More things. So many things.

src/include/geom.h

@@ -1,13 +1,19 @@
 #ifndef GEOM_H
 #define GEOM_H
 
-#include <stdlib.h>
-#include <stdbool.h>
 #include <raylib.h>
+#include <stdbool.h>
+#include <stdlib.h>
 
 // The maximum number of Tris in a Plate.
 #define NTRI 4
 
+// A two dimensional vector.
+typedef struct {
+    int x;
+    int y;
+} Vec2;
+
 typedef struct {
     int x, y;
 } Pt;
@@ -35,6 +41,13 @@ bool tri_within(Pt pt, Tri* tri);
 // Get the center point of a Tri.
 Pt tri_center(Tri* tri);
 
+// Compare two points.
+int pt_cmp(const void* a, const void* b);
+
+// Get the convex hull around the area. Given the points in the area and their
+// number.
+Pt* cvx_hull(Pt* area, size_t n, size_t* out_n);
+
 typedef struct {
     Color col;
     size_t ntris;