Problem Statement:
Implement DDA and Bresenham line drawing algorithm to draw:
i) Simple Line ii) Dotted Line iii) Dashed Line iv) Solid 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.
Program:
#include <GL/glut.h>
#include <stdlib.h>
#include <stdio.h>
void displayPoint(int x, int y)
{
glColor3f(0, 1, 0);
glPointSize(5);
glBegin(GL_POINTS);
glVertex2i(x, y);
glEnd();
}
float x01, x2, y01, y2;
int ch;
void SimpleLine(float x1, float y1, float x2, float y2)
{
float step;
float dx = x2 - x1;
float dy = y2 - y1;
if (abs(dx) > abs(dy))
{
step = abs(dx);
}
else
step = abs(dy);
float Xinc = dx / (float)step;
float Yinc = dy / (float)step;
float x = x1;
float y = y1;
for (int i = 0; i <= step; i++)
{
displayPoint(x, y);
x = x + Xinc;
y = y + Yinc;
}
glFlush();
}
void DottedLine(float x1, float y1, float x2, float y2)
{
float step;
float dx = x2 - x1;
float dy = y2 - y1;
if (abs(dx) > abs(dy))
{
step = abs(dx);
}
else
step = abs(dy);
float Xinc = dx / (float)step;
float Yinc = dy / (float)step;
float x = x1;
float y = y1;
displayPoint(x, y);
for (int i = 0; i <= step; i++)
{
x = x + Xinc;
y = y + Yinc;
if (i % 3 == 0)
{
displayPoint(x, y);
}
}
glFlush();
}
void DashedLine(float x1, float y1, float x2, float y2)
{
float step;
float dx = x2 - x1;
float dy = y2 - y1;
if (abs(dx) > abs(dy))
{
step = abs(dx);
}
else
step = abs(dy);
float Xinc = dx / (float)step;
float Yinc = dy / (float)step;
float x = x1;
float y = y1;
displayPoint(x, y);
for (int i = 0; i <= step; i++)
{
x = x + Xinc;
y = y + Yinc;
if (i % 7 == 0)
{
displayPoint(x, y);
}
}
glFlush();
}
void myMouse(int button, int state, int x, int y)
{
static int xst, yst, pt = 0;
if (button == GLUT_LEFT_BUTTON && state == GLUT_DOWN)
{
if (pt == 0)
{
xst = x;
yst = y;
x01 = xst;
y01 = yst;
pt = pt + 1;
}
else
{
x2 = x;
y2 = y;
if (ch == 1)
{
SimpleLine(xst, yst, x, y);
}
else if (ch == 2)
{
DottedLine(xst, yst, x, y);
}
else if (ch == 3)
{
DashedLine(xst, yst, x, y);
}
xst = x;
yst = y;
}
}
else if (button == GLUT_RIGHT_BUTTON && state == GLUT_DOWN)
pt = 0;
//Clear Screen
glFlush();
}
void keyboard(unsigned char key, int x, int y)
{
switch (key)
{
case 's':
{
ch = 1;
glutMouseFunc(myMouse);
break;
}
case 'd':
{
ch = 2;
glutMouseFunc(myMouse);
break;
}
case 'D':
{
ch = 3;
glutMouseFunc(myMouse);
break;
}
}
glutPostRedisplay();
}
void initialize(void)
{
glClearColor(1.0, 1.0, 1.0, 1.0);
glClear(GL_COLOR_BUFFER_BIT);
// gluOrtho2D(l,r,b,t)
gluOrtho2D(0, 600, 600, 0);
}
void primitives(void)
{
//glClearColor(1.0, 1.0, 1.0, 1.0);
//glClear(GL_COLOR_BUFFER_BIT);
glColor3f(1, 0, 0);
SimpleLine(0, 300, 600, 300);
SimpleLine(300, 0, 300, 600);
glutKeyboardFunc(keyboard);
}
int main(int argc, char **argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_SINGLE);
glutInitWindowPosition(0, 0);
glutInitWindowSize(600, 600);
glutCreateWindow("OpenGL - DDA Algo");
initialize();
printf("--------------------");
printf("\ns. Simple Line");
printf("\nd. Dotted Line");
printf("\nD. Dashed Line");
printf("\n--------------------\n");
glutDisplayFunc(primitives);
glutMainLoop();
return 0;
}
Output:
