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Matrix Help Still

Started by MatthewEva May 23, 2002 at 4:18 PM 2 replies 400+ views

Original Post

May 23, 2002 at 4:18 PM

Hi All, I got no responses from the last post I sent, and wondered if anyone anywhere knew of a method, or any links to any sites that can explain how I can obtain the rotations of the camera after I set the D3DXMATRIX* D3DXMatrixLookAtLH( function. I.e if I call the function D3DXMatrixLookAtLH( &D3DXVECTOR3(0.0f,10.0f,-10.0f), &D3DXVECTOR3(0.0f,0.0f,0.0f), &D3DXVECTOR3(0.0f,1.0f,0.0f)); I know from the coords given that the angle is roughly 45 degrees on the y axis (i.e. looking down or is it up 45 degrees) but there must be a method using one of the maths functions to calculate this. The matrix returned holds the transformed state, so im guessing that this may be the key, but im unsure which attributes in the matrix holds the rotations. maybe someone can help me with this. Thanks in advance #ifndef _DIRECTX PostQuitMessage(0); #endif

vImTo

May 23, 2002 at 4:33 PM

I thought as you know the position in 3D space of the camera, and the viewpoint before you set up the matrix with D3DXMatrixLookAtLH could you not use two basic right angle equations to work out the angle.

I feal this would be less work than trying to get an angle out of a D3DMatrix.

But my maths is not that hot. I can see it in my head

hope it helps :/

Gordon.

JoeyBlow2

May 23, 2002 at 5:03 PM

atan2 using variables in the matrix...

That returns Radian which you can easily convert to degree.

MatthewEva

Author

MatthewEva

May 24, 2002 at 2:11 AM

Thanks guys,

Yes I could use a cos/sin calc on the two positions to calc the rotations, as the cam is not tilting Im not too worried about the z angle, only the x and y.

#ifndef _DIRECTX
PostQuitMessage(0);
#endif

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