/*

	polyspan.cpp

	Polyspan

	Copyright (c) 2002-2005 Robert B. Quattlebaum Jr., Adrian Bentley

	Copyright (c) 2007, 2008 Chris Moore

	Copyright (c) 2012-2013 Carlos López

	......... ... 2015 Ivan Mahonin

	This package is free software; you can redistribute it and/or

	modify it under the terms of the GNU General Public License as

	published by the Free Software Foundation; either version 2 of

	the License, or (at your option) any later version.

	This package is distributed in the hope that it will be useful,

	but WITHOUT ANY WARRANTY; without even the implied warranty of

	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU

	General Public License for more details.

*/

#include <cassert>

#include "polyspan.h"

using namespace std;

Polyspan::Polyspan():

	open_index(0),

	cur_x(0.0),

	cur_y(0.0),

	close_x(0.0),

	close_y(0.0),

	flags(NotSorted)

{ }

void Polyspan::clear() {

	covers.clear();

	cur_x = cur_y = close_x = close_y = 0;

	open_index = 0;

	current.set(0, 0, 0, 0);

	flags = NotSorted;

}

// add the current cell, but only if there is information to add

void Polyspan::addcurrent() {

	if (current.cover || current.area) {

		if (covers.size() == covers.capacity())

			covers.reserve(covers.size() + 1024*1024);

		covers.push_back(current);

	}

}

// move to the next cell (cover values 0 initially), keeping the current if necessary

void Polyspan::move_pen(int x, int y) {

	if (y != current.y || x != current.x) {

		addcurrent();

		current.set(x, y, 0, 0);

	}

}

// close the primitives with a line (or rendering will not work as expected)

void Polyspan::close() {

	if (flags & NotClosed) {

		if (cur_x != close_x || cur_y != close_y) {

			line_to(close_x, close_y);

			addcurrent();

			current.setcover(0,0);

		}

		flags &= ~NotClosed;

	}

}

// Not recommended - destroys any separation of spans currently held

void Polyspan::merge_all() {

	sort(covers.begin(), covers.end());

	open_index = 0;

}

// will sort the marks if they are not sorted

void Polyspan::sort_marks() {

	if (flags & NotSorted) {

		// only sort the open index

		addcurrent();

		current.setcover(0, 0);

		sort(covers.begin() + open_index, covers.end());

		flags &= ~NotSorted;

	}

}

// encapsulate the current sublist of marks (used for drawing)

void Polyspan::encapsulate_current() {

	// sort the current list then reposition the open list section

	sort_marks();

	open_index = covers.size();

}

// move to start a new primitive list (enclose the last primitive if need be)

void Polyspan::move_to(Real x, Real y) {

	close();

	if (isnan(x)) x=0;

	if (isnan(y)) y=0;

	move_pen((int)floor(x), (int)floor(y));

	close_y = cur_y = y;

	close_x = cur_x = x;

}

// primitive_to functions

void Polyspan::line_to(Real x, Real y) {

	Real n[4] = {0, 0, 0, 0};

	bool afterx = false;

	const Real xin(x), yin(y);

	Real dx = x - cur_x;

	Real dy = y - cur_y;

	// CLIP IT!!!!

	// outside y - ignore entirely

	if ( (cur_y >= window.maxy && y >= window.maxy)

	  || (cur_y <  window.miny && y <  window.miny) )

	{

		cur_x = x;

		cur_y = y;

	} else { // not degenerate - more complicated

		if (dy > 0) { //be sure it's not tooooo small

			// cur_y ... window.miny ... window.maxy ... y

			// initial degenerate - initial clip

			if (cur_y < window.miny) {

				// new clipped start point (must also move pen)

				n[2] = cur_x + (window.miny - cur_y)*dx/dy;

				cur_x = n[2];

				cur_y = window.miny;

				move_pen((int)floor(cur_x), window.miny);

			}

			// generate data for the ending clipped info

			if (y > window.maxy) {

				// initial line to intersection (and degenerate)

				n[2] = x + (window.maxy - y)*dx/dy;

				//intersect coords

				x = n[2];

				y = window.maxy;

			}

		} else {

			// initial degenerate - initial clip

			if (cur_y > window.maxy) {

				// new clipped start point (must also move pen)

				n[2] = cur_x + (window.maxy - cur_y)*dx/dy;

				cur_x = n[2];

				cur_y = window.maxy;

				move_pen((int)floor(cur_x), window.maxy);

