Add new 'Offset' constraint, new 'curtain' model and clean up drawing code.

diff --git a/akamaru.c b/akamaru.c
index 1c97fc5181df8007cf83e49016d3195a55a4b84a..629d01f87b108e42ec18698aef41722129259751 100644 (file)
--- a/akamaru.c
+++ b/akamaru.c
@@ -35,6 +35,7 @@ struct _xy_pair {
 
 typedef struct _Object Object;
 typedef struct _Stick Stick;
+typedef struct _Offset Offset;
 typedef struct _Model Model;
 
 struct _Object {
@@ -53,11 +54,18 @@ struct _Stick {
   int length;
 };
 
+struct _Offset {
+  Object *a, *b;
+  int dx, dy;
+};
+
 struct _Model {
   int num_objects;
   Object *objects;
   int num_sticks;
   Stick *sticks;
+  int num_offsets;
+  Offset *offsets;
   double k;
   double friction;
 
@@ -78,6 +86,7 @@ model_init_snake (Model *model)
   model->num_objects = num_objects;
   model->sticks = g_new (Stick, num_sticks);
   model->num_sticks = num_sticks;
+  model->num_offsets = 0;
 
   for (i = 0; i < num_objects; i++) {
     model->objects[i].position.x = random() % 200 + 20;
@@ -129,6 +138,54 @@ model_init_rope (Model *model)
   model->anchor_object = NULL;
 }
 
+static void
+model_init_curtain (Model *model)
+{
+  const int num_ropes = 5;
+  const int num_rope_objects = 15;
+  const int num_objects = num_ropes * num_rope_objects;
+  const int num_sticks = num_ropes * (num_rope_objects - 1);
+  const int stick_length = 10;
+  const int rope_offset = 30;
+  double x, y;
+  int i, j, index, stick_index;
+
+  model->objects = g_new (Object, num_objects);
+  model->num_objects = num_objects;
+  model->sticks = g_new (Stick, num_sticks);
+  model->num_sticks = num_sticks;
+  model->offsets = g_new (Offset, num_ropes - 1);
+  model->num_offsets = num_ropes - 1;
+
+  for (i = 0; i < num_ropes; i++) {
+    for (j = 0; j < num_rope_objects; j++) {
+      x = 200 + i * rope_offset;
+      y = 40 + j * stick_length;
+      index = i * num_rope_objects + j;
+      model->objects[index].position.x = x;
+      model->objects[index].position.y = y;
+      model->objects[index].previous_position.x = x;
+      model->objects[index].previous_position.y = y;
+
+      if (j + 1 < num_rope_objects) {
+       stick_index = i * (num_rope_objects - 1) + j;
+       model->sticks[stick_index].a = &model->objects[index];
+       model->sticks[stick_index].b = &model->objects[index + 1];
+       model->sticks[stick_index].length = stick_length;
+      }
+    }
+
+    if (i + 1 < num_ropes) {
+      model->offsets[i].a = &model->objects[i * num_rope_objects];
+      model->offsets[i].b = &model->objects[(i + 1) * num_rope_objects];
+      model->offsets[i].dx = rope_offset;
+      model->offsets[i].dy = 0;
+    }
+  }
+
+  model->anchor_object = NULL;
+}
+
 static void
 model_accumulate_forces (Model *model)
 {
@@ -165,7 +222,7 @@ model_integrate (Model *model, double step)
 static void
 model_constrain (Model *model, double step)
 {
-  double dx, dy, x, y, distance, fraction, squared;
+  double dx, dy, x, y, distance, fraction;
   int i;
 
   /* Anchor object constraint. */
@@ -210,6 +267,16 @@ model_constrain (Model *model, double step)
     }
   }
 
