/*
OneLoneCoder.com - 3D Graphics Part #2 - Normals, Culling, Lighting & Object Files
"Tredimensjonal Grafikk" - @Javidx9

License
~~~~~~~
One Lone Coder Console Game Engine  Copyright (C) 2018  Javidx9
This program comes with ABSOLUTELY NO WARRANTY.
This is free software, and you are welcome to redistribute it
under certain conditions; See license for details.
Original works located at:
https://www.github.com/onelonecoder
https://www.onelonecoder.com
https://www.youtube.com/javidx9
GNU GPLv3
https://github.com/OneLoneCoder/videos/blob/master/LICENSE

From Javidx9 :)
~~~~~~~~~~~~~~~
Hello! Ultimately I don't care what you use this for. It's intended to be
educational, and perhaps to the oddly minded - a little bit of fun.
Please hack this, change it and use it in any way you see fit. You acknowledge
that I am not responsible for anything bad that happens as a result of
your actions. However this code is protected by GNU GPLv3, see the license in the
github repo. This means you must attribute me if you use it. You can view this
license here: https://github.com/OneLoneCoder/videos/blob/master/LICENSE
Cheers!

Background
~~~~~~~~~~
3D Graphics is an interesting, visually pleasing suite of algorithms. This is the
first video in a series that will demonstrate the fundamentals required to 
build your own software based 3D graphics systems.

Video
~~~~~
https://youtu.be/ih20l3pJoeU
https://youtu.be/XgMWc6LumG4

Author
~~~~~~
Twitter: @javidx9
Blog: http://www.onelonecoder.com
Discord: https://discord.gg/WhwHUMV


Last Updated: 29/07/2018
*/


#include "olcConsoleGameEngine.h"
#include <fstream>
#include <strstream>
#include <algorithm>
using namespace std;


struct vec3d
{
	float x, y, z;
};

struct triangle
{
	vec3d p[3];

	wchar_t sym;
	short col;
};

struct mesh
{
	vector<triangle> tris;

	bool LoadFromObjectFile(string sFilename)
	{
		ifstream f(sFilename);
		if (!f.is_open())
			return false;

		// Local cache of verts
		vector<vec3d> verts;

		while (!f.eof())
		{
			char line[128];
			f.getline(line, 128);

			strstream s;
			s << line;

			char junk;

			if (line[0] == 'v')
			{
				vec3d v;
				s >> junk >> v.x >> v.y >> v.z;
				verts.push_back(v);
			}

			if (line[0] == 'f')
			{
				int f[3];
				s >> junk >> f[0] >> f[1] >> f[2];
				tris.push_back({ verts[f[0] - 1], verts[f[1] - 1], verts[f[2] - 1] });
			}
		}

		return true;
	}

};

struct mat4x4
{
	float m[4][4] = { 0 };
};

class olcEngine3D : public olcConsoleGameEngine
{
public:
	olcEngine3D()
	{
		m_sAppName = L"3D Demo";
	}


private:
	mesh meshCube;
	mat4x4 matProj;

	vec3d vCamera;


	float fTheta;

	void MultiplyMatrixVector(vec3d &i, vec3d &o, mat4x4 &m)
	{
		o.x = i.x * m.m[0][0] + i.y * m.m[1][0] + i.z * m.m[2][0] + m.m[3][0];
