Engine filter: hide other-engine-only entries, list engine picks first

An Engine select (Any, Godot, Unity, Unreal Engine) on the catalog hides
entries whose engine_lock names another engine and sorts entries tagged
for the chosen engine (godot and godot-4, unity, unreal-engine and
unreal) first within each category. It is carried in the URL as engine=,
shown as an active-filter chip, and unknown values are ignored. On a
UE-only entry page the engine lock is now the first row of the facts
panel. Checked in Chromium: ?engine=godot shows 412 of 417 entries, with
the UE-only ones hidden and Godot tools first.

Closes #160

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

Author: TMHSDigital

site/lib/entry-page.mjs

@@ -81,13 +81,14 @@ export function entryPageHtml({ entry, leadHtml, restHtml, deprecatedReasonHtml,
   const licence =
     entry.license_spdx && entry.license_spdx !== entry.license ? `${entry.license} (${entry.license_spdx})` : entry.license;
   const rows = [
+    // Usable in one engine only: the first thing a reader must know.
+    entry.engine_lock ? ["Engine lock", esc(ENGINE_LOCK_NOTES[entry.engine_lock] || entry.engine_lock)] : null,
     ["Licence", esc(licence)],
     ["Commercial use", esc(commercialLabel(entry.commercial))],
     ["Credit", esc(c.value)],
     ["Status", `${esc(entry.status)}: ${esc(STATUS_NOTES[entry.status] || "")}`],
     ["Verified", `<span class="verified is-${age.bucket}">${esc(ageText)}</span>`],
     entry.maintenance ? ["Maintenance", `${esc(entry.maintenance)}: ${esc(MAINTENANCE_NOTES[entry.maintenance] || "")}`] : null,
-    entry.engine_lock ? ["Engine lock", esc(ENGINE_LOCK_NOTES[entry.engine_lock] || entry.engine_lock)] : null,
     entry.ue_versions ? ["Unreal Engine", `${esc(entry.ue_versions)}, as stated by the source`] : null,
     entry.publisher ? ["Publisher", esc(entry.publisher)] : null,
     ["Formats", esc((entry.formats || []).join(", ") || "none listed")],

site/lib/lib.test.mjs

@@ -763,7 +763,7 @@ eq("every word must match", kScore("ui zzz"), 0);
 eq("name hit outranks summary hit", kScore("kit") > kScore("panels"), true);
 eq("regex characters are literal", kScore("c++"), 0);
 
-const URL_DEF = { category: "all", q: "", active: true, review: true, deprecated: false, commercialOnly: false, noAttr: false, perspective: "any", license: "any", format: "any", sort: "name" };
+const URL_DEF = { category: "all", q: "", active: true, review: true, deprecated: false, commercialOnly: false, noAttr: false, perspective: "any", license: "any", format: "any", engine: "any", sort: "name" };
 const URL_ALLOWED = { category: ["all", "2d", "3d"], sort: ["name", "license", "verified"], perspective: ["any", "top_down"], license: ["any", "cc0"], format: ["any", "image"] };
 const urlSt = readState("?cat=2d&q=pixel&sort=bogus&view=top_down&deprecated=1&review=maybe&licence=cc0", URL_DEF, URL_ALLOWED);
 eq("url: known category kept", urlSt.category, "2d");
@@ -781,6 +781,16 @@ eq("url: blank q not written", stateQuery({ ...URL_DEF, q: "   " }, URL_DEF), ""
 const fmtGroups = { image: { formats: ["PNG", "SVG"] } };
 eq("filter: needs-review hidden when review off", passesFilters({ status: "needs-review" }, { ...URL_DEF, review: false }), false);
 eq("filter: deprecated hidden by default", passesFilters({ status: "deprecated" }, URL_DEF), false);
+{
+  const { ENGINES: EN, engineRank: er } = await import("./search.mjs");
+  eq("engine: godot hides UE-only", passesFilters({ status: "active", engine_lock: "unreal" }, { ...URL_DEF, engine: "godot" }), false);
+  eq("engine: unreal keeps UE-only", passesFilters({ status: "active", engine_lock: "unreal" }, { ...URL_DEF, engine: "unreal" }), true);
+  eq("engine: agnostic entries stay", passesFilters({ status: "active" }, { ...URL_DEF, engine: "godot" }), true);
+  eq("engine: godot-tagged ranks first", er({ tags: ["godot-4"] }, "godot") - er({ tags: ["pixel"] }, "godot"), -1);
+  eq("engine: url round-trips", readState("?engine=unity", URL_DEF, { engine: ["any", ...Object.keys(EN)] }).engine, "unity");
+  eq("engine: written to the url", stateQuery({ ...URL_DEF, engine: "godot" }, URL_DEF), "engine=godot");
+  eq("engine: unknown value ignored", readState("?engine=cryengine", URL_DEF, { engine: ["any", ...Object.keys(EN)] }).engine, "any");
+}
 eq("filter: commercial-only keeps varies", passesFilters({ status: "active", commercial: "varies" }, { ...URL_DEF, commercialOnly: true }), true);
 eq("filter: commercial-only drops unknown", passesFilters({ status: "active", commercial: "unknown" }, { ...URL_DEF, commercialOnly: true }), false);
 eq("filter: no-attribution needs false, not unknown", passesFilters({ status: "active", attribution_required: "unknown" }, { ...URL_DEF, noAttr: true }), false);

