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Point Clipping Algorithm in Computer Graphics

Clipping: In computer graphics our screen act as a 2-D coordinate system. it is not necessary that each and every point can be viewed on our viewing pane(i.e. our computer screen). We can view points, which lie in particular range (0,0) and (Xmax, Ymax). So, clipping is a procedure that identifies those portions of a picture that are either inside or outside of our viewing pane.
In case of point clipping, we only show/print points on our window which are in range of our viewing pane, others points which are outside the range are discarded.
Example

Input :
 clip 2
Output :
clip 3

Point Clipping Algorithm:

  1. Get the minimum and maximum coordinates of both viewing pane.
  2. Get the coordinates for a point.
  3. Check whether given input lies between minimum and maximum coordinate of viewing pane.
  4. If yes display the point which lies inside the region otherwise discard it.



C

// C program for point clipping Algorithm
#include<stdio.h>
//#include<graphics.h>
  
// Function for point clipping
void pointClip(int XY[][2], int n, int Xmin, int Ymin,
                                   int Xmax, int Ymax)
{
    /*************** Code for graphics view
    // initialize graphics mode
    detectgraph(&gm,&gr);
    initgraph(&gm,&gr,"d:\tc\BGI");
    for (int i=0; i<n; i++)
    {
    if ( (XY[i][0] >= Xmin) && (XY[i][0] <= Xmax))
    {
            if ( (XY[i][1] >= Ymin) && (XY[i][1] <= Ymax))
        putpixel(XY[i][0],XY[i][1],3);
    }
    }
    **********************/
    /**** Arithmetic view ****/
    printf ("Point inside the viewing pane: ");
    for (int i=0; i<n; i++)
    {
        if ((XY[i][0] >= Xmin) && (XY[i][0] <= Xmax))
        {
            if ((XY[i][1] >= Ymin) && (XY[i][1] <= Ymax))
                printf ("[%d, %d] ", XY[i][0], XY[i][1]);
        }
    }
  
    // print point coordinate outside viewing pane
    printf (" Point outside the viewing pane: ");
    for (int i=0; i<n; i++)
    {
        if ((XY[i][0] < Xmin) || (XY[i][0] > Xmax))
            printf ("[%d, %d] ", XY[i][0], XY[i][1]);
        if ((XY[i][1] < Ymin) || (XY[i][1] > Ymax))
            printf ("[%d, %d] ", XY[i][0], XY[i][1]);
    }
}
  
// Driver code
int main()
{
    int XY[6][2] = {{10,10}, {-10,10}, {400,100},
                    {100,400}, {400,400}, {100,40}};
  
    // getmaxx() & getmaxy() will return Xmax, Ymax
    // value if graphics.h is included
    int Xmin = 0;
    int Xmax = 350;
    int Ymin = 0;
    int Ymax = 350;
    pointClip(XY, 6,  Xmin, Ymin, Xmax, Ymax);
    return 0;
}

Java

// Java program for point clipping Algorithm
class GFG 
{
  
// Function for point clipping
static void pointClip(int XY[][], int n, 
                        int Xmin, int Ymin,
                        int Xmax, int Ymax)
{
    /*************** Code for graphics view
    // initialize graphics mode
    detectgraph(&gm,&gr);
    initgraph(&gm,&gr,"d:\tc\BGI");
    for (int i=0; i<n; i++)
    {
    if ( (XY[i][0] >= Xmin) && (XY[i][0] <= Xmax))
    {
            if ( (XY[i][1] >= Ymin) && (XY[i][1] <= Ymax))
        putpixel(XY[i][0],XY[i][1],3);
    }
    }
    **********************/
    /**** Arithmetic view ****/
    System.out.printf ("Point inside the viewing pane: ");
    for (int i = 0; i < n; i++)
    {
        if ((XY[i][0] >= Xmin) && (XY[i][0] <= Xmax))
        {
            if ((XY[i][1] >= Ymin) && (XY[i][1] <= Ymax))
                System.out.printf ("[%d, %d] ", XY[i][0], XY[i][1]);
        }
    }
  
    // print point coordinate outside viewing pane
    System.out.printf (" Point outside the viewing pane: ");
    for (int i=0; i<n; i++)
    {
        if ((XY[i][0] < Xmin) || (XY[i][0] > Xmax))
            System.out.printf ("[%d, %d] ", XY[i][0], XY[i][1]);
        if ((XY[i][1] < Ymin) || (XY[i][1] > Ymax))
            System.out.printf ("[%d, %d] ", XY[i][0], XY[i][1]);
    }
}
  
// Driver code
public static void main(String[] args) 
{
        int XY[][] = {{10,10}, {-10,10}, {400,100},
                    {100,400}, {400,400}, {100,40}};
  
    // getmaxx() & getmaxy() will return Xmax, Ymax
    // value if graphics.h is included
    int Xmin = 0;
    int Xmax = 350;
    int Ymin = 0;
    int Ymax = 350;
    pointClip(XY, 6, Xmin, Ymin, Xmax, Ymax);
}
}
  
