java - Android - 来自 Android Gaming Book 错误的 ObjLoader

Question

我很抱歉提出这样的问题，但我迷路了，不知道该怎么做。我正在阅读《开始 Android 游戏第 2 版》这本书. 我实际上是今天才读完这本书。我计划制作自己的小型 3D 游戏，只是为了测试我的知识。好吧，我的问题是我们为书中框架制作的 ObjLoader 不会显示我的 .obj 文件。它要么只是崩溃，要么显示一些三角形，要么填充使屏幕呈灰色。我曾尝试在 AutoDesk Maya 2013、Wings 3D 和 Blender 中制作这些 .obj 文件。但是它们都没有显示我设计的对象。即使只是一个简单的立方体。再次，我很抱歉提出这样的问题，但我想知道在导出过程中是否需要做一些特别的事情才能让这个 ObjLoader 加载它？我知道我正在做正确的加载。它适用于提供的 .obj 。这是 ObjLoader 的代码（直接来自书中）。提前致谢。

package com.badlogic.androidgames.framework.gl;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;

import com.badlogic.androidgames.framework.impl.GLGame;

public class ObjLoader {
    public static Vertices3 load(GLGame game, String file) {
        InputStream in = null;
        try {
            in = game.getFileIO().readAsset(file);
            List<String> lines = readLines(in);

            float[] vertices = new float[lines.size() * 3];
            float[] normals = new float[lines.size() * 3];
            float[] uv = new float[lines.size() * 2];

            int numVertices = 0;
            int numNormals = 0;
            int numUV = 0;
            int numFaces = 0;

            int[] facesVerts = new int[lines.size() * 3];
            int[] facesNormals = new int[lines.size() * 3];
            int[] facesUV = new int[lines.size() * 3];
            int vertexIndex = 0;
            int normalIndex = 0;
            int uvIndex = 0;
            int faceIndex = 0;


            for (int i = 0; i < lines.size(); i++) {
                String line = lines.get(i);

                if (line.startsWith("v ")) {
                    String[] tokens = line.split("[ ]+");
                    vertices[vertexIndex] = Float.parseFloat(tokens[1]);
                    vertices[vertexIndex + 1] = Float.parseFloat(tokens[2]);
                    vertices[vertexIndex + 2] = Float.parseFloat(tokens[3]);
                    vertexIndex += 3;
                    numVertices++;
                    continue;
                }

                if (line.startsWith("vn ")) {
                    String[] tokens = line.split("[ ]+");
                    normals[normalIndex] = Float.parseFloat(tokens[1]);
                    normals[normalIndex + 1] = Float.parseFloat(tokens[2]);
                    normals[normalIndex + 2] = Float.parseFloat(tokens[3]);
                    normalIndex += 3;
                    numNormals++;
                    continue;
                }

                if (line.startsWith("vt")) {
                    String[] tokens = line.split("[ ]+");
                    uv[uvIndex] = Float.parseFloat(tokens[1]);
                    uv[uvIndex + 1] = Float.parseFloat(tokens[2]);
                    uvIndex += 2;
                    numUV++;
                    continue;
                }

                if (line.startsWith("f ")) {
                    String[] tokens = line.split("[ ]+");

                    String[] parts = tokens[1].split("/");
                    facesVerts[faceIndex] = getIndex(parts[0], numVertices);
                    if (parts.length > 2)
                        facesNormals[faceIndex] = getIndex(parts[2], numNormals);
                    if (parts.length > 1)
                        facesUV[faceIndex] = getIndex(parts[1], numUV);
                    faceIndex++;

                    parts = tokens[2].split("/");
                    facesVerts[faceIndex] = getIndex(parts[0], numVertices);
                    if (parts.length > 2)
                        facesNormals[faceIndex] = getIndex(parts[2], numNormals);
                    if (parts.length > 1)
                        facesUV[faceIndex] = getIndex(parts[1], numUV);
                    faceIndex++;

                    parts = tokens[3].split("/");
                    facesVerts[faceIndex] = getIndex(parts[0], numVertices);
                    if (parts.length > 2)
                        facesNormals[faceIndex] = getIndex(parts[2], numNormals);
                    if (parts.length > 1)
                        facesUV[faceIndex] = getIndex(parts[1], numUV);
                    faceIndex++;
                    numFaces++;
                    continue;
                }
            }

            float[] verts = new float[(numFaces * 3)
                                      * (3 + (numNormals > 0 ? 3 : 0) + (numUV > 0 ? 2 : 0))];
            for (int i = 0, vi = 0; i < numFaces * 3; i++) {
                int vertexIdx = facesVerts[i] * 3;
                verts[vi++] = vertices[vertexIdx];
                verts[vi++] = vertices[vertexIdx + 1];
                verts[vi++] = vertices[vertexIdx + 2];

                if (numUV > 0) {
                    int uvIdx = facesUV[i] * 2;
                    verts[vi++] = uv[uvIdx];
                    verts[vi++] = 1 - uv[uvIdx + 1];
                }

                if (numNormals > 0) {
                    int normalIdx = facesNormals[i] * 3;
                    verts[vi++] = normals[normalIdx];
                    verts[vi++] = normals[normalIdx + 1];
                    verts[vi++] = normals[normalIdx + 2];
                }
            }

            Vertices3 model = new Vertices3(game.getGLGraphics(), numFaces * 3,
                    0, false, numUV > 0, numNormals > 0);
            model.setVertices(verts, 0, verts.length);
            return model;
        } catch (Exception ex) {
            throw new RuntimeException("couldn't load '" + file + "'", ex);
        } finally {
            if (in != null)
                try {
                    in.close();
                } catch (Exception ex) {

                }
        }
    }

    static int getIndex(String index, int size) {
        int idx = Integer.parseInt(index);
        if (idx < 0)
            return size + idx;
        else
            return idx - 1;
    }

    static List<String> readLines(InputStream in) throws IOException {
        List<String> lines = new ArrayList<String>();

        BufferedReader reader = new BufferedReader(new InputStreamReader(in));
        String line = null;
        while ((line = reader.readLine()) != null)
            lines.add(line);
        return lines;
    }
}