		o.y = i.x * m.m[0][1] + i.y * m.m[1][1] + i.z * m.m[2][1] + m.m[3][1];
		o.z = i.x * m.m[0][2] + i.y * m.m[1][2] + i.z * m.m[2][2] + m.m[3][2];
		float w = i.x * m.m[0][3] + i.y * m.m[1][3] + i.z * m.m[2][3] + m.m[3][3];

		if (w != 0.0f)
		{
			o.x /= w; o.y /= w; o.z /= w;
		}
	}

	// Taken From Command Line Webcam Video
	CHAR_INFO GetColour(float lum)
	{
		short bg_col, fg_col;
		wchar_t sym;
		int pixel_bw = (int)(13.0f*lum);
		switch (pixel_bw)
		{
		case 0: bg_col = BG_BLACK; fg_col = FG_BLACK; sym = PIXEL_SOLID; break;

		case 1: bg_col = BG_BLACK; fg_col = FG_DARK_GREY; sym = PIXEL_QUARTER; break;
		case 2: bg_col = BG_BLACK; fg_col = FG_DARK_GREY; sym = PIXEL_HALF; break;
		case 3: bg_col = BG_BLACK; fg_col = FG_DARK_GREY; sym = PIXEL_THREEQUARTERS; break;
		case 4: bg_col = BG_BLACK; fg_col = FG_DARK_GREY; sym = PIXEL_SOLID; break;

		case 5: bg_col = BG_DARK_GREY; fg_col = FG_GREY; sym = PIXEL_QUARTER; break;
		case 6: bg_col = BG_DARK_GREY; fg_col = FG_GREY; sym = PIXEL_HALF; break;
		case 7: bg_col = BG_DARK_GREY; fg_col = FG_GREY; sym = PIXEL_THREEQUARTERS; break;
		case 8: bg_col = BG_DARK_GREY; fg_col = FG_GREY; sym = PIXEL_SOLID; break;

		case 9:  bg_col = BG_GREY; fg_col = FG_WHITE; sym = PIXEL_QUARTER; break;
		case 10: bg_col = BG_GREY; fg_col = FG_WHITE; sym = PIXEL_HALF; break;
		case 11: bg_col = BG_GREY; fg_col = FG_WHITE; sym = PIXEL_THREEQUARTERS; break;
		case 12: bg_col = BG_GREY; fg_col = FG_WHITE; sym = PIXEL_SOLID; break;
		default:
			bg_col = BG_BLACK; fg_col = FG_BLACK; sym = PIXEL_SOLID;
		}

		CHAR_INFO c;
		c.Attributes = bg_col | fg_col;
		c.Char.UnicodeChar = sym;
		return c;
	}

public:
	bool OnUserCreate() override
	{
		//meshCube.tris = {

		//// SOUTH
		//{ 0.0f, 0.0f, 0.0f,    0.0f, 1.0f, 0.0f,    1.0f, 1.0f, 0.0f },
		//{ 0.0f, 0.0f, 0.0f,    1.0f, 1.0f, 0.0f,    1.0f, 0.0f, 0.0f },

		//// EAST                                                      
		//{ 1.0f, 0.0f, 0.0f,    1.0f, 1.0f, 0.0f,    1.0f, 1.0f, 1.0f },
		//{ 1.0f, 0.0f, 0.0f,    1.0f, 1.0f, 1.0f,    1.0f, 0.0f, 1.0f },

		//// NORTH                                                     
		//{ 1.0f, 0.0f, 1.0f,    1.0f, 1.0f, 1.0f,    0.0f, 1.0f, 1.0f },
		//{ 1.0f, 0.0f, 1.0f,    0.0f, 1.0f, 1.0f,    0.0f, 0.0f, 1.0f },

		//// WEST                                                      
		//{ 0.0f, 0.0f, 1.0f,    0.0f, 1.0f, 1.0f,    0.0f, 1.0f, 0.0f },
		//{ 0.0f, 0.0f, 1.0f,    0.0f, 1.0f, 0.0f,    0.0f, 0.0f, 0.0f },

		//// TOP                                                       
		//{ 0.0f, 1.0f, 0.0f,    0.0f, 1.0f, 1.0f,    1.0f, 1.0f, 1.0f },
		//{ 0.0f, 1.0f, 0.0f,    1.0f, 1.0f, 1.0f,    1.0f, 1.0f, 0.0f },

		//// BOTTOM                                                    
		//{ 1.0f, 0.0f, 1.0f,    0.0f, 0.0f, 1.0f,    0.0f, 0.0f, 0.0f },
