元のファイル ‎(SVG ファイル、400 × 400 ピクセル、ファイルサイズ: 8キロバイト)

このファイルは、ウィキメディア・コモンズから呼び出されています。

このファイルは、他のプロジェクトで使用されている可能性があります。

このファイルの解説やノートへの記入、履歴などの詳細の確認は、ウィキメディア・コモンズのファイルページ（ノート/履歴/ログ）を使用してください。
ウィキメディア・コモンズのファイルページにある説明を、以下に表示します。

概要

解説Sphere wireframe.svgEnglish: Sphere wireframe - orthogonal projection of a sphere. The image shows lines, which are drawn as they were painted onto the surface of a sphere. The angular distance between two lines is 10°. The SVG file is created by the below C++-program, which calculates each edge of a line as an ellipse-bow. The backside of the sphere has an opacity of 0.25. The axis tilt is 52.5°.
日付2008年11月
原典投稿者自身による著作物
作者Geek3
その他のバージョン

Sphere filled_blue.svg
Sphere wireframe 10deg 10r.svg
 W3C-validity not checked.
Source Code

This image can be completely generated by the following source code. If you have the gnu compiler collection installed, the programm can be compiled by the following commands:g++ sphere_wireframe.cpp -o sphere_wireframe

and run :./sphere_wireframe > Sphere_wireframe.svg

It creates file Sphere_wireframe.svg in working directory. This file can be viewed using rsvg-view program : rsvg-view Sphere_wireframe.svg

