20171106/pendulum-1.c

-#include <GL/gl.h>
-#include <GL/glu.h>
-#include <GL/freeglut.h>
-#include <math.h>
-#include "opengl-magic.h"
-
-#define phi0 1.0    /* geg. Anfangswert */
-#define omega0 0.0  /* geg. Anfangswert */
-#define dt 0.05
-#define g 9.81
-#define l 1.0
-
-double t = 0.0;
-double phi = phi0;
-double omega = omega0;
-
-void draw (void)
-{
-  glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
-  set_material_color (0.8, 0.8, 1.0);
-  glPushMatrix ();
-  glRotatef (90, 1.0, 0.0, 0.0);
-  glTranslatef (0.0, 0.0, -0.75);
-  glRotatef (180.0 + phi / M_PI * 180.0, 0.0, 1.0, 0.0);
-  glTranslatef (0.0, 0.0, -1.0);
-  glutSolidCylinder (0.01, l, 13, 1);
-  glutSolidSphere (0.1, 31, 10);
-  glPopMatrix ();
-  glFlush ();
-  glutSwapBuffers ();
-}
-
-void timer_handler (int value)
-{
-  t += dt;
-  glutPostRedisplay ();
-  glutTimerFunc (50, timer_handler, 0);
-}
-
-int main (int argc, char **argv)
-{
-  init_opengl (&argc, argv, "Pendulum");
-  glutDisplayFunc (draw);
-  glutTimerFunc (50, timer_handler, 0);
-  glutMainLoop ();
-  return 0;
-}

20171106/pendulum-2.c

-#include <GL/gl.h>
-#include <GL/glu.h>
-#include <GL/freeglut.h>
-#include <math.h>
-#include "opengl-magic.h"
-
-#define phi0 1.0    /* geg. Anfangswert */
-#define omega0 0.0  /* geg. Anfangswert */
-#define dt 0.05
-#define g 9.81
-#define l 1.0
-
-double t = 0.0;
-double phi = phi0;
-double omega = omega0;
-
-void draw (void)
-{
-  glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
-  set_material_color (0.8, 0.8, 1.0);
-  glPushMatrix ();
-  glRotatef (90, 1.0, 0.0, 0.0);
-  glTranslatef (0.0, 0.0, -0.75);
-  glRotatef (180.0 + phi / M_PI * 180.0, 0.0, 1.0, 0.0);
-  glTranslatef (0.0, 0.0, -1.0);
-  glutSolidCylinder (0.01, l, 13, 1);
-  glutSolidSphere (0.1, 31, 10);
-  glPopMatrix ();
-  glFlush ();
-  glutSwapBuffers ();
-}
-
-void timer_handler (int value)
-{
-  t += dt;
-  phi += dt * omega;
-  omega += dt * (-g / l) * sin (phi);
-  glutPostRedisplay ();
-  glutTimerFunc (50, timer_handler, 0);
-}
-
-int main (int argc, char **argv)
-{
-  init_opengl (&argc, argv, "Pendulum");
-  glutDisplayFunc (draw);
-  glutTimerFunc (50, timer_handler, 0);
-  glutMainLoop ();
-  return 0;
-}

20171106/pendulum-3.c

-#include <GL/gl.h>
-#include <GL/glu.h>
-#include <GL/freeglut.h>
-#include <math.h>
-#include "opengl-magic.h"
-
-#define phi0 1.0    /* geg. Anfangswert */
-#define omega0 0.0  /* geg. Anfangswert */
-#define dt 0.05
-#define g 9.81
-#define l 1.0
-
-double t = 0.0;
-double phi = phi0;
-double omega = omega0;
-
-void draw (void)
-{
-  glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
-  set_material_color (1.0, 1.0, 0.8);
-  glPushMatrix ();
-  glRotatef (90, 1.0, 0.0, 0.0);
-  glTranslatef (0.0, 0.0, -0.75);
-  glRotatef (180.0 + phi / M_PI * 180.0, 0.0, 1.0, 0.0);
-  glTranslatef (0.0, 0.0, -1.0);
-  glutSolidCylinder (0.01, l, 13, 1);
-  glutSolidSphere (0.1, 31, 10);
-  glPopMatrix ();
-  glFlush ();
-  glutSwapBuffers ();
-}
-
-void timer_handler (int value)
-{
-  t += dt;
-  phi += dt * omega;
-  omega += dt * (-g / l) * phi;
-  glutPostRedisplay ();
-  glutTimerFunc (50, timer_handler, 0);
-}
-
-int main (int argc, char **argv)
-{
-  init_opengl (&argc, argv, "Pendulum");
-  glutDisplayFunc (draw);
-  glutTimerFunc (50, timer_handler, 0);
-  glutMainLoop ();
-  return 0;
-}

20171106/pendulum-4.c

-#include <GL/gl.h>
-#include <GL/glu.h>
-#include <GL/freeglut.h>
-#include <math.h>
-#include "opengl-magic.h"
-
-#define phi0 0.5    /* geg. Anfangswert */
-#define omega0 0.0  /* geg. Anfangswert */
-#define dt 0.05
-#define g 9.81
-#define l 1.0
-
-double t = 0.0;
-double phi_with_sin = phi0;
-double omega_with_sin= omega0;
-double phi_without_sin = phi0;
-double omega_without_sin= omega0;
-
-void draw_pendulum (double phi)
-{
-  glPushMatrix ();
-  glRotatef (90, 1.0, 0.0, 0.0);
-  glTranslatef (0.0, 0.0, -0.75);
-  glRotatef (180.0 + phi / M_PI * 180.0, 0.0, 1.0, 0.0);
-  glTranslatef (0.0, 0.0, -1.0);
-  glutSolidCylinder (0.01, 1.0, 13, 1);
-  glutSolidSphere (0.1, 31, 10);
-  glPopMatrix ();
-  glutSwapBuffers ();
-}
-
-void draw (void)
-{
-  glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
-  set_material_color (0.8, 0.8, 1.0);
-  draw_pendulum (phi_with_sin);
-  set_material_color (1.0, 0.8, 0.8);
-  draw_pendulum (phi_without_sin);
-  set_material_color (0.8, 1.0, 0.8);
-  double A = phi0;
-  double B = 0.5 * M_PI;  /* 90° */
-  double phi_analytic = A * sin (sqrt (g / l) * t + B);
-  draw_pendulum (phi_analytic);
-  glFlush ();
-}
-
-void timer_handler (int value)
-{
-  t += dt;
-  phi_with_sin += dt * omega_with_sin;                   /* geg. Differentialgleichung */
-  omega_with_sin += - dt * g / l * sin (phi_with_sin);   /* geg. Differentialgleichung */
-                                                         /* _ohne_ Kleinwinkelnäherung */
-  phi_without_sin += dt * omega_without_sin;             /* geg. Differentialgleichung */
-  omega_without_sin += - dt * g / l * phi_without_sin;   /* geg. Differentialgleichung */
-                                                         /* _mit_ Kleinwinkelnäherung  */
-  glutPostRedisplay ();
-  glutTimerFunc (50, timer_handler, 0);
-}
-
-int main (int argc, char **argv)
-{
-  init_opengl (&argc, argv, "Pendulum");
-  glutDisplayFunc (draw);
-  glutTimerFunc (50, timer_handler, 0);
-  glutPostRedisplay ();
-  glutMainLoop ();
-  return 0;
-}