+  /* Offset constraints. */
+  for (i = 0; i < model->num_offsets; i++) {
+    x = (model->offsets[i].a->position.x + model->offsets[i].b->position.x) / 2;
+    y = (model->offsets[i].a->position.y + model->offsets[i].b->position.y) / 2;
+    model->offsets[i].a->position.x = x - model->offsets[i].dx / 2;
+    model->offsets[i].a->position.y = y - model->offsets[i].dy / 2;
+    model->offsets[i].b->position.x = x + model->offsets[i].dx / 2;
+    model->offsets[i].b->position.y = y + model->offsets[i].dy / 2;
+  }
+
 #if 1
   /* Stick constraints. */
   for (i = 0; i < model->num_sticks; i++) {
@@ -250,7 +317,7 @@ model_step (Model *model, double delta_t)
   model_accumulate_forces (model);
   model_integrate (model, delta_t);
 
-  for (i = 0; i < 50; i++)
+  for (i = 0; i < 5; i++)
     model_constrain (model, delta_t);
 
   model->theta += delta_t;
@@ -291,41 +358,34 @@ struct _Color {
 };
 
 static void
-draw_star (cairo_t      *cr,
-          gdouble      cx,
-          gdouble      cy,
-          double       theta,
-          Color        *color)
+draw_sticks (cairo_t *cr,
+            Model   *model,
+            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_set_source_rgba (cr, color->red, color->green, color->blue, 1);
   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_set_line_width (cr, 2);
+  cairo_set_line_join (cr, CAIRO_LINE_JOIN_ROUND);
+  cairo_set_line_cap (cr, CAIRO_LINE_CAP_ROUND);
+
+  for (i = 0; i < model->num_sticks; i++) {
+    cairo_move_to (cr,
+                  model->sticks[i].a->position.x,
+                  model->sticks[i].a->position.y);
+    cairo_line_to (cr,
+                  model->sticks[i].b->position.x,
+                  model->sticks[i].b->position.y);
   }
-  cairo_fill (cr);
+
+  cairo_stroke (cr);
 }
 
 static void
-draw_lines (cairo_t *cr,
-           Model   *model,
-           Color   *color)
+draw_offsets (cairo_t *cr,
+             Model   *model,
+             Color   *color)
 {
   int i;
 
@@ -335,13 +395,13 @@ draw_lines (cairo_t *cr,
   cairo_set_line_join (cr, CAIRO_LINE_JOIN_ROUND);
   cairo_set_line_cap (cr, CAIRO_LINE_CAP_ROUND);
 
-  for (i = 0; i < model->num_sticks; i++) {
+  for (i = 0; i < model->num_offsets; i++) {
     cairo_move_to (cr,
-                  model->sticks[i].a->position.x,
-                  model->sticks[i].a->position.y);
+                  model->offsets[i].a->position.x,
+                  model->offsets[i].a->position.y);
     cairo_line_to (cr,
-                  model->sticks[i].b->position.x,
-                  model->sticks[i].b->position.y);
+                  model->offsets[i].b->position.x,
+                  model->offsets[i].b->position.y);
   }
 
   cairo_stroke (cr);
@@ -369,8 +429,19 @@ draw_constraints (cairo_t *cr,
   cairo_fill (cr);
 }
 
+static void
+draw_objects (cairo_t *cr, Model *model, Color *color)
+{
+  int i;
+
+  for (i = 0; i < model->num_objects; i++) {
+  }
+}
+
 static Color blue = { 0, 0, 1 };
 static Color red = { 1, 0, 0 };
+static Color black = { 0, 0, 0 };
+static Color white = { 1, 1, 1 };
 
 static gboolean
 sproing_expose_event (GtkWidget      *widget,
@@ -386,14 +457,9 @@ sproing_expose_event (GtkWidget      *widget,
   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
+  draw_sticks (cr, model, &black);
+  draw_offsets (cr, model, &blue);
+  draw_objects (cr, model, &white);
 
   cairo_destroy (cr);
 
@@ -591,7 +657,7 @@ main (int argc, char *argv[])
   Model model;
 
   gtk_init (&argc, &argv);
-  model_init_snake (&model);
+  model_init_curtain (&model);
   closure.drawing_area = create_window (&model);
   closure.i = 0;
   gtk_widget_show_all (gtk_widget_get_toplevel (closure.drawing_area));