/**************************************************************

Problem Statement:Draw the polygons by using the mouse. Choose colors by clicking on the designed color
pane. Use window port to draw. (Use DDA algorithm for line drawing)

 ***************************************************************/


#include<stdio.h>

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

//------------------------------------------------------------
struct PIXEL
{
    int x,y;
};

struct COLOR
{
    float r,g,b;
};

//------------------------------------------------------------
void Display();
void Mouse(int ,int ,int ,int );

//------------------------------------------------------------

struct PIXEL start,temp;
struct COLOR fillcolor;
static int flag=0;

//------------------------------------------------------------
int main(int argc,char **argv)
{
    glutInit( &argc , argv );
    glutInitDisplayMode( GLUT_SINGLE | GLUT_RGB );
    glutInitWindowPosition(0,0);
    glutInitWindowSize(640,480);
    glutCreateWindow("POLYGON FILLING");
    
    glutDisplayFunc(Display);
    glutMouseFunc(Mouse);
    glutMainLoop();
}

//------------------------------------------------------------

COLOR getPixelColor(int X, int Y)
{
    COLOR temp;
    glReadPixels(X,Y,1,1,GL_RGB, GL_FLOAT, &temp);
    return temp;
}
void setPixelColor(int X, int Y, COLOR color)
{    glColor3f(color.r, color.g, color.b);
    glBegin(GL_POINTS);
        glVertex2i(X,Y);
    glEnd();
    glFlush();
}
void floodFill(int X, int Y, COLOR oldColor, COLOR fillColor)
{
    COLOR current;
    current= getPixelColor(X,Y);
    if(current.r == oldColor.r && current.g == oldColor.g && current.b == oldColor.b)
    {
        setPixelColor(X,Y, fillColor);
        floodFill(X+1,Y, oldColor, fillColor);
        floodFill(X,Y-1, oldColor, fillColor);
        floodFill(X-1,Y, oldColor, fillColor);
        floodFill(X,Y+1, oldColor, fillColor);
    }
}

void Display()
{

    glClearColor(1,1,1,0); //background color

    gluOrtho2D(0,640,0,480); //pixel scaling

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glColor3f(1.0,0.0,0.0);//red
    glRecti(10,30,60,10);
    glColor3f(0.0,1.0,0.0);//green
    glRecti(90,30,140,10);
    glColor3f(0.0,0.0,1.0);//blue
    glRecti(170,30,220,10);
    glColor3f(1.0,1.0,0.0);//red-green
    glRecti(250,30,300,10);
    glColor3f(0.0,1.0,1.0);//green-blue
    glRecti(330,30,380,10);
    glColor3f(1.0,0.0,1.0);//blue-red
    glRecti(410,30,460,10);
    
    glFlush();
}

void Mouse(int button,int state,int x,int y)
{
    if(button==GLUT_LEFT_BUTTON && state == GLUT_DOWN)
    {
        if(flag==0)//  // to accept first point
        {   
            flag=1;
            glColor3f(0,0,0);
            glBegin(GL_POINTS);
                glVertex2i(x,480-y);
                start.x=x;
                start.y=480-y;
                temp=start;
            glEnd();
            glFlush();
        }
        else if(flag==1)//to draw edges of poly
        {
            glColor3f(0,0,0);           
            glBegin(GL_LINES);
                glVertex2i(temp.x,temp.y);
                glVertex2i(x,480-y);
                temp.x=x;
                temp.y=480-y;
            glEnd();
            glFlush();
        }
        else if(flag==2)//  //accept desired color
        {
            fillcolor=getPixelColor(x,480-y);
            flag=3;
        }
        else if(flag==3) //fill polygon
        {
            COLOR fillColor={fillcolor.r,fillcolor.g,fillcolor.b};
         COLOR oldColor=getPixelColor(x,480-y);

            floodFill(x,480-y,oldColor,fillColor);
            flag=0;
        }
    }
    if(button==GLUT_RIGHT_BUTTON && state == GLUT_DOWN)
    {
        flag=2;
        glColor3f(0,0,0);
        glBegin(GL_LINES);
            glVertex2i(temp.x,temp.y);
            glVertex2i(start.x,start.y);
        glEnd();
        glFlush();
    }
}