// Written in the D Programming Language v1 ( http://www.digitalmars.com/d/1.0/ )

module render;

import std.stdio;
import std.file;
import std.path;
import std.string;
import std.conv;
import std.math;

bool[100][100] image, frame;

const header = "P4\n100 100\n";
//const EYEDISTANCE = 200f;
//const SCREENDISTANCE = EYEDISTANCE - 10.1f;
const STRIPE_HEIGHT = 5;
const STRIPE_APPEARANCES = 6;

void main(string[] args)
{
	loadImage(args[1]);
	/+foreach(ref row;image)
	{
		foreach(b;row)
			writef(b?"x":" ");
		writefln;
	}+/
	int frames = toInt(args[2]);
	float eyeDistance = toFloat(args[3]);
	float screenDistance = toFloat(args[4]) + 0.1f;
	float thickness = toFloat(args[5]);

	for (int f=0;f<frames;f++)
	{
		foreach(ref row;frame)
			row[] = false;
		float angle = PI*2*f/frames;

		float ff = cast(float)f/frames;
		float stripePos = fpart(ff*STRIPE_APPEARANCES);
		int stripeTop, stripeBottom;
		if (stripePos>0.5)
		{
			//stripePos = (ff + (stripePos-0.5)*2) / STRIPE_APPEARANCES;
			float segment = 1f / STRIPE_APPEARANCES;
			stripePos = segment * (cast(int)(ff / segment) + (stripePos-0.5)*2);
			stripeTop = cast(int)(stripePos*90);
			stripeBottom = stripeTop + STRIPE_HEIGHT*2;
		}

		foreach(int y,ref row;image)
			foreach(int x,p;row)
				if (p)
					for (float z=-thickness/2;z<=thickness/2;z+=0.50001)
					for (float ax = 0; ax < 1; ax += 0.501)
					for (float ay = 0; ay < 1; ay += 0.501)
					{
						float fx = x + ax - 50;
						float fy = y + ay - 50;
						float fz = z;
						float pixelAngle = getAngle(fx, fz);
						pixelAngle -= angle;
						float r = sqrt(fz*fz + fx*fx);
						fx = cos(pixelAngle)*r;
						fz = sin(pixelAngle)*r;

						float ratio = (screenDistance / (fz + eyeDistance));
						float sx = fx * ratio;
						float sy = fy * ratio;
						
						int ix = cast(int)sx + 50;
						int iy = cast(int)sy + 50;
						
						if (ix>=0 && ix<100 && iy>=0 && iy<100 && (iy&1)==0 && (iy<stripeTop || iy>=stripeBottom))
							frame[iy][ix] = true;
					}
		
		saveFrame(format("output/%s-%04d.pnm", getBaseName(args[1]), f));
	}
}

void loadImage(string fileName)
{
	auto data = cast(string)read(fileName);
	if (data[3]=='#')
		data = data[0..3] ~ data[3+find(data[3..$], '\n')+1..$];
	if (data.length != 1311) throw new Exception("Invalid type or dimensions (must be 100x100)");
	if (data[0..11]!=header) throw new Exception("Invalid type or dimensions (must be 100x100)");
	auto rows = cast(ubyte[13][])data[11..$];
	foreach (y,ref row;rows)
	{
		for (int x=0;x<100;x++)
			image[y][x] = (row[x/8] & (1 << (7-x%8))) != 0;
	}
}

void saveFrame(string fileName)
{
	string data;
	data.length = 1311;
	data[] = '\0';
	data[0..11] = header;
	foreach(y,ref row;frame)
		foreach(x,p;row)
			if (p)
				(cast(ubyte[])data)[11+13*y+x/8] |= (1 << (7-x%8));
	write(fileName, data);


	debug
	{
		foreach(ref row;frame)
		{
			foreach(b;row)
				writef(b?"x":" ");
			writefln;
		}
		writefln("================================================");
	}
}

float getAngle(float x, float y)
{
	if (x==0 && y==0)
		return 0;
	if (x==0 && y>0)
		return PI/2;
	if (x==0 && y<0)
		return 3*PI/2;

	if (x>0 && y>=0)
		return atan(y/x);
	if (x>0 && y<0)
		return atan(y/x) + 2*PI;
	if (x<0)
		return atan(y/x) + PI;
}

float fpart(float x)
{
	return x - trunc(x);
}