			}

			// generate data for the ending clipped info

			if (y < window.miny) {

				// initial line to intersection (and degenerate)

				n[2] = x + (window.miny - y)*dx/dy;

				// intersect coords

				x = n[2];

				y = window.miny;

			}

		}

		// all degenerate - but require bounded clipped values

		if ( (cur_x >= window.maxx && x >= window.maxx)

		  || (cur_x <  window.minx && x <  window.minx) )

		{

			//clip both vertices - but only needed in the x direction

			cur_x = max(cur_x,	(Real)window.minx);

			cur_x = min(cur_x,	(Real)window.maxx);

			//clip the dest values - y is already clipped

			x = max(x, (Real)window.minx);

			x = min(x, (Real)window.maxx);

			//must start at new point...

			move_pen((int)floor(cur_x), (int)floor(cur_y));

			draw_line(cur_x,cur_y,x,y);

			cur_x = xin;

			cur_y = yin;

		} else {

			// clip x

			if (dx > 0) {

				// initial degenerate - initial clip

				if (cur_x < window.minx) {

					// need to draw an initial segment from clippedx,cur_y to clippedx,intersecty

					n[2] = cur_y + (window.minx - cur_x)*dy/dx;

					move_pen(window.minx, (int)floor(cur_y));

					draw_line(window.minx, cur_y, window.minx, n[2]);

					cur_x = window.minx;

					cur_y = n[2];

				}

				// generate data for the ending clipped info

				if (x > window.maxx) {

					// initial line to intersection (and degenerate)

					n[2] = y + (window.maxx - x)*dy/dx;

					n[0] = window.maxx;

					n[1] = y;

					// intersect coords

					x = window.maxx;

					y = n[2];

					afterx = true;

				}

			} else {

				// initial degenerate - initial clip

				if (cur_x > window.maxx) {

					// need to draw an initial segment from clippedx,cur_y to clippedx,intersecty

					n[2] = cur_y + (window.maxx - cur_x)*dy/dx;

					move_pen(window.maxx, (int)floor(cur_y));

					draw_line(window.maxx, cur_y, window.maxx, n[2]);

					cur_x = window.maxx;

					cur_y = n[2];

				}

				// generate data for the ending clipped info

				if (x < window.minx) {

					//initial line to intersection (and degenerate)

					n[2] = y + (window.minx - x)*dy/dx;

					n[0] = window.minx;

					n[1] = y;

					//intersect coords

					x = window.minx;

					y = n[2];

					afterx = true;

				}

			}

			move_pen((int)floor(cur_x), (int)floor(cur_y));

			// draw the relevant line (clipped)

			draw_line(cur_x, cur_y, x, y);

			if (afterx)

				draw_line(x, y, n[0], n[1]);

			cur_x = xin;

			cur_y = yin;

		}

	}

	flags |= NotClosed | NotSorted;

}

bool Polyspan::clip_conic(const Vector *p, const ContextRect &r) {

	const Real minx = min(min(p[0][0], p[1][0]), p[2][0]);

	const Real miny = min(min(p[0][1], p[1][1]), p[2][1]);

	const Real maxx = max(max(p[0][0], p[1][0]), p[2][0]);

	const Real maxy = max(max(p[0][1], p[1][1]), p[2][1]);

	return 	(minx > r.maxx) ||

			(maxx < r.minx) ||

			(miny > r.maxy) ||

			(maxy < r.miny);

}

Real Polyspan::max_edges_conic(const Vector *p) {

	const Real x1 = p[1][0] - p[0][0];

	const Real y1 = p[1][1] - p[0][1];

	const Real x2 = p[2][0] - p[1][0];

	const Real y2 = p[2][1] - p[1][1];

	const Real d1 = x1*x1 + y1*y1;

	const Real d2 = x2*x2 + y2*y2;

	return max(d1,d2);

}

void Polyspan::subd_conic_stack(Vector *arc) {

	/*

	b0

	*		0+1 a

	b1 b	*		1+2*1+2 a

	*		1+2	b	*

	b2 		*

	*

	0.1.2 ->	0.1 2 3.4

	*/

	Real a, b;

	arc[4][0] = arc[2][0];

	b = arc[1][0];

	a = arc[1][0] = (arc[0][0] + b)/2;

	b = arc[3][0] = (arc[4][0] + b)/2;

	arc[2][0] = (a + b)/2;

	arc[4][1] = arc[2][1];

	b = arc[1][1];

	a = arc[1][1] = (arc[0][1] + b)/2;

	b = arc[3][1] = (arc[4][1] + b)/2;

	arc[2][1] = (a + b)/2;

