Implementation of a glTF extension loader for KHR_texture_transform (#1869)

* Implementation of a glTF extension loader for KHR_texture_transform

* Thread-safe version of the glTF extension loader for KHR_texture_transform

* Updated thread-safe version of the glTF extension loader for KHR_texture_transform

* Fix (switched indices of the translation matrix): thread-safe version of the glTF extension loader for KHR_texture_transform

* Added support for texCoord, fixed matrix comparison

* Simplified matrix comparison, removed trailing whitespaces

* Update to differentiate transformations applied to different UV sets

* Improved memory usage for transformMap

* Specified Map generic types & removed unnecessary cast

Co-authored-by: Manuel <Manuel@DESKTOP-6RJH3UF>

jme3-plugins/src/gltf/java/com/jme3/scene/plugins/gltf/CustomContentManager.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2009-2020 jMonkeyEngine
+ * Copyright (c) 2009-2022 jMonkeyEngine
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -57,6 +57,7 @@ public class CustomContentManager {
         defaultExtensionLoaders.put("KHR_materials_pbrSpecularGlossiness", new PBRSpecGlossExtensionLoader());
         defaultExtensionLoaders.put("KHR_lights_punctual", new LightsPunctualExtensionLoader());
         defaultExtensionLoaders.put("KHR_materials_unlit", new UnlitExtensionLoader());
+        defaultExtensionLoaders.put("KHR_texture_transform", new TextureTransformExtensionLoader());     
     }
 
     void init(GltfLoader gltfLoader) {

jme3-plugins/src/gltf/java/com/jme3/scene/plugins/gltf/GltfLoader.java

@@ -382,6 +382,7 @@ public class GltfLoader implements AssetLoader {
         for (JsonElement primitive : primitives) {
             JsonObject meshObject = primitive.getAsJsonObject();
             Mesh mesh = new Mesh();
+            addToCache("mesh", 0, mesh, 1);
             Integer mode = getAsInteger(meshObject, "mode");
             mesh.setMode(getMeshMode(mode));
             Integer indices = getAsInteger(meshObject, "indices");

jme3-plugins/src/gltf/java/com/jme3/scene/plugins/gltf/TextureTransformExtensionLoader.java

