Magic Cube

///////////////////////////////////////////////////////////////////////////////////////////////////

// Copyright 2019 Leszek Koltunski                                                               //

//                                                                                               //

// This file is part of Distorted.                                                               //

//                                                                                               //

// Distorted is free software: you can redistribute it and/or modify                             //

// it under the terms of the GNU General Public License as published by                          //

// the Free Software Foundation, either version 2 of the License, or                             //

// (at your option) any later version.                                                           //

//                                                                                               //

// Distorted is distributed in the hope that it will be useful,                                  //

// but WITHOUT ANY WARRANTY; without even the implied warranty of                                //

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the                                 //

// GNU General Public License for more details.                                                  //

//                                                                                               //

// You should have received a copy of the GNU General Public License                             //

// along with Distorted.  If not, see <http://www.gnu.org/licenses/>.                            //

///////////////////////////////////////////////////////////////////////////////////////////////////

package org.distorted.magic;

import android.app.ActivityManager;

import android.content.Context;

import android.content.pm.ConfigurationInfo;

import android.opengl.GLSurfaceView;

import android.util.AttributeSet;

import android.view.MotionEvent;

import org.distorted.library.type.Static4D;

///////////////////////////////////////////////////////////////////////////////////////////////////

class RubikSurfaceView extends GLSurfaceView

{

    // Moving the finger from the middle of the vertical screen to the right edge will rotate a

    // given face by SWIPING_SENSITIVITY/2 degrees.

    private final static int SWIPING_SENSITIVITY = 240;

    // Moving the finger by 1/12 the distance of min(scrWidth,scrHeight) will start a Rotation.

    private final static int ROTATION_SENSITIVITY=  12;

    private final static int NONE   =-1;

    private final static int FRONT  = 0;  // has to be 6 consecutive ints

    private final static int BACK   = 1;  // FRONT ... BOTTOM

    private final static int LEFT   = 2;  //

    private final static int RIGHT  = 3;  //

    private final static int TOP    = 4;  //

    private final static int BOTTOM = 5;  //

    static final int VECTX = 0;  //

    static final int VECTY = 1;  // don't change this

    static final int VECTZ = 2;  //

    private static final int[] VECT = {VECTX,VECTY,VECTZ};

    private boolean mDragging, mBeginningRotation, mContinuingRotation;

    private int mX, mY;

    private int mRotationVect;

    private RubikRenderer mRenderer;

    private float[] mPoint, mCamera, mTouchPointCastOntoFace, mDiff, mTouchPoint; // all in screen space

    private int mLastTouchedFace;

    private int mScreenWidth, mScreenHeight, mScreenMin;

    private float mCameraDistance;

    private static Static4D mQuatCurrent    =new Static4D(0,0,0,1);

    private static Static4D mQuatAccumulated=new Static4D(-0.25189602f,0.3546389f,0.009657208f,0.90038127f);

///////////////////////////////////////////////////////////////////////////////////////////////////

    public RubikSurfaceView(Context context, AttributeSet attrs)

      {

      super(context,attrs);

      if(!isInEditMode())

        {

        mRotationVect = VECT[0];

        mPoint = new float[3];

        mCamera= new float[3];

        mDiff  = new float[3];

        mTouchPoint = new float[3];

        mTouchPointCastOntoFace = new float[3];

        mScreenWidth = mScreenHeight = mScreenMin = 0;

        mRenderer = new RubikRenderer(this);

        mRenderer.setQuatAccumulated(mQuatAccumulated);

        final ActivityManager activityManager     = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);

        final ConfigurationInfo configurationInfo = activityManager.getDeviceConfigurationInfo();

        setEGLContextClientVersion( (configurationInfo.reqGlEsVersion>>16) >= 3 ? 3:2 );

        setRenderer(mRenderer);

        }

      }

///////////////////////////////////////////////////////////////////////////////////////////////////

    @Override

    public boolean onTouchEvent(MotionEvent event)

      {

      int action = event.getAction();

      int x = (int)event.getX();

      int y = (int)event.getY();

      switch(action)

         {

         case MotionEvent.ACTION_DOWN: mX = x;

                                       mY = y;

                                       mLastTouchedFace = faceTouched(x,y);

                                       if( mLastTouchedFace != NONE )