	/* //USING SIMD

	arc[4] = arc[2];

	arc[3] = (arc[2] + arc[1])/2;

	arc[1] = (arc[0] + arc[1])/2;

	arc[2] = (arc[1] + arc[3])/2;

	*/

}

void Polyspan::conic_to(Real x1, Real y1, Real x, Real y) {

	Vector *current = arc;

	int		level = 0;

	int 	num = 0;

	bool	onsecond = false;

	arc[0] = Vector(x, y);

	arc[1] = Vector(x1, y1);

	arc[2] = Vector(cur_x, cur_y);

	// just draw the line if it's outside

	if (clip_conic(arc, window))

	{

		line_to(x,y);

		return;

	}

	// Ok so it's not super degenerate, subdivide and draw (run through minimum subdivision levels first)

	while(current >= arc) {

		assert(num < MAX_SUBDIVISION_SIZE);

		// if the curve is clipping then draw degenerate

		if (clip_conic(current, window)) {

			line_to(current[0][0],current[0][1]); //backwards so front is destination

			current -= 2;

			if (onsecond) level--;

			onsecond = true;

			num--;

			continue;

		} else

		// if we are not at the level minimum

		if (level < MIN_SUBDIVISION_DRAW_LEVELS) {

			subd_conic_stack(current);

			current += 2; 		// cursor on second curve

			level ++;

			num ++;

			onsecond = false;

			continue;

		} else

		// split it again, if it's too big

		if (max_edges_conic(current) > 0.25) { // distance of .5 (cover no more than half the pixel)

			subd_conic_stack(current);

			current += 2; 		// cursor on second curve

			level ++;

			num ++;

			onsecond = false;

		} else { // NOT TOO BIG? RENDER!!!

			// cur_x, cur_y = current[2], so we need to go 1,0

			line_to(current[1][0], current[1][1]);

			line_to(current[0][0], current[0][1]);

			current -= 2;

			if (onsecond) level--;

			num--;

			onsecond = true;

		}

	}

}

bool Polyspan::clip_cubic(const Vector *p, const ContextRect &r) {

	return 	((p[0][0] > r.maxx) && (p[1][0] > r.maxx) && (p[2][0] > r.maxx) && (p[3][0] > r.maxx)) ||

			((p[0][0] < r.minx) && (p[1][0] < r.minx) && (p[2][0] < r.minx) && (p[3][0] < r.minx)) ||

			((p[0][1] > r.maxy) && (p[1][1] > r.maxy) && (p[2][1] > r.maxy) && (p[3][1] > r.maxy)) ||

			((p[0][1] < r.miny) && (p[1][1] < r.miny) && (p[2][1] < r.miny) && (p[3][1] < r.miny));

}

Real Polyspan::max_edges_cubic(const Vector *p) {

	const Real x1 = p[1][0] - p[0][0];

	const Real y1 = p[1][1] - p[0][1];

	const Real x2 = p[2][0] - p[1][0];

	const Real y2 = p[2][1] - p[1][1];

	const Real x3 = p[3][0] - p[2][0];

	const Real y3 = p[3][1] - p[2][1];

	const Real d1 = x1*x1 + y1*y1;

	const Real d2 = x2*x2 + y2*y2;

	const Real d3 = x3*x3 + y3*y3;

	return max(max(d1, d2), d3);

}

void Polyspan::subd_cubic_stack(Vector *arc) {

	Real a, b, c;

	/*

	b0

	*		0+1 a

	b1 b	*		1+2*1+2 a

	*		1+2	b	*			0+3*1+3*2+3

	b2 c	*		1+2*2+2	b	*

	*		2+3	c	*

	b3 		*

	*

	0.1 2.3 ->	0.1 2 3 4 5.6

	*/

	arc[6][0] = arc[3][0];

	b = arc[1][0];

	c = arc[2][0];

	a = arc[1][0] = (arc[0][0] + b)/2;

	b = (b + c)/2;

	c = arc[5][0] = (arc[6][0] + c)/2;

	a = arc[2][0] = (a + b)/2;

	b = arc[4][0] = (b + c)/2;

	arc[3][0] = (a + b)/2;

	arc[6][1] = arc[3][1];

	b = arc[1][1];

	c = arc[2][1];

	a = arc[1][1] = (arc[0][1] + b)/2;

	b = (b + c)/2;

	c = arc[5][1] = (arc[6][1] + c)/2;

	a = arc[2][1] = (a + b)/2;

	b = arc[4][1] = (b + c)/2;

	arc[3][1] = (a + b)/2;

