feat(assets): EXT_materials_bump für gltf-transform

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tests/bumpExtension.test.js

@@ -0,0 +1,65 @@
+import { describe, expect, it } from "vitest";
+import { Document, NodeIO } from "@gltf-transform/core";
+import { KHRTextureTransform } from "@gltf-transform/extensions";
+import { dedup, prune } from "@gltf-transform/functions";
+import sharp from "sharp";
+import { EXT_MATERIALS_BUMP, EXTMaterialsBump } from "../tools/assets/bumpExtension.mjs";
+
+/** 8 × 8 px mit wechselnden Werten — prune() ersetzt einfarbige Texturen sonst durch Faktoren. */
+function pattern() {
+    const data = Buffer.alloc(8 * 8 * 3);
+    for (let i = 0; i < data.length; i++) data[i] = (i * 37) & 0xff;
+    return sharp(data, { raw: { width: 8, height: 8, channels: 3 } }).png().toBuffer();
+}
+
+/** Ein Dreieck mit dem Material cont_a_side, Bump-Stärke 2,2 und Wellenteilung [3.2, 1]. */
+async function bumpDocument() {
+    const document = new Document();
+    document.createBuffer();
+    const bumpExtension = document.createExtension(EXTMaterialsBump);
+    const transformExtension = document.createExtension(KHRTextureTransform);
+    const texture = document.createTexture("wellblech").setImage(await pattern()).setMimeType("image/png");
+    const bump = bumpExtension.createBump().setBumpFactor(2.2).setBumpTexture(texture);
+    bump.getBumpTextureInfo().setExtension("KHR_texture_transform", transformExtension.createTransform().setScale([3.2, 1]));
+    const material = document.createMaterial("cont_a_side").setExtension(EXT_MATERIALS_BUMP, bump);
+    const positions = document.createAccessor().setType("VEC3").setArray(new Float32Array([0, 0, 0, 1, 0, 0, 0, 1, 0]));
+    const primitive = document.createPrimitive().setMaterial(material).setAttribute("POSITION", positions);
+    document.createScene().addChild(document.createNode().setMesh(document.createMesh().addPrimitive(primitive)));
+    return document;
+}
+
+/** JSON-Teil einer .glb: 12 Byte Kopf, dann Länge und Typ des ersten Blocks, dann das JSON. */
+function glbJson(glb) {
+    const view = new DataView(glb.buffer, glb.byteOffset, glb.byteLength);
+    return JSON.parse(new TextDecoder().decode(glb.subarray(20, 20 + view.getUint32(12, true))));
+}
+
+describe("EXT_materials_bump", () => {
+    const io = () => new NodeIO().registerExtensions([EXTMaterialsBump, KHRTextureTransform]);
+
+    // Bruch: @gltf-transform verwirft die Erweiterung (Wellblech flach), prune entfernt die Textur als
+    // unbenutzt, oder die Wellenteilung an der bumpTexture geht verloren (Wellen 3,2-mal zu breit).
+    it("übersteht dedup, prune, Schreiben und Einlesen mit Stärke, Textur und Teilung", async () => {
+        const document = await bumpDocument();
+        await document.transform(dedup(), prune());
+
+        const read = await io().readBinary(await io().writeBinary(document));
+
+        const bump = read.getRoot().listMaterials()[0].getExtension(EXT_MATERIALS_BUMP);
+        expect(bump.getBumpFactor()).toBe(2.2);
+        expect(bump.getBumpTexture().getSize()).toEqual([8, 8]);
+        expect(bump.getBumpTextureInfo().getExtension("KHR_texture_transform").getScale()).toEqual([3.2, 1]);
+    });
+
+    // Bruch: Feldnamen oder Aufbau weichen von der Spezifikation ab — three.js (GLTFLoader) liest
+    // genau materials[i].extensions.EXT_materials_bump.bumpFactor und .bumpTexture.index.
+    it("schreibt das JSON so, wie three.js es liest", async () => {
+        const json = glbJson(await io().writeBinary(await bumpDocument()));
+
+        expect(json.extensionsUsed).toContain(EXT_MATERIALS_BUMP);
+        const def = json.materials[0].extensions[EXT_MATERIALS_BUMP];
+        expect(def.bumpFactor).toBe(2.2);
+        expect(json.textures[def.bumpTexture.index]).toBeDefined();
+        expect(def.bumpTexture.extensions.KHR_texture_transform.scale).toEqual([3.2, 1]);
+    });
+});