commit 941d8f96d8decdfbce13418c5dde26816f0ca6d5
Author: David Vereb <dvereb@dvereb.com>
Date:   Mon Sep 7 11:19:24 2020 -0400

    Initial Commit.

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..8ca38d9
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,4 @@
+*~
+*.gpx
+.o
+a.out
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..407efad
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,2 @@
+a.out: main.cpp
+	clang++ -std=c++17 -g -o a.out main.cpp -lGL -lGLU -lglut -lstdc++fs
diff --git a/main.cpp b/main.cpp
new file mode 100644
index 0000000..22e5c49
--- /dev/null
+++ b/main.cpp
@@ -0,0 +1,164 @@
+#include <GL/glut.h>
+
+#include <experimental/filesystem>
+
+#include <cstdlib>
+#include <fstream>
+#include <iostream>
+#include <math.h> // fmod
+#include <unistd.h>
+#include <vector>
+
+GLfloat light_diffuse[] = {1.0, 0.0, 0.0, 1.0};  /* Red diffuse light. */
+GLfloat light_position[] = {1.0, 1.0, 1.0, 0.0};  /* Infinite light location. */
+
+struct Point {
+	float lat;
+	float lon;
+};
+
+static std::vector<std::vector<Point> > tracks;
+
+// TODO(dev):
+//  As per https://www.opengl.org/resources/libraries/glut/spec3/node11.html
+//  "Therefore, GLUT programs should not assume the window was created at the specified size or position.
+//   A GLUT program should use the window's reshape callback to determine the true size of the window."
+
+void draw(const std::vector<Point> &points)
+{
+	static float rot=0.0;
+	rot += 0.1f;
+
+	glLineWidth(0.5f);
+	glColor3d(1.0,1.0,1.0);
+
+	// Draw Sun:
+	glBegin(GL_LINE_STRIP);
+	for(auto p : points)
+		glVertex3f(p.lat, p.lon, 0.0);
+	glEnd();
+
+	// usleep(100000);
+
+	glutPostRedisplay();
+}
+
+void display()
+{
+	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+	for(auto track : tracks)
+		draw(track);
+	glutSwapBuffers();
+}
+
+void init()
+{
+	// dvereb:
+	srand(time(NULL));
+
+	/* Enable a single OpenGL light. */
+	// glLightfv(GL_LIGHT0, GL_DIFFUSE, light_diffuse);
+	// glLightfv(GL_LIGHT0, GL_POSITION, light_position);
+	// glEnable(GL_LIGHT0);
+	// glEnable(GL_LIGHTING);
+
+	/* Use depth buffering for hidden surface elimination. */
+	glEnable(GL_DEPTH_TEST);
+
+	/* Setup the view of the cube. */
+	glMatrixMode(GL_PROJECTION);
+	gluPerspective( /* field of view in degree */ 70.0,
+	                /* aspect ratio */ 1.0,
+	                /* Z near */ 1.0, /* Z far */ 1000.0);
+	glMatrixMode(GL_MODELVIEW);
+	gluLookAt(0.0, 0.0, 20.0,  /* eye is at */
+	          0.0, 0.0, 0.0,  /* center is at */
+	          0.0, 1.0, 0.);    /* up is in positive Y direction */
+}
+
+int main(int argc, char *argv[])
+{
+	if(argc != 2)
+	{
+		std::cerr << "You pust pass the folder which contains gpx files." << std::endl;
+		return -1;
+	}
+
+	std::vector<std::string> files;
+	for(const auto& entry : std::experimental::filesystem::directory_iterator(argv[1]))
+	{
+		auto extension = entry.path().extension();
+		if(extension == ".gpx")
+			files.push_back(entry.path().filename());
+	}
+
+	for(auto file : files)
+	{
+		std::ifstream ifs(file);
+		if(!ifs.is_open())
+		{
+			std::cerr << "Couldn't open " << file << "." << std::endl;
+			return -2;
+		}
+
+		std::string line = "";
+		bool first = true;
+		float diff_lat, diff_lon;
+		std::vector<Point> track;
+		while(std::getline(ifs, line))
+		{
+			// get starting position of field NAMES
+			auto lat = line.find("lat=\"");
+			if(lat == std::string::npos)
+				continue;
+			auto lon = line.find("lon=\"");
+			if(lon == std::string::npos)
+				continue;
+
+			// get ending position of field DATA
+			auto lat_to = line.find("\"", lat);
+			if(lat_to == std::string::npos)
+				continue;
+			auto lon_to = line.find("\"", lon);
+			if(lon_to == std::string::npos)
+				continue;
+
+			Point p;
+			try {
+				p.lat = std::atof(line.substr(lat + 5, lat_to).c_str()) * 500;
+				p.lon = std::atof(line.substr(lon + 5, lon_to).c_str()) * 500;
+			} catch (const std::exception &e) {
+				std::cerr << "Error in file " << file << ", line \"" << line << "\"." << std::endl;
+				continue;
+			}
+
+			if(first)
+			{
+				first = false;
+				diff_lat = p.lat;
+				diff_lon = p.lon;
+			}
+
+			p.lat -= diff_lat;
+			p.lon -= diff_lon;
+			track.push_back(p);
+		}
+		tracks.push_back(track);
+
+		ifs.close();
+	}
+
+	glutInitDisplayMode(GLUT_DOUBLE | GLUT_DEPTH | GLUT_ALPHA | GLUT_MULTISAMPLE);
+	glutInit(&argc, argv);
+	glutCreateWindow("test opengl program");
+	glutDisplayFunc(display);
+
+	// NOTE(dev): lmfao:
+	// glutSetCursor(GLUT_CURSOR_SPRAY);
+	glutSetCursor(GLUT_CURSOR_FULL_CROSSHAIR);
+
+	init();
+	glutMainLoop();
+
+	return 0;
+}