19BCS2605_Krishna_Kumar_Computer_Graphics_exp_3.1.pdf
- 1. Experiment no. – 3.1 Student Name: Krishna Kumar UID: 19BCS2605 Branch: CSE - 11 Section/Group : ‘C’ Semester: 5th Date of Performance: 21 Oct 2021 Subject Name: Computer Graphics Lab Subject Code: CSP - 305 1. Aim/Overview of the practical: a) To display 4-bit region code for end points of a line and check whether line is completely on the screen or off the screen b) To clip a line intersecting at one point with given window using Cohen Sutherland Line Clipping algorithm. c) To clip a line intersecting at Two or more points with given window using Cohen Sutherland Line Clipping algorithm 2. Task to be done: a) To display 4-bit region code for end points of a line b) To clip a line intersecting at one point with given window c) To clip a line intersecting at Two or more points with given window 3. Algorithm : a) algorithms for display 4-bit region code for end points of a line Step 1: Start Step 1.1: taking two point, starting point and end point of line for user Step 1.2: taking two co-ordinate of rectangle, starting co-ordinate and end co- ordinate of rectangle for user Step 1. 4: Assign a region code for two endpoints of given line Step 2 : If both endpoints have a region code 0000 then given line is completely inside and we will keep this line
- 2. Step 3 : If step 2 fails, perform the logical AND operation for both region codes. Step 3.1 : If the result is not 0000, then given line is completely outside. Step 3.2 : Else line is partially inside. Step 3.2.a : Choose an endpoint of the line that is outside the given rectangle. Step 3.2.b : Find the intersection point of the rectangular boundary (based on region code). Step 3.2.c : Replace endpoint with the intersection point and update the region code. Step 3.2.d : Repeat step 2 until we find a clipped line either trivially accepted or rejected. Step 4 : Repeat step 1 for all lines Step 5: using while for taking point of line again and again form user. Step 6: Displaying window, line and line in side window at a green colour at green colour Step 7: End b) algorithms for clip a line intersecting at one point with given window Step 1: Start Step 1.1: taking two point, starting point and end point of line for user Step 1.2: taking two co-ordinate of rectangle, starting co-ordinate and end co- ordinate of rectangle for user Step 1.3 : Assign a region code for two endpoints of given line Step 2 : If both endpoints have a region code 0000 then given line is completely inside and we will keep this line Step 3 : If step 2 fails, perform the logical AND operation for both region codes. Step 3.1 : If the result is not 0000, then given line is completely outside. Step 3.2 : Else line is partially inside. Step 3.2.a : Choose an endpoint of the line that is outside the given rectangle. Step 3.2.b : Find the intersection point of the rectangular boundary (based on region code). Step 3.2.c : Replace endpoint with the intersection point and update the region code. Step 3.2.d : Repeat step 2 until we find a clipped line either trivially accepted or rejected.
