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Changed function declaration to match what was requested.

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This commit is contained in:
Thompson Lee 2016-08-07 08:12:52 -04:00
parent 6eb0cacd0a
commit 2efedfe8d2
2 changed files with 21 additions and 19 deletions
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4
include/c3d/maths.h
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@ -624,10 +624,10 @@ void Mtx_FromQuat(C3D_Mtx* m, C3D_FQuat q);
/** /**
* @brief Get Quaternion equivalent to 4x4 matrix * @brief Get Quaternion equivalent to 4x4 matrix
* @note If the matrix is orthogonal or special orthogonal, where determinant(matrix) = +1.0f, then the matrix can be converted. * @note If the matrix is orthogonal or special orthogonal, where determinant(matrix) = +1.0f, then the matrix can be converted.
* @param[out] q Output Quaternion
* @param[in] m Input Matrix * @param[in] m Input Matrix
* @return Generated Quaternion
*/ */
void Quat_FromMtx(C3D_FQuat* q, C3D_Mtx m); C3D_FQuat Quat_FromMtx(C3D_Mtx m);
/** /**
* @brief Identity Quaternion * @brief Identity Quaternion

36
source/maths/quat_frommtx.c
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@ -1,6 +1,6 @@
#include <c3d/maths.h> #include <c3d/maths.h>
void Quat_FromMtx(C3D_FQuat* q, C3D_Mtx m) C3D_FQuat Quat_FromMtx(C3D_Mtx m)
{ {
//Taken from Gamasutra: //Taken from Gamasutra:
//http://www.gamasutra.com/view/feature/131686/rotating_objects_using_quaternions.php //http://www.gamasutra.com/view/feature/131686/rotating_objects_using_quaternions.php
@ -9,6 +9,7 @@ void Quat_FromMtx(C3D_FQuat* q, C3D_Mtx m)
//Variables we need. //Variables we need.
float trace, sqrtTrace; float trace, sqrtTrace;
C3D_FQuat q;
//Check the main diagonal of the passed-in matrix for positive/negative signs. //Check the main diagonal of the passed-in matrix for positive/negative signs.
trace = m.r[0].c[0] + m.r[1].c[1] + m.r[2].c[2]; trace = m.r[0].c[0] + m.r[1].c[1] + m.r[2].c[2];
@ -16,11 +17,11 @@ void Quat_FromMtx(C3D_FQuat* q, C3D_Mtx m)
{ {
//Diagonal is positive. //Diagonal is positive.
sqrtTrace = sqrtf(trace + 1.0f); sqrtTrace = sqrtf(trace + 1.0f);
q->w = sqrtTrace / 2.0f; q.w = sqrtTrace / 2.0f;
sqrtTrace = 0.5 / sqrtTrace; sqrtTrace = 0.5 / sqrtTrace;
q->x = (m.r[1].c[2] - m.r[2].c[1]) * sqrtTrace; q.x = (m.r[1].c[2] - m.r[2].c[1]) * sqrtTrace;
q->y = (m.r[2].c[0] - m.r[0].c[2]) * sqrtTrace; q.y = (m.r[2].c[0] - m.r[0].c[2]) * sqrtTrace;
q->z = (m.r[0].c[1] - m.r[1].c[0]) * sqrtTrace; q.z = (m.r[0].c[1] - m.r[1].c[0]) * sqrtTrace;
} }
else else
{ {
@ -28,26 +29,27 @@ void Quat_FromMtx(C3D_FQuat* q, C3D_Mtx m)
if (m.r[0].c[0] > m.r[1].c[1] && m.r[0].c[0] > m.r[2].c[2]) if (m.r[0].c[0] > m.r[1].c[1] && m.r[0].c[0] > m.r[2].c[2])
{ {
sqrtTrace = 2.0f * sqrtf(1.0f + m.r[0].c[0] - m.r[1].c[1] - m.r[2].c[2]); sqrtTrace = 2.0f * sqrtf(1.0f + m.r[0].c[0] - m.r[1].c[1] - m.r[2].c[2]);
q->w = (m.r[2].c[1] - m.r[1].c[2]) / sqrtTrace; q.w = (m.r[2].c[1] - m.r[1].c[2]) / sqrtTrace;
q->x = 0.25f * sqrtTrace; q.x = 0.25f * sqrtTrace;
q->y = (m.r[0].c[1] - m.r[1].c[0]) / sqrtTrace; q.y = (m.r[0].c[1] - m.r[1].c[0]) / sqrtTrace;
q->z = (m.r[0].c[2] - m.r[2].c[0]) / sqrtTrace; q.z = (m.r[0].c[2] - m.r[2].c[0]) / sqrtTrace;
} }
else if (m.r[1].c[1] > m.r[2].c[2]) else if (m.r[1].c[1] > m.r[2].c[2])
{ {
sqrtTrace = 2.0f * sqrtf(1.0f + m.r[1].c[1] - m.r[0].c[0] - m.r[2].c[2]); sqrtTrace = 2.0f * sqrtf(1.0f + m.r[1].c[1] - m.r[0].c[0] - m.r[2].c[2]);
q->w = (m.r[0].c[2] - m.r[2].c[0]) / sqrtTrace; q.w = (m.r[0].c[2] - m.r[2].c[0]) / sqrtTrace;
q->x = (m.r[0].c[1] - m.r[1].c[0]) / sqrtTrace; q.x = (m.r[0].c[1] - m.r[1].c[0]) / sqrtTrace;
q->y = 0.25f * sqrtTrace; q.y = 0.25f * sqrtTrace;
q->z = (m.r[1].c[2] - m.r[2].c[1]) / sqrtTrace; q.z = (m.r[1].c[2] - m.r[2].c[1]) / sqrtTrace;
} }
else else
{ {
sqrtTrace = 2.0f * sqrtf(1.0f + m.r[2].c[2] - m.r[0].c[0] - m.r[1].c[1]); sqrtTrace = 2.0f * sqrtf(1.0f + m.r[2].c[2] - m.r[0].c[0] - m.r[1].c[1]);
q->w = (m.r[1].c[0] - m.r[0].c[1]) / sqrtTrace; q.w = (m.r[1].c[0] - m.r[0].c[1]) / sqrtTrace;
q->x = (m.r[0].c[2] - m.r[2].c[0]) / sqrtTrace; q.x = (m.r[0].c[2] - m.r[2].c[0]) / sqrtTrace;
q->y = (m.r[1].c[2] - m.r[2].c[1]) / sqrtTrace; q.y = (m.r[1].c[2] - m.r[2].c[1]) / sqrtTrace;
q->z = 0.25f * sqrtTrace; q.z = 0.25f * sqrtTrace;
} }
} }
return q;
} }