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#include <iostream>
#include <fstream>
#include <string>
#include <cmath>
using namespace std;
string filename();
string filename2();
void readEGM(string fname, int &ncol, int &nrow, float &minel, float &maxel, float &hscale, float &vscale, float EGM[]); //reading in EGM function
float dot(float x, float y, float z, float x2, float y2, float z2); //dot product function
void cross(float x, float y, float z, float x2, float y2, float z2, float &i, float &j, float &k); //cross product function
void sun(float &azimuth, float &elevation); //prompting sun position function
void az2xyz(float azimuth, float elevation, float &x, float &y, float &z); //converting Azimuth and Elevation to x y z coordinates function
void normalize(float xin, float yin, float zin, float &x_norm, float &y_norm, float &z_norm); //normalizing vectors function
void illuminate(int ncol, int nrow, float EGM[], int PGM[], float azimuth, float elevation, float xscale, float yscale); //illuminating function
void writePGM(string fname2, int ncol, int nrow, int maxval, int PGM[]); //writing back PGM function
int main()
{
//declaring variables
float minel=0, maxel=0, hscale=0, vscale=0, xscale=0, yscale=0;
//float x_sun, y_sun, z_sun;
float azimuth=0, elevation=0;
float EGM[512 * 512]; //EGM array
int ncol = 0, nrow = 0;
int PGM[512 * 512]; //PGM array
int maxval = 255;
string fname = filename(); //filename declaration
string fname2 = filename2();
readEGM(fname, ncol, nrow, minel, maxel, hscale, vscale, EGM); //calling read EGM function
illuminate(ncol, nrow, EGM, PGM, azimuth, elevation, xscale, yscale); //calling illuminate function
writePGM(fname2, ncol, nrow, maxval, PGM);
return 0;
}
//function body for prompting input file of EGM
string filename()
{
string fname;
cout << "Please input filename of EGM: ";
cin >> fname;
return fname;
}
string filename2()
{
string fname2;
cout << "Please name file for PGM: ";
cin >> fname2;
return fname2;
}
//reading the EGM file function body
void readEGM(string fname, int &ncol, int &nrow, float &minel, float &maxel, float &hscale, float &vscale, float EGM[])
{
ifstream ifs;
string image_type;
ifs.open(fname);
ifs >> image_type >> ncol >> nrow >> minel >> maxel >> hscale >> vscale; //reading in header of EGM
if (image_type != "E1")
cout << "Can't handle the EGM, please try again" << endl; //if statement in case image type is not supported
for (int i = 0; i < nrow; i++) //nested for loop to read in EGM values to EGM array
{
for (int j = 0; j < ncol; j++)
{
int xy = i * ncol + j;
ifs >> EGM[xy];
}
}
}
//function body to prompt user for position of sun
void sun(float &azimuth, float &elevation)
{
cout << "Please input the position of sun in Azimuth and Elevation";
cin >> azimuth;
cin >> elevation;
}
//dot product function body
float dot(float x, float y, float z, float x2, float y2, float z2)
{
float result;
//calculating dot product
result = x * x2 + y * y2 + z * z2;
return result;
}
//cross product function body
void cross(float x, float y, float z, float x2, float y2, float z2, float &i, float &j, float &k)
{
//calculating and returning cross product
i = (y*z2) - (z*y2);
j = (z*x2) - (x*z2);
k = (x*y2) - (y*x2);
}
//converting azimuth and elevation to xyz coordinates
void az2xyz(float azimuth, float elevation, float &x, float &y, float &z)
{
//converting azimuth and elevation to xyz coordinates
x = cos(elevation) * cos(azimuth);
y = cos(elevation) * sin(azimuth);
z = sin(elevation);
}
//normalizing vector function body
void normalize(float xin, float yin, float zin, float &x_norm, float &y_norm, float &z_norm)
{
float unitvec;
unitvec = sqrt((xin*xin) + (yin*yin) + (zin * zin));
x_norm = xin / unitvec;
y_norm = yin / unitvec;
z_norm = zin / unitvec;
}
//illuminate function body
void illuminate(int ncol, int nrow, float EGM[], int PGM[], float azimuth, float elevation, float xscale, float yscale)
{
//declaring variables
int r, c;
float x, y, z, x_norm, y_norm, z_norm;
float Az[512 * 512], Bz[512 * 512];
float i, j, k;
float inorm, jnorm, knorm;
sun(azimuth, elevation); //prompts for input of sun's position
az2xyz(azimuth, elevation, x, y, z); //converts Azi and Ele to x y z coordinates
normalize(x, y, z, x_norm, y_norm, z_norm); //normalizes x y z coordinates
for (r = 0; r < ncol - 1; r++)
{
for (c = 0; c < nrow - 1; c++)
{
int index = (r*ncol) + (c + 1); //declaring array index
int index2 = (r + 1) * (ncol + c);
Az[index] = EGM[index + 1] - EGM[index];
Bz[index2] = EGM[index2] - EGM[index];
cross(xscale, 0, Az[index], 0, yscale, Bz[index2], i, j, k); //calling cross product function
normalize(i, j, k, inorm, jnorm, knorm); //calling normalize function
PGM[index] = (dot(inorm, jnorm, knorm, x_norm, y_norm, z_norm)) * 255;
cout << PGM[c] << " ";
}
}
}
void writePGM(string fname2, int ncol, int nrow, int maxval, int PGM[])
{
ofstream ofs(fname2);
ofs.open(fname2);
ofs << "P2" << " " << ncol << " " << nrow << " " << maxval << endl;
for (int i = 0; i < nrow; i++)
{
for (int j = 0; j < ncol; j++)
{
int xy = i * ncol + j;
ofs << PGM[xy];
}
}
}
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