/*

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

    This program 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 3 of the License, or

    (at your option) any later version.

    This program 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.

    You should have received a copy of the GNU General Public License

    along with this program.  If not, see <http: licenses="" www.gnu.org="">.</http:>

*/

#include <cmath></cmath>

#include <fstream></fstream>

#include <iostream></iostream>

#include <vector></vector>

#include <map></map>

#include <assert.h></assert.h>

#include <gl gl.h=""></gl>

#include <gl glext.h=""></gl>

#include <gl glx.h=""></gl>

#define GLX_CONTEXT_MAJOR_VERSION_ARB 0x2091

#define GLX_CONTEXT_MINOR_VERSION_ARB 0x2092

typedef GLXContext (*GLXCREATECONTEXTATTRIBSARBPROC)(Display*, GLXFBConfig, GLXContext, Bool, const int*);

using namespace std;

typedef pair<float, float=""> vec2;</float,>

typedef vector<vec2> contour;</vec2>

void save_rgba(const void *buffer, int width, int height, const string &filename) {

	// create file

	ofstream f(filename.c_str(), ofstream::out | ofstream::trunc | ofstream::binary);

	// write header

	unsigned char targa_header[] = {

		0,    // Length of the image ID field (0 - no ID field)

		0,    // Whether a color map is included (0 - no colormap)

		2,    // Compression and color types (2 - uncompressed true-color image)

		0, 0, 0, 0, 0, // Color map specification (not need for us)

		0, 0, // X-origin

		0, 0, // Y-origin

		(unsigned char)(width & 0xff), // Image width

		(unsigned char)(width >> 8),

		(unsigned char)(height & 0xff), // Image height

		(unsigned char)(height >> 8),

		32,   // Bits per pixel

		0     // Image descriptor (keep zero for capability)

	};

	f.write((char*)targa_header, sizeof(targa_header));

	// write data

	int line_size = 4*width;

	const char *end = (char*)buffer;

	const char *current = end + height*line_size;

	while(current > end) {

		current -= line_size;

		f.write(current, line_size);

	}

}

void save_viewport(const string &filename) {

	cout << filename << endl;

	glFinish();

	int vp[4] = {};

	glGetIntegerv(GL_VIEWPORT, vp);

	char *buffer = new char[vp[2]*vp[3]*4];

	glReadPixels(vp[0], vp[1], vp[2], vp[3], GL_BGRA, GL_UNSIGNED_BYTE, buffer);

	save_rgba(buffer, vp[2], vp[3], filename);

}

void build_contour(contour &c) {

	const float min_segment_length = 0.001f;

	const float rounds = 10.f;

	const float rounds2 = 1.f;

	contour back;

	float angle = 360.f;

	float offset = 0.25f/(rounds + 1.f);

	// go front

	while(true) {

		float radius = angle/360.f/(rounds + 1.f);

		float step = min_segment_length*180.f/M_PI/radius;

		if (radius > 1.f - 2.f*offset) break;

		float fr = radius + offset;

		float fx = fr*sinf(angle/180.f*M_PI);

		float fy = fr*cosf(angle/180.f*M_PI);

		float br = radius - offset;

		float bx = br*sinf(angle/180.f*M_PI);

		float by = br*cosf(angle/180.f*M_PI);

		c.push_back(vec2(fx, fy));

		back.push_back(vec2(bx, by));

		angle += step;

	}

	float max_angle = angle;

	while(true) {

		float radius = max_angle/360.f/(rounds + 1.f)

				     + (max_angle-angle)/360.f/rounds2;

		float step = min_segment_length*180.f/M_PI/radius;

		if (radius < 1.f/(rounds + 1.f))

			break;

		float fr = radius + offset;

		float fx = fr*sinf(angle/180.f*M_PI);

		float fy = fr*cosf(angle/180.f*M_PI);

		float br = radius - offset;

		float bx = br*sinf(angle/180.f*M_PI);

		float by = br*cosf(angle/180.f*M_PI);

		c.push_back(vec2(fx, fy));

		back.push_back(vec2(bx, by));

		angle += step;

	}

	// go back

	c.reserve(c.size() + back.size() + 1);

	for(contour::reverse_iterator ri = back.rbegin(); ri != back.rend(); ++ri)

		c.push_back(*ri);

	// close

	c.push_back(c.front());

	cout << c.size() << " vertices" << endl;

}

void draw_contour_strip(const contour &c) {

	glBegin(GL_TRIANGLE_STRIP);

	for(contour::const_iterator i = c.begin(); i != c.end(); ++i) {

		glVertex2f(i->first, i->second);

		glVertex2f(-1.f, i->second);

	}

	glEnd();

}

void draw_contour(const contour &c, bool even_odd, bool invert) {

	glPushAttrib(GL_ALL_ATTRIB_BITS);

	glEnable(GL_STENCIL_TEST);

	// render mask

	glClear(GL_STENCIL_BUFFER_BIT);

	glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE);

	glStencilFunc(GL_ALWAYS, 0, 0);

	if (even_odd) {

		glStencilOp(GL_KEEP, GL_KEEP, GL_INCR_WRAP);

