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(,,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[];
    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 <*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(,);
    glutInitWindowSize(,);
    glutCreateWindow("Points");

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

}