Here is cpp code in file : sphere_wireframe.cpp/* sphere - creates a svg vector-graphics file which depicts a wireframe sphere * * Copyright (C) 2008 Wikimedia foundation * * 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 2, 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, you can either send email to this * program's author (see below) or write to: * The Free Software Foundation, Inc. * 51 Franklin Street, Fifth Floor * Boston, MA 02110-1301 USA *//* The expressions in this code are not proven to be correct. * Hence this code probably contains lots of bugs. Be aware! */#include <iostream>#include <cmath>#include <cstdlib>#include <cstring>using namespace std;const double PI = 3.1415926535897932;const double DEG = PI / 180.0;/********************************* settings **********************************/int n_lon = 18; // number of latitude fields (18 => 10° each)int n_lat = 18; // half number of longitude fields (18 => 10° each)double lon_offset = 2.5 * DEG; // offset of the meridiansdouble w = 52.5 * DEG; // axial tilt (0° => axis is perpendicular to image plane)double stripe_grad = 0.5 * DEG; // width of each lineint image_size = 400; // width and height of the image in pixelsdouble back_opacity = 0.25; // opacity of the sphere's backsidechar color[] = "#334070"; // color of linesint istep = 2; // svg code indentation step/*****************************************************************************/double sqr(double x){ return(x * x);}// commands for svg-code:void indent(int n, bool in_tag = false){ n *= istep; if (in_tag) n += istep + 1; for (int i = 0; i < n; i++) cout << " ";}void M(){ cout << "M ";}void Z(){ cout << "Z ";}void xy(double x, double y){ cout << x << ","; cout << y << " ";}void arc(double a, double b, double x_axis_rot, bool large_arc, bool sweep){ // draws an elliptic arc if (b < 0.5E-6) { // flat ellipses are not rendered properly => use line cout << "L "; } else { cout << "A "; cout << a << ","; // semi-major axis cout << b << " "; // semi-minor axis cout << x_axis_rot << " "; cout << large_arc << " "; cout << sweep << " "; }}void circle(bool clockwise){ M(); xy(-1, 0); arc(1, 1, 0, 0, !clockwise); xy(1, 0); arc(1, 1, 0, 0, !clockwise); xy(-1, 0); Z();}void start_svg_file(){ cout << "<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"no\"?>\n"; cout << "<svg id=\"Sphere_wireframe\"\n"; cout << " version=\"1.1\"\n"; cout << " baseProfile=\"full\"\n"; cout << " xmlns=\"http://www.w3.org/2000/svg\"\n"; cout << " xmlns:xlink=\"http://www.w3.org/1999/xlink\"\n"; cout << " width=\"" << image_size << "\"\n"; cout << " height=\"" << image_size << "\">\n\n"; cout << " <title>Sphere wireframe</title>\n\n"; cout << " <desc>\n"; cout << " about: http://commons.wikimedia.org/wiki/Image:Sphere_wireframe.svg\n"; cout << " rights: GNU Free Documentation license,\n"; cout << " Creative Commons Attribution ShareAlike license\n"; cout << " </desc>\n\n"; cout << " <g id=\"sphere\" transform=\"scale(" << 0.5 * image_size; cout << ", " << -0.5 * image_size << ") translate(1, -1)\">\n";}void end_svg_file(){ cout << " </g>\n</svg>\n";}int main (int argc, char *argv[]){ // accept -lat and -lon as parameter for (int i = 2; i < argc; i++) { if (isdigit(argv[i][0]) |。(sizeof(argv[i]) > sizeof(char) && isdigit(argv[i][1]) && (argv[i][0] == '.' |。argv[i][0] == '-'))) { if (strcmp(argv[i - 1], "-lon") == 0) { lon_offset = atof(argv[i]) * DEG; } if (strcmp(argv[i - 1], "-lat") == 0) { w = atof(argv[i]) * DEG; } } } double cosw = cos(w), sinw = sin(w); double d = 0.5 * stripe_grad; start_svg_file(); int ind = 2; // initial indentation level indent(ind); cout << "<g id=\"sphere_back\" transform=\"rotate(180)\" "; cout << "opacity=\"" << back_opacity << "\">\n"; indent(++ind); cout << "<g id=\"sphere_half\">\n"; // meridians indent(++ind); cout << "<g id=\"meridians\"\n"; indent(ind++, true); cout << "style=\"stroke:none; fill:" << color << "; fill_rule:evenodd\">\n"; double a = abs(cos(d)); for (int i_lon = 0; i_lon < n_lat; i_lon++) { // draw one meridian double longitude = lon_offset + (i_lon * 180.0 / n_lat) * DEG; double lon[2]; lon[0] = longitude + d; lon[1] = longitude - d; indent(ind); cout << "<path id=\"meridian"; cout << i_lon << "\"\n"; indent(ind, true); cout << "d=\""; double axis_rot = atan2(-1.0 / tan(longitude), cosw); if (sinw < 0) axis_rot += PI; double w2 = sin(longitude) * sinw; double b = abs(w2 * cos(d)); double sinw1 = sin(d) / sqrt(1.0 - sqr(sin(longitude) * sinw)); if (abs(sinw1) >= 1.0) { // stripe covers edge of the circle double w3 = sqrt(1.0 - sqr(w2)) * sin(d); circle(false); // ellipse M(); xy(sin(axis_rot) * w3 - cos(axis_rot) * a, -cos(axis_rot) * w3 - sin(axis_rot) * a); arc(a, b, axis_rot / DEG, 0, 0); xy(sin(axis_rot) * w3 + cos(axis_rot) * a, -cos(axis_rot) * w3 + sin(axis_rot) * a); arc(a, b, axis_rot / DEG, 0, 0); xy(sin(axis_rot) * w3 - cos(axis_rot) * a, -cos(axis_rot) * w3 - sin(axis_rot) * a); Z(); } else { // draw a disrupted ellipse bow double w1 = asin(sinw1); M(); xy(-cos(axis_rot + w1), -sin(axis_rot + w1)); arc(a, b, axis_rot / DEG, 1, 0); xy(cos(axis_rot - w1), sin(axis_rot - w1)); arc(1, 1, 0, 0, 1); xy(cos(axis_rot + w1), sin(axis_rot + w1)); arc(a, b, axis_rot / DEG, 0, 1); xy(-cos(axis_rot - w1), -sin(axis_rot - w1)); arc(1, 1, 0, 0, 1); xy(-cos(axis_rot + w1), -sin(axis_rot + w1)); } Z(); cout << "\" />\n"; } indent(--ind); cout << "</g>\n"; cout << endl; // circles of latitude indent(ind); cout << "<g id=\"circles_of_latitude\"\n"; indent(ind, true); cout << "style=\"stroke:none; fill:" << color << "; fill_rule:evenodd\">\n"; ind++; for (int i_lat = 1; i_lat < n_lon; i_lat++) { // draw one circle of latitude double latitude = (i_lat * 180.0 / n_lon - 90.0) * DEG; double lat[2]; lat[0] = latitude + d; lat[1] = latitude - d; double x[2], yd[2], ym[2]; for (int i = 0; i < 2; i++) { x[i] = abs(cos(lat[i])); yd[i] = abs(cosw * cos(lat[i])); ym[i] = sinw * sin(lat[i]); } double h[4]; // height of each point above image plane h[0] = sin(lat[0] + w); h[1] = sin(lat[0] - w); h[2] = sin(lat[1] + w); h[3] = sin(lat[1] - w); if (h[0] > 0 |。