20171106/photo-20171106-170748.txt

-README: Fadenpendel: Aufstellung der Differentialgleichung

20171106/textured-spheres.c

-#include <stdio.h>
-#include <stdlib.h>
-#include <sys/stat.h>
-#include <png.h>
-#include "textured-spheres.h"
-
-#ifndef __USE_POSIX
-  extern int fileno (FILE *stream);
-#endif
-
-static png_byte *load_png_file (char *filename, unsigned *w, unsigned *h)
-{
-  FILE *f = fopen (filename, "rb");
-  if (!f)
-    return NULL;
-
-  /* is it a PNG file? */
-  png_byte buf[8];
-  if (fread (buf, 1, 8, f) != 8)
-    {
-      fclose (f);
-      return NULL;
-    }
-  if (!png_check_sig (buf, 8))
-    {
-      fclose (f);
-      return NULL;
-    }
-
-  png_struct *png_ptr = png_create_read_struct (PNG_LIBPNG_VER_STRING,
-                                                NULL, NULL, NULL);
-  if (!png_ptr)
-    {
-      fclose (f);
-      return NULL;
-    }
-
-  png_info *info_ptr = png_create_info_struct (png_ptr);
-  if (!info_ptr)
-    {
-      fclose (f);
-      png_destroy_read_struct (&png_ptr, NULL, NULL);
-      return NULL;
-    }
-
-  if (setjmp (png_jmpbuf (png_ptr)))
-    {
-      fclose (f);
-      png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
-      return NULL;
-    }
-
-  png_init_io (png_ptr, f);
-  png_set_sig_bytes (png_ptr, 8);
-  png_read_info (png_ptr, info_ptr);
-
-  png_uint_32 width;
-  png_uint_32 height;
-  int bit_depth;
-  int color_type;
-  png_get_IHDR (png_ptr, info_ptr, &width, &height, &bit_depth,
-                &color_type, NULL, NULL, NULL);
-
-  /* tell libpng to strip 16 bit/color files down to 8 bits/color */
-  if (bit_depth == 16)
-    png_set_strip_16 (png_ptr);
-  /* expand paletted colors into true RGB triplets */
-  if (color_type == PNG_COLOR_TYPE_PALETTE)
-    png_set_expand (png_ptr);
-  /* expand grayscale images to the full 8 bits from 1, 2, or 4 bits/pixel */
-  if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
-    png_set_expand (png_ptr);
-  /* expand paletted or RGB images with transparency to full alpha channels
-     so the data will be available as RGBA quartets. */
-  if (png_get_valid (png_ptr, info_ptr, PNG_INFO_tRNS))
-    png_set_expand (png_ptr);
-  /* transform grayscale images into rgb */
-  if (color_type == PNG_COLOR_TYPE_GRAY
-      || color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
-    png_set_gray_to_rgb (png_ptr);
-
-  if (color_type & PNG_COLOR_MASK_ALPHA)
-    png_set_strip_alpha (png_ptr);
-
-  png_read_update_info (png_ptr, info_ptr);
-  png_get_IHDR (png_ptr, info_ptr, &width, &height, &bit_depth,
-		&color_type, NULL, NULL, NULL);
-  if (color_type != PNG_COLOR_TYPE_RGB
-      && color_type != PNG_COLOR_TYPE_RGB_ALPHA)
-    {
-      fclose (f);
-      png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
-      return NULL;
-    }
-
-  png_uint_32 row_bytes = png_get_rowbytes (png_ptr, info_ptr);
-  if (row_bytes & 0x01)
-    row_bytes++;
-
-  png_byte *png_pixels = malloc (row_bytes * height * sizeof (png_byte));
-  if (png_pixels == NULL)
-    {
-      fclose (f);
-      png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
-      return NULL;
-    }
-
-  png_byte **row_pointers = malloc (height * sizeof (png_bytep));
-  if (row_pointers == NULL)
-    {
-      fclose (f);
-      png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
-      free (png_pixels);
-      png_pixels = NULL;
-      return NULL;
-    }
-
-  int i;
-  for (i = 0; i < height; i++)
-    row_pointers[i] = png_pixels + i * row_bytes;
-
-  png_read_image (png_ptr, row_pointers);
-
-  png_read_end (png_ptr, info_ptr);
-  png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
-  fclose (f);
-
-  if (w)
-    *w = width;
-  if (h)
-    *h = height;
-  free (row_pointers);
-
-  return png_pixels;
-}
-
-void init_texture (char *image_filename, GLuint *texture)
-{
-  unsigned image_width, image_height;
-  png_byte *image = load_png_file (image_filename, &image_width, &image_height);
-  if (!image)
-    {
-      fprintf (stderr, "textured-spheres.c: cannot open texture file \"%s\"",
-               image_filename);
-      exit (1);
-    }
-  glGenTextures (1, texture);
-  glBindTexture (GL_TEXTURE_2D, *texture);
-  glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
-  glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR_MIPMAP_LINEAR);
-  glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
-  glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
-  glTexEnvf (GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
-  gluBuild2DMipmaps (GL_TEXTURE_2D, 3, image_width, image_height, GL_RGB, GL_UNSIGNED_BYTE, image);
-}
-
-void draw_textured_sphere (GLuint texture, GLdouble radius, GLint slices, GLint stacks)
-{
-  static GLfloat white_color[] = { 1.0, 1.0, 1.0 };
-  glMaterialfv (GL_FRONT, GL_AMBIENT, white_color);
-  glMaterialfv (GL_FRONT, GL_DIFFUSE, white_color);
-  glBindTexture (GL_TEXTURE_2D, texture);
-  glEnable (GL_TEXTURE_2D);
-  GLUquadric *sphere = gluNewQuadric ();
-  gluQuadricTexture (sphere, GL_TRUE);
-  gluSphere (sphere, radius, slices, stacks);
-  glDisable (GL_TEXTURE_2D);
-}

