First commit of akamaru.

3 files changed, 603 insertions, 0 deletions

diff --git a/COPYING b/COPYING
new file mode 100644
index 0000000..76b4213
--- /dev/null
+++ b/COPYING
@@ -0,0 +1,20 @@
+Akamaru is Copyright © 2005 Kristian Høgsberg
+
+Permission to use, copy, modify, distribute, and sell this software
+and its documentation for any purpose is hereby granted without fee,
+provided that the above copyright notice appear in all copies and that
+both that copyright notice and this permission notice appear in
+supporting documentation, and that the name of Kristian Høgsberg not
+be used in advertising or publicity pertaining to distribution of the
+software without specific, written prior permission. Kristian Høgsberg
+makes no representations about the suitability of this software for
+any purpose.  It is provided "as is" without express or implied
+warranty.
+
+KRISTIAN HØGSBERG DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
+SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+FITNESS, IN NO EVENT SHALL KRISTIAN HØGSBERG BE LIABLE FOR ANY
+SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
+RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF
+CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..f16a831
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,12 @@
+CFLAGS = -Wall -g
+CPPFLAGS = $(shell pkg-config --cflags gtk+-2.0 cairo)
+LDLIBS = $(shell pkg-config --libs gtk+-2.0 cairo)
+LDFLAGS = -g
+
+target = akamaru
+objs = akamaru.o
+
+$(target) : $(objs)
+
+clean :
+	rm $(target) $(objs)
diff --git a/akamaru.c b/akamaru.c
new file mode 100644
index 0000000..7e3c348
--- /dev/null
+++ b/akamaru.c
@@ -0,0 +1,571 @@
+/*                                           -*- mode: c; c-basic-offset: 2 -*-
+ * To compile:
+ *
+ *     gcc -Wall -g $(pkg-config --cflags --libs gtk+-2.0 cairo) \
+ *             akamaru.c -o akamaru
+ *
+ * See:
+ *
+ *     http://en.wikipedia.org/wiki/Verlet_integration
+ *     http://www.teknikus.dk/tj/gdc2001.htm
+ *
+ * TODO:
+ *
+ *     - Fix box collision test
+ *     - Add stick objects instead of hardcoding sticks
+ *     - Add code to add boxes
+ *     - Add circle object
+ */
+
+#include <gtk/gtk.h>
+#include <cairo.h>
+#include <cairo-xlib.h>
+#include <gdk/gdkx.h>
+#include <math.h>
+
+const double stick_length = 10;
+const double ground_friction = 0.1, ground_level = 400;
+const double box_left = 200, box_top = 200, box_bottom = 210;
+const double elasticity = 0.7;
+const double edge_fuzz = 1;
+
+typedef struct _xy_pair Point;
+typedef struct _xy_pair Vector;
+struct _xy_pair {
+  double x, y;
+};
+
+typedef struct _Object Object;
+typedef struct _Stick Stick;
+typedef struct _Model Model;
+
+struct _Object {
+  Vector force;
+
+  Point position;
+  Point previous_position;
+  Vector velocity;
+
+  double mass;
+  double theta;
+};
+
+struct _Stick {
+  Object *a, *b;
+};
+
+struct _Model {
+  int num_objects;
+  Object *objects;
+  int num_sticks;
+  Stick *sticks;
+  double k;
+  double friction;
+
+  Object *anchor_object;
+  Vector anchor_position;
+
+  double theta;
+};
+
+static void
+model_init (Model *model)
+{
+  const int num_objects = 20;
+  const int num_sticks = 40 - 3;
+  int i;
+
+  model->objects = g_new (Object, num_objects);
+  model->num_objects = num_objects;
