Beispiel-Programme 19.11.2018

20181119/pendulum-0.c

+#include <gtk/gtk.h>
+#include <math.h>
+
+int width = 320;
+int height = 240;
+int gap = height / 20;
+int r = gap;
+double visual_length = height - 2 * gap - r;
+
+double phi0 = -0.5;
+double omega0 = 0.0;
+double t0 = 0.0;
+double g = 9.81;
+double l = 1.0;
+double dt = 0.02;
+
+double t = t0;
+double phi = phi0;
+double omega = omega0;
+
+gboolean draw (GtkWidget *widget, cairo_t *c, gpointer data)
+{
+  GdkRGBA blue = { 0.0, 0.5, 1.0, 1.0 };
+
+  int x = width / 2 + visual_length * sin (phi);
+  int y = gap + visual_length * cos (phi);
+
+  gdk_cairo_set_source_rgba (c, &blue);
+  cairo_move_to (c, width / 2, 10);
+  cairo_line_to (c, x, y);
+  cairo_stroke (c);
+  cairo_arc (c, x, y, r, 0, 2 * G_PI);
+  cairo_fill (c);
+
+  return FALSE;  /* TRUE to stop other handlers from being invoked for the event.
+                    FALSE to propagate the event further. */
+}
+
+gboolean timer (GtkWidget *widget)
+{
+  t += dt;
+  phi += omega * dt;
+  omega += - dt * g / l * sin (phi);
+
+  gtk_widget_queue_draw_area (widget, 0, 0, width, height);
+  g_timeout_add (50, (GSourceFunc) timer, widget);
+  return FALSE;
+}
+
+int main (int argc, char **argv)
+{
+  gtk_init (&argc, &argv);
+
+  GtkWidget *window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+  gtk_widget_show (window);
+  gtk_window_set_title (GTK_WINDOW (window), "Hello");
+  g_signal_connect (window, "destroy", G_CALLBACK (gtk_main_quit), NULL);
+
+  GtkWidget *drawing_area = gtk_drawing_area_new ();
+  gtk_widget_show (drawing_area);
+  gtk_container_add (GTK_CONTAINER (window), drawing_area);
+  gtk_widget_set_size_request (drawing_area, width, height);
+  g_signal_connect (drawing_area, "draw", G_CALLBACK (draw), NULL);
+
+  g_timeout_add (50, (GSourceFunc) timer, drawing_area);
+
+  gtk_main ();
+  return 0;
+}

20181119/pendulum-1.c

+#include <gtk/gtk.h>
+#include <math.h>
+
+#define WIDTH 320
+#define HEIGHT 240
+#define GAP (HEIGHT / 20)
+#define r GAP
+#define visual_length (HEIGHT - 2 * GAP - r)
+
+#define phi0 (-0.5)
+#define omega0 0.0
+#define t0 0.0
+#define g 9.81
+#define l 1.0
+#define dt 0.02
+
+double t = t0;
+double phi = phi0;
+double omega = omega0;
+
+gboolean draw (GtkWidget *widget, cairo_t *c, gpointer data)
+{
+  GdkRGBA blue = { 0.0, 0.5, 1.0, 1.0 };
+
+  int x = WIDTH / 2 + visual_length * sin (phi);
+  int y = GAP + visual_length * cos (phi);
+
+  gdk_cairo_set_source_rgba (c, &blue);
+  cairo_move_to (c, WIDTH / 2, 10);
+  cairo_line_to (c, x, y);
+  cairo_stroke (c);
+  cairo_arc (c, x, y, r, 0, 2 * G_PI);
+  cairo_fill (c);
+
+  return FALSE;  /* TRUE to stop other handlers from being invoked for the event.
+                    FALSE to propagate the event further. */
+}
+
+gboolean timer (GtkWidget *widget)
+{
+  t += dt;
+  phi += omega * dt;
+  omega += - dt * g / l * sin (phi);
+
+  gtk_widget_queue_draw_area (widget, 0, 0, WIDTH, HEIGHT);
+  g_timeout_add (50, (GSourceFunc) timer, widget);
+  return FALSE;
+}
+
+int main (int argc, char **argv)
+{
+  gtk_init (&argc, &argv);
+
+  GtkWidget *window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+  gtk_widget_show (window);
+  gtk_window_set_title (GTK_WINDOW (window), "Hello");
+  g_signal_connect (window, "destroy", G_CALLBACK (gtk_main_quit), NULL);
+
+  GtkWidget *drawing_area = gtk_drawing_area_new ();
+  gtk_widget_show (drawing_area);
+  gtk_container_add (GTK_CONTAINER (window), drawing_area);
+  gtk_widget_set_size_request (drawing_area, WIDTH, HEIGHT);
+  g_signal_connect (drawing_area, "draw", G_CALLBACK (draw), NULL);
+
+  g_timeout_add (50, (GSourceFunc) timer, drawing_area);
+
+  gtk_main ();
+  return 0;
+}

