opengl方面，用glclippplane将球体裁剪为球面三角形后，如何能在此基础上绘制别的图形而不受裁剪平面的影响

fhcggoodd 2014-08-27 03:49:27

球高手指导~

我现在需要绘制的图是这样的：

所以需要八个球面三角形里面还需要一个圆柱和圆锥，

最开始想要裁剪平面从球体得到球面三角形，但得到以后，再在坐标中心画那两个圆柱和圆锥却总是受到原先裁剪平面的影响，比如像这样

但是如果我把画球去掉，还是正常的，比如这样

请各位大神高手指导，看如何能够不受裁剪平面的影响画出圆柱和圆锥

或者我改用什么别的办法能把上面那幅图绘制出来呢~

请多多指教，谢谢大家~O(∩_∩)O~

关键代码在下面



void COpenGL::OnPaint() 

{

	//CPaintDC dc(this); // device context for painting

	

	// TODO: Add your message handler code here

	//调用OpenGL绘图函数进行图形绘制

	glRotatef(step,0,1,0);

	step= (step+10)/360;

	glMatrixMode(GL_MODELVIEW);

	glLoadIdentity();

	glMatrixMode(GL_PROJECTION); 

	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);	//清除颜色缓存和深度缓存



	glPushMatrix();

	

	glPushMatrix();

		glScalef(0.6,0.4,0.6);

		glTranslatef(0,0,-0.7);

                 //圆柱与圆锥

		DrawArrow(0.3);

		glLoadIdentity();

	glPopMatrix();

	   

	glPushMatrix();

                //裂开的球壳

		DrawSphere();

		//glLoadIdentity();

	glPopMatrix();	



	glPopMatrix();



	SwapBuffers(hdc);

	

	// Do not call CWnd::OnPaint() for painting messages

}



//圆柱与圆锥的绘制

void COpenGL::DrawArrow(float r)

{

	//cylinder

	glPushMatrix();

	glEnable(GL_BLEND);  

	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); 



		glColor4f(1,0.5,0.8,1.0);  

		//auxSolidCylinder(0.5,5);

		GLUquadricObj *objCylinder = gluNewQuadric();

		gluCylinder(objCylinder, r, r, 1.0, 32, 32);

		glTranslatef(0.0,0.0,1.0); 

		glutSolidCone(r+0.1,1.0,20.0,1);



	glDisable(GL_BLEND); 

	glPopMatrix();

}



//球面三角形的拼凑

void COpenGL::DrawSphere()

{

	glPushMatrix();



		//right top

		glPushMatrix();

		Drawclip(0.8);

		glPopMatrix();



		//right buttom

		glPushMatrix();

		glRotatef(90,1,0,0);

		Drawclip(0.8);

		glPopMatrix();



		//left front top

		glPushMatrix();

		glRotatef(90,0,0,1);

		Drawclip(0.8);

		glPopMatrix();



		//left front buttom

		glPushMatrix();

		glRotatef(90,0,-1,0);

		glRotatef(90,1,0,0);

		Drawclip(0.8);

		glPopMatrix();



		//right back top

		glPushMatrix();

		glRotatef(90,0,1,0);

		Drawclip(0.8);

		glPopMatrix();



		//left back buttom

		glPushMatrix();

		glRotatef(180,0,1,0);

		glRotatef(90,1,0,0);

		Drawclip(0.8);

		glPopMatrix();



		//right back top

		glPushMatrix();

		glRotatef(90,0,0,1);

		glRotatef(90,0,1,0);

		Drawclip(0.8);

		glPopMatrix();



		//left front top

		glPushMatrix();

		glRotatef(90,0,0,-1);

		glRotatef(90,0,1,0);

		Drawclip(0.8);

		glPopMatrix();



	glPopMatrix(); 

}



//球体的切割

void COpenGL::Drawclip(float r)

{

	float cut = 0.2*r;

 	GLdouble eqn1 [4] ={0.0,1.0,0.0,-cut};  

 	GLdouble eqn2 [4] ={1.0,0.0,0.0,-cut};

 	GLdouble eqn3 [4] ={0.0,0.0,1.0,-cut}; 

 

// 	glClear(GL_COLOR_BUFFER_BIT); 

 	glEnable(GL_BLEND);  

 	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);   

 	glColor4f(0.5,1.0,1.0,0.5);  

 

 	glPushMatrix(); 



		glDisable(GL_CLIP_PLANE0);

		glClipPlane(GL_CLIP_PLANE0,eqn1);  

 		glEnable(GL_CLIP_PLANE0);



 		glDisable(GL_CLIP_PLANE1);

 		glClipPlane(GL_CLIP_PLANE1,eqn2);  

 		glEnable(GL_CLIP_PLANE1);

 		

		glDisable(GL_CLIP_PLANE2);

 		glClipPlane(GL_CLIP_PLANE2,eqn3);  

 		glEnable(GL_CLIP_PLANE2);  

 		

 		glutSolidSphere(r,16,16); 

 

 	glPopMatrix(); 

 

 	glDisable(GL_BLEND);  

	glFlush();

}