- 3. Step 4 : Repeat step 1 for all lines Step 5: Displaying window and line before line clipping and after line clipping at green colour Step 6: End c) algorithms for clip a line intersecting at Two or more points with given window Step 1: Start Step 1.1: taking two point, starting point and end point of line for user Step 1.2: taking two co-ordinate of rectangle, starting co-ordinate and end co- ordinate of rectangle for user Step 1.3 : Assign a region code for two endpoints of given line Step 2 : If both endpoints have a region code 0000 then given line is completely inside and we will keep this line Step 3 : If step 2 fails, perform the logical AND operation for both region codes. Step 3.1 : If the result is not 0000, then given line is completely outside. Step 3.2 : Else line is partially inside. Step 3.2.a : Choose an endpoint of the line that is outside the given rectangle. Step 3.2.b : Find the intersection point of the rectangular boundary (based on region code). Step 3.2.c : Replace endpoint with the intersection point and update the region code. Step 3.2.d : Repeat step 2 until we find a clipped line either trivially accepted or rejected. Step 4 : Repeat step 1 for all lines Step 5: Displaying window and line before line clipping and after line clipping Step 6: End 4. Programming Code: a) Code for display 4-bit region code for end points of a line #include<iostream> #include<graphics.h> #include<math.h>
- 4. #include<conio.h> using namespace std; class CohenSutherLandAlgo { private: double x1,y1,x2,y2; double x_max,y_max,x_min,y_min; const int INSIDE = 0; const int LEFT = 1; const int RIGHT = 2; const int BOTTOM = 4; const int TOP = 8; public: CohenSutherLandAlgo() { x1 = 0.0; x2 = 0.0; y1 = 0.0; y2 = 0.0; } void getCoordinates(); void getClippingRectangle(); int generateCode(double x, double y); void cohenSutherland(); }; void CohenSutherLandAlgo::getCoordinates() { std::cout << "Enter Co-ordinates of P1(X1,Y1) of Line Segment : "; std::cin >> x1>>y1; std::cout << "Enter Co-ordinates of P2(X2,Y2) of Line Segment :"; std::cin >> x2>>y2; std::cout<<endl; setcolor(WHITE); line(x1,y1,x2,y2); } void CohenSutherLandAlgo::getClippingRectangle() { std::cout << "Enter the Co-ordinates of Interested Rectangle."<<endl; std::cout << "Enter the X_MAX and Enter the Y_MAX : "; std::cin >> x_max>>y_max; std::cout << "Enter the X_MIN and Enter the Y_MIN : ";
- 5. std::cin >> x_min>>y_min; rectangle(x_min,y_min,x_max,y_max); } int CohenSutherLandAlgo::generateCode(double x, double y) { int code = INSIDE; if (x < x_min) code |= LEFT; else if (x > x_max) code |= RIGHT; if (y < y_min) code |= BOTTOM; else if (y > y_max) code |= TOP; return code; } void CohenSutherLandAlgo::cohenSutherland() { int code1 = generateCode(x1, y1); int code2 = generateCode(x2, y2); bool accept = false; while (true) { if ((code1 == 0) && (code2 == 0)) { accept = true; break; } else if (code1 & code2) { break; } else { int code_out; double x, y; if (code1 != 0) code_out = code1; else code_out = code2; if (code_out & TOP)
- 6. { x = x1 + (x2 - x1) * (y_max - y1) / (y2 - y1); y = y_max; } else if (code_out & BOTTOM) { x = x1 + (x2 - x1) * (y_min - y1) / (y2 - y1); y = y_min; } else if (code_out & RIGHT) { y = y1 + (y2 - y1) * (x_max - x1) / (x2 - x1); x = x_max; } else if (code_out & LEFT) { y = y1 + (y2 - y1) * (x_min - x1) / (x2 - x1); x = x_min; } if (code_out == code1) { x1 = x; y1 = y; code1 = generateCode(x1, y1); } else { x2 = x; y2 = y; code2 = generateCode(x2, y2); } } } if (accept) { std::cout<<endl; std::cout <<"Line accepted from " <<"("<< x1 << ", " << y1 << ")" << " to "<< "(" << x2 << ", " << y2 << ")" << std::endl; setcolor(GREEN); line(x1,y1,x2,y2); }
