Task 001: .3DS File Format

Task 001 Response: .3DS File Format Specifications and Implementation

The .3DS file format, developed by Autodesk for 3D Studio, is a binary file format used for storing 3D scenes and models. Below, I address each part of the task: listing the intrinsic properties of the .3DS file format, followed by implementations in Python, Java, JavaScript, and C to read, decode, write, and print these properties. Due to the complexity of the .3DS format and the need for concise code, the implementations focus on reading and printing key properties, with basic writing functionality for demonstration.

1. Properties of the .3DS File Format Intrinsic to Its File System

The .3DS file format is structured as a hierarchical collection of binary chunks, each containing specific data about a 3D scene. The following properties are intrinsic to the .3DS file format, based on its specification as a binary, chunk-based structure:

File Header:

• Magic Number: A 2-byte identifier (0x4D4D) indicating the start of a .3DS file (Primary Chunk ID).
• Version: A 4-byte integer (stored at byte 29) indicating the file version (typically for 3D Studio version 3.0 or higher).

Chunk Structure:

• Chunk ID: A 2-byte identifier for each chunk, defining its type (e.g., 0x3D3D for mesh data, 0xAFFF for material data).
• Chunk Length: A 4-byte little-endian integer specifying the chunk's total length, including its header (6 bytes: 2 for ID, 4 for length) and any sub-chunks.
• Hierarchical Organization: Chunks are nested, forming a tree-like structure similar to an XML DOM, allowing parsers to skip unrecognized chunks.

Core Data Components:

• Mesh Data: Includes vertices, polygons (faces), and smoothing groups for 3D geometry (stored in chunks like 0x4100 for object blocks and 0x4110 for vertex lists).
• Material Properties: Defines surface attributes like color, texture maps, and shading (stored in chunks like 0xA000 for material names, 0xA200 for texture maps).
• Lighting Information: Specifies light sources, including position and intensity (stored in chunks like 0x4600 for light objects).
• Camera Information: Includes camera locations and settings for rendering (stored in chunks like 0x4700 for camera objects).
• Animation Data: Stores keyframes and animation tracks for dynamic scenes (stored in chunks like 0xB000 for keyframe data).
• Viewport Configurations: Defines how the scene is viewed (stored in chunks like 0x7012 for view settings).
• Bitmap References: Links to external texture files (stored in chunks like 0xA300 for texture filenames).

File Characteristics:

• Binary Format: Data is stored in binary, making it compact and faster to process than text-based formats.
• Little-Endian Encoding: Multi-byte values (e.g., integers) are stored with the least significant byte first.
• Extensibility: The chunk-based structure allows parsers to skip unrecognized chunks, supporting format extensions.
• File Size Limitations: The format has constraints on file size, which can limit its use for very large or complex models.

These properties are derived from the .3DS file format’s structure, as described in sources like Wikipedia, docs.fileformat.com, and Paul Bourke’s documentation.

2. Python Class for .3DS File Handling

Below is a Python class that opens, reads, decodes, writes, and prints the properties of a .3DS file. It focuses on parsing the main chunk (0x4D4D), version, and key sub-chunks (e.g., mesh, material, and camera data).

import struct
import os

class TDSFile:
    def __init__(self, filepath):
        self.filepath = filepath
        self.properties = {
            'magic_number': None,
            'version': None,
            'meshes': [],
            'materials': [],
            'cameras': [],
            'lights': [],
            'animations': []
        }

    def read_uint16(self, file):
        return struct.unpack('<H', file.read(2))[0]

    def read_uint32(self, file):
        return struct.unpack('<I', file.read(4))[0]

    def read_string(self, file):
        result = ""
        while True:
            char = file.read(1).decode('ascii')
            if char == '\0':
                break
            result += char
        return result

    def read_chunk(self, file):
        chunk_id = self.read_uint16(file)
        chunk_length = self.read_uint32(file)
        return chunk_id, chunk_length

    def parse_chunk(self, file, end_pos):
        while file.tell() < end_pos:
            chunk_id, chunk_length = self.read_chunk(file)
            chunk_end = file.tell() + chunk_length - 6

            if chunk_id == 0x4D4D:  # Main chunk
                self.properties['magic_number'] = '0x4D4D'
                self.parse_chunk(file, chunk_end)
            elif chunk_id == 0x0002:  # Version
                self.properties['version'] = self.read_uint32(file)
            elif chunk_id == 0x4100:  # Object block (mesh)
                mesh_name = self.read_string(file)
                self.properties['meshes'].append({'name': mesh_name})
                self.parse_chunk(file, chunk_end)
            elif chunk_id == 0xA000:  # Material name
                material_name = self.read_string(file)
                self.properties['materials'].append({'name': material_name})
            elif chunk_id == 0x4700:  # Camera
                camera_name = self.read_string(file)
                self.properties['cameras'].append({'name': camera_name})
            elif chunk_id == 0x4600:  # Light
                light_name = self.read_string(file)
                self.properties['lights'].append({'name': light_name})
            elif chunk_id == 0xB000:  # Keyframe data (animation)
                self.properties['animations'].append({'keyframe': 'present'})
            else:
                file.seek(chunk_end)  # Skip unrecognized chunks

    def read(self):
        with open(self.filepath, 'rb') as file:
            self.parse_chunk(file, os.path.getsize(self.filepath))
        return self.properties

    def write(self, output_filepath):
        with open(output_filepath, 'wb') as file:
            # Write main chunk header
            file.write(struct.pack('<H', 0x4D4D))
            file.write(struct.pack('<I', 10))  # Placeholder length
            file.write(struct.pack('<H', 0x0002))  # Version chunk
            file.write(struct.pack('<I', 10))  # Version chunk length
            file.write(struct.pack('<I', self.properties['version'] or 4))  # Write version
        print(f"Written basic .3DS file to {output_filepath}")

    def print_properties(self):
        print("3DS File Properties:")
        for key, value in self.properties.items():
            print(f"{key}: {value}")

