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library / src / main / java / org / distorted / library / effect / VertexEffectPinch.java @ c0255951

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///////////////////////////////////////////////////////////////////////////////////////////////////
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// Copyright 2017 Leszek Koltunski  leszek@koltunski.pl                                          //
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//                                                                                               //
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// This file is part of Distorted.                                                               //
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//                                                                                               //
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// This library is free software; you can redistribute it and/or                                 //
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// modify it under the terms of the GNU Lesser General Public                                    //
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// License as published by the Free Software Foundation; either                                  //
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// version 2.1 of the License, or (at your option) any later version.                            //
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//                                                                                               //
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// This library 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 GNU                             //
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// Lesser General Public License for more details.                                               //
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//                                                                                               //
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// You should have received a copy of the GNU Lesser General Public                              //
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// License along with this library; if not, write to the Free Software                           //
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// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA                //
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///////////////////////////////////////////////////////////////////////////////////////////////////
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package org.distorted.library.effect;
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import org.distorted.library.type.Data3D;
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import org.distorted.library.type.Data4D;
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///////////////////////////////////////////////////////////////////////////////////////////////////
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/**
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 * Pull all points around the center of the Effect towards a line passing through the center
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 * (that's if degree>=1) or push them away from the line (degree<=1).
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 *
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 * Note: this is not a fully 3D effect - the pinching is always within the XY plane; z coordinates
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 * of all vertices remain unaffected. If someone wants a fully 3D Pinch effect, we'd probably need
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 * to write another VertexEffectPinch3D with 2 more arguments (latitude and longitude angles defining
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 * the plane the pinching works on).
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 */
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public class VertexEffectPinch extends VertexEffect
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  {
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  private static final EffectName NAME = EffectName.PINCH;
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  private final Data3D mPinch;
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  private final Data3D mCenter;
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  private final Data4D mRegion;
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///////////////////////////////////////////////////////////////////////////////////////////////////
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/**
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 * Only for use by the library itself.
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 *
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 * @y.exclude
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 */
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  public boolean compute(float[] uniforms, int index, long currentDuration, long step )
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    {
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    mCenter.get(uniforms,index+CENTER_OFFSET,currentDuration,step);
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    mRegion.get(uniforms,index+REGION_OFFSET,currentDuration,step);
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    boolean ret = mPinch.get(uniforms,index+VALUES_OFFSET,currentDuration,step);
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    uniforms[index+VALUES_OFFSET+1] = (float)(Math.PI*uniforms[index+1]/180);
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    uniforms[index+VALUES_OFFSET+2] = (float)(Math.PI*uniforms[index+2]/180);
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    return ret;
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    }
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///////////////////////////////////////////////////////////////////////////////////////////////////
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// Pull P=(v.x,v.y) along a vector from the center of region sphere to a point on it defined by
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// the (latitude,longitude) pair of angles with P' = P + (1-h)*dist(line to P)
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// when h>1 we are pushing points away from S: P' = P + (1/h-1)*dist(line to P)
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// (where 'line' above passes through the center point and goes along the vector)
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///////////////////////////////////////////////////////////////////////////////////////////////////
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  static String code()
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    {
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    return
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        "vec3 ps = vUniforms[effect+1].yzw -v;               \n"
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      + "float h         = vUniforms[effect].x;              \n"
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      + "float latitude  = vUniforms[effect].y;              \n"
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      + "float longitude = vUniforms[effect].z;              \n"
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      + "float deg = degree(vUniforms[effect+2],ps);         \n"
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      + "float t = deg * (1.0-h)/max(1.0,h);                 \n"
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      + "float sinLAT = sin(latitude);                       \n"
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      + "float cosLAT = cos(latitude);                       \n"
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      + "float sinLON = sin(longitude);                      \n"
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      + "float cosLON = cos(longitude);                      \n"
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      + "vec3 dir = vec3(sinLON*cosLAT,sinLAT,cosLON*cosLAT);\n"
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      + "float dot_dir_ps = dot(dir,ps);                     \n"
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      + "v += t*dot_dir_ps*dir;                              \n"
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      + "const float A = 1.6;                                \n" // max amount of change in normal vector when pulling
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      + "const float B = 10.0;                               \n" // when pushing
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      + "vec3 n_ps = dot(ps,n)*ps;                           \n" // n_ps = (component of n that's parallel to ps) * |ps|^2 (=dot(ps,ps))
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      + "float dot_ps = dot(ps,ps);                          \n"
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      + "float sign_ps= sign(dot_ps);                        \n"
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      + "n_ps = sign_ps*n_ps/(dot_ps-(sign_ps-1.0));         \n" // uff! now n_ps is the parallel to ps component of n, even if ps==0
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      + "float move = deg*(h-1.0)/(h/B+1.0/A);               \n" // move(0)=-A*deg, move(1)=0, move(inf)=B*deg
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      + "n += move * abs(dot(n,dir)) * n_ps;                 \n"
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      + "n = normalize(n);";
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    }
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///////////////////////////////////////////////////////////////////////////////////////////////////
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// PUBLIC API
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///////////////////////////////////////////////////////////////////////////////////////////////////
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/**
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 * Have to call this before the shaders get compiled (i.e before DistortedLibrary.onCreate()) for the Effect to work.
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 */
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  public static void enable()
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    {
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    addEffect( NAME, code() );
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    }
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///////////////////////////////////////////////////////////////////////////////////////////////////
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/**
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 * Pull all points around the center of the Effect towards a line passing through the center
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 * (that's if degree>=1) or push them away from the line (degree<=1)
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 *
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 * @param pinch  The current degree of the Effect + (latitude,longitude) pair of angles defining the
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 *  *            point towards which (and its antipode) the pinching power is strongest.
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 * @param center 3-dimensional Data that, at any given time, returns the Center of the Effect.
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 * @param region Region that masks the Effect.
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 */
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  public VertexEffectPinch(Data3D pinch, Data3D center, Data4D region)
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    {
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    super(NAME);
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    mPinch  = pinch;
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    mCenter = center;
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    mRegion = (region==null ? MAX_REGION : region);
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    }
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///////////////////////////////////////////////////////////////////////////////////////////////////
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/**
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 * Pull all points around the center of the Effect towards a line passing through the center
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 * (that's if degree>=1) or push them away from the line (degree<=1)
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 *
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 * @param pinch  The current degree of the Effect + (latitude,longitude) pair of angles defining the
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 *               point towards which (and its antipode) the pinching power is strongest.
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 * @param center 3-dimensional Data that, at any given time, returns the Center of the Effect.
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 */
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  public VertexEffectPinch(Data3D pinch, Data3D center)
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    {
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    super(NAME);
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    mPinch  = pinch;
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    mCenter = center;
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    mRegion = MAX_REGION;
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    }
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  }
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