glCullFace( GL_BACK );								//draw only the front faces of the shadow volume		//clear the stencil buffer		glClear( GL_STENCIL_BUFFER_BIT );		//store current OpenGL state		glPushAttrib( GL_DEPTH_BUFFER_BIT | GL_LIGHTING_BIT | GL_STENCIL_BUFFER_BIT );			//pass 1 (scene)			//draw scene with light(s) enabled			Draw...( true );			...			//pass 2 (volumes)			glDisable( GL_TEXTURE_2D );			//store current OpenGL state			glPushAttrib( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_POLYGON_BIT | GL_STENCIL_BUFFER_BIT );				glColorMask( 0, 0, 0, 0 );					//do not write to the color buffer				glDepthMask( 0 );							//do not write to the depth (Z) buffer				glEnable( GL_STENCIL_TEST );				//enable stencil testing				glStencilFunc( GL_ALWAYS, 0, ~0 );			//set the reference stencil value to 0				//				glStencilOp( GL_KEEP, GL_INCR, GL_KEEP );	//increment the stencil value on Z fail				glCullFace( GL_FRONT );						//draw only the back faces of the shadow volume				//draw walls (+ caps)				ShadowVolumes->Draw( shadowVolumes_shader, true );				//				glStencilOp( GL_KEEP, GL_DECR, GL_KEEP );	//decrement the stencil value on Z fail				glCullFace( GL_BACK );						//draw only the front faces of the shadow volume				//draw walls (+ caps)				ShadowVolumes->Draw( shadowVolumes_shader, false );		//call VBO, shader extrudes correct quadrilaterals (plus animates ms3d:)			//restore OpenGL state			glPopAttrib();			//			//pass 3 (scene)			//re-draw scene with light(s) disabled,			glDepthFunc( GL_EQUAL );						//only where it has previously been drawn			glDepthMask( 0 );								//do not write to the depth (Z) buffer			//update the color only where the stencil value is NOT 0			glEnable( GL_STENCIL_TEST );			glStencilFunc( GL_NOTEQUAL, 0, ~0 );			glStencilOp( GL_KEEP, GL_KEEP, GL_KEEP );			//			Draw...( false );			...			}		//restore OpenGL state		glPopAttrib();	}