VS2012下基于Glut OpenGL绘制直线(添加设置直线宽度)示例程序：

// GlutLineswDemo.cpp : 定义控制台应用程序的入口点。
//
#include "stdafx.h"
#include <gl/glut.h>
#include <math.h>
//圆周率宏
#define GL_PI 3.1415f
//获取屏幕的宽度与高度
GLint SCREEN_WIDTH=0;
GLint SCREEN_HEIGHT=0;
//设置程序的窗口大小
GLint windowWidth=400;
GLint windowHeight=300;
//绕x轴旋转角度
GLfloat xRotAngle=0.0f;
//绕y轴旋转角度
GLfloat yRotAngle=0.0f;
//受支持的线宽大小范围
GLfloat width[2];
//受支持的线宽增量
GLfloat widthStep;
//显示回调函数
void renderScreen(void){
	GLfloat x,y,z,angle;
	//当前线的宽度
	GLfloat curWidth=0.0f;
	//把整个窗口清理为当前清理颜色：黑色
	glClear(GL_COLOR_BUFFER_BIT);
	//将当前Matrix状态入栈
	glPushMatrix();
	//坐标系绕x轴旋转xRotAngle
	glRotatef(xRotAngle,1.0f,0.0f,0.0f);
	//坐标系绕y轴旋转yRotAngle
	glRotatef(yRotAngle,0.0f,1.0f,0.0f);
	z=0.0f;
	curWidth=width[0];
	//进行平滑处理　
	glEnable(GL_LINE_SMOOTH);
	glHint(GL_LINE_SMOOTH,GL_NICEST);
	//glEnable(GL_DEPTH_TEST);
	//绘制平行的直线
	for(x=-80.0f;x<=80.0f;x+=20.0f){
		glLineWidth(curWidth);
		//开始绘直线
		glBegin(GL_LINES);
		glVertex3f(x,80.0f,z);
		glVertex3f(x,-80.0f,z);
		//结束绘直线
		glEnd();
		curWidth+=1.0f;//widthStep;
	}
	//恢复压入栈的Matrix
	glPopMatrix();
	//交换两个缓冲区的指针
	glutSwapBuffers();
}
//设置Redering State 
void setupRederingState(void){
	//设置清理颜色为黑色
	glClearColor(0.0f,0.0,0.0,1.0f);
	//设置绘画颜色为绿色
	glColor3f(0.0f,1.0f,0.0f);
	//获取受支持的线宽大小范围
	glGetFloatv(GL_LINE_WIDTH_RANGE,width);
	//获取受支持的线宽大小增量
	glGetFloatv(GL_LINE_WIDTH_GRANULARITY,&widthStep);
	printf("Line width range:%f-%f\n",width[0],width[1]);
	printf("Line width step:%f\n",widthStep);
}
//窗口大小变化回调函数
void changSize(GLint w,GLint h){
	//横宽比率
	GLfloat ratio;
	//设置坐标系为x(-100.0f,100.0f)、y(-100.0f,100.0f)、z(-100.0f,100.0f)
	GLfloat coordinatesize=100.0f;
	//窗口宽高为零直接返回
	if((w==0)||(h==0))
		return;
	//设置视口和窗口大小一致
	glViewport(0,0,w,h);
	//对投影矩阵应用随后的矩阵操作
	glMatrixMode(GL_PROJECTION);
	//重置当前指定的矩阵为单位矩阵　
	glLoadIdentity();
	ratio=(GLfloat)w/(GLfloat)h;
	//正交投影
	if(w<h)
		glOrtho(-coordinatesize,coordinatesize,-coordinatesize/ratio,coordinatesize/ratio,-coordinatesize,coordinatesize);
	else
		glOrtho(-coordinatesize*ratio,coordinatesize*ratio,-coordinatesize,coordinatesize,-coordinatesize,coordinatesize);
	//对模型视图矩阵堆栈应用随后的矩阵操作
	glMatrixMode(GL_MODELVIEW);
	//重置当前指定的矩阵为单位矩阵　
	glLoadIdentity();
}
//按键输入处理回调函数 
void specialKey(int key,int x,int y){

	if(key==GLUT_KEY_UP){
		xRotAngle-=5.0f;
	}
	else if(key==GLUT_KEY_DOWN){
		xRotAngle+=5.0f;
	}
	else if(key==GLUT_KEY_LEFT){
		yRotAngle-=5.0f;
	}
	else if(key==GLUT_KEY_RIGHT){
		yRotAngle+=5.0f;
	}
	//重新绘制
	glutPostRedisplay();
}

int main(int argc, char* argv[])
{
	//初始化glut
	glutInit(&argc,argv);
	//使用双缓冲区模式
	glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGBA|GLUT_DEPTH);
	//获取系统的宽像素
	SCREEN_WIDTH=glutGet(GLUT_SCREEN_WIDTH);
	//获取系统的高像素
	SCREEN_HEIGHT=glutGet(GLUT_SCREEN_HEIGHT);
	//创建窗口，窗口名字为OpenlGL Lines width Demo
	glutCreateWindow("OpenlGL Lines width Demo");
	//设置窗口大小
	glutReshapeWindow(windowWidth,windowHeight);
	//窗口居中显示
	glutPositionWindow((SCREEN_WIDTH-windowWidth)/2,(SCREEN_HEIGHT-windowHeight)/2);
	//设置窗口大小变化时的回调函数
	glutReshapeFunc(changSize);
	//设置显示回调函数
	glutDisplayFunc(renderScreen);
	//设置按键输入处理回调函数
	glutSpecialFunc(specialKey);
	//设置全局渲染参数
	setupRederingState();
	glutMainLoop();
	return 0;
}