+  model->sticks = g_new (Stick, num_sticks);
+  model->num_sticks = num_sticks;
+
+  for (i = 0; i < num_objects; i++) {
+    model->objects[i].position.x = 200;
+    model->objects[i].position.y = i * stick_length + 40;
+    model->objects[i].previous_position.x = 200;
+    model->objects[i].previous_position.y = i * stick_length + 40;
+
+    if (i + 1 < num_objects) {
+      model->sticks[i * 2].a = &model->objects[i];
+      model->sticks[i * 2].b = &model->objects[i + 1];
+    }
+    if (i + 2 < num_objects) {
+    model->sticks[i * 2 + 1].a = &model->objects[i];
+    model->sticks[i * 2 + 1].b = &model->objects[i + 2];
+    }
+  }
+
+  model->anchor_object = NULL;
+}
+
+static void
+model_accumulate_forces (Model *model)
+{
+  int i;
+
+  for (i = 0; i < model->num_objects; i++) {
+    model->objects[i].force.x = 0;
+    model->objects[i].force.y = 3;
+  }
+}
+
+static void
+model_integrate (Model *model, double step)
+{
+  double x, y;
+  Object *o;
+  int i;
+
+  for (i = 0; i < model->num_objects; i++) {
+    o = &model->objects[i];
+    x = o->position.x;
+    y = o->position.y;
+    
+    o->position.x =
+      x + (x - o->previous_position.x) + o->force.x * step * step;
+    o->position.y =
+      y + (y - o->previous_position.y) + o->force.y * step * step;
+
+    o->previous_position.x = x;
+    o->previous_position.y = y;
+  }
+}
+
+static void
+model_constrain (Model *model, double step)
+{
+  double dx, dy, x, y, distance, fraction, squared;
+  int i, j;
+
+  /* Anchor object constraint. */
+  if (model->anchor_object != NULL) {
+    model->anchor_object->position.x = model->anchor_position.x;
+    model->anchor_object->position.y = model->anchor_position.y;
+    model->anchor_object->previous_position.x = model->anchor_position.x;
+    model->anchor_object->previous_position.y = model->anchor_position.y;
+  }
+
+  /* FIXME: this should be "is point inside box" test instead. Figure
+   * out from previous_position which edge the point has passed
+   * through and reflect in that. */
+  for (i = 0; i < model->num_objects; i++) {
+    x = model->objects[i].position.x;
+    y = model->objects[i].position.y;
+    if (box_top - edge_fuzz <= y &&
+	model->objects[i].previous_position.y <= box_top + edge_fuzz &&
+	x < box_left) {
+      model->objects[i].position.y = box_top - (y - box_top) * elasticity;
+      model->objects[i].previous_position.y =
+	box_top - (model->objects[i].previous_position.y - box_top) * elasticity;
+    }
+  }
+
+  /* Ground collision detection constraints.  This puts a ground level
+   * in to make sure the points don't fall off the screen. */
+  for (i = 0; i < model->num_objects; i++) {
+    x = model->objects[i].position.x;
+    y = model->objects[i].position.y;
+
+    if (model->objects[i].position.y > ground_level) {
+      model->objects[i].position.y =
+	ground_level - (model->objects[i].position.y - ground_level) * elasticity;
+      model->objects[i].previous_position.y =
+	ground_level - (model->objects[i].previous_position.y - ground_level) * elasticity;
+
+      /* Friction on impact */
+      model->objects[i].position.x =
+	model->objects[i].position.x * (1 - ground_friction) +
+	model->objects[i].previous_position.x * ground_friction;
+    }
+  }
+
+#if 1
+  /* Stick constraints. */
+  for (i = 0; i < model->num_sticks; i++) {