                                         {

                                         mDragging           = false;

                                         mBeginningRotation  = mRenderer.canRotate();

                                         mContinuingRotation = false;

                                         }

                                       else

                                         {

                                         mDragging           = mRenderer.canDrag();

                                         mBeginningRotation  = false;

                                         mContinuingRotation = false;

                                         }

                                       break;

         case MotionEvent.ACTION_MOVE: if( mDragging )

                                         {

                                         mQuatCurrent.set(quatFromDrag(mX-x,mY-y));

                                         mRenderer.setQuatCurrent(mQuatCurrent);

                                         }

                                       if( mBeginningRotation )

                                         {

                                         int minimumDistToStartRotating = (mScreenMin*mScreenMin)/(ROTATION_SENSITIVITY*ROTATION_SENSITIVITY);

                                         if( (mX-x)*(mX-x)+(mY-y)*(mY-y) > minimumDistToStartRotating )

                                           {

                                           addNewRotation(x,y);

                                           mBeginningRotation = false;

                                           mContinuingRotation= true;

                                           }

                                         }

                                       else if( mContinuingRotation )

                                         {

                                         continueRotation(x,y);

                                         }

                                       break;

         case MotionEvent.ACTION_UP  : if( mDragging )

                                         {

                                         mQuatAccumulated.set(quatMultiply(mQuatCurrent, mQuatAccumulated));

                                         mQuatCurrent.set(0f, 0f, 0f, 1f);

                                         mRenderer.setQuatCurrent(mQuatCurrent);

                                         mRenderer.setQuatAccumulated(mQuatAccumulated);

                                         }

                                       if( mContinuingRotation )

                                         {

                                         finishRotation();

                                         }

                                       break;

         }

      return true;

      }

///////////////////////////////////////////////////////////////////////////////////////////////////

    RubikRenderer getRenderer()

      {

      return mRenderer;

      }

///////////////////////////////////////////////////////////////////////////////////////////////////

    void setScreenSize(int width, int height)

      {

      mScreenWidth = width;

      mScreenHeight= height;

      mScreenMin = width<height ? width:height;

      }

///////////////////////////////////////////////////////////////////////////////////////////////////

    void setCameraDist(float distance)

      {

      mCameraDistance = distance;

      }

///////////////////////////////////////////////////////////////////////////////////////////////////

    private int faceTouched(int xTouch, int yTouch)

      {

      float cubeHalfSize= mRenderer.returnCubeSizeInScreenSpace()*0.5f;

      convertTouchPointToScreenSpace(xTouch,yTouch);

      convertCameraPointToScreenSpace();

      for(int face=FRONT; face<=BOTTOM; face++)

        {

        if( faceIsVisible(face,cubeHalfSize) )

          {

          castTouchPointOntoFace(face,cubeHalfSize, mTouchPointCastOntoFace);

          float qX= (mTouchPointCastOntoFace[0]+cubeHalfSize) / (2*cubeHalfSize);

          float qY= (mTouchPointCastOntoFace[1]+cubeHalfSize) / (2*cubeHalfSize);

          float qZ= (mTouchPointCastOntoFace[2]+cubeHalfSize) / (2*cubeHalfSize);

          if( qX<=1 && qX>=0 && qY<=1 && qY>=0 && qZ<=1 && qZ>=0 ) return face;

          }

        }

      return NONE;

      }

///////////////////////////////////////////////////////////////////////////////////////////////////

    private void addNewRotation(int x, int y)

      {

      float cubeHalfSize= mRenderer.returnCubeSizeInScreenSpace()*0.5f;

      convertTouchPointToScreenSpace(x,y);

      castTouchPointOntoFace(mLastTouchedFace,cubeHalfSize,mDiff);

      mDiff[0] -= mTouchPointCastOntoFace[0];

      mDiff[1] -= mTouchPointCastOntoFace[1];

      mDiff[2] -= mTouchPointCastOntoFace[2];

      int xAxis = retFaceXaxis(mLastTouchedFace);

      int yAxis = retFaceYaxis(mLastTouchedFace);

      mRotationVect = (isVertical( mDiff[xAxis], mDiff[yAxis]) ? VECT[xAxis]:VECT[yAxis]);

      float offset= (mTouchPointCastOntoFace[mRotationVect]+cubeHalfSize)/(2*cubeHalfSize);

      mTouchPoint[0] = mPoint[0];

      mTouchPoint[1] = mPoint[1];

      mTouchPoint[2] = mPoint[2];

      mRenderer.getCube().addNewRotation(mRotationVect,offset);

