/*
CSCI 480 HW 1
Chin-Kai Chang
7557011081 
chinkaic@usc.edu
 
Usage:
drawline x1 y1 x2 y2
Or for extra point test 
drawline x1 y1 x2 y2 r1 g1 b1 r2 g2 b2 
All number should be in 0~255,
There is no number checked


*/ 
#include <cstdlib>
#include <iostream>

#define OUTFILE "out.ppm" 
const int XRES=256; 
const int YRES=256; 
using namespace std;
typedef struct 
{
 int r;
 int g;
 int b;       
}PIXEL; 

class Drawline{
      public:
      PIXEL graph[XRES][YRES]; 
      void drawline(int x1,int y1,int x2,int y2);      
      void drawline(int x1,int y1,int x2,int y2,PIXEL start,PIXEL end);
      void setpixel(int x,int y);   
      void setpixel(int x,int y,float r,float g,float b) ;                 
      void output(void); 
      void initGraph(void); 

      
} ; 
 


//Draw with default Color 
void Drawline::drawline(int x1,int y1,int x2,int y2)
{
  int dx, dy, d, incE, incNE, x, y, slope;
  //Swap point 
  if(x1 > x2) { 
      drawline(x2,y2,x1,y1);
      return; 
  }    
  dx = x2 - x1;
  dy = y2 - y1;
  if(dy < 0) 
  {
   slope  = -1;
   dy = -dy;      
  }else{
   slope  = 1;     
  }   
  //Draw vertical line 
  if(dx==0)
  {
   for(int i=0;i<=dy;i++)
   {     
    setpixel(x1,y1); 
    y1+=slope;
   }         
  }else{
  d = 2*dy - dx;
  incE = 2*dy;
  incNE = 2*(dy - dx);
  y = y1;
  for (x=x1; x<=x2; x++) {
    setpixel(x, y);
    if (d>0) {
      d += incNE;
      y +=slope;
    } else {
      d += incE;
    }
  }        
  } 
}
//Draw with  Color Change for Extra point 
void Drawline::drawline(int x1,int y1,int x2,int y2,PIXEL start,PIXEL end)
{
  int dx, dy, d, incE, incNE, x, y, slope;
  float  dr,dg,db,sr,sg,sb,r,g,b; 
  if(x1 > x2) { 
      drawline(x2,y2,x1,y1,end,start);
      return; 
  }    
  dx = x2 - x1;
  dy = y2 - y1;
  r =   start.r/255; 
  g =   start.g/255; 
  b =   start.b/255;   
  dr = start.r - end.r; 
  dg = start.g - end.g; 
  db = start.b - end.b;
  if(dx != 0){ 
    sr = dr/((float)dx*255); 
    sg = dg/((float)dx*255); 
    sb = db/((float)dx*255);        
  }  
  else{  
    sr = dr/((float)dy*255);        
    sg = dg/((float)dy*255);        
    sb = db/((float)dy*255);                     
  }
   
  if(dy < 0) 
  {
   slope  = -1;
   dy = -dy;      
  }else{
   slope  = 1;     
  } 
   if(dx==0)
  {
            
   for(int i=0;i<=dy;i++)
   {     
        
    setpixel(x1,y1,r,g,b);
    r -=sr; 
    g -=sg;
    b -=sb;        
    y1+=slope;
   }         
  }else{
  d = 2*dy - dx;
  incE = 2*dy;
  incNE = 2*(dy - dx);
  y = y1;
  for (x=x1; x<=x2; x++) {
    setpixel(x,y,r,g,b);
    r -=sr; 
    g -=sg;
    b -=sb;            
    if (d>0) {
      d += incNE;
      y +=slope;
    } else {
      d += incE;
    }
  }        
  } 
}

void Drawline::setpixel(int x,int y) 
{
     graph[y][x].r = 0 ; 
     graph[y][x].g = 0 ;
     graph[y][x].b = 0 ;          
     
} 
void Drawline::setpixel(int x,int y,float r,float g,float b) 
{
  
     graph[y][x].r = (int)(r*255) ; 
     graph[y][x].g = (int)(g*255) ;
     graph[y][x].b = (int)(b*255) ;        
           
     
} 
void Drawline::output(void) 
{
 FILE *fp;    
 fp = fopen(OUTFILE, "w");     
 fprintf(fp,"P3\n") ;
 fprintf(fp,"%d %d\n",XRES,YRES) ; 
 fprintf(fp,"255\n"); 
 
 for(int i=0;i<YRES;i++)
 {  
        for(int j=0;j<XRES;j++)
        {
          fprintf(fp,"%d %d %d ",graph[i][j].r,graph[i][j].g,graph[i][j].b) ;                 
        }          
        fprintf(fp,"\n\n") ;        
 }  
 cout<<"Output file out.ppm"<<endl;       
} 
void Drawline::initGraph(void) 
{
 for(int i=0;i<YRES;i++){  
        for(int j=0;j<XRES;j++){
                graph[i][j].r = 255; 
                graph[i][j].g = 255; 
                graph[i][j].b = 255; 
        }          
        
 }        
} 

int main(int argc, char *argv[])
{
    int x1,x2,y1,y2,expoint=0;     
    PIXEL start,end; 
    //Get input from argv 
    if(argc==5) {
                
               sscanf(argv[1],"%d",&x1);           
               sscanf(argv[2],"%d",&y1);           
               sscanf(argv[3],"%d",&x2);                                         
               sscanf(argv[4],"%d",&y2);                          
    }else if(argc==11) {
               sscanf(argv[5],"%d",&start.r);           
               sscanf(argv[6],"%d",&start.g);           
               sscanf(argv[7],"%d",&start.b);                                         
               sscanf(argv[8],"%d",&end.r);                          
               sscanf(argv[9],"%d",&end.g);           
               sscanf(argv[10],"%d",&end.b);                                               
               expoint = 1; 
    }else{
    cout <<"Usage:"<<endl;      
    cout <<"drawline x1 y1 x2 y2"<<endl;
    cout <<"Or extra point"<<endl;    
    cout <<"drawline x1 y1 x2 y2 r1 g1 b1 r2 g2 b2"<<endl;
    cout <<"All number should be in 0~255,"<<endl; 
    cout <<"There is no number checked"<<endl<<endl;       
    return EXIT_SUCCESS;
    } 
  Drawline dl;        
  dl.initGraph();//Set all pixel white 
  if(expoint) 
    dl.drawline(256,0,0,256,start,end) ;   
  else  
    dl.drawline(256,0,0,256) ;          
  dl.output();    
   
    return EXIT_SUCCESS;
}