Distorted Android

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// Copyright 2017 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/>.                            //

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package org.distorted.library.effect;

import android.opengl.Matrix;

import org.distorted.library.type.Data3D;

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/**

 * Shear the Mesh.

 */

public class MatrixEffectShear extends MatrixEffect

  {

  private Data3D mShear, mCenter;

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/**

 * Only for use by the library itself.

 *

 * @y.exclude

 */

  public boolean compute(float[] uniforms, int index, long currentDuration, long step )

    {

    mCenter.get(uniforms,index+CENTER_OFFSET,currentDuration,step);

    return mShear.get(uniforms,index,currentDuration,step);

    }

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/**

 * Only for use by the library itself.

 * <p>

 * Here and in Shear we have the whole reason why there are two separate 'P' and 'V' (Point and

 * Vector) matrices - Scale and Shear have to manipulate Points and Normal Vectors differently.

 *

 * @y.exclude

 */

  public void apply(float[] matrixP, float[] matrixV, float[] uniforms, int index)

    {

    float sx = uniforms[NUM_UNIFORMS*index  ];

    float sy = uniforms[NUM_UNIFORMS*index+1];

    float sz = uniforms[NUM_UNIFORMS*index+2];

    float x  = uniforms[NUM_UNIFORMS*index+CENTER_OFFSET  ];

    float y  = uniforms[NUM_UNIFORMS*index+CENTER_OFFSET+1];

    float z  = uniforms[NUM_UNIFORMS*index+CENTER_OFFSET+2];

    Matrix.translateM(matrixP, 0, x, y, z);

    matrixP[4] += sx*matrixP[0]; // Multiply viewMatrix by 1 x 0 0 , i.e. X-shear.

    matrixP[5] += sx*matrixP[1]; //                        0 1 0 0

    matrixP[6] += sx*matrixP[2]; //                        0 0 1 0

    matrixP[7] += sx*matrixP[3]; //                        0 0 0 1

    matrixP[0] += sy*matrixP[4]; // Multiply viewMatrix by 1 0 0 0 , i.e. Y-shear.

    matrixP[1] += sy*matrixP[5]; //                        y 1 0 0

    matrixP[2] += sy*matrixP[6]; //                        0 0 1 0

    matrixP[3] += sy*matrixP[7]; //                        0 0 0 1

    matrixP[4] += sz*matrixP[8]; // Multiply viewMatrix by 1 0 0 0 , i.e. Z-shear.

    matrixP[5] += sz*matrixP[9]; //                        0 1 0 0

    matrixP[6] += sz*matrixP[10];//                        0 z 1 0

    matrixP[7] += sz*matrixP[11];//                        0 0 0 1

    Matrix.translateM(matrixP, 0,-x,-y,-z);

    Matrix.translateM(matrixV, 0, x, y, z);

    matrixV[0] -= sx*matrixV[4]; // Multiply viewMatrix by 1 0 0 0 , i.e. vector X-shear.

    matrixV[1] -= sx*matrixV[5]; //                       -x 1 0 0

    matrixV[2] -= sx*matrixV[6]; //                        0 0 1 0

    matrixV[3] -= sx*matrixV[7]; //                        0 0 0 1

    matrixV[4] -= sy*matrixV[0]; // Multiply viewMatrix by 1-y 0 0 , i.e. vector Y-shear.

    matrixV[5] -= sy*matrixV[1]; //                        0 1 0 0

    matrixV[6] -= sy*matrixV[2]; //                        0 0 1 0

    matrixV[7] -= sy*matrixV[3]; //                        0 0 0 1

    matrixV[8] -= sz*matrixV[4]; // Multiply viewMatrix by 1 0 0 0 , i.e. vector Z-shear.

    matrixV[9] -= sz*matrixV[5]; //                        0 1-z 0

    matrixV[10]-= sz*matrixV[6]; //                        0 0 1 0

    matrixV[11]-= sz*matrixV[7]; //                        0 0 0 1

    Matrix.translateM(matrixV, 0,-x,-y,-z);

    }

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// PUBLIC API

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/**

 * Shear the Mesh.

 *

 * @param shear   The 3-tuple of shear factors. The first controls level

 *                of shearing in the X-axis, second - Y-axis and the third -

 *                Z-axis. Each is the tangent of the shear angle, i.e 0 -

 *                no shear, 1 - shear by 45 degrees (tan(45deg)=1) etc.

 * @param center  Center of shearing, i.e. the point which stays unmoved.

 */

  public MatrixEffectShear(Data3D shear, Data3D center)

    {

    super(EffectName.SHEAR);

    mShear = shear;

    mCenter = center;

    }

  }