}

void Polyspan::cubic_to(Real x1, Real y1, Real x2, Real y2, Real x, Real y) {

	Vector *current = arc;

	int		num = 0;

	int		level = 0;

	bool	onsecond = false;

	arc[0] = Vector(x, y);

	arc[1] = Vector(x2, y2);

	arc[2] = Vector(x1, y1);

	arc[3] = Vector(cur_x, cur_y);

	// just draw the line if it's outside

	if (clip_cubic(arc, window)) {

		line_to(x,y);

		return;

	}

	// Ok so it's not super degenerate, subdivide and draw (run through minimum subdivision levels first)

	while(current >= arc) { // once current goes below arc, there are no more curves left

		assert(num < MAX_SUBDIVISION_SIZE);

		// if we are not at the level minimum

		if (level < MIN_SUBDIVISION_DRAW_LEVELS) {

			subd_cubic_stack(current);

			current += 3; 		// cursor on second curve

			level ++;

			num ++;

			onsecond = false;

			continue;

		} else

		// if the curve is clipping then draw degenerate

		if (clip_cubic(current, window)) {

			line_to(current[0][0], current[0][1]); // backwards so front is destination

			current -= 3;

			if (onsecond) level--;

			onsecond = true;

			num --;

			continue;

		} else

		// split it again, if it's too big

		if (max_edges_cubic(current) > 0.25) { //could use max_edges<3>

			subd_cubic_stack(current);

			current += 3; 		// cursor on second curve

			level ++;

			num ++;

			onsecond = false;

		} else { // NOT TOO BIG? RENDER!!!

			// cur_x, cur_y = current[3], so we need to go 2,1,0

			line_to(current[2][0], current[2][1]);

			line_to(current[1][0], current[1][1]);

			line_to(current[0][0], current[0][1]);

			current -= 3;

			if (onsecond) level--;

			num --;

			onsecond = true;

		}

	}

}

void Polyspan::draw_scanline(int y, Real x1, Real y1, Real x2, Real y2) {

	int	ix1 = (int)floor(x1);

	int	ix2 = (int)floor(x2);

	Real fx1 = x1 - ix1;

	Real fx2 = x2 - ix2;

	Real dx,dy,dydx,mult;

	dx = x2 - x1;

	dy = y2 - y1;

	// case horizontal line

	if (y1 == y2) {

		move_pen(ix2, y); // pen needs to be at the last coord

		return;

	}

	// case all in same pixel

	if (ix1 == ix2) { // impossible for degenerate case (covered by the previous cases)

		current.addcover(dy, (fx1 + fx2)*dy/2); // horizontal trapezoid area

		return;

	}

	if (dx > 0) {

		// ---->	fx1...1  0...1  ...  0...1  0...fx2

		dydx = dy/dx;

		// set initial values

		// Iterate through the covered pixels

		mult = (1 - fx1)*dydx;	// next y intersection diff value (at 1)

		// first pixel

		current.addcover(mult, (1 + fx1)*mult/2);	// fx1, fy1, 1, fy@1 - starting trapezoidal area

		// move to the next pixel

		y1 += mult;

		ix1++;

		move_pen(ix1, y);

		// set up for whole ones

		while(ix1 != ix2) {

			// trapezoid(0, y1, 1, y1 + dydx);

			current.addcover(dydx,dydx/2); // accumulated area 1/2 the cover

			// move to next pixel (+1)

			ix1++;

			y1 += dydx;

			move_pen(ix1, y);

		}

		// last pixel

		// final y-pos - last intersect pos

		mult = fx2 * dydx;

		current.addcover(mult, (0 + fx2)*mult/2);

	} else {

		// fx2...1  0...1  ...  0...1  0...fx1   <----

		// mult = (0 - fx1) * dy / dx;

		// neg sign sucked into dydx

		dydx = -dy/dx;

		// set initial values

		// Iterate through the covered pixels

		mult = fx1*dydx; // next y intersection diff value

		// first pixel

		current.addcover(mult, fx1*mult/2); // fx1, fy1, 0, fy@0 - starting trapezoidal area

		// move to next pixel

		y1 += mult;

		ix1--;

		move_pen(ix1, y);