20171106/textured-spheres.h

-#ifndef TEXTURED_SPHERES_H
-#define TEXTURED_SPHERES_H
-
-#include <GL/gl.h>
-#include <GL/glu.h>
-
-extern void init_texture (char *image_filename, GLuint *texture);
-extern void draw_textured_sphere (GLuint texture, GLdouble radius, GLint slices, GLint stacks);
-
-#endif /* TEXTURED_SPHERES_H */

20171108/egal.txt

-GNU/Linux
-~~~~~~~~~
-Compilieren:  gcc -Wall -O cube-3c.c opengl-magic.c \
-              -lGL -lGLU -lglut -o cube-3c
-Aufrufen:     ./cube-3c
-
-MacOS
-~~~~~
-Compilieren:  gcc -Wall -O cube-3c.c opengl-magic.c \
-              -framework OpenGL -framework GLUT -o cube-3c
-Aufrufen:     ./cube-3c
-
-Cygwin mit X11
-~~~~~~~~~~~~~~
-Compilieren:  gcc -Wall -O cube-3c.c opengl-magic.c \
-              -lGL -lGLU -lglut -o cube-3c
-Aufrufen:     DISPLAY=:0.0 ./cube-3c
-oder:
-  einmalig:   export DISPLAY=:0.0
-  danach:     ./cube-3c
-
-Vorher einmalig: X-Server starten
-              XWin -multiwindow &
-
-Cygwin ohne X11
-~~~~~~~~~~~~~~~
-Compilieren:  i686-pc-mingw32-gcc -I freeglut/include -L freeglut/lib \
-              -Wall -O cube-3c.c opengl-magic.c \
-              -lOpenGL32 -lGLU32 -lfreeglut -o cube-3c
-Aufrufen:     ./cube-3c
-
-MinGW ohne X11
-~~~~~~~~~~~~~~
-Compilieren:  gcc -I freeglut/include -L freeglut/lib \
-              -Wall -O cube-3c.c opengl-magic.c \
-              -lOpenGL32 -lGLU32 -lfreeglut -o cube-3c
-Aufrufen:     ./cube-3c