		//{ 1.0f, 0.0f, 1.0f,    0.0f, 0.0f, 0.0f,    1.0f, 0.0f, 0.0f },

		//};

		meshCube.LoadFromObjectFile("VideoShip.obj");

		// Projection Matrix
		float fNear = 0.1f;
		float fFar = 1000.0f;
		float fFov = 90.0f;
		float fAspectRatio = (float)ScreenHeight() / (float)ScreenWidth();
		float fFovRad = 1.0f / tanf(fFov * 0.5f / 180.0f * 3.14159f);

		matProj.m[0][0] = fAspectRatio * fFovRad;
		matProj.m[1][1] = fFovRad;
		matProj.m[2][2] = fFar / (fFar - fNear);
		matProj.m[3][2] = (-fFar * fNear) / (fFar - fNear);
		matProj.m[2][3] = 1.0f;
		matProj.m[3][3] = 0.0f;

		return true;
	}

	bool OnUserUpdate(float fElapsedTime) override
	{
		// Clear Screen
		Fill(0, 0, ScreenWidth(), ScreenHeight(), PIXEL_SOLID, FG_BLACK);

		// Set up rotation matrices
		mat4x4 matRotZ, matRotX;
		fTheta += 1.0f * fElapsedTime;

		// Rotation Z
		matRotZ.m[0][0] = cosf(fTheta);
		matRotZ.m[0][1] = sinf(fTheta);
		matRotZ.m[1][0] = -sinf(fTheta);
		matRotZ.m[1][1] = cosf(fTheta);
		matRotZ.m[2][2] = 1;
		matRotZ.m[3][3] = 1;

		// Rotation X
		matRotX.m[0][0] = 1;
		matRotX.m[1][1] = cosf(fTheta * 0.5f);
		matRotX.m[1][2] = sinf(fTheta * 0.5f);
		matRotX.m[2][1] = -sinf(fTheta * 0.5f);
		matRotX.m[2][2] = cosf(fTheta * 0.5f);
		matRotX.m[3][3] = 1;
		
		// Store triagles for rastering later
		vector<triangle> vecTrianglesToRaster;

		// Draw Triangles
		for (auto tri : meshCube.tris)
		{
			triangle triProjected, triTranslated, triRotatedZ, triRotatedZX;

			// Rotate in Z-Axis
			MultiplyMatrixVector(tri.p[0], triRotatedZ.p[0], matRotZ);
			MultiplyMatrixVector(tri.p[1], triRotatedZ.p[1], matRotZ);
			MultiplyMatrixVector(tri.p[2], triRotatedZ.p[2], matRotZ);

			// Rotate in X-Axis
			MultiplyMatrixVector(triRotatedZ.p[0], triRotatedZX.p[0], matRotX);
			MultiplyMatrixVector(triRotatedZ.p[1], triRotatedZX.p[1], matRotX);
			MultiplyMatrixVector(triRotatedZ.p[2], triRotatedZX.p[2], matRotX);

			// Offset into the screen
			triTranslated = triRotatedZX;
			triTranslated.p[0].z = triRotatedZX.p[0].z + 8.0f;
			triTranslated.p[1].z = triRotatedZX.p[1].z + 8.0f;
			triTranslated.p[2].z = triRotatedZX.p[2].z + 8.0f;

			// Use Cross-Product to get surface normal
			vec3d normal, line1, line2;
			line1.x = triTranslated.p[1].x - triTranslated.p[0].x;
			line1.y = triTranslated.p[1].y - triTranslated.p[0].y;
			line1.z = triTranslated.p[1].z - triTranslated.p[0].z;

			line2.x = triTranslated.p[2].x - triTranslated.p[0].x;
			line2.y = triTranslated.p[2].y - triTranslated.p[0].y;
			line2.z = triTranslated.p[2].z - triTranslated.p[0].z;

			normal.x = line1.y * line2.z - line1.z * line2.y;
			normal.y = line1.z * line2.x - line1.x * line2.z;
			normal.z = line1.x * line2.y - line1.y * line2.x;

			// It's normally normal to normalise the normal
