I''m just about at the end of my wits from reading my code over and over again trying to solve this problem. I''ve copied code off this forum, from the sdk examples.... it just won''t work. My billboards are rotating to face the camera, but they do not retain their world positions!!! I''ve put in the little translation bit, and it doesn''t seem to make a lot of difference. They just slide around whenever the view is rotated. Please, can anyone help a man in dispair. My code looks something like this: D3DXMATRIX matTransposed,matView; D3DXMatrixIdentity(&matTransposed); D3DXMatrixIdentity(&matView); //get the current view matrix matView = g_pCamera->GetViewMatrix(); //get the transposed matrix D3DXMatrixTranspose(&matTransposed, &matView); matTransposed._14 = matTransposed._24 = matTransposed._34 = 0.0f; // do rendering for (int t=0; tm_vPosition.x; matTransposed._42 = m_pTrees[t]->m_vPosition.y; matTransposed._43 = m_pTrees[t]->m_vPosition.z; g_pd3dDevice->SetTransform( D3DTS_WORLD, &matTransposed ); if (FAILED(m_pTrees[t]->Render())) return E_FAIL; }

The billboard matrix in the inverse of the camera matrix, not the transposed matrix.

HTH
Laurent -- http://www.jeux-directx.com/

Instead of placing the x,y,z of your trees into your transposed matrix, I think this may work:

D3DXMATRIX matWorld;
D3DXMatrixTranslation(&matWorld, m_pTrees[t]->m_vPosition.x, m_pTrees[t]->m_vPosition.y, m_pTrees[t]->m_vPosition.z);

D3DXMatrixMultiply(&matWorld,&matTransposed,&matWorld);
g_pd3dDevice->SetTransform(D3DTS_WORLD, &matWorld);