/* This code contributed by PrinciRaj1992 */

Python3

# Python3 program for poclipping Algorithm
  
# Function for poclipping 
def pointClip(XY, n, Xmin, Ymin, Xmax, Ymax):
  
    """************** Code for graphics view 
    # initialize graphics mode 
    detectgraph(&gm, &gr) 
    initgraph(&gm, &gr, "d:\tc\BGI") 
    for (i=0 i<n i++) 
      
    if ((XY[i][0] >= Xmin) and 
        (XY[i][0] <= Xmax)) 
      
        if ((XY[i][1] >= Ymin) and 
            (XY[i][1] <= Ymax)) 
        putpixel(XY[i][0], XY[i][1], 3) 
      
    *********************"""
    """*** Arithmetic view ***"""
    print("Point inside the viewing pane:"
    for i in range(n):
        if ((XY[i][0] >= Xmin) and 
            (XY[i][0] <= Xmax)): 
            if ((XY[i][1] >= Ymin) and 
                (XY[i][1] <= Ymax)): 
                print("[", XY[i][0], ", ", XY[i][1], 
                      "]", sep = "", end = " ") 
          
    # prpocoordinate outside viewing pane 
    print(" Point outside the viewing pane:"
    for i in range(n):   
        if ((XY[i][0] < Xmin) or (XY[i][0] > Xmax)) :
            print("[", XY[i][0], ", ", XY[i][1],
                  "]", sep = "", end = " ") 
        if ((XY[i][1] < Ymin) or (XY[i][1] > Ymax)) :
            print("[", XY[i][0], ", ", XY[i][1], 
                  "]", sep = "", end = " ") 
  
# Driver Code
if __name__ == '__main__':
    XY = [[10, 10], [-10, 10], [400, 100], 
          [100, 400], [400, 400], [100, 40]] 
  
    # getmaxx() & getmaxy() will return Xmax, 
    # Ymax value if graphics.h is included 
    Xmin = 0
    Xmax = 350
    Ymin = 0
    Ymax = 350
    pointClip(XY, 6, Xmin, Ymin, Xmax, Ymax)
  
# This code is contributed by
# SHUBHAMSINGH10

C#

// C# program for point clipping Algorithm
using System;
  
class GFG 
{
  
// Function for point clipping
static void pointClip(int [,]XY, int n, 
                        int Xmin, int Ymin,
                        int Xmax, int Ymax)
{
    /*************** Code for graphics view
    // initialize graphics mode
    detectgraph(&gm,&gr);
    initgraph(&gm,&gr,"d:\tc\BGI");
    for (int i=0; i<n; i++)
    {
    if ( (XY[i,0] >= Xmin) && (XY[i,0] <= Xmax))
    {
            if ( (XY[i,1] >= Ymin) && (XY[i,1] <= Ymax))
        putpixel(XY[i,0],XY[i,1],3);
    }
    }
    **********************/
    /**** Arithmetic view ****/
    Console.Write("Point inside the viewing pane: ");
    for (int i = 0; i < n; i++)
    {
        if ((XY[i, 0] >= Xmin) && (XY[i, 0] <= Xmax))
        {
            if ((XY[i, 1] >= Ymin) && (XY[i, 1] <= Ymax))
                Console.Write("[{0}, {1}] ", XY[i, 0], XY[i, 1]);
        }
    }
  
    // print point coordinate outside viewing pane
    Console.Write(" Point outside the viewing pane: ");
    for (int i = 0; i < n; i++)
    {
        if ((XY[i, 0] < Xmin) || (XY[i, 0] > Xmax))
            Console.Write("[{0}, {1}] ", XY[i, 0], XY[i, 1]);
        if ((XY[i, 1] < Ymin) || (XY[i, 1] > Ymax))
            Console.Write("[{0}, {1}] ", XY[i, 0], XY[i, 1]);
    }
}
  
// Driver code
public static void Main(String[] args) 
{
        int [,]XY = {{10, 10}, {-10, 10}, {400, 100},
                    {100, 400}, {400, 400}, {100, 40}};
  
    // getmaxx() & getmaxy() will return Xmax, Ymax
    // value if graphics.h is included
    int Xmin = 0;
    int Xmax = 350;
    int Ymin = 0;
    int Ymax = 350;
    pointClip(XY, 6, Xmin, Ymin, Xmax, Ymax);
}
}
  
// This code contributed by Rajput-Ji

/div>

Output:

Point inside the viewing pane:
[10, 10] [100, 40] 

Point outside the viewing pane:
[-10, 10] [400, 100] [100, 400] [400, 400] [400, 400] 

Related Post :
Line Clipping | Set 1 (Cohen–Sutherland Algorithm)
Polygon Clipping | Sutherland–Hodgman Algorithm

Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.



This article is attributed to GeeksforGeeks.org

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