98 lines
3.0 KiB
C
98 lines
3.0 KiB
C
/** @file Quaternion structure, including operators when compiling in C++ */
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#ifndef AI_QUATERNION_H_INC
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#define AI_QUATERNION_H_INC
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#include <math.h>
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#include "aiTypes.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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// ---------------------------------------------------------------------------
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/** Represents a quaternion in a 4D vector. */
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struct aiQuaternion
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{
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#ifdef __cplusplus
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aiQuaternion() : w(0.0f), x(0.0f), y(0.0f), z(0.0f) {}
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aiQuaternion(float _w, float _x, float _y, float _z) : w(_w), x(_x), y(_y), z(_z) {}
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/** Construct from rotation matrix. Result is undefined if the matrix is not orthonormal. */
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aiQuaternion( const aiMatrix3x3& pRotMatrix);
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/** Returns a matrix representation of the quaternion */
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aiMatrix3x3 GetMatrix() const;
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#endif // __cplusplus
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//! w,x,y,z components of the quaternion
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float w, x, y, z;
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} ;
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#ifdef __cplusplus
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// ---------------------------------------------------------------------------
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// Constructs a quaternion from a rotation matrix
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inline aiQuaternion::aiQuaternion( const aiMatrix3x3 &pRotMatrix)
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{
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float t = 1 + pRotMatrix.a1 + pRotMatrix.b2 + pRotMatrix.c3;
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// large enough
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if( t > 0.00001f)
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{
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float s = sqrt( t) * 2.0f;
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x = (pRotMatrix.b3 - pRotMatrix.c2) / s;
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y = (pRotMatrix.c1 - pRotMatrix.a3) / s;
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z = (pRotMatrix.a2 - pRotMatrix.b1) / s;
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w = 0.25f * s;
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} // else we have to check several cases
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else if( pRotMatrix.a1 > pRotMatrix.b2 && pRotMatrix.a1 > pRotMatrix.c3 )
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{
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// Column 0:
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float s = sqrt( 1.0f + pRotMatrix.a1 - pRotMatrix.b2 - pRotMatrix.c3) * 2.0f;
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x = 0.25f * s;
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y = (pRotMatrix.a2 + pRotMatrix.b1) / s;
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z = (pRotMatrix.c1 + pRotMatrix.a3) / s;
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w = (pRotMatrix.b3 - pRotMatrix.c2) / s;
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}
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else if( pRotMatrix.b2 > pRotMatrix.c3)
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{
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// Column 1:
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float s = sqrt( 1.0f + pRotMatrix.b2 - pRotMatrix.a1 - pRotMatrix.c3) * 2.0f;
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x = (pRotMatrix.a2 + pRotMatrix.b1) / s;
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y = 0.25f * s;
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z = (pRotMatrix.b3 + pRotMatrix.c2) / s;
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w = (pRotMatrix.c1 - pRotMatrix.a3) / s;
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}
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else
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{
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// Column 2:
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float s = sqrt( 1.0f + pRotMatrix.c3 - pRotMatrix.a1 - pRotMatrix.b2) * 2.0f;
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x = (pRotMatrix.c1 + pRotMatrix.a3) / s;
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y = (pRotMatrix.b3 + pRotMatrix.c2) / s;
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z = 0.25f * s;
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w = (pRotMatrix.a2 - pRotMatrix.b1) / s;
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}
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}
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// ---------------------------------------------------------------------------
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// Returns a matrix representation of the quaternion
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inline aiMatrix3x3 aiQuaternion::GetMatrix() const
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{
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aiMatrix3x3 resMatrix;
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resMatrix.a1 = 1.0f - 2.0f * (y * y + z * z);
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resMatrix.a2 = 2.0f * (x * y + z * w);
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resMatrix.a3 = 2.0f * (x * z - y * w);
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resMatrix.b1 = 2.0f * (x * y - z * w);
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resMatrix.b2 = 1.0f - 2.0f * (x * x + z * z);
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resMatrix.b3 = 2.0f * (y * z + x * w);
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resMatrix.c1 = 2.0f * (x * z + y * w);
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resMatrix.c2 = 2.0f * (y * z - x * w);
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resMatrix.c3 = 1.0f - 2.0f * (x * x + y * y);
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return resMatrix;
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}
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} // end extern "C"
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#endif // __cplusplus
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#endif // AI_QUATERNION_H_INC
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