			float l = sqrtf(normal.x*normal.x + normal.y*normal.y + normal.z*normal.z);
			normal.x /= l; normal.y /= l; normal.z /= l;

			//if (normal.z < 0)
			if(normal.x * (triTranslated.p[0].x - vCamera.x) + 
			   normal.y * (triTranslated.p[0].y - vCamera.y) +
			   normal.z * (triTranslated.p[0].z - vCamera.z) < 0.0f)
			{
				// Illumination
				vec3d light_direction = { 0.0f, 0.0f, -1.0f };
				float l = sqrtf(light_direction.x*light_direction.x + light_direction.y*light_direction.y + light_direction.z*light_direction.z);
				light_direction.x /= l; light_direction.y /= l; light_direction.z /= l;

				// How similar is normal to light direction
				float dp = normal.x * light_direction.x + normal.y * light_direction.y + normal.z * light_direction.z;

				// Choose console colours as required (much easier with RGB)
				CHAR_INFO c = GetColour(dp);
				triTranslated.col = c.Attributes;
				triTranslated.sym = c.Char.UnicodeChar;

				// Project triangles from 3D --> 2D
				MultiplyMatrixVector(triTranslated.p[0], triProjected.p[0], matProj);
				MultiplyMatrixVector(triTranslated.p[1], triProjected.p[1], matProj);
				MultiplyMatrixVector(triTranslated.p[2], triProjected.p[2], matProj);
				triProjected.col = triTranslated.col;
				triProjected.sym = triTranslated.sym;

				// Scale into view
				triProjected.p[0].x += 1.0f; triProjected.p[0].y += 1.0f;
				triProjected.p[1].x += 1.0f; triProjected.p[1].y += 1.0f;
				triProjected.p[2].x += 1.0f; triProjected.p[2].y += 1.0f;
				triProjected.p[0].x *= 0.5f * (float)ScreenWidth();
				triProjected.p[0].y *= 0.5f * (float)ScreenHeight();
				triProjected.p[1].x *= 0.5f * (float)ScreenWidth();
				triProjected.p[1].y *= 0.5f * (float)ScreenHeight();
				triProjected.p[2].x *= 0.5f * (float)ScreenWidth();
				triProjected.p[2].y *= 0.5f * (float)ScreenHeight();

				// Store triangle for sorting
				vecTrianglesToRaster.push_back(triProjected);
			}

		}

		// Sort triangles from back to front
		sort(vecTrianglesToRaster.begin(), vecTrianglesToRaster.end(), [](triangle &t1, triangle &t2)
		{
			float z1 = (t1.p[0].z + t1.p[1].z + t1.p[2].z) / 3.0f;
			float z2 = (t2.p[0].z + t2.p[1].z + t2.p[2].z) / 3.0f;
			return z1 > z2;
		});

		for (auto &triProjected : vecTrianglesToRaster)
		{
			// Rasterize triangle
			FillTriangle(triProjected.p[0].x, triProjected.p[0].y,
				triProjected.p[1].x, triProjected.p[1].y,
				triProjected.p[2].x, triProjected.p[2].y,
				triProjected.sym, triProjected.col);

			/*DrawTriangle(triProjected.p[0].x, triProjected.p[0].y,
			triProjected.p[1].x, triProjected.p[1].y,
			triProjected.p[2].x, triProjected.p[2].y,
			PIXEL_SOLID, FG_BLACK);*/
		}


		return true;
	}

};




int main()
{
	olcEngine3D demo;
	if (demo.ConstructConsole(256, 240, 4, 4))
		demo.Start();
    return 0;
}