java - OBJ 加载器索引越界

Question

我正在编写 3D 引擎，而我的 OBJ LoaderClass 似乎在处理更复杂的模型时存在问题。

我收到一个 IndexOutOfBoundsException，但我不明白为什么。 索引 3522 上的 ArrayList 纹理的值似乎会导致此异常，但为什么呢？

这是我的 OBJ 加载器类

        package graphics.renderEngine;

    import java.io.BufferedReader;
    import java.io.File;
    import java.io.FileNotFoundException;
    import java.io.FileReader;
    import java.util.ArrayList;
    import java.util.List;

    import org.joml.Vector2f;
    import org.joml.Vector3f;

    import graphics.models.RawModel;

    public class OBJLoader 
    {

        public static RawModel loadObjModel(String fileName, Loader loader)
        {
            FileReader fr = null;
            try 
            {
                fr = new FileReader(new File("Ressources/Models/"+fileName+".obj"));
            } 
            catch (FileNotFoundException e) 
            {
                System.err.println("Could not load File!");
                e.printStackTrace();
            }
            BufferedReader reader = new BufferedReader(fr);
            String line;
            List<Vector3f> vertices = new ArrayList<Vector3f>();
            List<Vector2f> textures = new ArrayList<Vector2f>();
            List<Vector3f> normals = new ArrayList<Vector3f>();
            List<Integer> indices = new ArrayList<Integer>();
            float[] verticesArray = null;
            float[] normalsArray = null;
            float[] texturesArray = null;
            int[] indicesArray = null;

            try
            {
                while(true)
                {
                    line = reader.readLine();
                    String[] currentLine = line.split(" ");
                    if(line.startsWith("v "))
                    {
                        Vector3f vertex = new Vector3f(Float.parseFloat(currentLine[1]),Float.parseFloat(currentLine[2]), Float.parseFloat(currentLine[3]));
                        vertices.add(vertex);
                    }
                    else if(line.startsWith("vt "))
                    {
                        Vector2f texture = new Vector2f(Float.parseFloat(currentLine[1]), Float.parseFloat(currentLine[2]));
                        textures.add(texture);
                    }
                    else if(line.startsWith("vn "))
                    {
                        Vector3f normal = new Vector3f(Float.parseFloat(currentLine[1]),Float.parseFloat(currentLine[2]), Float.parseFloat(currentLine[3]));
                        normals.add(normal);
                    }
                    else if(line.startsWith("f "))
                    {
                        texturesArray = new float[vertices.size()*2];
                        normalsArray = new float[vertices.size()*3];
                        break;
                    }
                }

                while(line != null)
                {
                    if(!line.startsWith("f "))
                    {
                        line = reader.readLine();
                        continue;
                    }
                    String[] currentLine = line.split(" ");
                    String[] vertex1 = currentLine[1].split("/");
                    String[] vertex2 = currentLine[2].split("/");
                    String[] vertex3 = currentLine[3].split("/");

                    processVertex(vertex1, indices, textures, normals, texturesArray, normalsArray);
                    processVertex(vertex2, indices, textures, normals, texturesArray, normalsArray);
                    processVertex(vertex3, indices, textures, normals, texturesArray, normalsArray);
                    line = reader.readLine();
                }
                reader.close();

            }
            catch(Exception e)
            {
                e.printStackTrace();
            }

            verticesArray = new float[vertices.size()*3];
            indicesArray = new int[indices.size()];

            int vertexPointer = 0;
            for (Vector3f vertex:vertices)
            {
                verticesArray[vertexPointer++] = vertex.x;
                verticesArray[vertexPointer++] = vertex.y;
                verticesArray[vertexPointer++] = vertex.z;
            }

            for(int i=0;i<indices.size();i++)
            {
                indicesArray[i] = indices.get(i);

            }
            return 
                    loader.loadToVAO
                    (verticesArray, 
                            texturesArray, 
                            normalsArray,
                            indicesArray);

        }

        private static void processVertex(String[] vertexData, List<Integer> indices, List<Vector2f> textures, List<Vector3f> normals, float[] textureArray, float[] normalsArray)
        {
            System.out.println(textures.get(3522));
            int currentvertexPointer = Integer.parseInt(vertexData[0]) -1;
            indices.add(currentvertexPointer);
            Vector2f currentTex = textures.get(Integer.parseInt(vertexData[1])-1);
            textureArray[currentvertexPointer*2] = currentTex.x;
            textureArray[currentvertexPointer*2+1] = 1 - currentTex.y;
            Vector3f currentNorm = normals.get(Integer.parseInt(vertexData[2])-1);
            normalsArray[currentvertexPointer*3] = currentNorm.x;
            normalsArray[currentvertexPointer*3+1] = currentNorm.y;
            normalsArray[currentvertexPointer*3+2] = currentNorm.z;
        }
 }

This is the OBJFile of the Model im trying to load

当我每次读取纹理值时:

System.out.println(textures.get(Integer.parseInt(vertexData[1])-1));

我在异常(exception)之前得到的最后一个 vector 是:

( 4.260E-1  1.275E-1)
( 4.650E-1  1.664E-1)
( 4.706E-1  1.621E-1)
( 4.650E-1  1.664E-1)
( 4.925E-1  2.140E-1)
( 1.340E-1  8.170E-2)
( 1.947E-1  4.650E-2)
( 1.902E-1  3.560E-2)

查看 OBJ 文件后，除了最后两个之外，我无法按顺序找到。

这是我遇到的异常

java.lang.IndexOutOfBoundsException: Index: 3522, Size: 3522
    at java.util.ArrayList.rangeCheck(Unknown Source)
    at java.util.ArrayList.get(Unknown Source)
    at graphics.renderEngine.OBJLoader.processVertex(OBJLoader.java:122)
    at graphics.renderEngine.OBJLoader.loadObjModel(OBJLoader.java:82)
    at main.Main.init(Main.java:150)
    at main.Main.<init>(Main.java:82)
    at main.Main.main(Main.java:75)

我只是感到困惑，我不知道为什么会出现此异常，提前感谢您提供任何线索

Answer 1

列表的大小为 3522，索引值范围为 0 到 3521。但是您尝试使用不存在的索引 3522 来访问列表中的元素，因此出现异常。在访问列表元素之前，您需要有条件检查索引是否小于大小。