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///////////////////////////////////////////////////////////////////////////////////////////////////
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// Copyright 2021 Leszek Koltunski //
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// //
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// This file is part of Magic Cube. //
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// //
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// Magic Cube is free software: you can redistribute it and/or modify //
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// it under the terms of the GNU General Public License as published by //
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// the Free Software Foundation, either version 2 of the License, or //
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// (at your option) any later version. //
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// //
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// Magic Cube is distributed in the hope that it will be useful, //
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// but WITHOUT ANY WARRANTY; without even the implied warranty of //
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the //
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// GNU General Public License for more details. //
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// //
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// You should have received a copy of the GNU General Public License //
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// along with Magic Cube. If not, see <http://www.gnu.org/licenses/>. //
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///////////////////////////////////////////////////////////////////////////////////////////////////
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package org.distorted.helpers;
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import org.distorted.library.type.Static4D;
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///////////////////////////////////////////////////////////////////////////////////////////////////
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public class QuatHelper
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{
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///////////////////////////////////////////////////////////////////////////////////////////////////
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// return quat1*quat2
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public static Static4D quatMultiply( Static4D quat1, Static4D quat2 )
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{
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float qx = quat1.get0();
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float qy = quat1.get1();
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float qz = quat1.get2();
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float qw = quat1.get3();
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float rx = quat2.get0();
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float ry = quat2.get1();
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float rz = quat2.get2();
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float rw = quat2.get3();
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float tx = rw*qx - rz*qy + ry*qz + rx*qw;
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float ty = rw*qy + rz*qx + ry*qw - rx*qz;
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float tz = rw*qz + rz*qw - ry*qx + rx*qy;
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float tw = rw*qw - rz*qz - ry*qy - rx*qx;
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return new Static4D(tx,ty,tz,tw);
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}
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///////////////////////////////////////////////////////////////////////////////////////////////////
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// rotate 'vector' by quat ( i.e. return quat*vector*(quat^-1) )
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public static Static4D rotateVectorByQuat(Static4D vector, Static4D quat)
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{
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float qx = quat.get0();
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float qy = quat.get1();
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float qz = quat.get2();
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float qw = quat.get3();
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Static4D quatInverted= new Static4D(-qx,-qy,-qz,qw);
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Static4D tmp = quatMultiply(quat,vector);
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return quatMultiply(tmp,quatInverted);
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}
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///////////////////////////////////////////////////////////////////////////////////////////////////
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// rotate 'vector' by quat^(-1) ( i.e. return (quat^-1)*vector*quat )
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public static Static4D rotateVectorByInvertedQuat(Static4D vector, Static4D quat)
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{
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float qx = quat.get0();
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float qy = quat.get1();
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float qz = quat.get2();
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float qw = quat.get3();
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Static4D quatInverted= new Static4D(-qx,-qy,-qz,qw);
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Static4D tmp = quatMultiply(quatInverted,vector);
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return quatMultiply(tmp,quat);
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}
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///////////////////////////////////////////////////////////////////////////////////////////////////
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public static Static4D quatFromDrag(float dragX, float dragY)
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{
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float axisX = dragY; // inverted X and Y - rotation axis is perpendicular to (dragX,dragY)
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float axisY = dragX; // Why not (-dragY, dragX) ? because Y axis is also inverted!
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float axisZ = 0;
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float axisL = (float)Math.sqrt(axisX*axisX + axisY*axisY + axisZ*axisZ);
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if( axisL>0 )
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{
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axisX /= axisL;
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axisY /= axisL;
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axisZ /= axisL;
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float ratio = axisL;
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ratio = ratio - (int)ratio; // the cos() is only valid in (0,Pi)
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float cosA = (float)Math.cos(Math.PI*ratio);
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float sinA = (float)Math.sqrt(1-cosA*cosA);
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return new Static4D(axisX*sinA, axisY*sinA, axisZ*sinA, cosA);
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}
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return new Static4D(0f, 0f, 0f, 1f);
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}
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}
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