# Example usage
if __name__ == "__main__":
    tds = TDSFile("example.3ds")
    tds.read()
    tds.print_properties()
    tds.write("output.3ds")

Explanation:

• The class reads the .3DS file by parsing chunks, using struct for binary data.
• It extracts properties like magic number, version, mesh names, material names, cameras, lights, and animation presence.
• The write method creates a minimal .3DS file with a main chunk and version.
• The print_properties method displays all extracted properties.
• Note: Full writing of complex .3DS files requires detailed scene data, which is simplified here.

3. Java Class for .3DS File Handling

Below is a Java class that performs similar operations for .3DS files.

import java.io.*;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.util.*;

public class TDSFile {
    private String filepath;
    private Map<String, Object> properties;

    public TDSFile(String filepath) {
        this.filepath = filepath;
        this.properties = new HashMap<>();
        properties.put("magic_number", null);
        properties.put("version", 0);
        properties.put("meshes", new ArrayList<Map<String, String>>());
        properties.put("materials", new ArrayList<Map<String, String>>());
        properties.put("cameras", new ArrayList<Map<String, String>>());
        properties.put("lights", new ArrayList<Map<String, String>>());
        properties.put("animations", new ArrayList<Map<String, String>>());
    }

    private int readUInt16(DataInputStream file) throws IOException {
        return Short.reverseBytes(file.readShort()) & 0xFFFF;
    }

    private int readUInt32(DataInputStream file) throws IOException {
        return Integer.reverseBytes(file.readInt());
    }

    private String readString(DataInputStream file) throws IOException {
        StringBuilder result = new StringBuilder();
        while (true) {
            byte b = file.readByte();
            if (b == 0) break;
            result.append((char) b);
        }
        return result.toString();
    }

    private void parseChunk(DataInputStream file, long endPos) throws IOException {
        while (file.available() > 0 && file.readLong() < endPos) {
            int chunkId = readUInt16(file);
            int chunkLength = readUInt32(file);
            long chunkEnd = file.readLong() + chunkLength - 6;

            if (chunkId == 0x4D4D) { // Main chunk
                properties.put("magic_number", "0x4D4D");
                parseChunk(file, chunkEnd);
            } else if (chunkId == 0x0002) { // Version
                properties.put("version", readUInt32(file));
            } else if (chunkId == 0x4100) { // Object block (mesh)
                Map<String, String> mesh = new HashMap<>();
                mesh.put("name", readString(file));
                ((List<Map<String, String>>) properties.get("meshes")).add(mesh);
                parseChunk(file, chunkEnd);
            } else if (chunkId == 0xA000) { // Material name
                Map<String, String> material = new HashMap<>();
                material.put("name", readString(file));
                ((List<Map<String, String>>) properties.get("materials")).add(material);
            } else if (chunkId == 0x4700) { // Camera
                Map<String, String> camera = new HashMap<>();
                camera.put("name", readString(file));
                ((List<Map<String, String>>) properties.get("cameras")).add(camera);
            } else if (chunkId == 0x4600) { // Light
                Map<String, String> light = new HashMap<>();
                light.put("name", readString(file));
                ((List<Map<String, String>>) properties.get("lights")).add(light);
            } else if (chunkId == 0xB000) { // Keyframe data
                Map<String, String> animation = new HashMap<>();
                animation.put("keyframe", "present");
                ((List<Map<String, String>>) properties.get("animations")).add(animation);
            } else {
                file.skipBytes(chunkLength - 6); // Skip unrecognized chunks
            }
        }
    }

    public void read() throws IOException {
        try (DataInputStream file = new DataInputStream(new FileInputStream(filepath))) {
            parseChunk(file, new File(filepath).length());
        }
    }

    public void write(String outputFilepath) throws IOException {
        try (DataOutputStream file = new DataOutputStream(new FileOutputStream(outputFilepath))) {
            file.writeShort(Short.reverseBytes((short) 0x4D4D)); // Main chunk
            file.writeInt(Integer.reverseBytes(10)); // Placeholder length
            file.writeShort(Short.reverseBytes((short) 0x0002)); // Version chunk
            file.writeInt(Integer.reverseBytes(10)); // Version chunk length
            file.writeInt(Integer.reverseBytes((Integer) properties.get("version")));
            System.out.println("Written basic .3DS file to " + outputFilepath);
        }
    }

    public void printProperties() {
        System.out.println("3DS File Properties:");
        properties.forEach((key, value) -> System.out.println(key + ": " + value));
    }

    public static void main(String[] args) {
        try {
            TDSFile tds = new TDSFile("example.3ds");
            tds.read();
            tds.printProperties();
            tds.write("output.3ds");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Explanation:

• The Java class uses DataInputStream for binary reading and handles little-endian encoding.
• It parses the same properties as the Python class, storing them in a Map.
• The write method creates a minimal .3DS file with a main chunk and version.
• The printProperties method outputs the extracted properties.

4. JavaScript Class for .3DS File Handling

Below is a JavaScript class for Node.js, using the fs module to handle .3DS files.

const fs = require('fs');

class TDSFile {
    constructor(filepath) {
        this.filepath = filepath;
        this.properties = {
            magic_number: null,
            version: 0,
            meshes: [],
            materials: [],
            cameras: [],
            lights: [],
            animations: []
        };
    }

    readUInt16(buffer, offset) {
        return buffer.readUInt16LE(offset);
    }

    readUInt32(buffer, offset) {
        return buffer.readUInt32LE(offset);
    }

    readString(buffer, offset) {
        let result = '';
        while (buffer[offset] !== 0) {
            result += String.fromCharCode(buffer[offset]);
            offset++;
        }
        return [result, offset + 1];
    }

    parseChunk(buffer, offset, endPos) {
        while (offset < endPos) {
            const chunkId = this.readUInt16(buffer, offset);
            const chunkLength = this.readUInt32(buffer, offset + 2);
            const chunkEnd = offset + chunkLength;

            if (chunkId === 0x4D4D) { // Main chunk
                this.properties.magic_number = '0x4D4D';
                offset = this.parseChunk(buffer, offset + 6, chunkEnd);
            } else if (chunkId === 0x0002) { // Version
                this.properties.version = this.readUInt32(buffer, offset + 6);
                offset += 10;
            } else if (chunkId === 0x4100) { // Object block (mesh)
                const [meshName, newOffset] = this.readString(buffer, offset + 6);
                this.properties.meshes.push({ name: meshName });
                offset = this.parseChunk(buffer, newOffset, chunkEnd);
            } else if (chunkId === 0xA000) { // Material name
                const [materialName, newOffset] = this.readString(buffer, offset + 6);
                this.properties.materials.push({ name: materialName });
                offset = newOffset;
            } else if (chunkId === 0x4700) { // Camera
                const [cameraName, newOffset] = this.readString(buffer, offset + 6);
                this.properties.cameras.push({ name: cameraName });
                offset = newOffset;
            } else if (chunkId === 0x4600) { // Light
                const [lightName, newOffset] = this.readString(buffer, offset + 6);
                this.properties.lights.push({ name: lightName });
                offset = newOffset;
            } else if (chunkId === 0xB000) { // Keyframe data
                this.properties.animations.push({ keyframe: 'present' });
                offset = chunkEnd;
            } else {
                offset = chunkEnd; // Skip unrecognized chunks
            }
        }
        return offset;
    }

    read() {
        const buffer = fs.readFileSync(this.filepath);
        this.parseChunk(buffer, 0, buffer.length);
        return this.properties;
    }

    write(outputFilepath) {
        const buffer = Buffer.alloc(10);
        buffer.writeUInt16LE(0x4D4D, 0); // Main chunk
        buffer.writeUInt32LE(10, 2); // Placeholder length
        buffer.writeUInt16LE(0x0002, 6); // Version chunk
        buffer.writeUInt32LE(10, 8); // Version chunk length
        buffer.writeUInt32LE(this.properties.version || 4, 12);
        fs.writeFileSync(outputFilepath, buffer);
        console.log(`Written basic .3DS file to ${outputFilepath}`);
    }

    printProperties() {
        console.log('3DS File Properties:');
        for (const [key, value] of Object.entries(this.properties)) {
            console.log(`${key}: ${JSON.stringify(value)}`);
        }
    }
}

// Example usage
const tds = new TDSFile('example.3ds');
tds.read();
tds.printProperties();
tds.write('output.3ds');

Explanation:

• The JavaScript class uses Node.js’s fs module and Buffer for binary operations.
• It parses the same properties, handling little-endian encoding with readUInt16LE and readUInt32LE.
• The write method creates a minimal .3DS file.
• The printProperties method logs the properties to the console.

5. C Class for .3DS File Handling

Below is a C implementation simulating a class-like structure for .3DS files. C does not have classes, so we use a struct and functions.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct {
    char* filepath;
    char* magic_number;
    unsigned int version;
    char** meshes;
    int mesh_count;
    char** materials;
    int material_count;
    char** cameras;
    int camera_count;
    char** lights;
    int light_count;
    char** animations;
    int animation_count;
} TDSFile;

TDSFile* tds_create(const char* filepath) {
    TDSFile* tds = (TDSFile*)malloc(sizeof(TDSFile));
    tds->filepath = strdup(filepath);
    tds->magic_number = NULL;
    tds->version = 0;
    tds->meshes = NULL;
    tds->mesh_count = 0;
    tds->materials = NULL;
    tds->material_count = 0;
    tds->cameras = NULL;
    tds->camera_count = 0;
    tds->lights = NULL;
    tds->light_count = 0;
    tds->animations = NULL;
    tds->animation_count = 0;
    return tds;
}

unsigned short read_uint16(FILE* file) {
    unsigned char bytes[2];
    fread(bytes, 1, 2, file);
    return (bytes[1] << 8) | bytes[0];
}

unsigned int read_uint32(FILE* file) {
    unsigned char bytes[4];
    fread(bytes, 1, 4, file);
    return (bytes[3] << 24) | (bytes[2] << 16) | (bytes[1] << 8) | bytes[0];
}

char* read_string(FILE* file) {
    char* result = (char*)malloc(256);
    int i = 0;
    while (i < 255) {
        char c = fgetc(file);
        if (c == 0) break;
        result[i++] = c;
    }
    result[i] = '\0';
    return result;
}

void parse_chunk(TDSFile* tds, FILE* file, long end_pos) {
    while (ftell(file) < end_pos) {
        unsigned short chunk_id = read_uint16(file);
        unsigned int chunk_length = read_uint32(file);
        long chunk_end = ftell(file) + chunk_length - 6;

        if (chunk_id == 0x4D4D) { // Main chunk
            tds->magic_number = strdup("0x4D4D");
            parse_chunk(tds, file, chunk_end);
        } else if (chunk_id == 0x0002) { // Version
            tds->version = read_uint32(file);
        } else if (chunk_id == 0x4100) { // Object block (mesh)
            char* mesh_name = read_string(file);
            tds->meshes = (char**)realloc(tds->meshes, (tds->mesh_count + 1) * sizeof(char*));
            tds->meshes[tds->mesh_count++] = mesh_name;
            parse_chunk(tds, file, chunk_end);
        } else if (chunk_id == 0xA000) { // Material name
            char* material_name = read_string(file);
            tds->materials = (char**)realloc(tds->materials, (tds->material_count + 1) * sizeof(char*));
            tds->materials[tds->material_count++] = material_name;
        } else if (chunk_id == 0x4700) { // Camera
            char* camera_name = read_string(file);
            tds->cameras = (char**)realloc(tds->cameras, (tds->camera_count + 1) * sizeof(char*));
            tds->cameras[tds->camera_count++] = camera_name;
        } else if (chunk_id == 0x4600) { // Light
            char* light_name = read_string(file);
            tds->lights = (char**)realloc(tds->lights, (tds->light_count + 1) * sizeof(char*));
            tds->lights[tds->light_count++] = light_name;
        } else if (chunk_id == 0xB000) { // Keyframe data
            tds->animations = (char**)realloc(tds->animations, (tds->animation_count + 1) * sizeof(char*));
            tds->animations[tds->animation_count++] = strdup("present");
        } else {
            fseek(file, chunk_end, SEEK_SET); // Skip unrecognized chunks
        }
    }
}

void tds_read(TDSFile* tds) {
    FILE* file = fopen(tds->filepath, "rb");
    if (!file) {
        printf("Error opening file\n");
        return;
    }
    fseek(file, 0, SEEK_END);
    long end_pos = ftell(file);
    fseek(file, 0, SEEK_SET);
    parse_chunk(tds, file, end_pos);
    fclose(file);
}

void tds_write(TDSFile* tds, const char* output_filepath) {
    FILE* file = fopen(output_filepath, "wb");
    if (!file) {
        printf("Error opening output file\n");
        return;
    }
    fwrite("\x4D\x4D", 2, 1, file); // Main chunk
    fwrite("\x0A\x00\x00\x00", 4, 1, file); // Placeholder length
    fwrite("\x02\x00", 2, 1, file); // Version chunk
    fwrite("\x0A\x00\x00\x00", 4, 1, file); // Version chunk length
    unsigned int version = tds->version ? tds->version : 4;
    fwrite(&version, 4, 1, file);
    fclose(file);
    printf("Written basic .3DS file to %s\n", output_filepath);
}

void tds_print_properties(TDSFile* tds) {
    printf("3DS File Properties:\n");
    printf("magic_number: %s\n", tds->magic_number ? tds->magic_number : "null");
    printf("version: %u\n", tds->version);
    printf("meshes: [");
    for (int i = 0; i < tds->mesh_count; i++) {
        printf("%s%s", tds->meshes[i], i < tds->mesh_count - 1 ? ", " : "");
    }
    printf("]\n");
    printf("materials: [");
    for (int i = 0; i < tds->material_count; i++) {
        printf("%s%s", tds->materials[i], i < tds->material_count - 1 ? ", " : "");
    }
    printf("]\n");
    printf("cameras: [");
    for (int i = 0; i < tds->camera_count; i++) {
        printf("%s%s", tds->cameras[i], i < tds->camera_count - 1 ? ", " : "");
    }
    printf("]\n");
    printf("lights: [");
    for (int i = 0; i < tds->light_count; i++) {
        printf("%s%s", tds->lights[i], i < tds->light_count - 1 ? ", " : "");
    }
    printf("]\n");
    printf("animations: [");
    for (int i = 0; i < tds->animation_count; i++) {
        printf("%s%s", tds->animations[i], i < tds->animation_count - 1 ? ", " : "");
    }
    printf("]\n");
}

void tds_free(TDSFile* tds) {
    free(tds->filepath);
    free(tds->magic_number);
    for (int i = 0; i < tds->mesh_count; i++) free(tds->meshes[i]);
    free(tds->meshes);
    for (int i = 0; i < tds->material_count; i++) free(tds->materials[i]);
    free(tds->materials);
    for (int i = 0; i < tds->camera_count; i++) free(tds->cameras[i]);
    free(tds->cameras);
    for (int i = 0; i < tds->light_count; i++) free(tds->lights[i]);
    free(tds->lights);
    for (int i = 0; i < tds->animation_count; i++) free(tds->animations[i]);
    free(tds->animations);
    free(tds);
}

int main() {
    TDSFile* tds = tds_create("example.3ds");
    tds_read(tds);
    tds_print_properties(tds);
    tds_write(tds, "output.3ds");
    tds_free(tds);
    return 0;
}

Explanation:

• The C implementation uses a struct to store properties and functions to mimic class behavior.
• It reads and parses chunks, handling little-endian encoding manually.
• The write function creates a minimal .3DS file.
• The print_properties function outputs the properties to the console.
• Memory management is handled explicitly with malloc and free.

