BlueMap/BlueMapCore/src/main/java/de/bluecolored/bluemap/core/threejs/BufferGeometry.java

/*
 * This file is part of BlueMap, licensed under the MIT License (MIT).
 *
 * Copyright (c) Blue (Lukas Rieger) <https://bluecolored.de>
 * Copyright (c) contributors
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
package de.bluecolored.bluemap.core.threejs;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.stream.JsonReader;
import com.google.gson.stream.JsonWriter;

import java.io.IOException;
import java.io.StringReader;
import java.io.StringWriter;
import java.util.*;
import java.util.Map.Entry;

public class BufferGeometry {

    public Map<String, BufferAttribute> attributes;
    public MaterialGroup[] groups;

    private BufferGeometry() {}

    public BufferGeometry(float[] position, float[] normal, float[] color, float[] uv, MaterialGroup[] groups) {
        this.attributes = new HashMap<>();
        addAttribute("position", new BufferAttribute(position, 3));
        addAttribute("normal", new BufferAttribute(normal, 3));
        addAttribute("color", new BufferAttribute(color, 3));
        addAttribute("uv", new BufferAttribute(uv, 2));

        this.groups = groups;
    }

    public void addAttribute(String name, BufferAttribute attribute) {
        this.attributes.put(name, attribute);
    }

    public boolean isValid() {
        int faceCount = getFaceCount();

        for (BufferAttribute attribute : attributes.values()) {
            if (attribute.getItemCount() != faceCount) return false;
        }

        return true;
    }

    public int getFaceCount() {
        if (attributes.isEmpty()) return 0;
        BufferAttribute attribute = attributes.values().iterator().next();
        return attribute.getItemCount();
    }

    public String toJson() {
        try {

            StringWriter sw = new StringWriter();
            Gson gson = new GsonBuilder().create();
            JsonWriter json = gson.newJsonWriter(sw);

            json.beginObject(); // main-object
            json.name("tileGeometry").beginObject(); // tile-geometry-object

            // set special values
            json.name("type").value("BufferGeometry");
            json.name("uuid").value(UUID.randomUUID().toString().toUpperCase());

            json.name("data").beginObject(); // data
            json.name("attributes").beginObject(); // attributes

            for (Entry<String, BufferAttribute> entry : attributes.entrySet()) {
                json.name(entry.getKey());
                entry.getValue().writeJson(json);
            }

            json.endObject(); // attributes

            json.name("groups").beginArray(); // groups

            // write groups into json
            for (MaterialGroup g : groups) {
                json.beginObject();

                json.name("materialIndex").value(g.getMaterialIndex());
                json.name("start").value(g.getStart());
                json.name("count").value(g.getCount());

                json.endObject();
            }

            json.endArray(); // groups
            json.endObject(); // data
            json.endObject(); // tile-geometry-object
            json.endObject(); // main-object

            // save and return
            json.flush();
            return sw.toString();

        } catch (IOException e) {
            // since we are using a StringWriter there should never be an IO exception
            // thrown
            throw new RuntimeException(e);
        }
    }

    public static BufferGeometry fromJson(String jsonString) throws IOException {

        Gson gson = new GsonBuilder().create();
        JsonReader json = gson.newJsonReader(new StringReader(jsonString));

        List<MaterialGroup> groups = new ArrayList<>(10);
        Map<String, BufferAttribute> attributes = new HashMap<>();

        json.beginObject(); // root

        while (!"tileGeometry".equals(json.nextName())) json.skipValue(); // find tileGeometry
        json.beginObject(); // tileGeometry

        while (json.hasNext()) {
            String name1 = json.nextName();

            if (name1.equals("data")) {
                json.beginObject(); // data
                while (json.hasNext()) {
                    String name2 = json.nextName();

                    if (name2.equals("attributes")) {
                        json.beginObject(); // attributes
                        while (json.hasNext()) {
                            String name3 = json.nextName();
                            attributes.put(name3, BufferAttribute.readJson(json));
                        }
                        json.endObject(); // attributes
                    }

                    else if (name2.equals("groups")) {
                        json.beginArray(); // groups
                        while (json.hasNext()) {
                            MaterialGroup group = new MaterialGroup(0, 0, 0);
                            json.beginObject(); // group
                            while (json.hasNext()) {
                                String name3 = json.nextName();

                                if (name3.equals("materialIndex")) {
                                    group.setMaterialIndex(json.nextInt());
                                }

                                else if (name3.equals("start")) {
                                    group.setStart(json.nextInt());
                                }

                                else if (name3.equals("count")) {
                                    group.setCount(json.nextInt());
                                }

                                else json.skipValue();
                            }
                            json.endObject(); // group
                            groups.add(group);
                        }
                        json.endArray(); // groups
                    }

                    else json.skipValue();
                }
                json.endObject();// data
            }

            else json.skipValue();
        }
        json.endObject(); // tileGeometry

        while (json.hasNext()) json.skipValue(); // skip remaining values
        json.endObject(); // root

        groups.sort((g1, g2) -> (int) Math.signum(g1.getStart() - g2.getStart()));
        int nextGroup = 0;
        for (MaterialGroup g : groups) {
            if (g.getStart() != nextGroup)
                throw new IllegalArgumentException("Group did not start at correct index! (Got " + g.getStart() + " but expected " + nextGroup + ")");
            if (g.getCount() < 0) throw new IllegalArgumentException("Group has a negative count! (" + g.getCount() + ")");
            nextGroup += g.getCount();
        }

        BufferGeometry bufferGeometry = new BufferGeometry();
        bufferGeometry.attributes = attributes;
        bufferGeometry.groups = groups.toArray(new MaterialGroup[groups.size()]);

        return bufferGeometry;
    }

}