https://community.intel.com/t5/Developing-Games-on-Intel/Matrix-Math-Help-D3DXMatrixLookAtLH/m-p/834986#M309 Figured it out myself. Thanks anyway!<DIV></DIV><DIV>Inverse of D3DXMatrixLookAtLH:</DIV><DIV></DIV><DIV>zaxis = normal(At - Eye)</DIV><DIV>xaxis = normal(cross(Up, zaxis))</DIV><DIV>yaxis = cross(zaxis, xaxis)</DIV><DIV> </DIV><DIV>xaxis.x xaxis.y xaxis.z 0</DIV><DIV>yaxis.x yaxis.y yaxis.z 0</DIV><DIV>zaxis.x zaxis.y zaxis.z 0</DIV><DIV>eye.x, eye.y, eye.z, 1</DIV> Thu, 22 Apr 2010 17:17:12 GMT stephen-smolley 2010-04-22T17:17:12Z https://community.intel.com/t5/Developing-Games-on-Intel/Matrix-Math-Help-D3DXMatrixLookAtLH/m-p/834985#M308 <DIV id="_mcePaste">Hey there,</DIV><DIV id="_mcePaste">I needed some help, please. I need a matrix formula that returns the inverse of what D3DXMatrixLookAtLH normally would.</DIV><DIV id="_mcePaste">The inverse of this matrix can be used to transform objects to vEyePt and orient them along vLookAt and vUp if the inverse is used. However, using D3DXMatrixInverse is slow.</DIV><DIV id="_mcePaste">Here is the formula MSDN defines for D3DXMatrixLookAtLH.</DIV><DIV id="_mcePaste"></DIV><DIV id="_mcePaste"></DIV><DIV id="_mcePaste">zaxis = normal(At - Eye)</DIV><DIV id="_mcePaste">xaxis = normal(cross(Up, zaxis))</DIV><DIV id="_mcePaste">yaxis = cross(zaxis, xaxis)</DIV><DIV id="_mcePaste"> </DIV><DIV id="_mcePaste">xaxis.x yaxis.x zaxis.x 0</DIV><DIV id="_mcePaste">xaxis.y yaxis.y zaxis.y 0</DIV><DIV id="_mcePaste">xaxis.z yaxis.z zaxis.z 0</DIV><DIV id="_mcePaste">-dot(xaxis, eye) -dot(yaxis, eye) -dot(zaxis, eye) 1</DIV><DIV id="_mcePaste"></DIV><DIV id="_mcePaste"></DIV><DIV id="_mcePaste">Thanks in advance!</DIV><DIV id="_mcePaste">-Steve</DIV> Thu, 22 Apr 2010 16:29:56 GMT https://community.intel.com/t5/Developing-Games-on-Intel/Matrix-Math-Help-D3DXMatrixLookAtLH/m-p/834985#M308 stephen-smolley 2010-04-22T16:29:56Z https://community.intel.com/t5/Developing-Games-on-Intel/Matrix-Math-Help-D3DXMatrixLookAtLH/m-p/834986#M309 Figured it out myself. Thanks anyway!<DIV></DIV><DIV>Inverse of D3DXMatrixLookAtLH:</DIV><DIV></DIV><DIV>zaxis = normal(At - Eye)</DIV><DIV>xaxis = normal(cross(Up, zaxis))</DIV><DIV>yaxis = cross(zaxis, xaxis)</DIV><DIV> </DIV><DIV>xaxis.x xaxis.y xaxis.z 0</DIV><DIV>yaxis.x yaxis.y yaxis.z 0</DIV><DIV>zaxis.x zaxis.y zaxis.z 0</DIV><DIV>eye.x, eye.y, eye.z, 1</DIV> Thu, 22 Apr 2010 17:17:12 GMT https://community.intel.com/t5/Developing-Games-on-Intel/Matrix-Math-Help-D3DXMatrixLookAtLH/m-p/834986#M309 stephen-smolley 2010-04-22T17:17:12Z