fix: a harbour member is a true-metre object, not a scene-unit floor

`size(metres, floor)` took `floor` in scene units, tuned at 391 m to
the unit. On the merged California board those floors always won: a
340 m channel became 1.05 km. Floors are the metres those constants
measured on SoCal, so that board does not move and every other board
draws the same stone.

`portScale.test.ts` is the property that would have caught it: two
boards five times apart draw the same channel on the water.

src/engine/ports.ts

@@ -813,18 +813,21 @@ const CHANNEL_LIFT = 0.01;
  * How wide a breakwater is drawn, in metres, before the legibility floor.
  *
  * The federal breakwater at San Pedro is about ninety metres across its base,
- * which is 0.23 scene units — under half a pixel at the whole-board pose, where
+ * which is 0.23 scene units on Southern California — under half a pixel at the
- * this object has to do its most important work. So it carries a floor in scene
+ * whole-board pose, where this object has to do its most important work. So it
- * units the way `bridges.ts`'s members do, and for the same stated reason: an
+ * carries a floor in **metres** the way `bridges.ts`'s members do, and for the
- * invisible breakwater is a worse answer than a chunky one. `socal.ts`'s LA
+ * same stated reason: an invisible breakwater is a worse answer than a chunky
- * River sets the same precedent from the other direction, drawn at four times
+ * one. The floor used to be scene units (0.11 / 0.3), tuned at 391 m to the
- * its true width because anything narrower than a terrain cell renders as a
+ * unit. On the merged California board those always won, and the crest half
- * dotted line rather than a thin one.
+ * became 211 m. Floors are the metres those constants measured on SoCal, so
+ * that board does not move. `socal.ts`'s LA River sets the same precedent from
+ * the other direction, drawn at four times its true width because anything
+ * narrower than a terrain cell renders as a dotted line rather than a thin one.
  */
 const BREAKWATER_CREST_M = 44;
 const BREAKWATER_BASE_M = 140;
-const BREAKWATER_CREST_FLOOR = 0.11;
+const BREAKWATER_CREST_FLOOR_M = 43;
-const BREAKWATER_BASE_FLOOR = 0.3;
+const BREAKWATER_BASE_FLOOR_M = 117;
 /** Crest height above the waterline, metres. Exaggerated by the board like any height. */
 const BREAKWATER_CREST_HEIGHT_M = 7;
 
@@ -832,21 +835,40 @@ const BREAKWATER_CREST_HEIGHT_M = 7;
  * Dredged channel width, metres, and its floor.
  *
  * The Main Channel at San Pedro really is about 340 m between the shoal edges,
- * which is 0.87 units — legible at the Harbour pose and marginal at the whole
+ * which is 0.87 units on SoCal — legible at the Harbour pose and marginal at
- * board, hence the floor. It is one number for every channel on the board
+ * the whole board, hence the floor. The floor used to be 0.55 scene units:
- * rather than a field on `Port`, because a channel drawn wider than the water it
+ * 215 m at Los Angeles, 1.05 km on merged California. 340 m already clears
- * lies in laps onto the quay beside it, and 340 m is what the narrowest reach on
+ * 215 m, so both boards now draw the real channel. It is one number for every
- * this board can take.
+ * channel on the board rather than a field on `Port`, because a channel drawn
+ * wider than the water it lies in laps onto the quay beside it, and 340 m is
+ * what the narrowest reach on this board can take.
  */
 const CHANNEL_WIDTH_M = 340;
-const CHANNEL_FLOOR = 0.55;
+const CHANNEL_FLOOR_M = 215;
+
+/** Quay revetment toe, metres, and the floor that keeps it a strip of rock. */
+const QUAY_TOE_M = 26;
+const QUAY_TOE_FLOOR_M = 27;
 