@@ -0,0 +1,164 @@
+/*
+ * Copyright (c) 2009-2022 jMonkeyEngine
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ *
+ * * Neither the name of 'jMonkeyEngine' nor the names of its contributors
+ *   may be used to endorse or promote products derived from this software
+ *   without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package com.jme3.scene.plugins.gltf;
+
+import com.google.gson.JsonArray;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import com.jme3.asset.AssetLoadException;
+import com.jme3.math.Matrix3f;
+import com.jme3.math.Vector3f;
+import com.jme3.scene.Mesh;
+import com.jme3.scene.VertexBuffer;
+import static com.jme3.scene.plugins.gltf.GltfUtils.getAsInteger;
+import static com.jme3.scene.plugins.gltf.GltfUtils.getVertexBufferType;
+import com.jme3.texture.Texture2D;
+import java.io.IOException;
+import java.nio.FloatBuffer;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+/**
+ * Thread-safe extension loader for KHR_texture_transform. 
+ * It allows for UV coordinates to be scaled/rotated/translated  
+ * based on transformation properties from textures in the glTF model.
+ *
+ * See spec at https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Khronos/KHR_texture_transform
+ *
+ * @author manuelrmo - Created on 11/20/2022
+ */
+public class TextureTransformExtensionLoader implements ExtensionLoader {
+    
+    private final static Logger logger = Logger.getLogger(TextureTransformExtensionLoader.class.getName());
+        
+    /**
+     * Scale/rotate/translate UV coordinates based on a transformation matrix.
+     * Code adapted from scaleTextureCoordinates(Vector2f) in jme3-core/src/main/java/com/jme3/scene/Mesh.java
+     * @param mesh The mesh holding the UV coordinates
+     * @param transform The matrix containing the scale/rotate/translate transformations
+     * @param verType The vertex buffer type from which to retrieve the UV coordinates
+     */    
+    private void uvTransform(Mesh mesh, Matrix3f transform, VertexBuffer.Type verType) {
+        if (!transform.isIdentity()) { // if transform is the identity matrix, there's nothing to do
+            VertexBuffer tc = mesh.getBuffer(verType);
+            if (tc == null) {
+                throw new IllegalStateException("The mesh has no texture coordinates");
+            }
+            if (tc.getFormat() != VertexBuffer.Format.Float) {
+                throw new UnsupportedOperationException("Only float texture coord format is supported");
+            }
+            if (tc.getNumComponents() != 2) {
+                throw new UnsupportedOperationException("Only 2D texture coords are supported");
+            }
+            FloatBuffer fb = (FloatBuffer) tc.getData();
+            fb.clear();
+            for (int i = 0; i < fb.limit() / 2; i++) {
+                float x = fb.get();
+                float y = fb.get();
+                fb.position(fb.position() - 2);
+                Vector3f v = transform.mult(new Vector3f(x, y, 1));
+                fb.put(v.getX()).put(v.getY());
+            }
+            fb.clear();
+            tc.updateData(fb);   
+        }
+    }
+    
+    // The algorithm relies on the fact that the GltfLoader.class object 
+    // loads all textures of a given mesh before doing so for the next mesh.    
+    @Override
+    public Object handleExtension(GltfLoader loader, String parentName, JsonElement parent, JsonElement extension, Object input) throws IOException {
+        if (!(input instanceof Texture2D)) {
+            logger.log(Level.WARNING, "KHR_texture_transform extension added on an unsupported element, the loaded scene result will be unexpected.");
+        }
+        Mesh mesh = loader.fetchFromCache("mesh", 0, Mesh.class);
+        if (mesh != null) {
+            Matrix3f translation = new Matrix3f();
+            Matrix3f rotation = new Matrix3f();
+            Matrix3f scale = new Matrix3f();
+            Integer texCoord = getAsInteger(parent.getAsJsonObject(), "texCoord");
+            texCoord = texCoord != null ? texCoord : 0;
+            JsonObject jsonObject = extension.getAsJsonObject();
+            if (jsonObject.has("offset")) {
+                JsonArray jsonArray = jsonObject.getAsJsonArray("offset");
+                translation.set(0, 2, jsonArray.get(0).getAsFloat());
+                translation.set(1, 2, jsonArray.get(1).getAsFloat());                    
+            }
+            if (jsonObject.has("rotation")) {
+                float rad = jsonObject.get("rotation").getAsFloat();
+                rotation.set(0, 0, (float) Math.cos(rad));
+                rotation.set(0, 1, (float) Math.sin(rad));
+                rotation.set(1, 0, (float) -Math.sin(rad));
+                rotation.set(1, 1, (float) Math.cos(rad));
+            }                
+            if (jsonObject.has("scale")) {
+                JsonArray jsonArray = jsonObject.getAsJsonArray("scale");
+                scale.set(0, 0, jsonArray.get(0).getAsFloat());
+                scale.set(1, 1, jsonArray.get(1).getAsFloat());
+            }     
+            if (jsonObject.has("texCoord")) {
+                texCoord = jsonObject.get("texCoord").getAsInt(); // it overrides the parent's texCoord value
+            }                 
+            Matrix3f transform = translation.mult(rotation).mult(scale);
+            Mesh meshLast = loader.fetchFromCache("textureTransformData", 0, Mesh.class);
+            Map<Integer, Matrix3f> transformMap = loader.fetchFromCache("textureTransformData", 1, HashMap.class);
+            if (mesh != meshLast || (transformMap != null && transformMap.get(texCoord) == null)) {
+                // at this point, we're processing a new mesh or the same mesh as before but for a different UV set
+                if (mesh != meshLast) { // it's a new mesh
+                    loader.addToCache("textureTransformData", 0, mesh, 2);
+                    if (transformMap == null) {
+                        transformMap = new HashMap<>(); // initialize transformMap
+                        loader.addToCache("textureTransformData", 1, transformMap, 2);
+                    } else {
+                        transformMap.clear(); // reset transformMap
+                    }
+                }
+                transformMap.put(texCoord, transform); // store the transformation matrix applied to this UV set
+                uvTransform(mesh, transform, getVertexBufferType("TEXCOORD_" + texCoord));
+                logger.log(Level.FINE, "KHR_texture_transform extension successfully applied."); 
+            }
+            else {
+                // at this point, we're processing the same mesh as before for an already transformed UV set
+                Matrix3f transformLast = transformMap.get(texCoord);
+                if (!transform.equals(transformLast)) {
+                    logger.log(Level.WARNING, "KHR_texture_transform extension: use of different texture transforms for the same mesh's UVs is not supported, the loaded scene result will be unexpected.");
+                }
+            }
+            return input;
+        }
+        else {
+            throw new AssetLoadException("KHR_texture_transform extension applied to a null mesh.");
+        }
+    }
+}