Hi All, I have objects being drawn in my 3D engine. the objects are LPD3DXMESH loaded from X Files. My issue is that when I move the camera around, sometimes parts of object A show in front of object B. But object A is behind object B. Has anyone had issues like this? Thanks Hamfiend m_pd3dDevice->SetRenderState(D3DRS_NORMALIZENORMALS, true); m_pd3dDevice->SetRenderState(D3DRS_SPECULARENABLE, true); m_pd3dDevice->SetRenderState( D3DRS_LIGHTING, true ); m_pd3dDevice->SetRenderState(D3DRS_ALPHABLENDENABLE,true); m_pd3dDevice->SetRenderState(D3DRS_SRCBLEND,D3DBLEND_SRCALPHA); m_pd3dDevice->SetRenderState(D3DRS_DESTBLEND,D3DBLEND_INVSRCALPHA); m_pd3dDevice->SetTextureStageState(0, D3DTSS_ALPHAOP, D3DTOP_MODULATE); m_pd3dDevice->SetTextureStageState(0, D3DTSS_ALPHAARG1, D3DTA_TEXTURE); m_pd3dDevice->SetTextureStageState(0, D3DTSS_ALPHAARG2, D3DTA_TFACTOR); m_pd3dDevice->SetRenderState( D3DRS_ZENABLE, D3DZB_TRUE ); m_pd3dDevice->SetRenderState( D3DRS_CULLMODE, D3DCULL_CCW);

What are your near and far clip planes set to (They're parameters to D3DXMatrixPerspectiveFovLH if you use it)? Setting the near clip plane to a very small value (or worse, zero) is A Bad Thing, and setting the far clip plane to a very big number is also A Bad Thing.

And are you creating a Z-buffer (Is the EnableAutoDepthStencil member of your present parameters set to true)? And what format is it (the AutoDepthStencilFormat parameter of your present parameters)?

And just to round out everything that could go wrong... ;)

Ensure these render states haven't been disabled elsewhere.

D3DRS_ZWRITEENABLE, true
D3DRS_ZFUNC, D3DCMP_LESSEQUAL

And if you use SetViewport, ensure the min and max Z values make sense (usually 0.0f, and 1.0f)

Hi,

I do not create a viewport.

I create the device using this:
D3DPRESENT_PARAMETERS d3dpp;
ZeroMemory( &d3dpp, sizeof(d3dpp) );
d3dpp.Windowed = FALSE;
d3dpp.EnableAutoDepthStencil = TRUE;
d3dpp.AutoDepthStencilFormat = m_DepthStencilFormat; // D3DFMT_D16
d3dpp.SwapEffect = D3DSWAPEFFECT_COPY;
d3dpp.BackBufferFormat = m_ColorFormat; // D3DFMT_A8R8G8B8
d3dpp.BackBufferWidth = m_iWidth; // 800
d3dpp.BackBufferHeight = m_iHeight; // 600
d3dpp.PresentationInterval = D3DPRESENT_INTERVAL_IMMEDIATE;
m_pD3D->CreateDevice( D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL, m_hWnd, m_dwVertexProcessing, &d3dpp, &m_pd3dDevice );


My projection matrix is as follows:
D3DXMATRIX matProj;
D3DXMatrixPerspectiveFovLH( &matProj, (D3DX_PI/ 8), ((float)m_iWidth/(float)m_iHeight), 0.1f, 2000.0f );
m_pd3dDevice->SetTransform( D3DTS_PROJECTION, &matProj );

I use this to clear my world:
m_pd3dDevice->Clear( 0, NULL, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER,
D3DCOLOR_COLORVALUE(0.0f,0.0f,0.0f,1.0f), 1.0f, 0 );

Maybe I am using not so good values for the projection matrix.
I have it set to PI/8 because I need the objects to look like they are straight on. When I set it to PI/2, the objects appear like they are moving away from the camera as I move it closer to the object.

Do you think that could be the reason?

D3DXMatrixPerspectiveFovLH( &matProj, (D3DX_PI/ 8), ((float)m_iWidth/(float)m_iHeight), 0.1f, 2000.0f );

changed to:

D3DXMatrixPerspectiveFovLH( &matProj, (D3DX_PI/ 8), ((float)m_iWidth/(float)m_iHeight), 50.0f, 2000.0f );

Z-value of the near view-plane is too small¡£

Hi hiber,

I made the change you suggested and it seems to be working good now.

Thanks
Hamfiend