feat(nav): 17.1/17.3 - ludic.nav over Recast & Detour v1.6.0 (zlib), built here from the pinned tag on the Mac and the PC (the DLL imports KERNEL32 alone): a navmesh per kind of walker from triangles with an area byte each and cylinders nothing stands in, saved and loaded as bytes; the nearest point, a path as corners (partial when the end cannot be reached), whether a straight line stays walkable, a cost per kind of ground. Tests on a hand-built meadow: round a post, over a ford, stopped at a bank, a saved mesh answering alike - Mac and PC

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/ludic.nav/tests/nav_test.ludic

@@ -0,0 +1,110 @@
+# nav_test.ludic - ludic.nav on ground built by hand: a 40 m meadow of metre squares, a post in its
+# middle, a river across it (area 0) with a ford or without one. A path goes round the post and over
+# the ford, stops at the bank when there is none, and a saved mesh answers as the built one did.
+import "ludic.nav"
+import "ludic.base"
+program NavTest {
+  numbers float
+
+  # the meadow, flat at y = 0; river 1 has a ford at z 30..34, river 2 none, river 0 is no river
+  function meadow(nav_st: mut NavState, kind: int, river: int, post: bool) -> bool {
+    let n = 40
+    let v = floats((n + 1) * (n + 1) * 3)
+    for j in 0 .. n + 1 {
+      for i in 0 .. n + 1 {
+        let o = (j * (n + 1) + i) * 3
+        v[o] = float(i)
+        v[o + 1] = 0.0
+        v[o + 2] = float(j)
+      }
+    }
+    let t = new []int
+    let area = buffer(n * n * 2)
+    for j in 0 .. n {
+      for i in 0 .. n {
+        let a = j * (n + 1) + i
+        push(t, a)
+        push(t, a + n + 1)
+        push(t, a + 1)
+        push(t, a + 1)
+        push(t, a + n + 1)
+        push(t, a + n + 2)
+        var k = 1
+        if river > 0 and i >= 18 and i < 22 and not (river == 1 and j >= 30 and j < 34) { k = 0 }
+        area[(j * n + i) * 2] = k
+        area[(j * n + i) * 2 + 1] = k
+      }
+    }
+    let cyl = floats(5)
+    cyl[0] = 20.0
+    cyl[1] = -1.0
+    cyl[2] = 20.0
+    cyl[3] = 2.0
+    cyl[4] = 4.0
+    var nc = 0
+    if post { nc = 1 }
+    return nav_build(nav_st, kind, v, (n + 1) * (n + 1), t, n * n * 2, area, cyl, nc, new NavConfig)
+  }
+  function last_x(nav_st: NavState) -> float { return nav_corner_x(nav_st, nav_corners(nav_st) - 1) }
+  function last_z(nav_st: NavState) -> float { return nav_corner_z(nav_st, nav_corners(nav_st) - 1) }
+
+  test "a path goes round a post, and the straight line through it is not walkable" (nav_st: mut NavState) {
+    expect(meadow(nav_st, NAV_PERSON, 0, true))
+    expect(nav_polygons(nav_st, NAV_PERSON) > 0)
+    let n = nav_path(nav_st, NAV_PERSON, 5.0, 0.0, 20.0, 35.0, 0.0, 20.0)
+    expect(n >= 3)
+    expect(not nav_partial(nav_st, NAV_PERSON))
+    expect(Math.abs(last_x(nav_st) - 35.0) < 0.1)
+    for i in 0 .. n {
+      let dx = nav_corner_x(nav_st, i) - 20.0
+      let dz = nav_corner_z(nav_st, i) - 20.0
+      expect(dx * dx + dz * dz > 2.0 * 2.0)
+    }
+    expect(not nav_straight(nav_st, NAV_PERSON, 5.0, 0.0, 20.0, 35.0, 20.0))
+    expect(nav_straight(nav_st, NAV_PERSON, 5.0, 0.0, 5.0, 35.0, 5.0))
+  }
+
+  test "a river is crossed at its ford" (nav_st: mut NavState) {
+    expect(meadow(nav_st, NAV_PERSON, 1, false))
+    let n = nav_path(nav_st, NAV_PERSON, 5.0, 0.0, 10.0, 35.0, 0.0, 10.0)
+    expect(n >= 3)
+    expect(not nav_partial(nav_st, NAV_PERSON))
+    var ford = false
+    for i in 0 .. n { if nav_corner_z(nav_st, i) > 29.0 { ford = true } }
+    expect(ford)
+  }
+
+  test "without a ford the path stops at the near bank and says so" (nav_st: mut NavState) {
+    expect(meadow(nav_st, NAV_PERSON, 2, false))
+    let n = nav_path(nav_st, NAV_PERSON, 5.0, 0.0, 10.0, 35.0, 0.0, 10.0)
+    expect(n >= 1)
+    expect(nav_partial(nav_st, NAV_PERSON))
+    expect(last_x(nav_st) < 18.0)
+  }
+
+  test "the nearest walkable point, and nothing off the mesh" (nav_st: mut NavState) {
+    expect(meadow(nav_st, NAV_PERSON, 0, false))
+    expect(nav_nearest(nav_st, NAV_PERSON, 10.0, 1.0, 10.0))
+    expect(Math.abs(nav_near_y(nav_st)) < 0.3)
+    expect(Math.abs(nav_near_x(nav_st) - 10.0) < 0.1)
+    expect(not nav_nearest(nav_st, NAV_PERSON, -50.0, 0.0, -50.0))
+    expect_eq(nav_path(nav_st, NAV_PERSON, -50.0, 0.0, -50.0, 10.0, 0.0, 10.0), -1)
+    expect_eq(nav_path(nav_st, NAV_LARGE, 5.0, 0.0, 5.0, 10.0, 0.0, 10.0), -1)
+  }
+
+  test "a mesh saved and loaded answers as the built one did" (nav_st: mut NavState) {
+    expect(meadow(nav_st, NAV_PERSON, 1, true))
+    let path = Os.temp_dir() + "/ludic_nav_test.navmesh"
+    expect(nav_save_file(nav_st, NAV_PERSON, path))
+    expect(nav_load_file(nav_st, NAV_SMALL, path))
+    let a = nav_path(nav_st, NAV_PERSON, 5.0, 0.0, 10.0, 35.0, 0.0, 10.0)
+    let ax = last_x(nav_st)
+    let az = last_z(nav_st)
+    let b = nav_path(nav_st, NAV_SMALL, 5.0, 0.0, 10.0, 35.0, 0.0, 10.0)
+    expect_eq(a, b)
+    expect_near(last_x(nav_st), ax, 0.0001)
+    expect_near(last_z(nav_st), az, 0.0001)
+    nav_reset(nav_st)
+    expect_eq(nav_polygons(nav_st, NAV_SMALL), 0)
+  }
+}