20171108/hp-2017ws-p2.tex

-% hp-2017ws-p2.pdf - Labor Notes on Low-Level Programming
-% Copyright (C) 2014, 2015, 2016, 2017  Peter Gerwinski
-%
-% This document is free software: you can redistribute it and/or
-% modify it either under the terms of the Creative Commons
-% Attribution-ShareAlike 3.0 License, or 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 document 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 document.  If not, see <http://www.gnu.org/licenses/>.
-%
-% You should have received a copy of the Creative Commons
-% Attribution-ShareAlike 3.0 Unported License along with this
-% document.  If not, see <http://creativecommons.org/licenses/>.
-
-% README: Versuch 2, 8. und 15.11.2017: Basketball-Simulation
-
-\documentclass[a4paper]{article}
-
-\usepackage{pgscript}
-\usepackage{multicol}
-\usepackage{amsmath}
-\usepackage{sfmath}
-
-\sloppy
-\pagestyle{empty}
-\newcommand{\sep}{~$\cdot$~}
-\newcommand{\mylicense}{CC-by-sa (Version 3.0) oder GNU GPL (Version 3 oder höher)}
-
-\begin{document}
-
-  \makebox(0,0)[tl]{\includegraphics[scale=0.57]{logo-hochschule-bochum-cvh-text.pdf}}\hfill
-  \makebox(0,0)[tr]{\includegraphics[scale=0.5]{logo-hochschule-bochum.pdf}}
-  \par\bigskip\bigskip
-  \begin{center}
-    \Large\textbf{Praktikumsversuch 2: Basketball-Simulation}
-    \par\medskip
-    \normalsize Hardwarenahe Programmierung / Angewandte Informatik\\
-    Wintersemester 2017/18\sep
-    Prof.~Dr.~Peter Gerwinski
-  \end{center}
-
-  Aufgabe: Schreiben Sie ein C-Programm, das
-  den schrägen Wurf einer Kugel ("`Basketball"')
-  durch einen horizontalen Ring ("`Korb"') simuliert und visualisiert
-  -- sowohl ohne als auch mit Berücksichtigung der Luftreibung.
-
-  \bigskip
-
-  Hinweise:
-  \vspace*{-\medskipamount}
-
-  \begin{multicols}{2}
-
-    \begin{itemize}
-      \item
-        Die Beispielprogramme \file{pendulum-}\lstinline{*}\file{.c} zeigen,
-        wie eine Simulation mit Visualisierung
-        mit Hilfe der 3d-Grafikbibliothek OpenGL
-        programmiert werden kann.
-
-      \item
-        Als Basketball eignet sich eine Kugel;
-        alternativ ist auch eine Teekanne zulässig.
-        Als Basketballkorb eignet sich ein Ring (Torus).
-
-      \item
-        Zum Verschieben der gezeichneten Gegenstände
-        im dreidimensionalen Zeichenraum
-        eignet sich die Funktion \lstinline{glTranslatef()}.
-        Genau wie \lstinline{glRotatef()} wirkt sich auch \lstinline{glTranslatef()}
-        auf \emph{alle nachfolgenden\/} Zeichenoperationen aus,
-        und der Wirkungsbereich läßt sich mit
-        \lstinline{glPushMatrix()} und \lstinline{glPopMatrix()} begrenzen.
-
-      \item
-        \textbf{Bonus:}
-        Zusätzliche Elemente wie z.\,B.\ das Abprallen des Balls am Brett,
-        an der Wand oder auf dem Boden sind optional.
-
-        Falls Sie über eine Textur für den Basketball verfügen,
-        zeigt Ihnen das Beispielprogramm \file{orbit-1.c},
-        wie Sie den Ball damit ausstatten können.
-
-      \vfill\columnbreak
-
-      \item
-        In der Differentialgleichung (Bewegungsgleichung) für einen schrägen Wurf
-        sind die $x$- und $y$-Komponente entkoppelt.
-
-      \item
-        In beiden Komponenten gibt es jeweils einen Anfangsort
-        und eine Anfangsgeschwindigkeit.
-
-      \item
-        Bei Vernachlässigung der Luftreibung
-        wirkt in $x$-Richtung keinerlei Kraft;
-        in $y$-Richtung wirkt die Schwerkraft $F = m\cdot g$
-        mit $g = 9.81\frac{\text{m}}{\text{s}^2}$.
-
-      \item
-        Die Luftreibung wirkt grundsätzlich der Bewegung entgegengerichtet.
-        Wir nehmen an, daß die Stärke der Reibungskraft
-        proportional zur Geschwindigkeit ist (laminarer Strömungswiderstand).
-
-      \item
-        Auch bei der Reibungskraft
-        können Sie die $x$- und $y$-Komponente entkoppelt rechnen.
-
-    \end{itemize}
-
-    \bigskip
-
-    \strut\hfill\emph{Viel Erfolg!}
-    \vfill\strut
-
-  \end{multicols}
-
-  \vfill
-
-  \begingroup
-
-    \small
-
-    \setlength{\leftskip}{3cm}
-
-    Stand: 6.\ November 2017
-
-%    Soweit nicht anders angegeben:\\
-    Copyright \copyright\ 2014, 2015, 2016, 2017\quad Peter Gerwinski\\
-    Lizenz: \mylicense
-
-    Sie können diese Praktikumsunterlagen einschließlich Quelltext
-%    und Beispielprogramme\\
-    herunterladen unter:\\
-    \url{https://gitlab.cvh-server.de/pgerwinski/hp}
-
-  \endgroup
-
-\end{document}

