绘制图形与3D增强技巧(二)----直线图元

一.

glBegin(GL_LINES);

glend();

二.线带和线环

glBegin(GL_LINE_STRIP);

glend();

glBegin(GL_LINE_LOOP);

glend();

三.设置直线宽度

glLineWidth(GLfloat width);

四.获得直线宽度范围和增量

GLfloat sizes[2];

GLfloat add;

glGetFloatv(GL_LINE_WIDTH_RANGE,sizes);

glGetFloatv(GL_LINE_WIDTH_GRANULARITY,&add);

直线示范例程序

/

#include "stdafx.h"
#include<GL\glut.h>
#include<math.h>
#define PI 3.14

GLfloat xRot=0.0f;
GLfloat yRot=0.0f;
void Init()
{
glClearColor(0.0,0.0,0.0,0.0);

}
void ChangeSize(int w,int h)
{
glViewport(0,0,w,h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
GLfloat aspect=w/h;
if (w<=h)
{
glOrtho(-100.0,100.0,-100.0/aspect,100.0/aspect,-100.0,100.0);
}
else
{
glOrtho(-100.0*aspect,100.0*aspect,-100.0,100.0,-100.0,100.0);
}
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();

}

void Mydisplay()
{
GLfloat x,y,angle,z=0.0f;
GLfloat sizes[2];
glColor3f(0.0f,1.0f,0.0f);
glClear(GL_COLOR_BUFFER_BIT);
glPushMatrix();
glRotatef(xRot,1.0,0.0,0.0);
glRotatef(yRot,0.0,1.0,0.0);

for (angle = 0.0f; angle <2*PI; angle+=0.1f)
{

glBegin(GL_LINES);
x=50.0f*cos(angle);
y=50.0f*sin(angle);
glVertex3f(x,y,z);
x=50.0f*cos(angle+PI);
y=50.0f*sin(angle+PI);
glVertex3f(x,y,z);
glEnd();
}

glPopMatrix();
glutSwapBuffers();

}
void Mykeys(int key,int x,int y)
{
if (key==GLUT_KEY_LEFT)
{
yRot-=5.0f;
}
if (key==GLUT_KEY_RIGHT)
{
yRot+=5.0f;
}
if (key==GLUT_KEY_UP)
{
xRot-=5.0f;
}
if (key==GLUT_KEY_DOWN)
{
xRot+=5.0f;
}
if (xRot>355.0f)
{
xRot=0.0f;
}
if (xRot<=-5.0f)
{
xRot=355.0f;
}
if (yRot>355.0f)
{
yRot=0.0f;
}
if (yRot<=-5.0f)
{
yRot=355.0f;
}

glutPostRedisplay();

}
int main(int argc,char ** argv)
{

glutInit(&argc,argv);
glutInitDisplayMode(GLUT_RGB|GLUT_DOUBLE);

glutInitWindowPosition(500,500);
glutInitWindowSize(800,800);
glutCreateWindow("Points");

Init();
glutDisplayFunc(Mydisplay);
glutReshapeFunc(ChangeSize);
glutSpecialFunc(Mykeys);
glutMainLoop();

}