 /** A gantry's dimensions, metres, and the floors that keep the members visible. */
 const CRANE_RAIL_GAUGE_M = 30;
 const CRANE_MEMBER_M = 5;
-const CRANE_GAUGE_FLOOR = 0.115;
+const CRANE_GAUGE_FLOOR_M = 45;
-const CRANE_MEMBER_FLOOR = 0.032;
+const CRANE_MEMBER_FLOOR_M = 12.5;
-const CRANE_OUTREACH_FLOOR = 0.26;
+const CRANE_OUTREACH_FLOOR_M = 102;
+
+/**
+ * Cross-section in metres, never thinner than `floorM` metres.
+ *
+ * The second argument used to be scene units, tuned at 391 m/unit. On a board
+ * 1,919 m to the unit those floors always won: a 340 m channel became 1.05 km.
+ * Floors are the metres those old constants measured on SoCal, so that board
+ * does not move and every other board draws the same stone.
+ */
+function size(world: World, metres: number, floorM: number): number {
+  return Math.max(metres, floorM) / world.metresPerUnit;
+}
+
 /** Degrees the boom stands at when it is raised. A stowed gantry is near vertical. */
 const CRANE_BOOM_IDLE_DEG = 74;
 
@@ -970,7 +992,6 @@ function buildPort(
   bandTotal: number,
 ): void {
   const unit = 1 / world.metresPerUnit;
-  const size = (metres: number, floor: number) => Math.max(metres * unit, floor);
   const plate = plateHeight(world, port);
 
   // ---- The breakwater -----------------------------------------------------
@@ -989,8 +1010,8 @@ function buildPort(
       "ports:stone",
       bermGeometry(
         points,
-        size(BREAKWATER_CREST_M / 2, BREAKWATER_CREST_FLOOR),
+        size(world, BREAKWATER_CREST_M / 2, BREAKWATER_CREST_FLOOR_M),
-        size(BREAKWATER_BASE_M / 2, BREAKWATER_BASE_FLOOR),
+        size(world, BREAKWATER_BASE_M / 2, BREAKWATER_BASE_FLOOR_M),
         world.metres(BREAKWATER_CREST_HEIGHT_M),
         SEA_Y - 0.02,
       ),
@@ -1008,7 +1029,7 @@ function buildPort(
     });
     batch.add(
       "ports:channel",
-      stripGeometry(points, size(CHANNEL_WIDTH_M, CHANNEL_FLOOR)),
+      stripGeometry(points, size(world, CHANNEL_WIDTH_M, CHANNEL_FLOOR_M)),
       paints.channel,
       { receive: false },
     );
@@ -1037,7 +1058,7 @@ function buildPort(
      * stops the wall reading as a razor-thin line where the concrete meets the
      * water. Two quads, and it is the third thing the STONE bucket is for.
      */
-    const toe = size(26, 0.07);
+    const toe = size(world, QUAY_TOE_M, QUAY_TOE_FLOOR_M);
     const toeA: [number, number] = [a[0] + outward[0] * toe, a[1] + outward[1] * toe];
     const toeB: [number, number] = [b[0] + outward[0] * toe, b[1] + outward[1] * toe];
     batch.add(
@@ -1184,12 +1205,10 @@ function pushCraneMatrices(
   plate: number,
   out: THREE.Matrix4[],
 ): void {
-  const unit = 1 / world.metresPerUnit;
+  const gauge = size(world, CRANE_RAIL_GAUGE_M, CRANE_GAUGE_FLOOR_M);
-  const size = (metres: number, floor: number) => Math.max(metres * unit, floor);
+  const member = size(world, CRANE_MEMBER_M, CRANE_MEMBER_FLOOR_M);
-  const gauge = size(CRANE_RAIL_GAUGE_M, CRANE_GAUGE_FLOOR);
-  const member = size(CRANE_MEMBER_M, CRANE_MEMBER_FLOOR);
   const portal = world.metres(crane.height);
-  const outreach = size(crane.outreach, CRANE_OUTREACH_FLOOR);
+  const outreach = size(world, crane.outreach, CRANE_OUTREACH_FLOOR_M);
 
