OpenGL二維圖形

概括、openGL中所有的圖形都是三維的，這裏所說的二維是三維圖形投影到二維窗口的結果。

void gl_point(void) {
	int vpoint[]={200,200,0};
	
	glClear(GL_COLOR_BUFFER_BIT);
	glColor3f(0.0f,1.0f,0.0f);
	glPointSize(10.0);//設置點的大小

	glBegin(GL_POINTS);
		glVertex2i(0,0);
		glVertex2i(50,50);
		glVertex3i(100,100,0);
		glVertex3iv(vpoint);
	glEnd();
	glFlush();
}


void gl_line(void) {
	glClear(GL_COLOR_BUFFER_BIT);
	glColor3f(1,0,0);

	glBegin(GL_LINES);
		glVertex2i(0,0);//前後兩點成一線，最後的奇數點省略
		glVertex2i(100,100);
		glVertex2i(100,100);
		glVertex2i(200,0);		
	glEnd();

	
	glBegin(GL_LINE_STRIP);//前後兩點依次連線
		glVertex2i(200,0);
		glVertex2i(300,100);
		glVertex2i(400,0);
		glVertex2i(500,100);
		glVertex2i(600,0);		
	glEnd();

	glLineWidth(2.0);//設置線寬
	glEnable(GL_LINE_STIPPLE);
	glLineStipple(1,0x8888); //設置虛線,後面的16進制參數代表256個像素的虛實情況
	glBegin(GL_LINE_LOOP);//前後兩點依次連線且首尾兩點相連
		glVertex2i(200,150);
		glVertex2i(400,150);
		glVertex2i(300,350);
	glEnd();

	glDisable(GL_LINE_STIPPLE);
	glShadeModel(GL_SMOOTH);//設置漸變色
	glBegin(GL_LINE_STRIP);
		glColor3f(1,0,0);
		glVertex2i(50,120);
		glColor3f(0,1,0);
		glVertex2i(350,120);
		glColor3f(0,0,0);
		glVertex2i(550,120);
	glEnd();

	glFlush();
}

void gl_rect(void) {
	glClear(GL_COLOR_BUFFER_BIT);
	glColor3f(0,1,0);

	glRecti(0,0,100,100);//矩形填充區
	
	glBegin(GL_POLYGON); //多邊形填充區
		glVertex2i(200,0);
		glVertex2i(400,0);
		glVertex2i(300,100);
	glEnd();

	glFlush();
}