5. Assignments No. 2
Implement DDA and Bresenham line drawing algorithm to draw:
- i) Simple Line
- ii) Dotted Line
- iii) Dashed Line
Using mouse interface Divide the screen in four quadrants with center as (0, 0). The line should work for all the slopes positive as well as negative.
Code
#include<iostream>
#include<GL/glut.h>
using namespace std;
int Algo,type;
void Init()
{
glClearColor(0,0,0,0);
glColor3f(0,1,0);
gluOrtho2D(0,640,0,480);
glClear(GL_COLOR_BUFFER_BIT);
}
int sign(float a){
if(a==0){
return 0;
}
if(a>0){
return 1;
}
return -1;
}
void B_Line(int x_1,int y_1,int x_2,int y_2,int t){
float dy, dx, m , P;
dy = y_2 - y_1;
dx = x_2 - x_1;
m = dy/dx;
P = 2*dy - dx;
int x = x_1, y = y_1;
cout<<"\n x1 = "<<x<<" y1 = "<<y;
if(m<1){
int cnt=1;
for(int i=0; i<=dx;i++){
if(t == 1){
glBegin(GL_POINTS);
glVertex2i(x,y);
glEnd();
}
if(t == 2){
if(i%2==0){
glBegin(GL_POINTS);
glVertex2i(x,y);
glEnd();
}
}
if(t == 3){
if(cnt <= 10){
glBegin(GL_POINTS);
glVertex2i(x,y);
glEnd();
}
cnt++;
if(cnt == 15){
cnt =1;
}
}
if(P<0){
x = x +1;
y =y;
P = P + 2*dy;
}
else{
x= x+1;
y = y+1;
P = P + 2*dy - 2*dx;
}
}
}
else{
int cnt = 1;
for(int i=0;i<=dy;i++){
if(t == 1){
glBegin(GL_POINTS);
glVertex2i(x,y);
glEnd();
}
if(t == 2){
if(i%2==0){
glBegin(GL_POINTS);
glVertex2i(x,y);
glEnd();
}
}
if(t == 3){
if(cnt <= 10){
glBegin(GL_POINTS);
glVertex2i(x,y);
glEnd();
}
cnt++;
if(cnt == 15){
cnt =1;
}
}
if(P<0){
x = x;
y =y+1;
P = P + 2*dx;
}
else{
x= x+1;
y = y+1;
P = P + 2*dx - 2*dy;
}
}
}
cout<<"\n xlast = "<<x<<" ylast = "<<y;
glFlush();
}
void DDA_LINE(int x_1,int y_1,int x_2,int y_2, int t){
float dx,dy,length;
dx = x_2-x_1;
dy = y_2-y_1;
if(abs(dx) >= abs(dy)){
length = abs(dx);
}
else{
length = abs(dy);
}
float xin, yin;
xin = dx/length;
yin = dy/length;
float x,y;
x = x_1 + 0.5 * sign(xin);
y = y_1 + 0.5 * sign(yin);
int i=0;
int cnt =1;
while(i<=length){
if(t == 1){
glBegin(GL_POINTS);
glVertex2i(x,y);
glEnd();
}
if(t == 2){
if(i%2==0){
glBegin(GL_POINTS);
glVertex2i(x,y);
glEnd();
}
}
if(t == 3){
if(cnt <= 10){
glBegin(GL_POINTS);
glVertex2i(x,y);
glEnd();
}
cnt++;
if(cnt == 15){
cnt =1;
}
}
x = x + xin;
y = y + yin;
i++ ;
}
glFlush();
}
void display()
{
DDA_LINE(0,240,640,240,1);
B_Line(320,0,320,640,1);
glFlush();
}
void mymouse(int b,int s, int x, int y)
{
static int x_s,y_s,x_e,y_e,pt=0;
if(b==GLUT_LEFT_BUTTON && s==GLUT_DOWN)
{
if(pt==0)
{
x_s =x;
y_s =480 - y;
pt++;
glBegin(GL_POINTS);
glVertex2i(x_s,y_s);
glEnd();
}
else
{
x_e=x;
y_e=480-y;
cout<<"\n x_1_click "<<x_s<<" y_1_click "<<y_s;
cout<<"\n x_2_click "<<x_e<<" y_2_click "<<y_e<<"\n";
glBegin(GL_POINTS);
glVertex2i(x_e,y_e);
glEnd();
if(Algo == 1){
DDA_LINE(x_s,y_s,x_e,y_e,type);
}
if(Algo == 2){
B_Line(x_s,y_s,x_e,y_e,type);
}
}
}
else if(b==GLUT_RIGHT_BUTTON && s==GLUT_DOWN)
{
pt=0;
}
glFlush();
}
int main(int argc ,char **argv)
{
cout<<"\n Select the Algorithm \n 1. DDA \n 2. Bresenham's \n";
cin>>Algo;
cout<<"Select the Line Type \n 1. Simple Line \n 2. Dotted Line\n 3. Dashed Line \n";
cin>>type;
if((Algo == 1 || Algo == 2 )&&(type==1 || type==2 || type==3)){
}
else{
cout<<"\n Option enter are wrong \n";
return 0;
}
glutInit(&argc,argv);
glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);
glutInitWindowPosition(100,100);
glutInitWindowSize(640,480);
glutCreateWindow("DDA-Line");
Init();
glutDisplayFunc(display);
glutMouseFunc(mymouse);
glutMainLoop();
return 0;
}
OUTPUT
g++ filename.cpp -lGL -lGLU -lglut
./a.out