site/lib/search.mjs

@@ -78,6 +78,7 @@ export function passesFilters(entry, state, formatGroups = {}) {
   if (state.noAttr && entry.attribution_required !== false) return false;
   if (state.perspective !== "any" && entry.camera_perspective !== state.perspective) return false;
   if (state.license !== "any" && entry.licenseFamily !== state.license) return false;
+  if (state.engine && state.engine !== "any" && entry.engine_lock && entry.engine_lock !== state.engine) return false;
   if (state.format !== "any") {
     const wanted = formatGroups[state.format]?.formats || [];
     if (!(entry.formats || []).some((f) => wanted.includes(f))) return false;
@@ -86,12 +87,32 @@ export function passesFilters(entry, state, formatGroups = {}) {
 }
 
 /** Choice params: URL key -> state field. `allowed` supplies each field's legal values. */
+/**
+ * The engine filter. An entry locked to another engine (engine_lock) is
+ * hidden; entries tagged for the chosen engine sort first. Everything else
+ * is engine-agnostic and stays listed.
+ */
+export const ENGINES = {
+  godot: { label: "Godot", tags: ["godot", "godot-4"] },
+  unity: { label: "Unity", tags: ["unity"] },
+  unreal: { label: "Unreal Engine", tags: ["unreal-engine", "unreal"] },
+};
+
+/** 0 when an entry is made for `engine` (tagged for it or locked to it), else 1. */
+export function engineRank(entry, engine) {
+  const e = ENGINES[engine];
+  if (!e) return 0;
+  if (entry.engine_lock === engine) return 0;
+  return (entry.tags || []).some((t) => e.tags.includes(t)) ? 0 : 1;
+}
+
 const CHOICES = [
   ["cat", "category"],
   ["sort", "sort"],
   ["view", "perspective"],
   ["licence", "license"],
   ["format", "format"],
+  ["engine", "engine"],
 ];
 /** On/off params: URL key -> state field, written as 1 or 0. */
 const SWITCHES = [
@@ -132,7 +153,7 @@ export function stateQuery(state, defaults) {
   const field = Object.fromEntries(CHOICES);
   if (state.category !== defaults.category) p.set("cat", state.category);
   if (state.q.trim()) p.set("q", state.q.trim());
-  for (const key of ["sort", "view", "licence", "format"]) {
+  for (const key of ["sort", "view", "licence", "format", "engine"]) {
     if (state[field[key]] !== defaults[field[key]]) p.set(key, state[field[key]]);
   }
   for (const [key, f] of SWITCHES) {

site/public/app.js

@@ -1,4 +1,4 @@
-import { closestEntries, passesFilters as passes, queryTests as compileQuery, readState, scoreFields, searchFields, slugOf, stateQuery } from "./search.js";
+import { closestEntries, passesFilters as passes, queryTests as compileQuery, readState, scoreFields, searchFields, slugOf, stateQuery, ENGINES, engineRank } from "./search.js";
 import { CARD_LIMIT, LIST_LIMIT, commercialLabel, entryCardHtml, escapeHtml, groupHeadingHtml, groupMoreHtml, PERSPECTIVE_LABELS } from "./cards.mjs";
 import { installViewToggles } from "./views.js";
 
