kezunhai@gmail.com

http://blog.csdn.net/kezunhai

           在OpenGl中，图形都是有一些基本的图元组成的，图元是把一组定点或顶点列表解释为屏幕上绘制的某些图形，OpenGL中的最小图元就是点。在OpenGL中有10中图元，可以实现从空间中绘制的简单的点到任意变数的封闭多边形，这十种图元分别是：

绘制图形的格式如下：

glBegin("图元类型");
	glVertex3f(GLfloat x, GLfloat y, GLfloat z);
	glVertex3f(GLfloat x, GLfloat y, GLfloat z);
	glVertex3f(GLfloat x, GLfloat y, GLfloat z);
	......
glEnd();

#include "stdafx.h"
#include <gl/glut.h>
#include <cmath>
#include <iostream>
using namespace std;

#ifndef GL_PI
#define  GL_PI 3.14159
#endif

GLfloat xRot = 45.0f;
GLfloat yRot = 30.0f;

void SetupRC_GRAPHIC(void)
{
	// black background
	glClearColor(0.0f, 0.0f, 0.0f, 1.0f);

	// Set drawing color to Green
	glColor3f(1.0f, 1.0f, 0.0f);
}

// Called to draw scene
void RenderScene_GRAPHIC(void)
{
	GLfloat X, Y, Z, angle;

	GLfloat fR = 50.0f;

	// Clear the window with current color
	glClear(GL_COLOR_BUFFER_BIT);

	// Save matrix state and do the rotation
	glPushMatrix();

	// Rotate
	glRotatef(xRot, 1.0f, 0.0f, 0.0f);
	glRotatef(yRot, 0.0f, 1.0f, 0.0f);

	glBegin(GL_POINTS);
		Z = -fR;
		for ( angle = 0.0f; angle<=2.0f*GL_PI*5.0f; angle+=0.1f) // 5圈
		{
			X = fR * sin(angle);
			Y = fR * cos(angle);

			glVertex3f(X, Y, Z);
			Z += 0.5;
		}
		
	glEnd();

	// restore transformations
	glPopMatrix();

	// Flush drawing commands
	glFlush();
}

// called by GLUT library when the window has changed size
void ChangeSize_GRAPHIC(GLsizei w, GLsizei h)
{
	GLfloat nRange = 100.0f;
	if ( h ==0)
		h = 1;

	// Set Viewport to window dimensions
	glViewport(0, 0, w, h);

	// Reset coordinate system
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();

	if ( w<= h)
		glOrtho(-nRange, nRange, -nRange*h/w, nRange*h/w, -nRange, nRange);
	else
		glOrtho(-nRange*w/h, nRange*w/h, -nRange, nRange, -nRange, nRange);
	
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
}

int _tmain(int argc, char* argv[])
{
	glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);
	glutCreateWindow("Graphics");	

	glutDisplayFunc(RenderScene_GRAPHIC);
	glutReshapeFunc(ChangeSize_GRAPHIC);

	SetupRC_GRAPHIC();
	glutMainLoop();

	return 0;
}

作者：kezunhai出处：http://blog.csdn.net/kezunhai欢迎转载或分享，但请务必声明文章出处。