kmVec3* const kmMat3RotationToAxisAngle(kmVec3* pAxis, kmScalar* radians, const kmMat3* pIn)
{
/*Surely not this easy?*/
kmQuaternion temp;
kmQuaternionRotationMatrix(&temp, pIn);
kmQuaternionToAxisAngle(&temp, pAxis, radians);
return pAxis;
}
/**
* Take the rotation from a 4x4 transformation matrix, and return it as an axis and an angle (in radians)
* returns the output axis.
*/
kmVec3* kmMat4RotationToAxisAngle(kmVec3* pAxis, kmScalar* radians, const kmMat4* pIn)
{
/*Surely not this easy?*/
kmQuaternion temp;
kmMat3 rotation;
kmMat4ExtractRotation(&rotation, pIn);
kmQuaternionRotationMatrix(&temp, &rotation);
kmQuaternionToAxisAngle(&temp, pAxis, radians);
return pAxis;
}
kmQuaternion* kmQuaternionLookRotation(kmQuaternion* pOut, const kmVec3* direction, const kmVec3* upDirection) {
kmMat4 lookAt;
kmMat3 rot;
kmMat4LookAt(&lookAt, &KM_VEC3_ZERO, direction, upDirection);
kmMat4ExtractRotationMat3(&lookAt, &rot);
kmQuaternionRotationMatrix(pOut, &rot);
kmQuaternionNormalize(pOut, pOut);
return pOut;
}
kmQuaternion* kmQuaternionLookRotation(kmQuaternion* pOut, const kmVec3* direction, const kmVec3* up) {
kmMat3 tmp;
kmMat3LookAt(&tmp, &KM_VEC3_ZERO, direction, up);
return kmQuaternionNormalize(pOut, kmQuaternionRotationMatrix(pOut, &tmp));
/*
if(!direction->x && !direction->y && !direction->z) {
return kmQuaternionIdentity(pOut);
}
kmVec3 right;
kmVec3Cross(&right, up, direction);
pOut->w = sqrtf(1.0f + right.x + up->y + direction->z) * 0.5f;
float w4_recip = 1.0f / (4.0f * pOut->w);
pOut->x = (up->z - direction->y) * w4_recip;
pOut->y = (direction->x - right.z) * w4_recip;
pOut->z = (right.y - up->x) * w4_recip;
return kmQuaternionNormalize(pOut, pOut);*/
}