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Nicholl-Lee-Nicholl.cpp
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Nicholl-Lee-Nicholl.cpp
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#include <GL/glut.h>
#include <stdlib.h>
#include <math.h>
#include <cstdlib>
using namespace std;
double y_max = 100, y_min = 50, x_max = 100, x_min = 50; // Old viewport
double ny_max = 300, ny_min = 200, nx_max = 300, nx_min = 200; // New ViewPort
double t1 = 0.0, t2 = 1.0;
double X1 = 70;
double Y1 = 50;
double X2 = 120;
double Y2 = 120;
double xx1, xx2, yy1, yy2;
void init()
{
glLoadIdentity();
glClearColor(1.0, 1.0, 1.0, 1.0);
glMatrixMode(GL_PROJECTION);
gluOrtho2D(0, 500, 0, 500);
glMatrixMode(GL_MODELVIEW);
}
void draw_lineAndPort(double x1, double y1, double x2, double y2, double y_max, double y_min,
double x_max, double x_min)
{
glColor3d(1, 0, 0);
glBegin(GL_LINE_LOOP);
glVertex2d(x_min, y_min);
glVertex2d(x_max, y_min);
glVertex2d(x_max, y_max);
glVertex2d(x_min, y_max);
glEnd();
glColor3d(0, 0, 0);
glBegin(GL_LINES);
glVertex2d(x1, y1);
glVertex2d(x2, y2);
glEnd();
}
void clipline1(int x1, int y1, int x2, int y2)
{
int draw = 1;
float m, m1, m2, m3, m4;
m = ((float)(y2 - y1)) / (x2 - x1);
m1 = ((float)(y_min - y1)) / (x_min - x1);
m2 = ((float)(y_min - y1)) / (x_max - x1);
m3 = ((float)(y_max - y1)) / (x_max - x1);
m4 = ((float)(y_max - y1)) / (x_min - x1);
xx1 = x1; yy1 = y1;
if (((abs(m) >= m1 && x2 < x1) || (abs(m) > abs(m2) && x2 > x1)) && y1 > y2)
{if (y2 > y_min)
{
xx2 = x2;
yy2 = y2;
}
else
{
yy2 = y_min;
xx2 = x1 + (y_min - y1) / m;
}
}
else if (m > m2 && m < m3 && x2 >= x_max)
{if (x2 < x_max)
{
xx2 = x2;
yy2 = y2;
}
else
{
xx2 = x_max;
yy2 = y1 + (x_max - x1) * m;
}
}
else if ((abs(m) >= m3 && x2 > x1) || (abs(m) > abs(m4) && x2 < x1))
{if (y2 < y_max)
{
xx2 = x2;
yy2 = y2;
}
else
{
yy2 = y_max;
xx2 = x1 + (y_max - y1) / m;
}}
else if (m > m4 && m < m1)
{ if (x2 > x_min)
{
xx2 = x2;
yy2 = y2;
}
else
{
xx2 = x_min;
yy2 = y1 + (x_min - x1) * m;
}}
}
void clipline2(int x1, int y1, int x2, int y2)
{
int draw = 1;
float m, m1, m2, m3, m4;
m = ((float)(y2 - y1)) / (x2 - x1);
m1 = ((float)(y_min - y1)) / (x_min - x1);
m2 = ((float)(y_min - y1)) / (x_max - x1);
m3 = ((float)(y_max - y1)) / (x_max - x1);
m4 = ((float)(y_max - y1)) / (x_min - x1);
if (m > m1 && m < m2)
{if (y2 > y_min)
{
xx1 = x_min;
yy1 = y1 + m * (x_min - x1);
xx2 = x2;
yy2 = y2;
}
else
{
xx1 = x_min;
yy1 = y1 + m * (x_min - x1);
yy2 = y_min;
xx2 = x1 + (y_min - y1) / m;
}}
else if (m > m2 && m < m3)
{
if (x2 < x_max)
{
xx1 = x_min;
yy1 = y1 + m * (x_min - x1);
xx2 = x2;
yy2 = y2;
}
else
{
xx1 = x_min;
yy1 = y1 + m * (x_min - x1); xx2 = x_max;
yy2 = y1 + (x_max - x1) * m;
}}
else if (m > m3 && m < m4)
{if (y2 < y_max)
{
xx1 = x_min;
yy1 = y1 + m * (x_min - x1);
xx2 = x2;
