How can I get Pitch, Yaw and Roll values from matRotation?

**Edited by Medo3337, 19 May 2012 - 04:50 PM.**

6 replies to this topic

Posted 19 May 2012 - 10:53 PM

This routine served me well (the one time I used it), always be careful with these three angles, usually it ends up in tears and gimbal locks:

The routine is a member of a 4x4 matrix with these members:

void ToEulerAngles( float& fAngleX, float& fAngleY, float& fAngleZ ) { static float fRadiansToDegree = 180.0f / 3.1415926f; fAngleY = asinf( M[8] ); // Calculate Y-axis angle float fCY = cosf( fAngleY ); fAngleY *= fRadiansToDegree; if ( fabsf( fCY ) > 0.005f ) { float ftrx = M[10] / fCY; // No, so get X-axis angle float ftry = -M[9] / fCY; fAngleX = atan2f( ftry, ftrx ) * fRadiansToDegree; ftrx = M[0] / fCY; // Get Z-axis angle ftry = -M[4] / fCY; fAngleZ = atan2f( ftry, ftrx ) * fRadiansToDegree; } else { // Gimbal lock? fAngleX = 0; // Set X-axis angle to zero float ftrx = M[5]; // And calculate Z-axis angle float ftry = M[1]; fAngleZ = atan2f( ftry, ftrx ) * fRadiansToDegree; } if ( fAngleX < 0 ) { fAngleX += 360; } if ( fAngleY < 0 ) { fAngleY += 360; } if ( fAngleZ < 0 ) { fAngleZ += 360; } }

The routine is a member of a 4x4 matrix with these members:

struct tStruct { float _11, _12, _13, _14; float _21, _22, _23, _24; float _31, _32, _33, _34; float _41, _42, _43, _44; }; union { tStruct ms; float m[4][4]; float M[16]; };

**Edited by Endurion, 19 May 2012 - 10:55 PM.**

Fruny: Ftagn! Ia! Ia! std::time_put_byname! Mglui naflftagn std::codecvt eY'ha-nthlei!,char,mbstate_t>

Posted 20 May 2012 - 02:47 AM

How do you use this method with

**Remember, I want the EXACT values of Pitch, Yaw and Roll from **

matRotation?

The method I want is to be able to pass matRotation which is "D3DXMATRIX" and get the rotation X, Y and Z.

D3DXMATRIX.

**Edited by Medo3337, 20 May 2012 - 03:09 AM.**

Posted 21 May 2012 - 12:28 AM

A D3DXMATRIX has these members:

typedef struct _D3DMATRIX {

union {

struct {

float _11, _12, _13, _14;

float _21, _22, _23, _24;

float _31, _32, _33, _34;

float _41, _42, _43, _44;

};

float m[4][4];

};

} D3DMATRIX;

You can map all the M[x] accesses to m[x][y], you just need to use the right order of columns/rows.

typedef struct _D3DMATRIX {

union {

struct {

float _11, _12, _13, _14;

float _21, _22, _23, _24;

float _31, _32, _33, _34;

float _41, _42, _43, _44;

};

float m[4][4];

};

} D3DMATRIX;

You can map all the M[x] accesses to m[x][y], you just need to use the right order of columns/rows.

Fruny: Ftagn! Ia! Ia! std::time_put_byname! Mglui naflftagn std::codecvt eY'ha-nthlei!,char,mbstate_t>

Posted 21 May 2012 - 01:15 AM

Here's what I use:

http://www.euclideanspace.com/maths/geometry/rotations/conversions/matrixToEuler/

http://www.euclideanspace.com/maths/geometry/rotations/conversions/matrixToEuler/

Posted 21 May 2012 - 02:57 AM

I see some issues stated about converting matrix to Euler, I want to guarantee that I will receive VALID values and EXACTLY the same rotation values from a D3DXMATRIX every time I convert D3DXMATRIX to Euler without any problem, is that possible?

Posted 21 May 2012 - 05:59 AM

I see some issues stated about converting matrix to Euler, I want to guarantee that I will receive VALID values and EXACTLY the same rotation values from a D3DXMATRIX every time I convert D3DXMATRIX to Euler without any problem, is that possible?

Barring rounding errors, you'll get the exact same rotation in euler angles. However, euler angles do not represent orientations uniquely, meaning there's more than one set of euler angles for any given orientation.

Of course, as long you'll use the same algorithm for conversion, matrix M will always give the same angles X, Y and Z. But, for instance, if your rotate M by 45 degrees around the Y axis, you won't necessarily get X, Y+45 and Z. Just another set of angles that represent that orientation.

So, if you want to keep the exact euler values, e.g. as entered, you have to save them...