Notes and Limitations

• Reading: The implementations parse key chunks (main, version, mesh, material, camera, light, animation) but skip detailed data (e.g., vertex coordinates, texture maps) for brevity. Full parsing would require handling all chunk types, which is extensive.
• Writing: The write functionality creates a minimal .3DS file with a main chunk and version. Writing a complete .3DS file with meshes, materials, etc., requires detailed scene data, which is application-specific and beyond the scope of a general example.
• Testing: The code assumes an example.3ds file exists. For testing, use a valid .3DS file or modify the filepath.
• Error Handling: Basic error handling is included (e.g., file not found). Production code would need more robust checks.
• Sources: The implementations are based on the .3DS file format specifications from sources like Wikipedia and Paul Bourke’s documentation.

This response provides a comprehensive solution to the task while keeping the code manageable and focused on the core requirements. Let me know if you need further details or specific chunk parsing (e.g., vertices, textures)!

1. List of Properties Intrinsic to the .3DS File Format

The .3DS file format is a binary, chunk-based format for 3D models, originally from Autodesk 3D Studio. "Properties intrinsic to its file system" are interpreted as the core structural and data elements that define the file's layout and content, including the chunk hierarchy, headers, and extractable data such as geometry, materials, lights, cameras, and animation. Based on the specifications from reliable sources (e.g., Paul Bourke's documentation, Wikipedia, and other detailed breakdowns), here is a comprehensive list of these properties:

• File Header/Magic Number: 2 bytes (0x4D4D), identifying the file as .3DS.
• Chunk Structure: Every section is a chunk with 2-byte ID (unsigned short), 4-byte length (unsigned int, little-endian, including header and subchunks).
• Version: 4-byte unsigned int representing the file version (typically 3 or higher).
• Mesh Version: 4-byte unsigned int for mesh data version.
• Master Scale: 4-byte float for global scaling factor.
• Object Blocks: ASCIIZ string for object name, containing sub-properties for type (mesh, light, camera).
• Vertex List: 2-byte unsigned short (number of vertices), followed by repeating 12-byte groups (3 floats: X, Y, Z coordinates).
• Vertex Flags/Options: 2-byte unsigned short (number of vertices), followed by 2-byte unsigned short per vertex (selection bits and flags).
• Faces List: 2-byte unsigned short (number of faces), followed by repeating 8-byte groups per face (3 unsigned shorts for vertex indices v1, v2, v3; 1 unsigned short for visibility/edge flags).
• Faces Material Assignment: ASCIIZ string (material name), 2-byte unsigned short (number of faces), followed by unsigned shorts (face indices assigned to material).
• Smoothing Groups: 4-byte unsigned int per face (bitfield for up to 32 smoothing groups).
• Mapping Coordinates (UV): 2-byte unsigned short (number of UVs), followed by repeating 8-byte groups (2 floats: U, V).
• Local Transformation Matrix: 12 floats (4x3 matrix for object orientation/position).
• Material Name: ASCIIZ string (up to 16 characters).
• Ambient Color: Color chunk (either 3 bytes RGB or 3 floats).
• Diffuse Color: Color chunk (either 3 bytes RGB or 3 floats).
• Specular Color: Color chunk (either 3 bytes RGB or 3 floats).
• Shininess Percentage: 2-byte short or 4-byte float percentage.
• Transparency Percentage: 2-byte short or 4-byte float percentage.
• Texture Map Filename: ASCIIZ string (8.3 DOS format).
• Texture Map Parameters: Floats for U/V tiling, offset, angle, etc.
• Bump Map Filename and Parameters: Similar to texture map.
• Reflection Map Filename and Parameters: Similar to texture map.
• Light Position: 3 floats (X, Y, Z).
• Light Color: Color chunk.
• Light Multiplier: Float for intensity.
• Spotlight Target: 3 floats (X, Y, Z).
• Spotlight Hotspot: Float (angle in degrees).
• Spotlight Falloff: Float (angle in degrees).
• Camera Position: 3 floats (X, Y, Z).
• Camera Target: 3 floats (X, Y, Z).
• Camera Bank Angle: Float (roll in degrees).
• Camera Lens: Float (focal length in mm).
• Keyframe Data: Includes frame range (start/end), hierarchy, position keys (frame, 3 floats), rotation keys (frame, angle, axis 3 floats), scale keys (frame, 3 floats).
• Ambient Light Color: Color chunk.
• Background Color: Color chunk or bitmap reference.
• Fog Parameters: 4 floats (near plane, near density, far plane, far density).
• Shadow Parameters: Floats for bias, filter, range; short for map size.

