OpenGL入門示例6——黑色背景繪製彩色點畫多邊形

#include<GL/glut.h>			//OpenGL實用工具包

void init(void)
{
	glClearColor(0.0,0.0,0.0,0.0);		//指定清除顏色（黑色），即背景顏色
	glShadeModel(GL_FLAT);				//設置着色模式，採用恆定着色
}

void display(void)
{

	GLubyte fly[]={								//32*32位圖的指針，該位圖被視爲0和1組成的掩碼，1表示繪製多邊形中對應的像素，0表示不繪製
	0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
	0x03,0x80,0x01,0xC0,0x06,0xC0,0x03,0x60,
	0x04,0x60,0x06,0x20,0x04,0x30,0x0C,0x20,
	0x04,0x18,0x18,0x20,0x04,0x0C,0x30,0x20,
	0x04,0x06,0x60,0x20,0x44,0x03,0xC0,0x22,
	0x44,0x01,0x80,0x22,0x44,0x01,0x80,0x22,
	0x44,0x01,0x80,0x22,0x44,0x01,0x80,0x22,
	0x44,0x01,0x80,0x22,0x44,0x01,0x80,0x22,
	0x66,0x01,0x80,0x66,0x33,0x01,0x80,0xCC,
	0x19,0x81,0x81,0x98,0x0C,0xC1,0x83,0x30,
	0x07,0xE1,0x87,0xE0,0x03,0x3F,0xFC,0xC0,
	0x03,0x31,0x8C,0xC0,0x03,0x33,0xCC,0xC0,
	0x06,0x64,0x26,0x60,0x0C,0xCC,0x33,0x30,
	0x18,0xCC,0x33,0x18,0x10,0xC4,0x23,0x08,
	0x10,0x63,0xC6,0x08,0x10,0x30,0x0C,0x08,
	0x10,0x18,0x18,0x08,0x10,0x00,0x00,0x08};

	GLubyte halftone[]={
	0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,
	0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,
	0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,
	0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,
	0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,
	0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,
	0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,
	0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,
	0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,
	0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,
	0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,
	0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,
	0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,
	0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,
	0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,
	0xAA,0xAA,0xAA,0xAA,0x55,0x55,0x55,0x55,};
	
	glClear(GL_COLOR_BUFFER_BIT);			//清除所有的像素

	glColor3f(1.0,1.0,0.0);					//繪製顏色
	glRectf(25.0,25.0,125.0,125.0);
	
	glEnable(GL_POLYGON_STIPPLE);			//啓用多邊形點畫功能

	glColor3f(0.0,1.0,1.0);					//繪製顏色
	glPolygonStipple(fly);					//指定點畫模式（默認情況下使用純色繪製填充多邊形），參數是一個指向32*32位圖的指針
	glRectf(125.0,25.0,225.0,125.0);

	glColor3f(1.0,0.0,1.0);					//繪製顏色
	glPolygonStipple(halftone);
	glRectf(225.0,25.0,325.0,125.0);

	glFlush();								//立刻開始處理保存在緩衝區中的OpenGL函數調用
}

void reshape(int w,int h)
{
	glViewport(0,0,(GLsizei)w,(GLsizei)h);			 //爲了選擇一個更小的繪圖區域，在窗口中定義一個像素矩形，將圖像映射到這個矩形中
	glMatrixMode(GL_PROJECTION);			  		 //指定哪一個矩陣是當前矩陣（GL_PROJECTION,對投影矩陣應用隨後的矩陣操作）
	glLoadIdentity();							  	 //將當前的用戶座標系的原點移到了屏幕中心：類似於一個復位操作  
	gluOrtho2D(0.0,(GLdouble)w,0.0,(GLdouble)h);	 //將當前的可視空間設置爲正投影空間,這個函數描述了一個平行修剪空間,意味着離觀察者較遠的對象看上去不會變小  
}

int main(int argc,char** argv)						//注意參數
{
	glutInit(&argc,argv);							//初始化GLUT並處理命令行參數
	glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);		//指定模式：單緩存OR雙緩存；RGBA模式OR顏色索引模式
	glutInitWindowSize(350,150);					//指定窗口大小（像素）
	glutInitWindowPosition(100,100);				//指定窗口左上角在屏幕上的位置
	glutCreateWindow(argv[0]);						//使用OpenGL場景創建一個窗口，參數爲窗口名稱
	init();											//調用初始化函數
	glutDisplayFunc(display);						//註冊用於顯示圖形的回調函數，每當GLUT認爲需要重繪窗口時，都會執行該函數，故應將重繪場景所需調用的函數都放到顯示回調函數中。
	glutReshapeFunc(reshape);						//重繪回調函數
	glutMainLoop();									//進入主循環並處理事件，此時創建的所有窗口都會顯示出來，被渲染到這些窗口中的內容也將顯示出來，程序開始處理事件，註冊的顯示回調函數被觸發

	return 0;										//ANSI C要求函數main()返回一個int值
}

//補充說明：爲最大限度提高效率，可使用顯示列表來存儲點畫模式

運行結果：