1.图元
1.点图元
glBegin(GL_POINTS);
glend();
程序：点图元的应用
#include "stdafx.h"
#include<stdio.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=-50.0f;
GLfloat sizes[];
GLfloat step;
GLfloat CurPointSize;
glGetFloatv(GL_POINT_SIZE_RANGE,sizes);
glGetFloatv(GL_POINT_SIZE_GRANULARITY,&step);
CurPointSize=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)
{
x=50.0f*cos(angle);
y=50.0f*sin(angle);
glBegin(GL_POINTS);
glVertex3f(x,y,z);
glEnd();
z+=0.5f;
CurPointSize+=step;
} 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(); }
知识点：
1.键盘响应函数
2.矩阵堆栈
3.矩阵初始化
4.点图元的大小:glpointsize();
5.获得点图元的大小范围和增量大小
GLfloat sizes[2];
GLfloat step;
glGetFloatv(GL_POINT_SIZE_RANGE,sizes);
glGetFloatv(GL_POINT_SIZE_GRANULARITY,&step);