refactor: move quadtree and util functions into separate headers and clean up names

1 files changed, 45 insertions, 23 deletions

diff --git a/experimental/tectonics/world.c b/experimental/tectonics/world.c
index a1dd4de..5aead24 100644
--- a/experimental/tectonics/world.c
+++ b/experimental/tectonics/world.c
@@ -2,19 +2,17 @@
 #include <math.h>
 
 #include "tectonics.h"
-
-struct centroid_t {
-   double x, y;
-   int updates;
-};
+#include "geometry.h"
+#include "util.h"
 
 static void rebuild_tree(struct world_t *world)
 {
+   // remove any existing tree
    if (world->tree.nw != NULL) {
-      free_tree(world->tree.nw);
-      free_tree(world->tree.ne);
-      free_tree(world->tree.sw);
-      free_tree(world->tree.se);
+      quadtree_free(world->tree.nw);
+      quadtree_free(world->tree.ne);
+      quadtree_free(world->tree.sw);
+      quadtree_free(world->tree.se);
       world->tree.nw = NULL;
       world->tree.ne = NULL;
       world->tree.sw = NULL;
@@ -22,16 +20,28 @@ static void rebuild_tree(struct world_t *world)
    }
    world->tree.id = -1;
 
+   // build a new tree
    for (int i=0; i<world->n_points; i++) {
-      insert(&(world->tree), world->points, i);
+      quadtree_insert(&(world->tree), world->points, i);
    }
 }
 
+
+/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */
+
+struct centroid_t {
+   double x, y;
+   int updates;
+};
+
+// monte-carlo lloyd's algorithm
 static void relax_points(struct world_t *world, int iterations)
 {
+   // centroids to compute
    struct centroid_t *centroid =
       malloc(sizeof(struct centroid_t) * world->n_points);
-   
+
+   // initialize centroids with current locations
    for (int i=0; i<world->n_points; i++) {
       struct point_t *pt = world->points + i;
       struct centroid_t *c = centroid + i;
@@ -40,18 +50,22 @@ static void relax_points(struct world_t *world, int iterations)
       c->updates = 1;
    }
 
+   // approximate centroids
    for (int i=0; i<iterations; i++) {
       printf("%02f%%\n", 100*((double)i+1)/iterations);
+      // generate a random point and find the closest
+      // terrain point
       double x = rand01();
       double y = rand01();
-      int closest = get_closest(&(world->tree),
-				world->points,
-				(struct point_t){x, y});
+      int closest = quadtree_get_closest(&(world->tree),
+					 world->points,
+					 (struct point_t){x, y});
 
       if (closest == -1) {
 	 printf("WARN: bad closest point!\n");
       }
       else {
+	 // average the centroid towards that random point
 	 struct centroid_t *c = centroid + closest;
 	 int u = c->updates;
 	 c->x = (u*c->x + x)/(u+1);
@@ -60,6 +74,7 @@ static void relax_points(struct world_t *world, int iterations)
       }
    }
 
+   // update positions from centroids
    for (int i=0; i<world->n_points; i++) {
       struct point_t *pt = world->points + i;
       struct centroid_t *c = centroid + i;
@@ -72,6 +87,9 @@ static void relax_points(struct world_t *world, int iterations)
    free(centroid);
 }
 
+
+/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */
+
 void create_world(struct world_t *world, int n_points)
 {
    world->n_points = n_points;
@@ -84,35 +102,39 @@ void create_world(struct world_t *world, int n_points)
    }
 
    struct point_t center = { 0.5, 0.5 };
-   world->tree = new_node(center, 0.5);
+   world->tree = quadtree_new_node(center, 0.5);
 
    for (int i=0; i<n_points; i++) {
       struct point_t *pt = world->points + i;
       pt->x = rand01();
       pt->y = rand01();
 
-      //insert(&(world->tree), world->points, i);
+      //quadtree_insert(&(world->tree), world->points, i);
    }
 
    rebuild_tree(world);
 
-   for (int i=0; i<10; i++)
-      relax_points(world, 100000);
+   for (int i=0; i<3; i++)
+      relax_points(world, 10*world->n_points);
 }
 
 
+/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */
+
 void free_world(struct world_t *world)
 {
    if (world->tree.nw != NULL) {
-      free_tree(world->tree.nw);
-      free_tree(world->tree.ne);
-      free_tree(world->tree.sw);
-      free_tree(world->tree.se);
+      quadtree_free(world->tree.nw);
+      quadtree_free(world->tree.ne);
+      quadtree_free(world->tree.sw);
+      quadtree_free(world->tree.se);
    }
    free(world->points);
 }
 
 
+/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */
+
 void render_world(cairo_t *cr, struct world_t *world)
 {
    int width, height;
@@ -128,5 +150,5 @@ void render_world(cairo_t *cr, struct world_t *world)
       cairo_stroke(cr);
    }
 
-   draw_quadtree(cr, &(world->tree));
+   //draw_quadtree(cr, &(world->tree));
 }