+    x = model->sticks[i].a->position.x;
+    y = model->sticks[i].a->position.y;
+    dx = model->sticks[j].b->position.x - x;
+    dy = model->sticks[j].b->position.y - y;
+    distance = sqrt (dx * dx + dy * dy);
+    fraction = (distance - stick_length) / distance / 2;
+    model->sticks[i].a->position.x = x + dx * fraction;
+    model->sticks[i].a->position.y = y + dy * fraction;
+    model->sticks[j].b->position.x = x + dx * (1 - fraction);
+    model->sticks[j].b->position.y = y + dy * (1 - fraction);
+  }
+#else
+  /* Stick constraints, without square roots. */
+  squared = stick_length * stick_length;
+  for (i = 0; i < model->num_objects - 1; i++) {
+    j = i + 1;
+    x = model->objects[i].position.x;
+    y = model->objects[i].position.y;
+    dx = model->objects[j].position.x - x;
+    dy = model->objects[j].position.y - y;
+    fraction = squared / (dx * dx + dy * dy + squared) - 0.5;
+    model->objects[i].position.x = x + dx * fraction;
+    model->objects[i].position.y = y + dy * fraction;
+    model->objects[j].position.x = x + dx * (1 - fraction);
+    model->objects[j].position.y = y + dy * (1 - fraction);
+  }
+#endif
+}
+
+static void
+model_step (Model *model, double delta_t)
+{
+  int i;
+
+  model_accumulate_forces (model);
+  model_integrate (model, delta_t);
+
+  for (i = 0; i < 10; i++)
+    model_constrain (model, delta_t);
+
+  model->theta += delta_t;
+}
+
+static double
+object_distance (Object *object, double x, double y)
+{
+  double dx, dy;
+
+  dx = object->position.x - x;
+  dy = object->position.y - y;
+
+  return sqrt (dx*dx + dy*dy);
+}
+
+static Object *
+model_find_nearest (Model *model, double x, double y)
+{
+  Object *object;
+  double distance, min_distance;
+  int i;
+
+  for (i = 0; i < model->num_objects; i++) {
+    distance = object_distance (&model->objects[i], x, y);
+    if (i == 0 || distance < min_distance) {
+      min_distance = distance;
+      object = &model->objects[i];
+    }
+  }
+
+  return object;
+}
+
+typedef struct _Color Color;
+struct _Color {
+  double red, green, blue;
+};
+
+static void
+draw_star (cairo_t      *cr,
+	   gdouble	cx,
+	   gdouble	cy,
+	   double	theta,
+	   Color	*color)
+{
+  const int spike_count = 5;
+  const int inner_radius = 2;
+  const int outer_radius = 4;
+  double x, y;
+  int i;
+
+  cairo_set_source_rgba (cr, color->red, color->green, color->blue, 0.5);
+  cairo_new_path (cr);
+  for (i = 0; i < spike_count; i++) {
+    x = cx + cos ((i * 2) * M_PI / spike_count + theta) * inner_radius;
+    y = cy + sin ((i * 2) * M_PI / spike_count + theta) * inner_radius;
+
+    if (i == 0)
+      cairo_move_to (cr, x, y);
+    else
+      cairo_line_to (cr, x, y);
+		 
+    x = cx + cos ((i * 2 + 1) * M_PI / spike_count + theta) * outer_radius;
+    y = cy + sin ((i * 2 + 1) * M_PI / spike_count + theta) * outer_radius;
+
+    cairo_line_to (cr, x, y);
+  }
+  cairo_fill (cr);
+}
+
+static void
+draw_lines (cairo_t *cr,
+	    Model   *model,
+	    Color   *color)
+{
+  int i;
+
+  cairo_set_source_rgba (cr, color->red, color->green, color->blue, 0.5);
+  cairo_new_path (cr);
+  cairo_set_line_width (cr, 4);
+  cairo_set_line_join (cr, CAIRO_LINE_JOIN_ROUND);
+  cairo_set_line_cap (cr, CAIRO_LINE_CAP_ROUND);
+
+  for (i = 0; i < model->num_objects; i++) {
