/*
		graphic effect lib.
		  test Filter

		h. Toda 1994 6 3
*/

#include <stdio.h>
#include <stdlib.h>
#include <egb.h>
#include "g_eff.h"

#define NOERR 0		/* no error */

static int mx ;
static int aSen ;
static int mSen ;
static int cMax ;
static int aMax ;
static int x1 ;
static int y1 ;
static int x2 ;
static int y2 ;
static int (*read1)() ;
static int (*write)() ;
static int (*mask)() ;

g_3hFilter( BASICPARA *para )
{
	unsigned char a[4][4] ;
	int i, x, y ;
	int n ;

	mx = para->mix ;
	aSen = para->alphaSen ;
	mSen = para->maskSen ;
	cMax = para->colorMax ;
	aMax = para->alphaMax ;
	x1 = para->lupx ;
	y1 = para->lupy ;
	x2 = para->rdwx ;
	y2 = para->rdwy ;
	read1 = para->read1 ;
	write = para->write ;
	mask = para->mask ;

	for( y = y1 ; y <= y2 ; y++ )
	{
		for( x=x1 ; x <= x2 ; x++ )
		{
			read1( x-1, y,   a[0] ) ;
			read1( x,   y,   a[1] ) ;
			read1( x+1, y,   a[2] ) ;

			for( i=0 ; i<3 ; i++ )
			{
				n = ck3(
						 a[0][i], a[1][i], a[2][i]
					   ) ;
				a[3][i] = a[n][i] ;
			}
			mixWrite( x, y, a[3], a[1] ) ;
		}
	}

	return NOERR ;
}

static mixWrite( int x, int y, unsigned char *a, unsigned char *b )
{
	unsigned char c[4] ;
	int mix ;

	if( mSen )
	{
		if( mask( x, y ) >= mSen )
			return NOERR ;
	}

	mix = mx ;
	if( aSen )
	{
		mix = mix * b[3] / aMax ;
	}

	c[0] = ( a[0] * mix + b[0] * ( 256 - mix ) + 0x80 ) >> 8 ;
	c[1] = ( a[1] * mix + b[1] * ( 256 - mix ) + 0x80 ) >> 8 ;
	c[2] = ( a[2] * mix + b[2] * ( 256 - mix ) + 0x80 ) >> 8 ;
	c[3] = b[3] ;

	if( mix )
	{
		write( x, y, c ) ;
	}

	return NOERR ;
}

static ck3( int a, int b, int c )
{
	int temp ;
	int n0, n1, n2 ;

	n0 = 0 ; n1 = 1 ; n2 = 2 ;

	if( a > b )
	{
		temp = a ;
		a = b ;
		b = temp ;

		temp = n0 ;
		n0 = n1 ;
		n1 = temp ;
	}

	if( a > c )
	{
		temp = a ;
		a = c ;
		c = temp ;

		temp = n0 ;
		n0 = n2 ;
		n2 = temp ;
	}

	if( b > c )
	{
		temp = b ;
		b = c ;
		c = temp ;

		temp = n1 ;
		n1 = n2 ;
		n2 = temp ;
	}

	return n1 ;
}