Computer graphics program to implement Cohen-Sutherland Line Clipping algorithm

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Computer graphics program in Python graphics.py and C++ graphics

Python

#Experiment 7.3 - Cohen-Sutherland Line Clipping
INSIDE = 0  # 0000
LEFT = 1    # 0001
RIGHT = 2   # 0010
BOTTOM = 4  # 0100
TOP = 8     # 1000
 
x_max = 10.0
y_max = 8.0
x_min = 4.0
y_min = 4.0
 
def computeCode(x, y):
   code = INSIDE
   if x < x_min:      # left of rectangle
       code |= LEFT
   elif x > x_max:    # right of rectangle
       code |= RIGHT
   if y < y_min:      # below
       code |= BOTTOM
   elif y > y_max:    # above
       code |= TOP
    return code
 
def cohenSutherlandClip(x1, y1, x2, y2):
     code1 = computeCode(x1, y1)
   code2 = computeCode(x2, y2)
   accept = False
    while True:
 
       if code1 == 0 and code2 == 0:
           accept = True
           break
        
       elif (code1 & code2) != 0:
           break
 
       else:
 
           x = 1.0
           y = 1.0
           if code1 != 0:
               code_out = code1
           else:
               code_out = code2
  
           if code_out & TOP:
 
               x = x1 + (x2 - x1) * (y_max - y1) / (y2 - y1)
               y = y_max
            elif code_out & BOTTOM:
 
               x = x1 + (x2 - x1) * (y_min - y1) / (y2 - y1)
               y = y_min
            elif code_out & RIGHT:
                
       
               y = y1 + (y2 - y1) * (x_max - x1) / (x2 - x1)
               x = x_max
            elif code_out & LEFT:
   
               y = y1 + (y2 - y1) * (x_min - x1) / (x2 - x1)
               x = x_min
 
           if code_out == code1:
               x1 = x
               y1 = y
               code1 = computeCode(x1, y1)
            else:
               x2 = x
               y2 = y
               code2 = computeCode(x2, y2)
    if accept:
       print ("Line accepted from %.2f, %.2f to %.2f, %.2f" % (x1, y1, x2, y2))
  
    else:
       print("Line rejected")
 
cohenSutherlandClip(3, 5, 5, 7)
cohenSutherlandClip(9, 9, 10, 4)
cohenSutherlandClip(1, 5, 4, 1)

C++

 

#include <bits/stdc++.h>
#include <graphics.h>
using namespace std;
int xmin, xmax, ymin, ymax;
class lines {
 public:
  int x1, y1, x2, y2;
  lines() { x1 = y1 = x2 = y2 = 0; }
  void set(int a, int b, int c, int d) {
    x1 = a;
    y1 = b;
    x2 = c;
    y2 = d;
  }
};
 
int sign(int x) {
  if (x > 0)
    return 1;
  else
    return 0;
}
 
void clip(lines mylines) {
  int bits[4], bite[4], i, var;
  setcolor(RED);
  bits[0] = sign(xmin - mylines.x1);
  bite[0] = sign(xmin - mylines.x2);
  bits[1] = sign(mylines.x1 - xmax);
  bite[1] = sign(mylines.x2 - xmax);
  bits[2] = sign(ymin - mylines.y1);
  bite[2] = sign(ymin - mylines.y2);
  bits[3] = sign(mylines.y1 - ymax);
  bite[3] = sign(mylines.y2 - ymax);
 
  string initial = "", end = "", temp = "";
 
  for (i = 0; i < 4; i++) {
    if (bits[i] == 0)
      initial += '0';
    else
      initial += '1';
  }
  for (i = 0; i < 4; i++) {
    if (bite[i] == 0)
      end += '0';
    else
      end += '1';
  }
 
  float m = (mylines.y2 - mylines.y1) / (float)(mylines.x2 - mylines.x1);
  float c = mylines.y1 - m * mylines.x1;
 
  if (initial == end && end == "0000") {
    line(mylines.x1, mylines.y1, mylines.x2, mylines.y2);
    return;
  }
 
  else {
    for (i = 0; i < 4; i++) {
      int val = (bits[i] & bite[i]);
      if (val == 0)
        temp += '0';
      else
        temp += '1';
    }
 
    if (temp != "0000") return;
 
    for (i = 0; i < 4; i++) {
      if (bits[i] == bite[i]) continue;
 
      if (i == 0 && bits[i] == 1) {
        var = round(m * xmin + c);
        mylines.y1 = var;
        mylines.x1 = xmin;
      }
 
      if (i == 0 && bite[i] == 1) {
        var = round(m * xmin + c);
        mylines.y2 = var;
        mylines.x2 = xmin;
      }
 
      if (i == 1 && bits[i] == 1) {
        var = round(m * xmax + c);
        mylines.y1 = var;
        mylines.x1 = xmax;
      }
 
      if (i == 1 && bite[i] == 1) {
        var = round(m * xmax + c);
        mylines.y2 = var;
        mylines.x2 = xmax;
      }
      if (i == 2 && bits[i] == 1) {
        var = round((float)(ymin - c) / m);
        mylines.y1 = ymin;
        mylines.x1 = var;
      }
      if (i == 2 && bite[i] == 1) {
        var = round((float)(ymin - c) / m);
        mylines.y2 = ymin;
        mylines.x2 = var;
      }
      if (i == 3 && bits[i] == 1) {
        var = round((float)(ymax - c) / m);
        mylines.y1 = ymax;
        mylines.x1 = var;
      }
      if (i == 3 && bite[i] == 1) {
        var = round((float)(ymax - c) / m);
        mylines.y2 = ymax;
        mylines.x2 = var;
      }
      bits[0] = sign(xmin - mylines.x1);
      bite[0] = sign(xmin - mylines.x2);
      bits[1] = sign(mylines.x1 - xmax);
      bite[1] = sign(mylines.x2 - xmax);
      bits[2] = sign(ymin - mylines.y1);
      bite[2] = sign(ymin - mylines.y2);
      bits[3] = sign(mylines.y1 - ymax);
      bite[3] = sign(mylines.y2 - ymax);
    }
    initial = "", end = "";
    for (i = 0; i < 4; i++) {
      if (bits[i] == 0)
        initial += '0';
      else
        initial += '1';
    }
    for (i = 0; i < 4; i++) {
      if (bite[i] == 0)
        end += '0';
      else
        end += '1';
    }
    if (initial == end && end == "0000") {
      line(mylines.x1, mylines.y1, mylines.x2, mylines.y2);
      return;
    } else
      return;
  }
}
 
int main() {
  xmin = 40;
  xmax = 100;
  ymin = 40;
  ymax = 80;
 
  int gd = DETECT, gm;
  initgraph(&gd, &gm, NULL);
 
  rectangle(xmin, ymin, xmax, ymax);
 
  lines mylines[4];
 
  mylines[0].set(30, 65, 55, 30);
  mylines[1].set(60, 20, 100, 90);
  mylines[2].set(60, 100, 80, 70);
  mylines[3].set(85, 50, 120, 75);
 
  for (int i = 0; i < 4; i++) {
    line(mylines[i].x1, mylines[i].y1, mylines[i].x2, mylines[i].y2);
    delay(1000);
  }
 
  for (int i = 0; i < 4; i++) {
    clip(mylines[i]);
    delay(1000);
  }
  delay(4000);
  getch();
 
  closegraph();
  return 0;
}
Sutherland Line Clipping algorithm computer graphics

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