	} else {

		glStencilOpSeparate(GL_FRONT, GL_INCR_WRAP, GL_INCR_WRAP, GL_INCR_WRAP);

		glStencilOpSeparate(GL_BACK, GL_DECR_WRAP, GL_DECR_WRAP, GL_DECR_WRAP);

	}

	draw_contour_strip(c);

	// fill mask

	glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);

	glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);

	if (!even_odd && !invert)

		glStencilFunc(GL_NOTEQUAL, 0, -1);

	if (!even_odd &&  invert)

		glStencilFunc(GL_EQUAL, 0, -1);

	if ( even_odd && !invert)

		glStencilFunc(GL_EQUAL, 1, 1);

	if ( even_odd &&  invert)

		glStencilFunc(GL_EQUAL, 0, 1);

	glBegin(GL_TRIANGLE_STRIP);

	glVertex2d(-1.f, -1.f);

	glVertex2d( 1.f, -1.f);

	glVertex2d(-1.f,  1.f);

	glVertex2d( 1.f,  1.f);

	glEnd();

	glPopAttrib();

}

class test_wrapper {

private:

	string filename;

	clock_t t;

	test_wrapper(const test_wrapper&): t() { }

	test_wrapper& operator= (const test_wrapper&) { return *this; }

public:

	test_wrapper(const string &filename): filename(filename), t(clock()) { }

	~test_wrapper() {

		glFinish();

		cout << 1000.0*(double)(clock() - t)/(double)(CLOCKS_PER_SEC) << " ms" << endl;

		cout << filename << endl;

		save_viewport(filename);

		glClear(GL_COLOR_BUFFER_BIT);

	}

};

void test() {

	contour c;

	build_contour(c);

	glColor4f(0.f, 0.f, 1.f, 1.f);

	{

		test_wrapper t("test_contour.tga");

		glBegin(GL_LINE_STRIP);

		for(contour::const_iterator i = c.begin(); i != c.end(); ++i)

			glVertex2f(i->first, i->second);

		glEnd();

	}

	{

		test_wrapper t("test_contour_fill.tga");

		draw_contour(c, false, false);

	}

	{

		test_wrapper t("test_contour_fill_invert.tga");

		draw_contour(c, false, true);

	}

	{

		test_wrapper t("test_contour_evenodd.tga");

		draw_contour(c, true, false);

	}

	{

		test_wrapper t("test_contour_evenodd_invert.tga");

		draw_contour(c, true, true);

	}

}

int main() {

	// open display (we will use default display and screen 0)

	Display *display = XOpenDisplay(NULL);

	assert(display);

	// choose config

	int config_attribs[] = {

		GLX_DOUBLEBUFFER,      False,

		GLX_RED_SIZE,          8,

		GLX_GREEN_SIZE,        8,

		GLX_BLUE_SIZE,         8,

		GLX_ALPHA_SIZE,        8,

		GLX_DEPTH_SIZE,        24,

		GLX_STENCIL_SIZE,      8,

		GLX_ACCUM_RED_SIZE,    8,

		GLX_ACCUM_GREEN_SIZE,  8,

		GLX_ACCUM_BLUE_SIZE,   8,

		GLX_ACCUM_ALPHA_SIZE,  8,

		GLX_DRAWABLE_TYPE,     GLX_PBUFFER_BIT,

		None };

	int nelements = 0;

	GLXFBConfig *configs = glXChooseFBConfig(display, 0, config_attribs, &nelements);

	assert(configs != NULL && nelements > 0);

	GLXFBConfig config = configs[0];

	assert(config);

	// create pbuffer

	int pbuffer_width = 1024;

	int pbuffer_height = 1024;

	int pbuffer_attribs[] = {

		GLX_PBUFFER_WIDTH, pbuffer_width,

		GLX_PBUFFER_HEIGHT, pbuffer_height,

		None };

	GLXPbuffer pbuffer = glXCreatePbuffer(display, config, pbuffer_attribs);

	assert(pbuffer);

	// create context

	int context_attribs[] = {

		GLX_CONTEXT_MAJOR_VERSION_ARB, 2,

		GLX_CONTEXT_MINOR_VERSION_ARB, 1,

		None };

	GLXCREATECONTEXTATTRIBSARBPROC glXCreateContextAttribsARB = (GLXCREATECONTEXTATTRIBSARBPROC) glXGetProcAddress((const GLubyte*)"glXCreateContextAttribsARB");

	GLXContext context = glXCreateContextAttribsARB(display, config, NULL, True, context_attribs);

	assert(context);

	// make context current

	glXMakeContextCurrent(display, pbuffer, pbuffer, context);

	// set view port

	glViewport(0, 0, pbuffer_width, pbuffer_height);

	// do something

	test();

	// deinitialization

	glXMakeContextCurrent(display, None, None, NULL);

	glXDestroyContext(display, context);

	glXDestroyPbuffer(display, pbuffer);

	XCloseDisplay(display);

	cout << "done" << endl;

	return 0;

}