These properties are hierarchical, with subchunks nested within parent chunks (e.g., vertices under mesh objects). Unknown chunks can be skipped using the length field.

2. Python Class for .3DS Files

import struct
import os

class ThreeDSFile:
    def __init__(self, filepath):
        self.filepath = filepath
        self.properties = {
            'version': 0,
            'mesh_version': 0,
            'master_scale': 1.0,
            'objects': [],  # list of dicts: {'name': str, 'type': str, 'vertices': [], 'faces': [], 'uvs': [], 'matrix': [], 'materials': []}
            'materials': [],  # list of dicts: {'name': str, 'ambient': (r,g,b), 'diffuse': (r,g,b), 'specular': (r,g,b), 'shininess': 0, 'transparency': 0, 'texture': ''}
            'lights': [],  # list of dicts: {'position': (x,y,z), 'color': (r,g,b), 'multiplier': 1.0, 'is_spot': False, 'target': (x,y,z), 'hotspot': 0, 'falloff': 0}
            'cameras': [],  # list of dicts: {'position': (x,y,z), 'target': (x,y,z), 'bank': 0, 'lens': 0}
            'keyframes': {}  # dict: {'start': 0, 'end': 0, 'positions': [], 'rotations': [], 'scales': []}
        }
        self.chunk_map = {
            0x0002: self._read_version,
            0x3D3E: self._read_mesh_version,
            0x0100: self._read_master_scale,
            0x4000: self._read_object_block,
            0xA000: self._read_material_name,
            0xA010: self._read_ambient_color,
            0xA020: self._read_diffuse_color,
            0xA030: self._read_specular_color,
            0xA040: self._read_shininess,
            0xA050: self._read_transparency,
            0xA200: self._read_texture_map,
            0x4600: self._read_light,
            0x4610: self._read_spotlight,
            0x4700: self._read_camera,
            0xB000: self._read_keyframes,
            # Add more mappings as needed for other properties
        }

    def _read_chunk(self, f):
        data = f.read(6)
        if len(data) < 6:
            return None, 0
        id, length = struct.unpack('<HI', data)
        return id, length

    def _read_string(self, f):
        s = b''
        while True:
            c = f.read(1)
            if c == b'\x00':
                break
            s += c
        return s.decode('ascii')

    def _read_color(self, f):
        chunk_id, chunk_len = self._read_chunk(f)
        if chunk_id == 0x0011:
            r, g, b = struct.unpack('<BBB', f.read(3))
        else:
            r, g, b = struct.unpack('<fff', f.read(12))
        return (r/255, g/255, b/255) if chunk_id == 0x0011 else (r, g, b)

    def _read_percentage(self, f):
        chunk_id, chunk_len = self._read_chunk(f)
        if chunk_id == 0x0030:
            return struct.unpack('<h', f.read(2))[0]
        else:
            return struct.unpack('<f', f.read(4))[0]

    def _read_version(self, f, length):
        self.properties['version'] = struct.unpack('<I', f.read(4))[0]
        f.seek(length - 10, os.SEEK_CUR)

    def _read_mesh_version(self, f, length):
        self.properties['mesh_version'] = struct.unpack('<I', f.read(4))[0]
        f.seek(length - 10, os.SEEK_CUR)

    def _read_master_scale(self, f, length):
        self.properties['master_scale'] = struct.unpack('<f', f.read(4))[0]
        f.seek(length - 10, os.SEEK_CUR)

    def _read_object_block(self, f, length):
        obj = {'name': self._read_string(f), 'type': '', 'vertices': [], 'faces': [], 'uvs': [], 'matrix': [], 'materials': []}
        end = f.tell() + length - 6 - len(obj['name']) - 1
        while f.tell() < end:
            chunk_id, chunk_len = self._read_chunk(f)
            if chunk_id == 0x4100:
                obj['type'] = 'mesh'
                self._read_tri_mesh(f, chunk_len, obj)
            elif chunk_id == 0x4600:
                obj['type'] = 'light'
                self._read_light(f, chunk_len, obj)
            elif chunk_id == 0x4700:
                obj['type'] = 'camera'
                self._read_camera(f, chunk_len, obj)
            else:
                f.seek(chunk_len - 6, os.SEEK_CUR)
        self.properties['objects'].append(obj)

    def _read_tri_mesh(self, f, length, obj):
        end = f.tell() + length - 6
        while f.tell() < end:
            chunk_id, chunk_len = self._read_chunk(f)
            if chunk_id in self.chunk_map:
                self.chunk_map[chunk_id](f, chunk_len)
            elif chunk_id == 0x4110:
                num_verts = struct.unpack('<H', f.read(2))[0]
                for _ in range(num_verts):
                    x, y, z = struct.unpack('<fff', f.read(12))
                    obj['vertices'].append((x, y, z))
            elif chunk_id == 0x4120:
                num_faces = struct.unpack('<H', f.read(2))[0]
                for _ in range(num_faces):
                    v1, v2, v3, flag = struct.unpack('<HHHH', f.read(8))
                    obj['faces'].append((v1, v2, v3, flag))
                self._read_subchunks(f, chunk_len - 2 - num_faces*8 - 6, obj)  # For smoothing, materials
            elif chunk_id == 0x4140:
                num_uvs = struct.unpack('<H', f.read(2))[0]
                for _ in range(num_uvs):
                    u, v = struct.unpack('<ff', f.read(8))
                    obj['uvs'].append((u, v))
            elif chunk_id == 0x4160:
                matrix = []
                for _ in range(12):
                    matrix.append(struct.unpack('<f', f.read(4))[0])
                obj['matrix'] = matrix
            else:
                f.seek(chunk_len - 6, os.SEEK_CUR)

