<?php
///////////////////////////////////////////////////////////////////////////////////////////
/////////// Author    : Reza Salehi
///////////	Contact   : hide@address.com
/////////// Copyright : free for non-commercial use . 
///////////////////////////////////////////////////////////////////////////////////////////

	class bezier
		{
		function bezier($x0, $y0, $x1, $y1, $x2, $y2, $x3, $y3)
			{
			$this->dimx=400;
			$this->dimy=400;
			$this->br=0;
			$this->bg=0;
			$this->bb=0;
			$this->ar=255;
			$this->ag=255;
			$this->ab=255;
			$this->hasgrid=0;
			$this->t_start=0;
			$this->t_end=1;
			$this->render=0;
			$this->step=.01;
			$this->x0=$x0;
			$this->y0=$y0;
			$this->x1=$x1;
			$this->y1=$y1;
			$this->x2=$x2;
			$this->y2=$y2;
			$this->x3=$x3;
			$this->y3=$y3;
			
			//----
			/*
			cx = 3 (x1 - x0)
			bx = 3 (x2 - x1) - cx
			ax = x3 - x0 - cx - bx
			cy = 3 (y1 - y0)
			by = 3 (y2 - y1) - cy
			ay = y3 - y0 - cy - by
			*/
			
			$this->cx=3*($x1-$x0);
			$this->bx=3*($x2-$x1)-$this->cx;
			$this->ax=$x3-$x0-$this->cx-$this->bx;
			
			$this->cy=3*($y1-$y0);
			$this->by=3*($y2-$y1)-$this->cy;
			$this->ay=$y3-$y0-$this->cy-$this->by;
			//----
			
			$this->function_x='('.$this->ax.')*$t*$t*$t+('.$this->bx.')*$t*$t+('.$this->cx.')*$t+'.$this->x0;
			$this->function_y='('.$this->ay.')*$t*$t*$t+('.$this->by.')*$t*$t+('.$this->cy.')*$t+'.$this->y0;
			$this->function_z=2;
			
			}
			
		//---- some validations.
		function zscale()
			{
			return(1);
			}
		function yscale()
			{
			return(1);
			}
		function xscale()
			{
			return(1);
			}
		//----main function.
		function draw()
			{
			header("Content-type: image/jpeg");
			$image=imagecreate($this->dimx,$this->dimy+20);
			$col=imagecolorallocate($image,$this->br,$this->bg,$this->bb);
			$col1=imagecolorallocate($image,$this->ar,$this->ag,$this->ab);
			$col2=imagecolorallocate($image, 250, 250, 100);
			$col3=imagecolorallocate($image, 50, 50, 50);
			$grcol=imagecolorallocate($image,8,100,8);
					
			imageline($image, $this->dimx/2, 0, $this->dimx/2, $this->dimy, $col3);
			imageline($image, 0, $this->dimy/2, $this->dimx, $this->dimy/2, $col3);
			
			imageline($image, $this->x0+$this->dimx/2, -$this->y0+$this->dimy/2, $this->x1+$this->dimx/2, -$this->y1+$this->dimy/2, $col2);
			imageline($image, $this->x2+$this->dimx/2, -$this->y2+$this->dimy/2, $this->x3+$this->dimx/2, -$this->y3+$this->dimy/2, $col2);
			
			//imagestring ( resource image, int font, int x, int y, string s, int col)
			
			imagestring ($image, 2, $this->x0+$this->dimx/2, -$this->y0+$this->dimy/2, 'A', $col1);
			imagestring ($image, 2, $this->x1+$this->dimx/2, -$this->y1+$this->dimy/2, 'B', $col1);
			imagestring ($image, 2, $this->x2+$this->dimx/2, -$this->y2+$this->dimy/2, 'C', $col1);
			imagestring ($image, 2, $this->x3+$this->dimx/2, -$this->y3+$this->dimy/2, 'D', $col1);
			
			//----
			$j=0;
			$colx=$col1;
				for($t=$this->t_start; $t<$this->t_end; $t+=$this->step)
				{
					eval('$this->x_points[$j]='.$this->xscale().'*'.$this->function_x.';');
					eval('$this->y_points[$j]='.$this->yscale().'*'.$this->function_y.';');
					eval('$this->z_points[$j]='.$this->zscale().'*'.$this->function_z.';');
					imagearc($image, $this->x_points[$j]+$this->dimx/2, ($this->y_points[$j]*(-1))+$this->dimy/2, $this->z_points[$j], $this->z_points[$j], 0, 360, $colx);
					$j++;	
				}
			//----
			imagefilledrectangle ($image, 5, $this->dimy-30, $this->dimx/2, $this->dimy+10, $col);
			//imagerectangle ($image, 5, 100, 100, 400, $col);
			imagestring ($image, 2, 10, $this->dimy-40, 'start point (A) = ('.$this->x0.','.$this->y0.')', $col1);
			imagestring ($image, 2, 10, $this->dimy-28, 'end point (D) = ('.$this->x3.','.$this->y3.')', $col1);
			imagestring ($image, 2, 10, $this->dimy-15, 'control 1 (B) = ('.$this->x1.','.$this->y1.')', $col1);
			imagestring ($image, 2, 10, $this->dimy-3 , 'control 2 (C) = ('.$this->x2.','.$this->y2.')', $col1);
			imagejpeg($image,"",100);
			}	
		}				
?>