yy2 = y2;
}
else
{
xx1 = x_min;
yy1 = y1 + m * (x_min - x1);
yy2 = y_max;
xx2 = x1 + (y_max - y1) / m;
}}}
void clipline3(int x1, int y1, int x2, int y2)
{ int draw = 1;
float m, m1, m2, m3, m4, tm1, tm2;
int flag, t;
tm1 = ((float)(y_min - y1)) / (x_min - x1);
tm2 = ((float)(y_max - y_min)) / (x_max - x_min); //diagonal slope
m = ((float)(y2 - y1)) / (x2 - x1);
m1 = ((float)(y_min - y1)) / (x_max - x1);
m2 = ((float)(y_max - y1)) / (x_max - x1);
m3 = ((float)(y_min - y1)) / (x_min - x1);
m4 = ((float)(y_max - y1)) / (x_min - x1);
if (tm1 < tm2)
{
flag = 2;
t = m2;
m2 = m3;
m3 = t;
}
else
flag = 1;
if (m > m1 && m < m2)
{if (x2 > x_max && y2 > y_min)
{ yy1 = y_min;
xx1 = x1 + (y_min - y1) / m;
xx2 = x_max; yy2 = y1 + m * (x_max - x1);
}
else if (y2 > y_min && x2 < x_max)
{ yy1 = y_min;
xx1 = x1 + (y_min - y1) / m;
yy2 = y2;
xx2 = x2;
}}
else if (m > m2 && m < m3)
{if (flag == 1)
{if (y2 >= y_max)
{ yy1 = y_min;
xx1 = x1 + (y_min - y1) / m;
xx2 = x1 + (y_max - y1) / m;
yy2 = y_max; }
else if (y2 >= y_min)
{
yy1 = y_min;
xx1 = x1 + (y_min - y1) / m;
xx2 = x2;
yy2 = y2;
}}
else
{if (x2 >= x_max)
{
xx1 = x_min;
yy1 = y1 + m * (x_min - x1);
xx2 = x_max;
yy2 = y1 + m * (x_max - x1);
}
else if (x2 >= x_min)
{
xx1 = x_min;
yy1 = y1 + m * (x_min - x1); xx2 = x2;
yy2 = y2;
}}}
else if (m > m3 && m < m4)
{
if (y2 >= y_max)
{
xx1 = x_min;
yy1 = y1 + m * (x_min - x1);
xx2 = x1 + (y_max - y1) / m;
yy2 = y_max;
}
else if (y2 >= y_min)
{
xx1 = x_min;
yy1 = y1 + m * (x_min - x1);
yy2 = y2;
xx2 = x2;
}}
}
int first_end_point_region(int x, int y)
{
if (x >= x_min && x <= x_max && y >= y_min && y <= y_max)
return 1;
else if (x < x_min && y >= y_min && y <= y_max)
return 2;
else if (x <= x_min && y <= y_min)
return 3;
else
return 0;
}
void nicholl_lee(double x1, double y1, double x2, double y2)
{
int ch = first_end_point_region(x1, y1);
switch (ch)
{
case 1:
clipline1(x1, y1, x2, y2);
break;
case 2:
clipline2(x1, y1, x2, y2);
break;
case 3:
clipline3(x1, y1, x2, y2);
break;
}
// Scaling to new View port
double scale_x = (nx_max - nx_min) / (x_max - x_min);
double scale_y = (ny_max - ny_min) / (y_max - y_min);
// New coordinates of the points
// Point 1
double nx1 = nx_min + (xx1 - x_min) * scale_x;
double ny1 = ny_min + (yy1 - y_min) * scale_y;
// Point 2
double nx2 = nx_min + (xx2 - x_min) * scale_x;
double ny2 = ny_min + (yy2 - y_min) * scale_y;
draw_lineAndPort(nx1, ny1, nx2, ny2, ny_max, ny_min, nx_max, nx_min);
}
void display()
{
glClear(GL_COLOR_BUFFER_BIT);
draw_lineAndPort(X1, Y1, X2, Y2, y_max, y_min, x_max, x_min);
nicholl_lee(X1, Y1, X2, Y2);
glFlush();
}
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
glutInitWindowPosition(0, 0);
glutInitWindowSize(500, 500);
glutCreateWindow("Nicholl-Lee");
glutDisplayFunc(display);
init();
glutMainLoop();
return 0;
}