@@ -29,6 +29,7 @@ import { installViewToggles } from "./views.js";
     perspective: "any",
     license: "any",
     format: "any",
+    engine: "any",
     sort: "name",
   };
   const state = { ...DEFAULTS };
@@ -78,6 +79,7 @@ import { installViewToggles } from "./views.js";
         sort: Object.keys(SORTS),
         perspective: ["any", ...Object.keys(PERSPECTIVE_LABELS)],
         license: ["any", ...Object.keys(LICENSE_FAMILIES)],
+        engine: ["any", ...Object.keys(ENGINES)],
         format: ["any", ...Object.keys(FORMAT_GROUPS)],
       })
     );
@@ -143,7 +145,7 @@ import { installViewToggles } from "./views.js";
       // Searching under the default sort: best match first, then by name.
       list.sort((a, b) => score.get(b.id) - score.get(a.id) || SORTS.name(a, b));
     } else {
-      list.sort(SORTS[state.sort] || SORTS.name);
+      list.sort(sorter());
     }
     return { list, counts, total: pool.length, ranked };
   }
@@ -179,6 +181,13 @@ import { installViewToggles } from "./views.js";
       a.name.localeCompare(b.name),
   };
 
+  /** The chosen sort, with entries made for the chosen engine first. */
+  function sorter() {
+    const by = SORTS[state.sort] || SORTS.name;
+    if (state.engine === "any") return by;
+    return (a, b) => engineRank(a, state.engine) - engineRank(b, state.engine) || by(a, b);
+  }
+
   /* ---------------------------------------------------------- rendering */
 
   /** A category's view on this page: the config default (cards or list). */
@@ -278,6 +287,7 @@ import { installViewToggles } from "./views.js";
       });
     if (state.license !== DEFAULTS.license)
       chips.push({ key: "license", label: `licence: ${LICENSE_FAMILIES[state.license] || state.license}` });
+    if (state.engine !== DEFAULTS.engine) chips.push({ key: "engine", label: `engine: ${ENGINES[state.engine]?.label || state.engine}` });
     if (state.format !== DEFAULTS.format)
       chips.push({ key: "format", label: `format: ${FORMAT_GROUPS[state.format]?.label || state.format}` });
     if (!state.active) chips.push({ key: "active", label: "hiding active" });
@@ -443,7 +453,7 @@ import { installViewToggles } from "./views.js";
       placedKey = key;
       const shown = new Set(list.map((e) => e.id));
       const rest = data.entries.filter((e) => !shown.has(e.id));
-      const all = ranked ? [...list, ...rest] : data.entries.slice().sort(SORTS[state.sort] || SORTS.name);
+      const all = ranked ? [...list, ...rest] : data.entries.slice().sort(sorter());
       // Entries not rendered yet (the preview page) are simply not placed.
       const node = (e) => cardNodes.get(e.id);
       const order = [flatHeading];
@@ -670,6 +680,7 @@ import { installViewToggles } from "./views.js";
 
     const selects = [
       ["#license-family", "license", LICENSE_FAMILIES],
+      ["#engine", "engine", Object.fromEntries(Object.entries(ENGINES).map(([k, e]) => [k, e.label]))],
       ["#format-group", "format", Object.fromEntries(Object.entries(FORMAT_GROUPS).map(([k, g]) => [k, g.label]))],
     ];
     for (const [sel, field, choices] of selects) {
@@ -870,6 +881,7 @@ import { installViewToggles } from "./views.js";
     $("#sort").value = state.sort;
     $("#perspective").value = state.perspective;
     $("#license-family").value = state.license;
+    $("#engine").value = state.engine;
     $("#format-group").value = state.format;
   }
 

site/public/index.html

@@ -140,6 +140,12 @@ <h2 id="catalog-title">Catalog</h2>
                 <option value="any">Any</option>
               </select>
             </label>
+            <label class="check sort-field" title="Hides entries licensed for another engine only, and lists ones made for this engine first">
+              <span>Engine</span>
+              <select id="engine">
+                <option value="any">Any</option>
+              </select>
+            </label>
             <label class="check sort-field" title="Entries offering at least one of these formats">
               <span>Format</span>
               <select id="format-group">