      }

///////////////////////////////////////////////////////////////////////////////////////////////////

    private boolean isVertical(float x, float y)

      {

      return (y>x) ? (y>=-x) : (y< -x);

      }

///////////////////////////////////////////////////////////////////////////////////////////////////

    private void continueRotation(int x, int y)

      {

      convertTouchPointToScreenSpace(x,y);

      mDiff[0] = mPoint[0]-mTouchPoint[0];

      mDiff[1] = mPoint[1]-mTouchPoint[1];

      mDiff[2] = mPoint[2]-mTouchPoint[2];

      int xAxis= retFaceXaxis(mLastTouchedFace);

      int yAxis= retFaceYaxis(mLastTouchedFace);

      int sign = retFaceRotationSign(mLastTouchedFace);

      float angle = (mRotationVect==xAxis ? mDiff[yAxis] : -mDiff[xAxis]);

      mRenderer.getCube().continueRotation(SWIPING_SENSITIVITY*sign*angle/mScreenMin);

      }

///////////////////////////////////////////////////////////////////////////////////////////////////

    private void finishRotation()

      {

      mRenderer.finishRotation();

      }

///////////////////////////////////////////////////////////////////////////////////////////////////

// return quat1*quat2

    static Static4D quatMultiply( Static4D quat1, Static4D quat2 )

      {

      float qx = quat1.get1();

      float qy = quat1.get2();

      float qz = quat1.get3();

      float qw = quat1.get4();

      float rx = quat2.get1();

      float ry = quat2.get2();

      float rz = quat2.get3();

      float rw = quat2.get4();

      float tx = rw*qx - rz*qy + ry*qz + rx*qw;

      float ty = rw*qy + rz*qx + ry*qw - rx*qz;

      float tz = rw*qz + rz*qw - ry*qx + rx*qy;

      float tw = rw*qw - rz*qz - ry*qy - rx*qx;

      return new Static4D(tx,ty,tz,tw);

      }

///////////////////////////////////////////////////////////////////////////////////////////////////

// rotate 'vector' by quat^(-1)  ( i.e. return (quat^-1)*vector*quat )

    static Static4D rotateVectorByInvertedQuat(Static4D vector, Static4D quat)

      {

      float qx = quat.get1();

      float qy = quat.get2();

      float qz = quat.get3();

      float qw = quat.get4();

      Static4D quatInverted= new Static4D(-qx,-qy,-qz,qw);

      Static4D tmp = quatMultiply(quatInverted,vector);

      return quatMultiply(tmp,quat);

      }

///////////////////////////////////////////////////////////////////////////////////////////////////

// rotate 'vector' by quat  ( i.e. return quat*vector*(quat^-1) )

    static Static4D rotateVectorByQuat(Static4D vector, Static4D quat)

      {

      float qx = quat.get1();

      float qy = quat.get2();

      float qz = quat.get3();

      float qw = quat.get4();

      Static4D quatInverted= new Static4D(-qx,-qy,-qz,qw);

      Static4D tmp = quatMultiply(quat,vector);

      return quatMultiply(tmp,quatInverted);

      }

///////////////////////////////////////////////////////////////////////////////////////////////////

    private Static4D quatFromDrag(float dragX, float dragY)

      {

      float axisX = dragY;  // inverted X and Y - rotation axis is

      float axisY = dragX;  // perpendicular to (dragX,dragY)   Why not (-dragY, dragX) ? because Y axis is also inverted!

      float axisZ = 0;

      float axisL = (float)Math.sqrt(axisX*axisX + axisY*axisY + axisZ*axisZ);

      if( axisL>0 )

        {

        axisX /= axisL;

        axisY /= axisL;

        axisZ /= axisL;

        float cosA = (float)Math.cos(axisL*Math.PI/mScreenMin);

        float sinA = (float)Math.sqrt(1-cosA*cosA);

        return new Static4D(axisX*sinA, axisY*sinA, axisZ*sinA, cosA);

