/* ----------------------------------------
Image Processing pf1.c
Affine Transformation
Ichinoseki National College Advanced Course
------------------------------------------ */

#include <stdio.h>
#include <stdlib.h>
#include <math.h>  

main(argc,argv)
int argc;
char *argv[]; 
{
	static int  i,j,m,n,x,y,u,v,x0,y0,u0,v0;
	static int pixel,line;
	static double a,b,c,d,e,f;
	static int g[1000*1000];
	static int h[1000*1000];
	FILE *fp1,*fp2;

	a=0.70711;/*cos(45)*/
	b=0.70711;/*sin(45)*/
	c=0;
	d=-0.70711/*sin(45)*/;
	e=0.70711;/*sin(45)*/
	f=0;
	x0=0;
	y0=0;
	u0=0;
	v0=0;

	/* Command parameter check  */
	if (argc!=5){
		printf("Usage : command input_file pixel line output_file\n");
		return 1;
	}

	/* Image size parameter load */
	sscanf(argv[2],"%d",&pixel);
	sscanf(argv[3],"%d",&line);
	
	if (pixel*line >= 3000000){
		printf("Too big image size\n");
		return 1;
	}

	/*回転軸の設定*/
	x0=pixel/2;
	y0=line/2;
	u0=pixel/2;
	v0=line/2;

	/* Input image file check */
	if (( fp1=fopen(argv[1],"r") )==NULL){
		printf("Can't open input_file\n");
		return 1;
	}

	/* Output image file check */
	if (( fp2=fopen(argv[4],"w") )==NULL){
		printf("Can't open output_file\n");
		return 1;
	}

	/* Skip header data of Input Image */
	fseek(fp1,60,0);

	/* Load Image Data from Input File to Image Array */
	for (j=0; j<line; j++)
	{
	for (i=0; i<pixel; i++)
	{
		
		g[j*pixel+i]=getc(fp1);
		
	}
	}

	/* Affine Transformation with x0,y0,u0,v0 */
	for (j=0; j<line; j++)
	{
	for (i=0; i<pixel; i++)
	{
		x=x0+((i-u0)*e-(j-v0)*b+b*f-c*e)/(a*e-b*d);
		y=y0+((i-u0)*d-(j-v0)*a+a*f-c*d)/(b*d-a*e);
		if (x<0 || x>pixel || y<0 || y>line){
		h[j*pixel+i]=0;
		}
		else{
		h[j*pixel+i]=g[y*pixel+x];
		}
	}
	}

	/* ppm header output */
	fprintf(fp2,"P5\n");
	fprintf(fp2,"# INCT\n");
	fprintf(fp2,"%s %s\n",argv[2],argv[3]);
	fprintf(fp2,"255\n");

	/* Output from Image Array to Image file */
	for (j=0; j<line; j++)
	{
	for (i=0; i<pixel; i++)
	{
		putc(h[j*pixel+i],fp2);
	}
	}

	fclose(fp1);
	fclose(fp2);
	return 0;
}