feat(assets): EXT_materials_bump für gltf-transform

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

tools/assets/bumpExtension.mjs

@@ -0,0 +1,101 @@
+// EXT_materials_bump für @gltf-transform (docs/superpowers/specs/2026-09-14-hood-yard-design.md).
+// @gltf-transform 4.5.0 kennt die Erweiterung nicht und verwirft sie beim Einlesen. Das Wellblech der
+// Container aus three-d-stage steckt aber allein darin, die Container selbst sind flache Kästen.
+// Aufgebaut wie KHR_materials_transmission in @gltf-transform/extensions: bumpTexture ist eine echte
+// Texturreferenz, damit dedup, prune und compressTexture sie sehen. Ihre TextureInfo läuft über
+// setTextureInfo/createTextureInfoDef, so kommt KHR_texture_transform (die Wellenteilung, etwa
+// scale [3.2, 1]) mit. three.js liest die Erweiterung selbst (GLTFLoader: bumpFactor -> bumpScale,
+// bumpTexture -> bumpMap).
+import { Extension, ExtensionProperty, PropertyType, TextureChannel, TextureInfo } from "@gltf-transform/core";
+
+export const EXT_MATERIALS_BUMP = "EXT_materials_bump";
+
+export class Bump extends ExtensionProperty {
+    static EXTENSION_NAME = EXT_MATERIALS_BUMP;
+
+    init() {
+        this.extensionName = EXT_MATERIALS_BUMP;
+        this.propertyType = "Bump";
+        this.parentTypes = [PropertyType.MATERIAL];
+    }
+
+    getDefaults() {
+        return Object.assign(super.getDefaults(), {
+            bumpFactor: 1,
+            bumpTexture: null,
+            bumpTextureInfo: new TextureInfo(this.graph, "bumpTextureInfo"),
+        });
+    }
+
+    getBumpFactor() {
+        return this.get("bumpFactor");
+    }
+
+    setBumpFactor(factor) {
+        return this.set("bumpFactor", factor);
+    }
+
+    getBumpTexture() {
+        return this.getRef("bumpTexture");
+    }
+
+    getBumpTextureInfo() {
+        return this.getRef("bumpTexture") ? this.getRef("bumpTextureInfo") : null;
+    }
+
+    setBumpTexture(texture) {
+        return this.setRef("bumpTexture", texture, { channels: TextureChannel.R });
+    }
+}
+
+export class EXTMaterialsBump extends Extension {
+    static EXTENSION_NAME = EXT_MATERIALS_BUMP;
+    extensionName = EXT_MATERIALS_BUMP;
+    prereadTypes = [PropertyType.MESH];
+    prewriteTypes = [PropertyType.MESH];
+
+    createBump() {
+        return new Bump(this.document.getGraph());
+    }
+
+    read() {
+        return this;
+    }
+
+    write() {
+        return this;
+    }
+
+    preread(context) {
+        const materialDefs = context.jsonDoc.json.materials ?? [];
+        const textureDefs = context.jsonDoc.json.textures ?? [];
+        materialDefs.forEach((materialDef, index) => {
+            const def = materialDef.extensions?.[EXT_MATERIALS_BUMP];
+            if (!def) return;
+            const bump = this.createBump();
+            context.materials[index].setExtension(EXT_MATERIALS_BUMP, bump);
+            if (def.extras) bump.setExtras(def.extras);
+            if (def.bumpFactor !== undefined) bump.setBumpFactor(def.bumpFactor);
+            if (def.bumpTexture !== undefined) {
+                bump.setBumpTexture(context.textures[textureDefs[def.bumpTexture.index].source]);
+                context.setTextureInfo(bump.getBumpTextureInfo(), def.bumpTexture);
+            }
+        });
+        return this;
+    }
+
+    prewrite(context) {
+        for (const material of this.document.getRoot().listMaterials()) {
+            const bump = material.getExtension(EXT_MATERIALS_BUMP);
+            if (!bump) continue;
+            const materialDef = context.jsonDoc.json.materials[context.materialIndexMap.get(material)];
+            const def = context.createPropertyDef(bump);
+            def.bumpFactor = bump.getBumpFactor();
+            const texture = bump.getBumpTexture();
+            if (texture) def.bumpTexture = context.createTextureInfoDef(texture, bump.getBumpTextureInfo());
+            materialDef.extensions = materialDef.extensions ?? {};
+            materialDef.extensions[EXT_MATERIALS_BUMP] = def;
+        }
+        return this;
+    }
+}