20181119/pendulum-2.c

+#include <gtk/gtk.h>
+#include <math.h>
+
+#define WIDTH 320
+#define HEIGHT 240
+#define GAP (HEIGHT / 20)
+#define r GAP
+#define visual_length (HEIGHT - 2 * GAP - r)
+
+#define phi0 (-0.5)
+#define omega0 0.0
+#define t0 0.0
+#define g 9.81
+#define l 1.0
+#define dt 0.02
+
+double t = t0;
+double phi = phi0;
+double omega = omega0;
+
+gboolean draw (GtkWidget *widget, cairo_t *c, gpointer data)
+{
+  GdkRGBA orange = { 1.0, 0.5, 0.0, 1.0 };
+
+  int x = WIDTH / 2 + visual_length * sin (phi);
+  int y = GAP + visual_length * cos (phi);
+
+  gdk_cairo_set_source_rgba (c, &orange);
+  cairo_move_to (c, WIDTH / 2, 10);
+  cairo_line_to (c, x, y);
+  cairo_stroke (c);
+  cairo_arc (c, x, y, r, 0, 2 * G_PI);
+  cairo_fill (c);
+
+  return FALSE;  /* TRUE to stop other handlers from being invoked for the event.
+                    FALSE to propagate the event further. */
+}
+
+gboolean timer (GtkWidget *widget)
+{
+  t += dt;
+  phi += omega * dt;
+  omega += - dt * g / l * phi;
+
+  gtk_widget_queue_draw_area (widget, 0, 0, WIDTH, HEIGHT);
+  g_timeout_add (50, (GSourceFunc) timer, widget);
+  return FALSE;
+}
+
+int main (int argc, char **argv)
+{
+  gtk_init (&argc, &argv);
+
+  GtkWidget *window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+  gtk_widget_show (window);
+  gtk_window_set_title (GTK_WINDOW (window), "Hello");
+  g_signal_connect (window, "destroy", G_CALLBACK (gtk_main_quit), NULL);
+
+  GtkWidget *drawing_area = gtk_drawing_area_new ();
+  gtk_widget_show (drawing_area);
+  gtk_container_add (GTK_CONTAINER (window), drawing_area);
+  gtk_widget_set_size_request (drawing_area, WIDTH, HEIGHT);
+  g_signal_connect (drawing_area, "draw", G_CALLBACK (draw), NULL);
+
+  g_timeout_add (50, (GSourceFunc) timer, drawing_area);
+
+  gtk_main ();
+  return 0;
+}

20181119/pendulum-3.c

+#include <gtk/gtk.h>
+#include <math.h>
+
+#define WIDTH 320
+#define HEIGHT 240
+#define GAP (HEIGHT / 20)
+#define r GAP
+#define visual_length (HEIGHT - 2 * GAP - r)
+
+#define phi0 (-0.5)
+#define omega0 0.0
+#define t0 0.0
+#define g 9.81
+#define l 1.0
+#define dt 0.02
+
+double t = t0;
+double phi_with_sin = phi0;
+double omega_with_sin= omega0;
+double phi_without_sin = phi0;
+double omega_without_sin= omega0;
+
+void draw_pendulum (cairo_t *c, double phi, GdkRGBA *colour)
+{
+  int x = WIDTH / 2 + visual_length * sin (phi);
+  int y = GAP + visual_length * cos (phi);
+
+  gdk_cairo_set_source_rgba (c, colour);
+  cairo_move_to (c, WIDTH / 2, 10);
+  cairo_line_to (c, x, y);
+  cairo_stroke (c);
+  cairo_arc (c, x, y, r, 0, 2 * G_PI);
+  cairo_fill (c);
+}
+
+gboolean draw (GtkWidget *widget, cairo_t *c, gpointer data)
+{
+  GdkRGBA blue   = { 0.0, 0.5, 1.0, 1.0 };
+  GdkRGBA orange = { 1.0, 0.5, 0.0, 1.0 };
+  GdkRGBA green  = { 0.0, 0.5, 0.0, 1.0 };
+
+  double A = phi0;
+  double B = 0.5 * M_PI;  /* 90° */
+  double phi_analytic = A * sin (sqrt (g / l) * t + B);
+
+  draw_pendulum (c, phi_with_sin, &blue);
+  draw_pendulum (c, phi_without_sin, &orange);
+  draw_pendulum (c, phi_analytic, &green);
+
+  return FALSE;  /* TRUE to stop other handlers from being invoked for the event.
+                    FALSE to propagate the event further. */
+}
+
+gboolean timer (GtkWidget *widget)
+{
+  t += dt;
+  phi_with_sin += omega_with_sin * dt;
+  omega_with_sin += - dt * g / l * phi_with_sin;
+  phi_without_sin += omega_without_sin * dt;
+  omega_without_sin += - dt * g / l * phi_without_sin;
+
+  gtk_widget_queue_draw_area (widget, 0, 0, WIDTH, HEIGHT);
+  g_timeout_add (50, (GSourceFunc) timer, widget);
+  return FALSE;
+}
+
+int main (int argc, char **argv)
+{
+  gtk_init (&argc, &argv);
+
+  GtkWidget *window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+  gtk_widget_show (window);
+  gtk_window_set_title (GTK_WINDOW (window), "Hello");
+  g_signal_connect (window, "destroy", G_CALLBACK (gtk_main_quit), NULL);
+
+  GtkWidget *drawing_area = gtk_drawing_area_new ();
+  gtk_widget_show (drawing_area);
+  gtk_container_add (GTK_CONTAINER (window), drawing_area);
+  gtk_widget_set_size_request (drawing_area, WIDTH, HEIGHT);
+  g_signal_connect (drawing_area, "draw", G_CALLBACK (draw), NULL);
+
+  g_timeout_add (50, (GSourceFunc) timer, drawing_area);
+
+  gtk_main ();
+  return 0;
+}