    def _read_subchunks(self, f, remaining, obj):
        end = f.tell() + remaining
        while f.tell() < end:
            chunk_id, chunk_len = self._read_chunk(f)
            if chunk_id == 0x4130:
                mat_name = self._read_string(f)
                num_faces = struct.unpack('<H', f.read(2))[0]
                faces = []
                for _ in range(num_faces):
                    faces.append(struct.unpack('<H', f.read(2))[0])
                obj['materials'].append({'name': mat_name, 'faces': faces})
            elif chunk_id == 0x4150:
                for face in obj['faces']:
                    smoothing = struct.unpack('<I', f.read(4))[0]
                    face = face + (smoothing,)
            else:
                f.seek(chunk_len - 6, os.SEEK_CUR)

    # Similar methods for _read_material_name, _read_ambient_color, etc., following the pattern above
    # For brevity, not all are expanded; implement similarly using struct.unpack for each property

    def read(self):
        with open(self.filepath, 'rb') as f:
            chunk_id, length = self._read_chunk(f)
            if chunk_id != 0x4D4D:
                raise ValueError("Not a valid .3DS file")
            end = f.tell() + length - 6
            while f.tell() < end:
                sub_id, sub_len = self._read_chunk(f)
                if sub_id in self.chunk_map:
                    self.chunk_map[sub_id](f, sub_len)
                else:
                    f.seek(sub_len - 6, os.SEEK_CUR)

    def _write_chunk(self, f, id, data):
        f.write(struct.pack('<HI', id, len(data) + 6))
        f.write(data)

    def write(self):
        with open(self.filepath, 'wb') as f:
            data = b''
            # Append version chunk
            data += struct.pack('<HI', 0x0002, 10) + struct.pack('<I', self.properties['version'])
            # Similarly append other properties' chunks recursively
            # For objects, materials, etc., build hierarchical data bytes
            # For brevity, implement recursive writing similar to reading, building bytes for each property
            self._write_chunk(f, 0x4D4D, data)  # Main chunk wrapping all

3. Java Class for .3DS Files

import java.io.*;
import java.nio.*;
import java.util.*;

public class ThreeDSFile {
    private String filepath;
    private Map<String, Object> properties = new HashMap<>();

    public ThreeDSFile(String filepath) {
        this.filepath = filepath;
        properties.put("version", 0);
        properties.put("mesh_version", 0);
        properties.put("master_scale", 1.0f);
        properties.put("objects", new ArrayList<Map<String, Object>>());
        properties.put("materials", new ArrayList<Map<String, Object>>());
        properties.put("lights", new ArrayList<Map<String, Object>>());
        properties.put("cameras", new ArrayList<Map<String, Object>>());
        properties.put("keyframes", new HashMap<String, Object>());
    }

    private ByteBuffer buffer;

    private int readShort() {
        return buffer.getShort() & 0xFFFF;
    }

    private int readInt() {
        return buffer.getInt();
    }

    private float readFloat() {
        return buffer.getFloat();
    }

    private String readString() {
        StringBuilder sb = new StringBuilder();
        byte b;
        while ((b = buffer.get()) != 0) {
            sb.append((char) b);
        }
        return sb.toString();
    }

    private void readChunk(Map<Integer, Runnable> chunkHandlers) throws IOException {
        FileInputStream fis = new FileInputStream(filepath);
        byte[] bytes = new byte[(int) new File(filepath).length()];
        fis.read(bytes);
        fis.close();
        buffer = ByteBuffer.wrap(bytes).order(ByteOrder.LITTLE_ENDIAN);
        int id = readShort();
        int length = readInt();
        if (id != 0x4D4D) throw new IOException("Not .3DS");
        while (buffer.position() < length) {
            int subId = readShort();
            int subLen = readInt();
            int pos = buffer.position();
            if (chunkHandlers.containsKey(subId)) {
                chunkHandlers.get(subId).run();
            } else {
                buffer.position(pos + subLen - 6);
            }
        }
    }

    public void read() throws IOException {
        Map<Integer, Runnable> handlers = new HashMap<>();
        handlers.put(0x0002, () -> properties.put("version", readInt()));
        handlers.put(0x3D3E, () -> properties.put("mesh_version", readInt()));
        handlers.put(0x0100, () -> properties.put("master_scale", readFloat()));
        // Add handlers for object, material, light, camera, etc., similar to Python
        // For example:
        handlers.put(0x4000, () -> {
            Map<String, Object> obj = new HashMap<>();
            obj.put("name", readString());
            // Recursively handle subchunks like vertices, faces
            // Implement parsing loop for subchunks
        });
        // Expand for other properties
        readChunk(handlers);
    }

    public void write() throws IOException {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        DataOutputStream dos = new DataOutputStream(baos);
        // Write version
        dos.writeShort(0x0002);
        dos.writeInt(10);
        dos.writeInt((Integer) properties.get("version"));
        // Similarly write other chunks hierarchically
        // Wrap in main chunk 0x4D4D
        byte[] data = baos.toByteArray();
        FileOutputStream fos = new FileOutputStream(filepath);
        dos = new DataOutputStream(fos);
        dos.writeShort(0x4D4D);
        dos.writeInt(data.length + 6);
        dos.write(data);
        dos.close();
    }
}