		// set up for whole ones

		while(ix1 != ix2) {

			// trapezoid(0, y1, 1, y1+dydx);

			current.addcover(dydx, dydx/2); // accumulated area 1/2 the cover

			// move to next pixel (-1)

			y1 += dydx;

			ix1--;

			move_pen(ix1, y);

		}

		// last pixel

		mult = y2 - y1; // final y-pos - last intersect pos

		current.addcover(mult, (fx2+1)*mult/2);

	}

}

void Polyspan::draw_line(Real x1, Real y1, Real x2, Real y2) {

	int iy1 = (int)floor(y1);

	int iy2 = (int)floor(y2);

	Real fy1 = y1 - iy1;

	Real fy2 = y2 - iy2;

	assert(!isnan(fy1));

	assert(!isnan(fy2));

	Real dx,dy,dxdy,mult,x_from,x_to;

	const Real SLOPE_EPSILON = 1e-10;

	// case all one scanline

	if (iy1 == iy2) {

		draw_scanline(iy1, x1, y1, x2, y2);

		return;

	}

	// difference values

	dy = y2 - y1;

	dx = x2 - x1;

	// case vertical line

	if (dx < SLOPE_EPSILON && dx > -SLOPE_EPSILON) {

		// calc area and cover on vertical line

		if (dy > 0) {

			// ---->	fx1...1  0...1  ...  0...1  0...fx2

			Real sub;

			int ix1 = (int)floor(x1);

			Real fx1 = x1 - ix1;

			// current pixel

			sub = 1 - fy1;

			current.addcover(sub, fx1*sub);

			// next pixel

			iy1++;

			// move pen to next pixel

			move_pen(ix1, iy1);

			while(iy1 != iy2) {

				// accumulate cover

				current.addcover(1,fx1);

				// next pixel

				iy1++;

				move_pen(ix1, iy1);

			}

			// last pixel

			current.addcover(fy2, fy2*fx1);

		} else {

			Real sub;

			int	ix1 = (int)floor(x1);

			Real fx1 = x1 - ix1;

			// current pixel

			sub = 0 - fy1;

			current.addcover(sub, fx1*sub);

			// next pixel

			iy1--;

			move_pen(ix1, iy1);

			while(iy1 != iy2) {

				// accumulate in current pixel

				current.addcover(-1,-fx1);

				// move to next

				iy1--;

				move_pen(ix1,iy1);

			}

			current.addcover(fy2-1,(fy2-1)*fx1);

		}

		return;

	}

	// case normal line - guaranteed dx != 0 && dy != 0

	// calculate the initial intersection with "next" scanline

	if (dy > 0) {

		dxdy = dx/dy;

		mult = (1 - fy1)*dxdy;

		// x intersect scanline

		x_from = x1 + mult;

		draw_scanline(iy1, x1, fy1, x_from, 1);

		// move to next line

		iy1++;

		move_pen((int)floor(x_from), iy1);

		while(iy1 != iy2) {

			// keep up on the x axis, and render the current scanline

			x_to = x_from + dxdy;

			draw_scanline(iy1, x_from, 0, x_to, 1);

			x_from = x_to;

			// move to next pixel

			iy1++;

			move_pen((int)floor(x_from), iy1);

		}

		//draw the last one, fractional

		draw_scanline(iy2, x_from, 0, x2, fy2);

	} else {

		dxdy = -dx/dy;

		mult = fy1*dxdy;

		// x intersect scanline

		x_from = x1 + mult;

		draw_scanline(iy1,x1,fy1,x_from,0);

		// each line after

		iy1--;

		move_pen((int)floor(x_from), iy1);

		while(iy1 != iy2) {

			x_to = x_from + dxdy;

			draw_scanline(iy1, x_from, 1, x_to, 0);

			x_from = x_to;

			iy1--;

			move_pen((int)floor(x_from), iy1);

		}

		// draw the last one, fractional

		draw_scanline(iy2, x_from, 1, x2, fy2);

	}

}

Real Polyspan::extract_alpha(Real area, bool evenodd) const {

	if (area < 0)

		area = -area;

	if (evenodd) {

		// even-odd winding style

		while (area > 1)

			area -= 2;

		// want pyramid like thing

		if (area < 0)

			area = -area;

	} else {

		// non-zero winding style

		if (area > 1)

			return 1;

	}

	return area;

}

/* === E N T R Y P O I N T ================================================= */