繪制一個彩色的三角形
glBegin(GL_TRIANGLES);
glColor3f(1, 0, 0);//控制顔色
glVertex2f(0, 1);//控制線條
glColor3f(0, 1, 0);
glVertex2f(0.8, -0.5);
glColor3f(0, 0, 1);
glVertex2f(-0.8, -0.5);
glEnd();
glPointSize(3);//添加三個彩色的點
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條白線構成一個三角形
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;
}