+    cairo_line_to (cr,
+		   model->objects[i].position.x,
+		   model->objects[i].position.y);
+  }
+
+  cairo_stroke (cr);
+}
+
+static void
+draw_constraints (cairo_t *cr,
+		  Model	  *model,
+		  Color   *color)
+{
+  cairo_set_source_rgba (cr, color->red, color->green, color->blue, 0.5);
+
+  cairo_move_to (cr, 0, ground_level);
+  cairo_line_to (cr, 1500, ground_level);
+  cairo_line_to (cr, 1500, ground_level + 10);
+  cairo_line_to (cr, 0, ground_level + 10);
+  cairo_close_path (cr);
+
+  cairo_move_to (cr, 0, box_top);
+  cairo_line_to (cr, box_left, box_top);
+  cairo_line_to (cr, box_left, box_bottom);
+  cairo_line_to (cr, 0, box_bottom);
+  cairo_close_path (cr);
+
+  cairo_fill (cr);
+}
+
+static Color blue = { 0, 0, 1 };
+static Color red = { 1, 0, 0 };
+
+static gboolean
+sproing_expose_event (GtkWidget      *widget,
+		      GdkEventExpose *event,
+		      gpointer	      data)
+{
+  Model *model = data;
+  int i;
+  cairo_t *cr;
+
+  cr = gdk_cairo_create (widget->window);
+
+  cairo_set_source_rgb (cr, 1, 1, 1);
+  cairo_paint (cr);
+
+  draw_constraints (cr, model, &red);
+  draw_lines (cr, model, &blue);
+
+#if 0
+  for (i = 0; i < model->num_objects; i++) {
+    draw_star (widget, model->objects[i].position.x,
+	       model->objects[i].position.y, model->objects[i].theta, &blue);
+  }
+#endif
+
+  cairo_destroy (cr);
+
+  return TRUE;
+}
+
+static gboolean
+sproing_button_press_event (GtkWidget	   *widget,
+			    GdkEventButton *event,
+			    gpointer	    data)
+{
+  Model *model = data;
+
+  if (event->button != 1)
+    return TRUE;
+
+  model->anchor_position.x = event->x;
+  model->anchor_position.y = event->y;
+  model->anchor_object = model_find_nearest (model, event->x, event->y);
+
+  return TRUE;
+}
+
+static gboolean
+sproing_button_release_event (GtkWidget	     *widget,
+			      GdkEventButton *event,
+			      gpointer	      data)
+{
+  Model *model = data;
+
+  if ((event->state & GDK_BUTTON1_MASK) == 0)
+    return TRUE;
+
+  model->anchor_object = NULL;
+
+  return TRUE;
+}
+
+static gboolean
+sproing_motion_notify_event (GtkWidget	    *widget,
+			     GdkEventMotion *event,
+			     gpointer	     data)
+{
+  Model *model = data;
+  int x, y;
+  GdkModifierType state;
+
+  gdk_window_get_pointer (event->window, &x, &y, &state);
+
+  model->anchor_position.x = x + 0.5;
+  model->anchor_position.y = y + 0.5;
+
+  return TRUE;
+}
+
+static void
+spring_constant_changed (GtkSpinButton *spinbutton, gpointer user_data)
+{
+  Model *model = user_data;
+
+  model->k = gtk_spin_button_get_value (spinbutton);
+}
+
+static void
+friction_changed (GtkSpinButton *spinbutton, gpointer user_data)
+{
+  Model *model = user_data;
+
+  model->friction = gtk_spin_button_get_value (spinbutton);
+}
+
+static GtkWidget *
+create_spinners (Model *model)
+{
+  GtkWidget *hbox;
+  GtkWidget *spinner, *label;
+
+  hbox = gtk_hbox_new (FALSE, 8);
+
+  label = gtk_label_new_with_mnemonic ("_Spring constant:");
+  gtk_box_pack_start (GTK_BOX (hbox), label, FALSE, FALSE, 0);
+  spinner = gtk_spin_button_new_with_range  (0.05, 30.00, 0.05);
+  gtk_label_set_mnemonic_widget (GTK_LABEL (label), spinner);
+  gtk_box_pack_start (GTK_BOX (hbox), spinner, FALSE, FALSE, 0);
+  gtk_spin_button_set_value (GTK_SPIN_BUTTON (spinner), model->k);
