dotted_lines.cpp

#include <iostream>
#include <math.h>
#include <GL/glut.h>

double X1, Y1, X2, Y2;
const double D = 50;

float round_value(float v)
{
  return floor(v + 0.5);
}
void SolidLines(double X1_, double Y1_, double X2_ , double Y2_)
{
  double dx=(X2_-X1_);
  double dy=(Y2_-Y1_);
  double steps;
  float xInc,yInc,x=X1_,y=Y1_;
  steps=(abs(dx)>abs(dy))?(abs(dx)):(abs(dy));
  xInc=dx/(float)steps;
  yInc=dy/(float)steps;

  glBegin(GL_POINTS);

  glVertex2d(x,y);
  int k;

  for(k=0;k<steps;k++)
  {
    x+=xInc;
    y+=yInc;

    glVertex2d(round_value(x), round_value(y));
  }
  glEnd();

  glFlush();
}
void DottedLinesLowDensity(double X1_, double Y1_, double X2_ , double Y2_){
  double dx=(X2_-X1_);
  double dy=(Y2_-Y1_);
  double steps;
  float xInc,yInc,x=X1_,y=Y1_;
  steps=(abs(dx)>abs(dy))?(abs(dx)):(abs(dy));
  xInc=dx/(float)steps;
  yInc=dy/(float)steps;
  glBegin(GL_POINTS);

  glVertex2d(x,y);
  int k;

  for(k=0;k<steps;k++)
  {
    x+=xInc;
    y+=yInc;
    if(int(x)%5== 0  || int(y) % 5 == 0){
    glVertex2d(round_value(x), round_value(y));
    }
  }
  glEnd();

  glFlush();
}

void DottedLinesHighDensity(double X1_, double Y1_, double X2_ , double Y2_){
  double dx=(X2_-X1_);
  double dy=(Y2_-Y1_);
  double steps;
  float xInc,yInc,x=X1_,y=Y1_;
  steps=(abs(dx)>abs(dy))?(abs(dx)):(abs(dy));
  xInc=dx/(float)steps;
  yInc=dy/(float)steps;
  glBegin(GL_POINTS);

  glVertex2d(x,y);
  int k;

  for(k=0;k<steps;k++)
  {
    x+=xInc;
    y+=yInc;
    if(int(x)%2== 0  || int(y) % 2 == 0){
    glVertex2d(round_value(x), round_value(y));
    }
  }
  glEnd();

  glFlush();
}


void drawDifferentLines(void){
SolidLines(X1, Y1, X2, Y2);
DottedLinesLowDensity(X1, Y1 + D, X2, Y2+D);
DottedLinesHighDensity(X1, Y1 + 2*D, X2, Y2 + 2*D);
}
void Init()
{
  glClearColor(1.0,1.0,1.0,0);
  glColor3f(1.0,0.0,0.0);
  gluOrtho2D(0 , 640 , 0 , 480);
}
int main(int argc, char **argv)
{
  std::cout << "Enter Two Points : \n";
  std::cout << "Enter first point :";
  std::cin >> X1 >> Y1 ;
  std::cout << "Enter second point : ";
  std::cin >> X2 >> Y2;
  glutInit(&argc,argv);
  glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
  glutInitWindowPosition(0,0);
  glutInitWindowSize(640,480);
  glutCreateWindow("DDA_Line");
  Init();
   glClear(GL_COLOR_BUFFER_BIT);
  glutDisplayFunc(drawDifferentLines);
  glutMainLoop();
}

rhombus_triangle.cpp

#include <iostream>
#include <math.h>
#include <GL/glut.h>

double X1, Y1, len;

float round_value(float v)
{
  return floor(v + 0.5);
}

void LineDDA(double X1_, double Y1_, double X2_, double Y2_)
{
  double dx=(X2_-X1_);
  double dy=(Y2_-Y1_);
  double steps;
  float xInc,yInc,x=X1_,y=Y1_;
  steps=(abs(dx)>abs(dy))?(abs(dx)):(abs(dy));
  xInc=dx/(float)steps;
  yInc=dy/(float)steps;
  glBegin(GL_POINTS);

  glVertex2d(x,y);
  int k;

  for(k=0;k<steps;k++)
  {
    x+=xInc;
    y+=yInc;

    glVertex2d(round_value(x), round_value(y));
  }
  glEnd();
  glFlush();
}
void drawSquare(){
//For outer square
LineDDA(X1, Y1, X1, Y1 + len);
LineDDA(X1 , Y1+len, X1+len, Y1 + len);
LineDDA(X1 +len, Y1+len, X1+len, Y1);
LineDDA(X1, Y1, X1+len, Y1 );

//For rhombus
LineDDA(X1, Y1 + len/2, X1 + len/2, Y1 + len);
LineDDA(X1+ len/2, Y1 + len, X1 + len, Y1 + len/2);
LineDDA(X1+len, Y1 + len/2, X1 + len/2, Y1 );
LineDDA(X1+len/2, Y1 , X1 , Y1 + len/2);

//For innermost square

LineDDA(X1+ len/4, Y1 + len/4, X1 + (3*len)/4, Y1 + len/4);
LineDDA(X1 + (3*len)/4, Y1 + len/4, X1 + (3*len)/4, Y1 + (3*len)/4);
LineDDA(X1 + (3*len)/4, Y1 + (3*len)/4, X1 + (len)/4, Y1 + (3*len)/4);
LineDDA(X1 + (len)/4, Y1 + (3*len)/4, X1+ len/4, Y1 + len/4);
}

void drawSlopedSquare(){
//glClear(GL_COLOR_BUFFER_BIT);
LineDDA(X1, len/2, len/2, Y1 + len);
}
void Init()
{
  glClearColor(1.0,1.0,1.0,1);
  glColor3f(1.0,0.0,0.0);
  gluOrtho2D(0 , 640 , 0 , 480);
}
int main(int argc, char **argv)
{
  std::cout << "Enter one co-ordinate of outer most square : \n";
  std::cout << "Enter point :";
  std::cin >> X1 >> Y1 ;
  std::cout << "Enter edge length of outer most square : ";
  std::cin >> len;
  glutInit(&argc,argv);
  glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
  glutInitWindowPosition(0,0);
  glutInitWindowSize(640,480);
  glutCreateWindow("SQUARE FORMATION");
  Init();
  glClear(GL_COLOR_BUFFER_BIT);
  glutDisplayFunc(drawSquare);
  //glutDisplayFunc(drawSlopedSquare);
  glutMainLoop();
}