272 lines
9 KiB
C++
272 lines
9 KiB
C++
///////////////////////////////////////////////////////////////////////////////////
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// File : APSF.cpp
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///////////////////////////////////////////////////////////////////////////////////
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//
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// LumosQuad - A Lightning Generator
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// Copyright 2007
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// The University of North Carolina at Chapel Hill
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//
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///////////////////////////////////////////////////////////////////////////////////
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//
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// This program 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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// This program 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 this program; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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//
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// The University of North Carolina at Chapel Hill makes no representations
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// about the suitability of this software for any purpose. It is provided
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// "as is" without express or implied warranty.
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//
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// Permission to use, copy, modify and distribute this software and its
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// documentation for educational, research and non-profit purposes, without
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// fee, and without a written agreement is hereby granted, provided that the
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// above copyright notice and the following three paragraphs appear in all
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// copies.
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//
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// THE UNIVERSITY OF NORTH CAROLINA SPECIFICALLY DISCLAIM ANY WARRANTIES,
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// INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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// FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN
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// "AS IS" BASIS, AND THE UNIVERSITY OF NORTH CAROLINA HAS NO OBLIGATION TO
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// PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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//
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// Please send questions and comments about LumosQuad to kim@cs.unc.edu.
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//
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///////////////////////////////////////////////////////////////////////////////////
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//
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// This program uses OpenEXR, which has the following restrictions:
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//
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// Copyright (c) 2002, Industrial Light & Magic, a division of Lucas
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// Digital Ltd. LLC
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//
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// distribution.
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// * Neither the name of Industrial Light & Magic nor the names of
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// its contributors may be used to endorse or promote products derived
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// from this software without specific prior written permission.
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//
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#include "APSF.h"
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#include <cstdio>
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//////////////////////////////////////////////////////////////////////
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// Construction/Destruction
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//////////////////////////////////////////////////////////////////////
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APSF::APSF(int res) :
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_res(res)
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{
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// make sure kernel is odd dimensions
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if (!(_res % 2)) _res++;
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_kernel = new float[_res * _res];
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_q = 0.999;
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_R = 400.0f;
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_D = 2000.0f;
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_T = 1.001f;
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_sigma = 0.5f;
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_maxTerms = 600;
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_I0 = 1.0f;
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_retinaSize = 0.01f;
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_eyeSize = 0.025f;
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}
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APSF::~APSF()
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{
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delete[] _kernel;
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}
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//////////////////////////////////////////////////////////////////////
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// Legendre polymonial
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//////////////////////////////////////////////////////////////////////
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float APSF::legendreM(int m, float mu)
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{
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vector<float> memoized;
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memoized.push_back(1.0f);
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memoized.push_back(mu);
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for (int x = 2; x <= m; x++)
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{
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float newMemo = ((2.0f * (float)x - 1.0f) * mu * memoized[x - 1] -
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((float)x - 1.0f) * memoized[x - 2]) / (float)x;
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memoized.push_back(newMemo);
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}
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return memoized[m];
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}
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//////////////////////////////////////////////////////////////////////
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// scattering function at a point
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//////////////////////////////////////////////////////////////////////
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float APSF::pointAPSF(float mu)
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{
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float total = 0.0f;
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for (int m = 0; m < _maxTerms; m++)
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total += (gM(_I0, m) + gM(_I0, m + 1)) * legendreM(m, mu);
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return total;
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}
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//////////////////////////////////////////////////////////////////////
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// generate a convolution kernel
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//////////////////////////////////////////////////////////////////////
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void APSF::generateKernelFast()
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{
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float dx = _retinaSize / (float)_res;
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float dy = _retinaSize / (float)_res;
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int halfRes = _res / 2;
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float* oneD = new float[_res];
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float max = 0.0f;
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float min = 1000.0f;
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int x,y = halfRes;
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for (x = 0; x < _res; x++)