        }

      return new Static4D(0f, 0f, 0f, 1f);

      }

///////////////////////////////////////////////////////////////////////////////////////////////////

    private boolean faceIsVisible(int face, float cubeHalfSize)

      {

      int sign = retFaceSign(face);

      int zAxis= retFaceZaxis(face);

      return sign*mCamera[zAxis] > cubeHalfSize;

      }

///////////////////////////////////////////////////////////////////////////////////////////////////

    private void convertTouchPointToScreenSpace(int x, int y)

      {

      float halfScrWidth  = mScreenWidth *0.5f;

      float halfScrHeight = mScreenHeight*0.5f;

      Static4D touchPoint = new Static4D(x-halfScrWidth, halfScrHeight-y, 0, 0);

      Static4D rotatedTouchPoint= rotateVectorByInvertedQuat(touchPoint, mQuatAccumulated);

      mPoint[0] = rotatedTouchPoint.get1();

      mPoint[1] = rotatedTouchPoint.get2();

      mPoint[2] = rotatedTouchPoint.get3();

      }

///////////////////////////////////////////////////////////////////////////////////////////////////

    private void convertCameraPointToScreenSpace()

      {

      Static4D cameraPoint = new Static4D(0, 0, mCameraDistance, 0);

      Static4D rotatedCamera= rotateVectorByInvertedQuat(cameraPoint, mQuatAccumulated);

      mCamera[0] = rotatedCamera.get1();

      mCamera[1] = rotatedCamera.get2();

      mCamera[2] = rotatedCamera.get3();

      }

///////////////////////////////////////////////////////////////////////////////////////////////////

// given precomputed mCamera and mPoint, respectively camera and touch point positions in ScreenSpace,

// cast this touch point onto the surface defined by the 'face' and write the cast coords to 'output'.

// Center of the 'face' = (0,0), third coord always +- cubeHalfSize.

    private void castTouchPointOntoFace(int face, float cubeHalfSize, float[] output)

      {

      int sign = retFaceSign(face);

      int zAxis= retFaceZaxis(face);

      float diff = mPoint[zAxis]-mCamera[zAxis];

      float ratio =  diff!=0.0f ? (sign*cubeHalfSize-mCamera[zAxis])/diff : 0.0f;

      output[0] = (mPoint[0]-mCamera[0])*ratio + mCamera[0];

      output[1] = (mPoint[1]-mCamera[1])*ratio + mCamera[1];

      output[2] = (mPoint[2]-mCamera[2])*ratio + mCamera[2];

      }

///////////////////////////////////////////////////////////////////////////////////////////////////

    private int retFaceSign(int face)

      {

      return (face==FRONT || face==RIGHT || face==TOP) ? 1:-1;

      }

///////////////////////////////////////////////////////////////////////////////////////////////////

    private int retFaceRotationSign(int face)

      {

      return (face==BACK || face==RIGHT || face==TOP) ? 1:-1;

      }

///////////////////////////////////////////////////////////////////////////////////////////////////

// retFace{X,Y,Z}axis: 3 functions which return which real AXIS gets mapped to which when we look

// directly at a given face. For example, when we look at the RIGHT face of the cube (with TOP still

// in the top) then the 'real' X axis becomes the 'Z' axis, thus retFaceZaxis(RIGHT) = VECTX.

    private int retFaceXaxis(int face)

      {

      switch(face)

        {

        case FRONT :

        case BACK  : return VECTX;

        case LEFT  :

        case RIGHT : return VECTZ;

        case TOP   :

        case BOTTOM: return VECTX;

        }

      return -1;

      }

///////////////////////////////////////////////////////////////////////////////////////////////////

    private int retFaceYaxis(int face)

      {

      switch(face)

        {

        case FRONT :

        case BACK  : return VECTY;

        case LEFT  :

        case RIGHT : return VECTY;

        case TOP   :

        case BOTTOM: return VECTZ;

        }

      return -1;

      }

///////////////////////////////////////////////////////////////////////////////////////////////////

    private int retFaceZaxis(int face)

      {

      switch(face)

        {

        case FRONT :

        case BACK  : return VECTZ;

        case LEFT  :

        case RIGHT : return VECTX;

        case TOP   :

        case BOTTOM: return VECTY;

        }

      return -1;

      }

}