   // The boom's horizontal direction in scene space: x east, z south.
   const [east, north] = bearingVector(crane.bearing);
@@ -1268,9 +1287,9 @@ function pushCraneMatrices(
     // Still two legs and not four. A real gantry has a leg at each corner of a
     // 27 × 30 m footprint, and at SoCal's 391 m to the unit that 14 m along the
     // quay is 0.036 units while the member floor that keeps a leg visible at
-    // all is 0.032 — the pair would overlap by ninety per cent and cost 56
+    // all is 12.5 m — 0.032 units on this board. The pair would overlap by
-    // extra boxes to draw one slightly fatter leg. The board's own scale is the
+    // ninety per cent and cost 56 extra boxes to draw one slightly fatter
-    // argument, not the triangle count.
+    // leg. The board's own scale is the argument, not the triangle count.
     push(rx, base + portal / 2, rz, member, portal, member);
     push(rx - boomX * gauge, base + portal / 2, rz - boomZ * gauge, member, portal, member);
 
@@ -1367,8 +1386,8 @@ function pushCraneMatrices(
 export function craneLights(world: World, port: Port): { heads: number[] } {
   const heads: number[] = [];
   const plate = plateHeight(world, port);
-  const gauge = Math.max(CRANE_RAIL_GAUGE_M / world.metresPerUnit, CRANE_GAUGE_FLOOR);
+  const gauge = size(world, CRANE_RAIL_GAUGE_M, CRANE_GAUGE_FLOOR_M);
-  const member = Math.max(CRANE_MEMBER_M / world.metresPerUnit, CRANE_MEMBER_FLOOR);
+  const member = size(world, CRANE_MEMBER_M, CRANE_MEMBER_FLOOR_M);
   const setback = gauge * CRANE_APEX_SETBACK;
   for (const crane of port.cranes ?? []) {
     // Clear of the apex cap, for the reason `bridges.ts` lifts its head lights
@@ -1396,7 +1415,7 @@ export function craneLights(world: World, port: Port): { heads: number[] } {
  * the crane it is supposed to be on, and nothing but a screenshot would catch it.
  */
 function craneApexY(world: World, crane: Crane, plate: number): number {
-  const member = Math.max(CRANE_MEMBER_M / world.metresPerUnit, CRANE_MEMBER_FLOOR);
+  const member = size(world, CRANE_MEMBER_M, CRANE_MEMBER_FLOOR_M);
   const portal = world.metres(crane.height);
   return plate + portal + member * 1.4 + portal * CRANE_MAST_RISE;
 }

src/test/render/craneLights.test.ts

@@ -132,7 +132,7 @@ describe("the container gantries mark themselves after dark", () => {
     // that height within a member of the drawn apex. The clearance is what stops
     // the sprite being half-eaten by the apex cap's own depth; more than a
     // member above it and the light has come off the crane.
-    const member = Math.max(5 / world.metresPerUnit, 0.032);
+    const member = Math.max(5, 12.5) / world.metresPerUnit;
     for (let i = 1; i < heads.length; i += 3) {
       const y = heads[i]!;
       assert.ok(