20171108/logo-hochschule-bochum-cvh-text.pdf

-../common/logo-hochschule-bochum-cvh-text.pdf
\ No newline at end of file

20171108/opengl-magic.c

-#if defined(__APPLE__) || defined(MACOSX)
-  #include <OpenGL/gl.h>
-  #include <OpenGL/glu.h>
-  #include <GLUT/glut.h>
-#else
-  #include <GL/gl.h>
-  #include <GL/glu.h>
-  #include <GL/glut.h>
-#endif
-
-#include "opengl-magic.h"
-
-void init_opengl (int *argcp, char **argv, char *window_name)
-{
-  glutInit (argcp, argv);
-  glutInitDisplayMode (GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH);
-  glutInitWindowSize (1024, 768);
-  glutCreateWindow (window_name);
-  glMatrixMode (GL_PROJECTION);
-  glLoadIdentity ();
-  gluPerspective (20.0, -1.33333, 3.0, 7.0);
-  glMatrixMode (GL_MODELVIEW);
-  glLoadIdentity ();
-  glTranslatef (0.0, 0.0, -5.0);
-  glClearColor (0.0, 0.0, 0.0, 0.0);
-  glEnable (GL_DEPTH_TEST);
-  glEnable (GL_LIGHTING);
-  glEnable (GL_LIGHT0);
-  static GLfloat light0_position[] = { 1.0, 0.0, 1.0, 0.0 };
-  glLightfv (GL_LIGHT0, GL_POSITION, light0_position);
-}
-
-void set_material_color (float r, float g, float b)
-{
-  GLfloat color[] = { r, g, b };
-  glMaterialfv (GL_FRONT, GL_AMBIENT, color);
-  glMaterialfv (GL_FRONT, GL_DIFFUSE, color);
-}
-
-#if defined(__APPLE__) || defined(MACOSX)
-
-void glutSolidCylinder (double radius, double height, int slices, int stacks)
-{
-  GLUquadricObj *q = gluNewQuadric ();
-  gluCylinder (q, radius, radius, height, slices, stacks);
-  gluDeleteQuadric (q);
-}
-
-#endif

20171108/opengl-magic.h

-#ifndef OPENGL_MAGIC_H
-#define OPENGL_MAGIC_H
-
-extern void init_opengl (int *argcp, char **argv, char *window_name);
-extern void set_material_color (float r, float g, float b);
-
-#ifdef __MACOSX__
-  extern void glutSolidCylinder (double radius, double height, int slices, int stacks);
-#endif
-
-#endif /* OPENGL_MAGIC_H */

20171108/orbit-1.c

-#include <GL/gl.h>
-#include <GL/glu.h>
-#include <GL/glut.h>
-#include "opengl-magic.h"
-#include "textured-spheres.h"
-
-float t = 0.0;
-GLuint earth_texture, moon_texture;
-
-void draw_earth (void)
-{
-  glPushMatrix ();
-  glRotatef (90, 1.0, 0.0, 0.0);
-  glRotatef (100.0 * t, 0.0, 0.0, 1.0);
-  draw_textured_sphere (earth_texture, 0.25512, 63, 20);
-  glPopMatrix ();
-}
-
-void draw_moon (void)
-{
-  glPushMatrix ();
-  glRotatef (90, 1.0, 0.0, 0.0);
-  glRotatef (-90, 0.0, 0.0, 1.0);
-  draw_textured_sphere (moon_texture, 0.06952, 31, 10);
-  glPopMatrix ();
-}
-
-void draw (void)
-{
-  glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
-  glPushMatrix ();
-  glRotatef (23.44, 1.0, 0.0, -1.0);
-  draw_earth ();
-  glRotatef (5.145, 0.0, 1.0, 1.0);
-  glRotatef (30.0 * t, 0.0, -1.0, 0.0);
-  glTranslatef (0.9, 0.0, 0.0);
-  draw_moon ();
-  glPopMatrix ();
-  glFlush ();
-  glutSwapBuffers ();
-}
-
-void timer_handler (int value)
-{
-  t += 0.05;
-  glutPostRedisplay ();
-  glutTimerFunc (50, timer_handler, 0);
-}
-
-int main (int argc, char **argv)
-{
-  init_opengl (&argc, argv, "Orbit");
-  init_texture ("earth-texture.png", &earth_texture);
-  init_texture ("moon-texture.png", &moon_texture);
-  glutDisplayFunc (draw);
-  glutTimerFunc (50, timer_handler, 0);
-  glutMainLoop ();
-  return 0;
-}

