C++ CModel::DrawMesh方法代码示例

/*!****************************************************************************
 @Function		RenderScene
 @Return		bool		true if no error occured
 @Description	Main rendering loop function of the program. The shell will
				call this function every frame.
				eglSwapBuffers() will be performed by PVRShell automatically.
				PVRShell will also manage important OS events.
				Will also manage relevent OS events. The user has access to
				these events through an abstraction layer provided by PVRShell.
******************************************************************************/
bool OGLES2StencilBuffer::RenderScene()
{
	m_fAngle += 0.005f;

	// Clear the color, depth and stencil buffers
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);

	// Use shader program
	glUseProgram(m_ShaderProgram.uiId);

	/*
		Set up the transformation matrices for our two shapes (the cylinder and the sphere)
	*/
	PVRTMat4 mSphere, mCylinder;
	PVRTMat4 mTrans, mRotZ, mRotX, mScale;

	mScale = PVRTMat4::Scale((float)PVRShellGet(prefHeight)/(float)PVRShellGet(prefWidth), 1.0f, 1.0f);
	mRotZ  = PVRTMat4::RotationX(m_fAngle);

	mSphere = mRotZ * mScale;

	mTrans = PVRTMat4::Translation(-0.4f, -0.5f, 0.0f);
	mRotZ  = PVRTMat4::RotationZ(m_fAngle);
	mRotX  = PVRTMat4::RotationX(m_fAngle);

	mCylinder = mScale * mRotX * mRotZ * mTrans;

	// Bind texture and set transform
	glActiveTexture(GL_TEXTURE0);
	glBindTexture(GL_TEXTURE_2D, m_uiStoneTex);
	glUniformMatrix4fv(m_ShaderProgram.auiLoc[eMVPMatrix], 1, GL_FALSE, mSphere.ptr());

	// Set culling to cull the back faces
	glCullFace(GL_BACK);

	/*
		Draw the sphere

		This sphere is textured with the stone texture and will be visible outside the stencil volume as
		we are drawing a second sphere with a green tiles texture everywhere within the stencil
		geometry.

		Also this sphere is used to set the depth values in the Z-Buffer.
	*/
	m_Sphere.DrawMesh(0);


	/*
		Enable the stencil test, disable color and depth writes
	*/
	glEnable(GL_STENCIL_TEST);
	glColorMask( GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE );
	glDepthMask(GL_FALSE);

	/*
		What we are going to do is draw a volume (a cylinder) so that all front faces that are in front of
		the already rendered geometry (the sphere) increase the stencil value by one, while all back faces
		that are in front of the rendered geometry decrease the stencil value. This way only surfaces that
		intersect the stencil volume will get a stencil value != 0.

		Since OpenGL ES 2.0 offers two-sided stencil, we can do this in a single pass.
	*/
	// Disable culling as we want to use the back and front faces of the geometry.
	glDisable(GL_CULL_FACE);

	/*
		glStencilFunc tells OGLES2 the type of per-pixel test that we want to do. In the case below GL_ALWAYS says we
		want the test to always pass. The third value is the mask value which is ANDed with the second value
		(the reference value) to create the value that is put in the stencil buffer.

		Alternative values for the first value are

		GL_NEVER which causes the test to never pass.
		GL_LESS	    Passes if (	ref & mask ) < ( stencil & mask ).
		GL_LEQUAL	Passes if (	ref & mask ) < ( stencil & mask ).
		GL_GREATER	Passes if (	ref & mask ) > ( stencil & mask ).
		GL_GEQUAL	Passes if (	ref & mask ) > ( stencil & mask ).
		GL_EQUAL	Passes if (	ref & mask ) = ( stencil & mask ).
		GL_NOTEQUAL	Passes if (	ref & mask ) / ( stencil & mask ).

		A call to glStencilFunc is the same as calling glStencilFuncSeparate with GL_FRONT_AND_BACK
	*/
	glStencilFunc(GL_ALWAYS, 1, 0xFFFFFFFF);

	/*
		glStencilOp has 3 parameters. The first parameter specifies the action to take if the
		stencil test fails. The second specifies the stencil action to take if the stencil test passes
		but the depth test fails. The third one specifies the stencil action when the stencil test and
		the depth test pass, or when the stencil test passes and their is no depth testing done.

//.........这里部分代码省略.........