+  g_signal_connect (spinner, "value-changed",
+		    G_CALLBACK (spring_constant_changed), model);
+
+  label = gtk_label_new_with_mnemonic ("_Friction:");
+  gtk_box_pack_start (GTK_BOX (hbox), label, FALSE, FALSE, 0);
+  spinner = gtk_spin_button_new_with_range  (0.05, 15.00, 0.05);
+  gtk_label_set_mnemonic_widget (GTK_LABEL (label), spinner);
+  gtk_box_pack_start (GTK_BOX (hbox), spinner, FALSE, FALSE, 0);
+  gtk_spin_button_set_value (GTK_SPIN_BUTTON (spinner), model->friction);
+  g_signal_connect (spinner, "value-changed",
+		    G_CALLBACK (friction_changed), model);
+
+  return hbox;
+}
+
+static GtkWidget *
+create_window (Model *model)
+{
+  GtkWidget *window;
+  GtkWidget *frame;
+  GtkWidget *vbox;
+  GtkWidget *da;
+  GtkWidget *spinners;
+
+  window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+  gtk_window_set_title (GTK_WINDOW (window), "Drawing Area");
+
+  g_signal_connect (window, "destroy",
+		    G_CALLBACK (gtk_main_quit), &window);
+
+  gtk_container_set_border_width (GTK_CONTAINER (window), 8);
+
+  vbox = gtk_vbox_new (FALSE, 8);
+  gtk_container_set_border_width (GTK_CONTAINER (vbox), 8);
+  gtk_container_add (GTK_CONTAINER (window), vbox);
+
+  /*
+   * Create the drawing area
+   */
+      
+  frame = gtk_frame_new (NULL);
+  gtk_frame_set_shadow_type (GTK_FRAME (frame), GTK_SHADOW_IN);
+  gtk_box_pack_start (GTK_BOX (vbox), frame, TRUE, TRUE, 0);
+      
+  da = gtk_drawing_area_new ();
+  /* set a minimum size */
+  gtk_widget_set_size_request (da, 600, 500);
+
+  gtk_container_add (GTK_CONTAINER (frame), da);
+
+  /* Signals used to handle backing pixmap */
+      
+  g_signal_connect (da, "expose_event",
+		    G_CALLBACK (sproing_expose_event), model);
+      
+  /* Event signals */
+      
+  g_signal_connect (da, "motion_notify_event",
+		    G_CALLBACK (sproing_motion_notify_event), model);
+  g_signal_connect (da, "button_press_event",
+		    G_CALLBACK (sproing_button_press_event), model);
+  g_signal_connect (da, "button_release_event",
+		    G_CALLBACK (sproing_button_release_event), model);
+
+  /* Ask to receive events the drawing area doesn't normally
+   * subscribe to
+   */
+  gtk_widget_set_events (da, gtk_widget_get_events (da)
+			 | GDK_LEAVE_NOTIFY_MASK
+			 | GDK_BUTTON_PRESS_MASK
+			 | GDK_BUTTON_RELEASE_MASK
+			 | GDK_POINTER_MOTION_MASK
+			 | GDK_POINTER_MOTION_HINT_MASK);
+
+  spinners = create_spinners (model);
+  gtk_box_pack_start (GTK_BOX (vbox), spinners, FALSE, FALSE, 0);
+
+  return da;
+}
+
+typedef struct _Closure Closure;
+struct _Closure {
+  GtkWidget *drawing_area;
+  Model *model;
+  int i;
+};
+
+static gint
+timeout_callback (gpointer data)
+{
+  Closure *closure = data;
+  int i;
+
+  for (i = 0; i < 3; i++)
+    model_step (closure->model, 0.5);
+
+  closure->i++;
+  if (closure->i == 1) {
+    gtk_widget_queue_draw (closure->drawing_area);
+    closure->i = 0;
+  }
+
+  return TRUE;
+}
+
+int
+main (int argc, char *argv[])
+{
+  Closure closure;
+  Model model;
+
+  gtk_init (&argc, &argv);
+  model_init (&model);
+  closure.drawing_area = create_window (&model);
+  closure.i = 0;
+  gtk_widget_show_all (gtk_widget_get_toplevel (closure.drawing_area));
+  closure.model = &model;
+  g_timeout_add (100, timeout_callback, &closure);
+  gtk_main ();
+
+  return 0;
+}