20171108/pendulum-1.c

-#include <GL/gl.h>
-#include <GL/glu.h>
-#include <GL/freeglut.h>
-#include <math.h>
-#include "opengl-magic.h"
-
-#define phi0 1.0    /* geg. Anfangswert */
-#define omega0 0.0  /* geg. Anfangswert */
-#define dt 0.05
-#define g 9.81
-#define l 1.0
-
-double t = 0.0;
-double phi = phi0;
-double omega = omega0;
-
-void draw (void)
-{
-  glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
-  set_material_color (0.8, 0.8, 1.0);
-  glPushMatrix ();
-  glRotatef (90, 1.0, 0.0, 0.0);
-  glTranslatef (0.0, 0.0, -0.75);
-  glRotatef (180.0 + phi / M_PI * 180.0, 0.0, 1.0, 0.0);
-  glTranslatef (0.0, 0.0, -1.0);
-  glutSolidCylinder (0.01, l, 13, 1);
-  glutSolidSphere (0.1, 31, 10);
-  glPopMatrix ();
-  glFlush ();
-  glutSwapBuffers ();
-}
-
-void timer_handler (int value)
-{
-  t += dt;
-  glutPostRedisplay ();
-  glutTimerFunc (50, timer_handler, 0);
-}
-
-int main (int argc, char **argv)
-{
-  init_opengl (&argc, argv, "Pendulum");
-  glutDisplayFunc (draw);
-  glutTimerFunc (50, timer_handler, 0);
-  glutMainLoop ();
-  return 0;
-}

20171108/pendulum-2.c

-#include <GL/gl.h>
-#include <GL/glu.h>
-#include <GL/freeglut.h>
-#include <math.h>
-#include "opengl-magic.h"
-
-#define phi0 1.0    /* geg. Anfangswert */
-#define omega0 0.0  /* geg. Anfangswert */
-#define dt 0.05
-#define g 9.81
-#define l 1.0
-
-double t = 0.0;
-double phi = phi0;
-double omega = omega0;
-
-void draw (void)
-{
-  glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
-  set_material_color (0.8, 0.8, 1.0);
-  glPushMatrix ();
-  glRotatef (90, 1.0, 0.0, 0.0);
-  glTranslatef (0.0, 0.0, -0.75);
-  glRotatef (180.0 + phi / M_PI * 180.0, 0.0, 1.0, 0.0);
-  glTranslatef (0.0, 0.0, -1.0);
-  glutSolidCylinder (0.01, l, 13, 1);
-  glutSolidSphere (0.1, 31, 10);
-  glPopMatrix ();
-  glFlush ();
-  glutSwapBuffers ();
-}
-
-void timer_handler (int value)
-{
-  t += dt;
-  phi += dt * omega;
-  omega += dt * (-g / l) * sin (phi);
-  glutPostRedisplay ();
-  glutTimerFunc (50, timer_handler, 0);
-}
-
-int main (int argc, char **argv)
-{
-  init_opengl (&argc, argv, "Pendulum");
-  glutDisplayFunc (draw);
-  glutTimerFunc (50, timer_handler, 0);
-  glutMainLoop ();
-  return 0;
-}