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{
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// calc angle
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float diffX = (x - halfRes) * dx;
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float diffY = (y - halfRes) * dy;
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float distance = sqrt(diffX * diffX + diffY * diffY);
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if ((distance / _eyeSize) > (_R / _D))
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oneD[x] = 0.0f;
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else
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{
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float i = -distance * distance * _D * _D + _eyeSize * _eyeSize * _R * _R + distance * distance * _R * _R;
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i = _eyeSize * _eyeSize * _D - _eyeSize * sqrt(i);
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i /= _eyeSize * _eyeSize + distance * distance;
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float mu = M_PI - atan(_retinaSize / distance) - asin((_D - i) / _R);
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oneD[x] = pointAPSF(cos(mu));
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min = (oneD[x] < min) ? oneD[x] : min;
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}
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max = (oneD[x] > max) ? oneD[x] : max;
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}
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// floor
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if (min > 0.0f)
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{
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for (int i = 0; i < _res; i++)
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if (oneD[i] > 0.0f)
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oneD[i] -= min;
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max -= min;
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}
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// normalize
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if (max > 1.0f)
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{
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float maxInv = 1.0f / max;
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for (int i = 0; i < _res; i++)
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oneD[i] *= maxInv;
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}
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// interpolate the kernel
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int index = 0;
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for (y = 0; y < _res; y++)
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for (x = 0; x < _res; x++, index++)
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{
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float dx = fabs((float)(x - halfRes));
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float dy = fabs((float)(y - halfRes));
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float magnitude = sqrtf(dx * dx + dy * dy);
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int lower = floor(magnitude);
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if (lower > halfRes - 1)
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{
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_kernel[index] = 0.0f;
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continue;
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}
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float lerp = magnitude - lower;
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_kernel[index] = (1.0f - lerp) * oneD[halfRes + lower] +
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lerp * oneD[halfRes + lower + 1];
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}
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delete[] oneD;
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}
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//////////////////////////////////////////////////////////////////////
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// save the kernel in binary
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//////////////////////////////////////////////////////////////////////
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void APSF::write(const char* filename)
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{
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// open file
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FILE* file;
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file = fopen(filename, "wb");
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fwrite((void*)&_res, sizeof(int), 1, file);
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fwrite((void*)&_q, sizeof(float), 1, file);
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fwrite((void*)&_T, sizeof(float), 1, file);
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fwrite((void*)&_I0, sizeof(float), 1, file);
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fwrite((void*)&_sigma, sizeof(float), 1, file);
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fwrite((void*)&_R, sizeof(float), 1, file);
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fwrite((void*)&_D, sizeof(float), 1, file);
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fwrite((void*)&_retinaSize, sizeof(float), 1, file);
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fwrite((void*)&_eyeSize, sizeof(float), 1, file);
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fwrite((void*)&_maxTerms, sizeof(int), 1, file);
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fwrite((void*)&_kernel, sizeof(float) * _res * _res, 1, file);
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fclose(file);
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}
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//////////////////////////////////////////////////////////////////////
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// load a binary kernel
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//////////////////////////////////////////////////////////////////////
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void APSF::read(const char* filename)
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{
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// open file
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FILE* file;
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file = fopen(filename, "rb");
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if (_kernel) delete[] _kernel;
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fread((void*)&_res, sizeof(int), 1, file);
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fread((void*)&_q, sizeof(float), 1, file);
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fread((void*)&_T, sizeof(float), 1, file);
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fread((void*)&_I0, sizeof(float), 1, file);
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fread((void*)&_sigma, sizeof(float), 1, file);
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fread((void*)&_R, sizeof(float), 1, file);
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fread((void*)&_D, sizeof(float), 1, file);
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fread((void*)&_retinaSize, sizeof(float), 1, file);
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fread((void*)&_eyeSize, sizeof(float), 1, file);
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fread((void*)&_maxTerms, sizeof(int), 1, file);
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_kernel = new float[_res * _res];
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fread((void*)&_kernel, sizeof(float) * _res * _res, 1, file);
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fclose(file);
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}
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//////////////////////////////////////////////////////////////////////
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// write the kernel to a PPM file
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//////////////////////////////////////////////////////////////////////
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void APSF::writePPM(const char* filename)
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{
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unsigned char* ppm = new unsigned char[3 * _res * _res];
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for (int x = 0; x < _res * _res; x++)
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{
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ppm[3 * x] = 255 * _kernel[x];
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ppm[3 * x + 1] = 255 * _kernel[x];
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ppm[3 * x + 2] = 255 * _kernel[x];
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}
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WritePPM(filename, ppm, _res, _res);
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delete[] ppm;
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}
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