   basic directx question (primitives and movements)
  In the experimenting I''ve done with basic direct3d8 stuff, I''ve managed to load and use textures, and have one primitive rotating around one axis while another primitive rotates around a different axis.  My question now is how can I have a primitive "move around" like go in one direction for a few seconds and move in the opposite direction for another few seconds while in the rendering loop?  I tried to use the Translation matrix in d3d and setting it in the loop, but that just shifts it''s position from the way the vertex buffer defines it.  Also, how can I have a rotating object rotating around an axis without sort of orbiting it and staying at the same coordinates?  I can only achieve the desired effect when the object is placed at the origin.The (partial) code:VOID direct3d::initMatrices(){D3DXMATRIX matWorld;D3DXMatrixIdentity(&matWorld);gpd3ddevice->SetTransform(D3DTS_WORLD, &matWorld);D3DXMATRIX matView;D3DXMatrixLookAtLH(&matView, &D3DXVECTOR3(0.0f, 0.0f, -10.0f),&D3DXVECTOR3(0.0f, 0.0f, 0.0f),&D3DXVECTOR3(0.0f, 1.0f, 0.0f));gpd3ddevice->SetTransform(D3DTS_VIEW, &matView);D3DXMATRIX matProj;D3DXMatrixPerspectiveFovLH(&matProj, D3DX_PI/4, 1.0f, 1.0f, 100.0f);gpd3ddevice->SetTransform(D3DTS_PROJECTION, &matProj);}VOID direct3d::texrender(){if(NULL==gpd3ddevice)return;ZeroMemory(&pd3dtex, sizeof(pd3dtex));D3DXCreateTextureFromFileEx(gpd3ddevice, "tex1.bmp", D3DX_DEFAULT, D3DX_DEFAULT, D3DX_DEFAULT, 0, D3DFMT_A8R8G8B8, D3DPOOL_MANAGED, D3DX_FILTER_TRIANGLE, D3DX_FILTER_TRIANGLE, D3DCOLOR_RGBA(255,255,255,255), NULL, NULL, &pd3dtex);gpd3ddevice->SetRenderState(D3DRS_ALPHATESTENABLE, TRUE);gpd3ddevice->SetRenderState(D3DRS_ALPHAREF, 0xff);gpd3ddevice->SetRenderState(D3DRS_ALPHAFUNC, D3DCMP_LESSEQUAL);gpd3ddevice->Clear(0, NULL, D3DCLEAR_TARGET|D3DCLEAR_ZBUFFER, D3DCOLOR_XRGB(128,128,128), 1.0f, 0);gpd3ddevice->BeginScene();initMatrices();gpd3ddevice->SetStreamSource(0, gpvb, sizeof(vertices));gpd3ddevice->SetVertexShader(texture);gpd3ddevice->SetTexture(0, pd3dtex);D3DXMatrixRotationY(&matWorld, timeGetTime()/250.0f);gpd3ddevice->SetTransform(D3DTS_WORLD, &matWorld);gpd3ddevice->DrawPrimitive(D3DPT_TRIANGLEFAN, 0, 2);gpd3ddevice->EndScene();gpd3ddevice->BeginScene();D3DXMatrixRotationZ(&matWorld, timeGetTime()/500.0f);gpd3ddevice->SetTransform(D3DTS_WORLD, &matWorld);gpd3ddevice->DrawPrimitive(D3DPT_TRIANGLEFAN, 4, 2);gpd3ddevice->EndScene();gpd3ddevice->SetTexture(0, NULL);gpd3ddevice->SetRenderState(D3DRS_ALPHATESTENABLE, FALSE);gpd3ddevice->Present(NULL, NULL, NULL, NULL);} 