- 7. else std::cout << "Line rejected" << std::endl; } int main() { int gd=DETECT,gm; initgraph(&gd,&gm,"c:turboc3bgi"); int x; outtextxy(5,5,"White color that part of line segment is not accept "); setcolor(GREEN); outtextxy(5,20,"Green color that part of line segment is accept "); setcolor(WHITE); CohenSutherLandAlgo c; c.getClippingRectangle(); do{ c.getCoordinates(); c.cohenSutherland(); std::cout<<endl; cout<<"Please press 1 (one) for continue :"; cin>>x; } while(x==1); getch(); closegraph(); } b) Code for clip a line intersecting at one point with given window #include<iostream> #include<graphics.h> #include<math.h> #include<conio.h> using namespace std; class CohenSutherLandAlgo { private:
- 8. double x1,y1,x2,y2; double x_max,y_max,x_min,y_min; const int INSIDE = 0; const int LEFT = 1; const int RIGHT = 2; const int BOTTOM = 4; const int TOP = 8; public: CohenSutherLandAlgo() { x1 = 0.0; x2 = 0.0; y1 = 0.0; y2 = 0.0; } void getCoordinates(); void getClippingRectangle(); int generateCode(double x, double y); void cohenSutherland(); }; void CohenSutherLandAlgo::getCoordinates() { std::cout << "Enter Co-ordinates of P1(X1,Y1) of Line Segment : "; std::cin >> x1>>y1; std::cout << "Enter Co-ordinates of P2(X2,Y2) of Line Segment :"; std::cin >> x2>>y2; std::cout<<endl; line(x1,y1,x2,y2); } void CohenSutherLandAlgo::getClippingRectangle() { std::cout << "Enter the Co-ordinates of Interested Rectangle."<<endl; std::cout << "Enter the X_MAX and Enter the Y_MAX : ";
- 9. std::cin >> x_max>>y_max; std::cout << "Enter the X_MIN and Enter the Y_MIN : "; std::cin >> x_min>>y_min; rectangle(x_min,y_min,x_max,y_max); outtextxy(x_min,y1-20,"Before line Clipping"); setcolor(GREEN); outtextxy(x_max+50,y1-20,"After line Clipping"); rectangle(x_max+50,y_min,x_max+50+x_max-x_min,y_max); } int CohenSutherLandAlgo::generateCode(double x, double y) { int code = INSIDE; if (x < x_min) code |= LEFT; else if (x > x_max) code |= RIGHT; if (y < y_min) code |= BOTTOM; else if (y > y_max) code |= TOP; return code; } void CohenSutherLandAlgo::cohenSutherland() { int code1 = generateCode(x1, y1); int code2 = generateCode(x2, y2); bool accept = false; while (true) { if ((code1 == 0) && (code2 == 0)) { accept = true; break; } else if (code1 & code2) {
- 10. break; } else { int code_out; double x, y; 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; } else if (code_out & BOTTOM) { x = x1 + (x2 - x1) * (y_min - y1) / (y2 - y1); y = y_min; } else if (code_out & RIGHT) { y = y1 + (y2 - y1) * (x_max - x1) / (x2 - x1); x = x_max; } else if (code_out & LEFT) { y = y1 + (y2 - y1) * (x_min - x1) / (x2 - x1); x = x_min; } if (code_out == code1) { x1 = x; y1 = y; code1 = generateCode(x1, y1); }
- 11. else { x2 = x; y2 = y; code2 = generateCode(x2, y2); } } } if (accept) { std::cout<<endl; std::cout <<"Line accepted from " <<"("<< x1 << ", " << y1 << ")" << " to "<< "(" << x2 << ", " << y2 << ")" << std::endl; setcolor(GREEN); line(x1+x_max-x_min+50,y1,x2+x_max-x_min+50,y2); } else std::cout << "Line rejected" << std::endl; } int main() { int gd=DETECT,gm; initgraph(&gd,&gm,"c:turboc3bgi"); CohenSutherLandAlgo c; c.getCoordinates(); c.getClippingRectangle(); c.cohenSutherland(); getch(); closegraph(); } c) Code for clip a line intersecting at Two or more points with given window #include<iostream> #include<graphics.h>