src/test/render/portScale.test.ts

@@ -0,0 +1,131 @@
+/**
+ * A harbour member is a true-metre object, and every board has to agree.
+ *
+ * `size(metres, floor)` used to take `floor` in scene units, tuned at 391 m to
+ * the unit on Southern California. On the merged California board (1,919 m/unit)
+ * those floors always won: a 340 m channel became 1.05 km, and San Pedro Bay
+ * read as a river. The floor is metres now. This is the property that would
+ * have caught it: two boards five times apart draw the same channel on the
+ * water.
+ */
+
+import assert from "node:assert/strict";
+import test from "node:test";
+import * as THREE from "three";
+
+import { createPorts } from "../../engine/ports.ts";
+import type { Port } from "../../engine/types.ts";
+import type { World } from "../../engine/world.ts";
+
+/**
+ * One straight channel and one gantry. Widths come from the kit, not from the
+ * pack, so the fixture only has to exist — two points of water, two points of
+ * rail.
+ */
+const SAMPLE: Port = {
+  id: "USXXX",
+  name: "Sample",
+  lat: 33.74,
+  lng: -118.27,
+  harborType: "CB",
+  channel: [
+    [33.74, -118.27],
+    [33.75, -118.27],
+  ],
+  cranes: [
+    {
+      from: [33.74, -118.26],
+      to: [33.741, -118.26],
+      count: 1,
+      bearing: 90,
+      height: 82,
+      outreach: 70,
+      idleFraction: 0,
+    },
+  ],
+};
+
+function board(latScale: number): World {
+  const centre = { lat: 33.82, lng: -118.05 };
+  const lngScale = latScale * Math.cos((centre.lat * Math.PI) / 180);
+  const metresPerUnit = 111_320 / latScale;
+  return {
+    project(lat: number, lng: number): [number, number] {
+      return [(lng - centre.lng) * lngScale, -(lat - centre.lat) * latScale];
+    },
+    groundAt(): number {
+      return 0;
+    },
+    metres(value: number): number {
+      return (value / metresPerUnit) * 3.4;
+    },
+    metresPerUnit,
+  } as unknown as World;
+}
+
+function namedMesh(root: THREE.Object3D, name: string): THREE.Mesh {
+  let found: THREE.Mesh | undefined;
+  root.traverse((object) => {
+    if (object instanceof THREE.Mesh && object.name === name) found = object;
+  });
+  assert.ok(found, `no mesh named ${name}`);
+  return found;
+}
+
+/** The dredged strip's width, in metres of real water. */
+function channelMetres(world: World): number {
+  const mesh = namedMesh(createPorts(world, [SAMPLE]), "ports:channel");
+  const pos = mesh.geometry.getAttribute("position");
+  assert.ok(pos && pos.count >= 2, "the channel strip has no rails to measure");
+  const width =
+    Math.hypot(pos.getX(0) - pos.getX(1), pos.getZ(0) - pos.getZ(1)) * world.metresPerUnit;
+  return width;
+}
+
+/**
+ * Distance between the two portal legs of the one gantry, in metres.
+ *
+ * `pushCraneMatrices` emits the waterside leg first and the landside leg next,
+ * `gauge` apart along the boom. Measuring the drawn matrices is the same move
+ * `craneLights.test.ts` makes for the apex: a helper that recomputes the
+ * number would pass while the mesh drifted.
+ */
+function craneGaugeMetres(world: World): number {
+  const mesh = namedMesh(createPorts(world, [SAMPLE]), "ports:cranes") as THREE.InstancedMesh;
+  assert.ok(mesh.count >= 2, "a gantry is at least two portal legs");
+  const a = new THREE.Matrix4();
+  const b = new THREE.Matrix4();
+  const pa = new THREE.Vector3();
+  const pb = new THREE.Vector3();
+  mesh.getMatrixAt(0, a);
+  mesh.getMatrixAt(1, b);
+  pa.setFromMatrixPosition(a);
+  pb.setFromMatrixPosition(b);
+  return Math.hypot(pa.x - pb.x, pa.z - pb.z) * world.metresPerUnit;
+}
+
+test("San Pedro's channel is the same width on a 391 m board and a 1,919 m one", () => {
+  const metro = channelMetres(board(285));
+  const state = channelMetres(board(58));
+  assert.ok(
+    Math.abs(metro - state) < 2,
+    `channel is ${metro.toFixed(0)} m at Los Angeles and ${state.toFixed(0)} m on California`,
+  );
+  assert.ok(
+    metro > 300 && metro < 400,
+    `channel measures ${metro.toFixed(0)} m; that is not a river`,
+  );
+});
+
+test("a gantry's rail gauge is the same metres on both boards", () => {
+  const metro = craneGaugeMetres(board(285));
+  const state = craneGaugeMetres(board(58));
+  assert.ok(
+    Math.abs(metro - state) < 1,
+    `gauge is ${metro.toFixed(1)} m at Los Angeles and ${state.toFixed(1)} m on California`,
+  );
+  assert.ok(
+    metro > 30 && metro < 60,
+    `gauge measures ${metro.toFixed(1)} m; that is not a city block`,
+  );
+});