20171108/pendulum-3.c

-#include <GL/gl.h>
-#include <GL/glu.h>
-#include <GL/freeglut.h>
-#include <math.h>
-#include "opengl-magic.h"
-
-#define phi0 1.0    /* geg. Anfangswert */
-#define omega0 0.0  /* geg. Anfangswert */
-#define dt 0.05
-#define g 9.81
-#define l 1.0
-
-double t = 0.0;
-double phi = phi0;
-double omega = omega0;
-
-void draw (void)
-{
-  glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
-  set_material_color (1.0, 1.0, 0.8);
-  glPushMatrix ();
-  glRotatef (90, 1.0, 0.0, 0.0);
-  glTranslatef (0.0, 0.0, -0.75);
-  glRotatef (180.0 + phi / M_PI * 180.0, 0.0, 1.0, 0.0);
-  glTranslatef (0.0, 0.0, -1.0);
-  glutSolidCylinder (0.01, l, 13, 1);
-  glutSolidSphere (0.1, 31, 10);
-  glPopMatrix ();
-  glFlush ();
-  glutSwapBuffers ();
-}
-
-void timer_handler (int value)
-{
-  t += dt;
-  phi += dt * omega;
-  omega += dt * (-g / l) * phi;
-  glutPostRedisplay ();
-  glutTimerFunc (50, timer_handler, 0);
-}
-
-int main (int argc, char **argv)
-{
-  init_opengl (&argc, argv, "Pendulum");
-  glutDisplayFunc (draw);
-  glutTimerFunc (50, timer_handler, 0);
-  glutMainLoop ();
-  return 0;
-}

20171108/pendulum-4.c

-#include <GL/gl.h>
-#include <GL/glu.h>
-#include <GL/freeglut.h>
-#include <math.h>
-#include "opengl-magic.h"
-
-#define phi0 0.5    /* geg. Anfangswert */
-#define omega0 0.0  /* geg. Anfangswert */
-#define dt 0.05
-#define g 9.81
-#define l 1.0
-
-double t = 0.0;
-double phi_with_sin = phi0;
-double omega_with_sin= omega0;
-double phi_without_sin = phi0;
-double omega_without_sin= omega0;
-
-void draw_pendulum (double phi)
-{
-  glPushMatrix ();
-  glRotatef (90, 1.0, 0.0, 0.0);
-  glTranslatef (0.0, 0.0, -0.75);
-  glRotatef (180.0 + phi / M_PI * 180.0, 0.0, 1.0, 0.0);
-  glTranslatef (0.0, 0.0, -1.0);
-  glutSolidCylinder (0.01, 1.0, 13, 1);
-  glutSolidSphere (0.1, 31, 10);
-  glPopMatrix ();
-  glutSwapBuffers ();
-}
-
-void draw (void)
-{
-  glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
-  set_material_color (0.8, 0.8, 1.0);
-  draw_pendulum (phi_with_sin);
-  set_material_color (1.0, 0.8, 0.8);
-  draw_pendulum (phi_without_sin);
-  set_material_color (0.8, 1.0, 0.8);
-  double A = phi0;
-  double B = 0.5 * M_PI;  /* 90° */
-  double phi_analytic = A * sin (sqrt (g / l) * t + B);
-  draw_pendulum (phi_analytic);
-  glFlush ();
-}
-
-void timer_handler (int value)
-{
-  t += dt;
-  phi_with_sin += dt * omega_with_sin;                   /* geg. Differentialgleichung */
-  omega_with_sin += - dt * g / l * sin (phi_with_sin);   /* geg. Differentialgleichung */
-                                                         /* _ohne_ Kleinwinkelnäherung */
-  phi_without_sin += dt * omega_without_sin;             /* geg. Differentialgleichung */
-  omega_without_sin += - dt * g / l * phi_without_sin;   /* geg. Differentialgleichung */
-                                                         /* _mit_ Kleinwinkelnäherung  */
-  glutPostRedisplay ();
-  glutTimerFunc (50, timer_handler, 0);
-}
-
-int main (int argc, char **argv)
-{
-  init_opengl (&argc, argv, "Pendulum");
-  glutDisplayFunc (draw);
-  glutTimerFunc (50, timer_handler, 0);
-  glutPostRedisplay ();
-  glutMainLoop ();
-  return 0;
-}