- 12. #include<math.h> #include<conio.h> using namespace std; class CohenSutherLandAlgo { private: double x1,y1,x2,y2; double x_max,y_max,x_min,y_min; const int INSIDE = 0; const int LEFT = 1; const int RIGHT = 2; const int BOTTOM = 4; const int TOP = 8; public: CohenSutherLandAlgo() { x1 = 0.0; x2 = 0.0; y1 = 0.0; y2 = 0.0; } void getCoordinates(); void getClippingRectangle(); int generateCode(double x, double y); void cohenSutherland(); }; void CohenSutherLandAlgo::getCoordinates() { std::cout << "Enter Co-ordinates of P1(X1,Y1) of Line Segment : "; std::cin >> x1>>y1; std::cout << "Enter Co-ordinates of P2(X2,Y2) of Line Segment :"; std::cin >> x2>>y2; std::cout<<endl; line(x1,y1,x2,y2);
- 13. } void CohenSutherLandAlgo::getClippingRectangle() { std::cout << "Enter the Co-ordinates of Interested Rectangle."<<endl; std::cout << "Enter the X_MAX and Enter the Y_MAX : "; std::cin >> x_max>>y_max; std::cout << "Enter the X_MIN and Enter the Y_MIN : "; std::cin >> x_min>>y_min; rectangle(x_min,y_min,x_max,y_max); outtextxy(x_min,y1-20,"Before line Clipping"); setcolor(GREEN); outtextxy(x_max+50,y1-20,"After line Clipping"); rectangle(x_max+50,y_min,x_max+50+x_max-x_min,y_max); } int CohenSutherLandAlgo::generateCode(double x, double y) { int code = INSIDE; if (x < x_min) code |= LEFT; else if (x > x_max) code |= RIGHT; if (y < y_min) code |= BOTTOM; else if (y > y_max) code |= TOP; return code; } void CohenSutherLandAlgo::cohenSutherland() { int code1 = generateCode(x1, y1); int code2 = generateCode(x2, y2); bool accept = false; while (true)
- 14. { if ((code1 == 0) && (code2 == 0)) { accept = true; break; } else if (code1 & code2) { break; } else { int code_out; double x, y; 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; } else if (code_out & BOTTOM) { x = x1 + (x2 - x1) * (y_min - y1) / (y2 - y1); y = y_min; } else if (code_out & RIGHT) { y = y1 + (y2 - y1) * (x_max - x1) / (x2 - x1); x = x_max; } else if (code_out & LEFT) { y = y1 + (y2 - y1) * (x_min - x1) / (x2 - x1);
- 15. x = x_min; } if (code_out == code1) { x1 = x; y1 = y; code1 = generateCode(x1, y1); } else { x2 = x; y2 = y; code2 = generateCode(x2, y2); } } } if (accept) { std::cout<<endl; std::cout <<"Line accepted from " <<"("<< x1 << ", " << y1 << ")" << " to "<< "(" << x2 << ", " << y2 << ")" << std::endl; setcolor(GREEN); line(x1+x_max-x_min+50,y1,x2+x_max-x_min+50,y2); } else std::cout << "Line rejected" << std::endl; } int main() { int gd=DETECT,gm; initgraph(&gd,&gm,"c:turboc3bgi"); CohenSutherLandAlgo c; c.getCoordinates(); c.getClippingRectangle(); c.cohenSutherland();
- 16. getch(); closegraph(); } 5. Output: a) Output for display 4-bit region code for end points of a line
- 17. b) Output for clip a line intersecting at one point with given window c) Output for clip a line intersecting at Two or more points with given window
- 18. 6. Learning outcomes (What I have learnt): 1. I have gathered detail knowledge about how to display 4-bit region code for end points of a line and check whether line is completely on the screen or off the screen 2. I have gathered detail knowledge about how to clip a line intersecting at one point with given window using Cohen Sutherland Line Clipping algorithm. 3. I have gathered detail knowledge about how to clip a line intersecting at Two or more points with given window using Cohen Sutherland Line Clipping algorithm 4. I have learn how to display 4-bit region code for end points of a line and check whether line is completely on the screen or off the screen 5. I have learn how to clip a line intersecting at one point and two or more point with given window using Cohen Sutherland Line Clipping algorithm. 6. I get to know about proper logic & algorithm in computation of clip a line intersecting at one point andTwo or more points with given window using Cohen Sutherland Line Clipping algorithm 7. Evaluation Grid (To be created as per the SOP and Assessment guidelines by the faculty): Sr. No. Parameters Marks Obtained Maximum Marks 1. 2. 3.