4. JavaScript Class for .3DS Files

const fs = require('fs');

class ThreeDSFile {
    constructor(filepath) {
        this.filepath = filepath;
        this.properties = {
            version: 0,
            mesh_version: 0,
            master_scale: 1.0,
            objects: [],
            materials: [],
            lights: [],
            cameras: [],
            keyframes: {}
        };
    }

    readLittleEndian(buffer, offset, type) {
        if (type === 'uint16') return buffer.readUInt16LE(offset);
        if (type === 'uint32') return buffer.readUInt32LE(offset);
        if (type === 'float') return buffer.readFloatLE(offset);
    }

    readString(buffer, offset) {
        let str = '';
        let i = offset;
        while (buffer[i] !== 0) {
            str += String.fromCharCode(buffer[i]);
            i++;
        }
        return {str, length: i - offset + 1};
    }

    parseChunk(buffer, offset, end) {
        while (offset < end) {
            const id = this.readLittleEndian(buffer, offset, 'uint16');
            offset += 2;
            const length = this.readLittleEndian(buffer, offset, 'uint32');
            offset += 4;
            const chunkEnd = offset + length - 6;
            switch (id) {
                case 0x0002:
                    this.properties.version = this.readLittleEndian(buffer, offset, 'uint32');
                    break;
                // Add cases for other chunk IDs, parsing subdata accordingly
                // For example, for 0x4110 (vertices):
                // const numVerts = this.readLittleEndian(buffer, offset, 'uint16');
                // offset += 2;
                // for (let i = 0; i < numVerts; i++) { /* read 3 floats */ }
                default:
                    // Skip unknown
                    break;
            }
            offset = chunkEnd;
        }
    }

    read() {
        const buffer = fs.readFileSync(this.filepath);
        const id = this.readLittleEndian(buffer, 0, 'uint16');
        const length = this.readLittleEndian(buffer, 2, 'uint32');
        if (id !== 0x4D4D) throw new Error('Not .3DS');
        this.parseChunk(buffer, 6, length);
    }

    write() {
        let buffer = Buffer.alloc(0);
        // Append chunks, e.g.:
        // let versionChunk = Buffer.alloc(10);
        // versionChunk.writeUInt16LE(0x0002, 0);
        // versionChunk.writeUInt32LE(10, 2);
        // versionChunk.writeUInt32LE(this.properties.version, 6);
        // buffer = Buffer.concat([buffer, versionChunk]);
        // Wrap in main chunk
        let main = Buffer.alloc(6 + buffer.length);
        main.writeUInt16LE(0x4D4D, 0);
        main.writeUInt32LE(main.length, 2);
        buffer.copy(main, 6);
        fs.writeFileSync(this.filepath, main);
    }
}

5. C "Class" for .3DS Files

Since standard C does not have classes, this uses a struct with associated functions for equivalent functionality.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>

// Properties struct
typedef struct {
    uint32_t version;
    uint32_t mesh_version;
    float master_scale;
    // Arrays for objects, materials, etc. (use dynamic allocation)
    // For brevity, use simple fields; expand with malloc for lists
} ThreeDSProperties;

typedef struct {
    char *filepath;
    ThreeDSProperties props;
} ThreeDSFile;

// Helper to read little-endian
uint16_t read_uint16(FILE *f) {
    uint16_t val;
    fread(&val, 2, 1, f);
    return val;
}

uint32_t read_uint32(FILE *f) {
    uint32_t val;
    fread(&val, 4, 1, f);
    return val;
}

float read_float(FILE *f) {
    float val;
    fread(&val, 4, 1, f);
    return val;
}

char* read_string(FILE *f) {
    char *str = malloc(256); // Arbitrary max
    int i = 0;
    char c;
    while (fread(&c, 1, 1, f) && c != 0) {
        str[i++] = c;
    }
    str[i] = 0;
    return str;
}

// Init
ThreeDSFile* three_ds_file_new(const char *filepath) {
    ThreeDSFile *self = malloc(sizeof(ThreeDSFile));
    self->filepath = strdup(filepath);
    self->props.version = 0;
    // Init other props
    return self;
}

void three_ds_file_free(ThreeDSFile *self) {
    free(self->filepath);
    // Free lists
    free(self);
}

void parse_chunk(ThreeDSFile *self, FILE *f, long end) {
    while (ftell(f) < end) {
        uint16_t id = read_uint16(f);
        uint32_t length = read_uint32(f);
        long chunk_end = ftell(f) + length - 6;
        switch (id) {
            case 0x0002:
                self->props.version = read_uint32(f);
                break;
            // Add cases for other IDs, reading data accordingly
            default:
                fseek(f, length - 6, SEEK_CUR);
                break;
        }
        fseek(f, chunk_end, SEEK_SET);
    }
}

void three_ds_file_read(ThreeDSFile *self) {
    FILE *f = fopen(self->filepath, "rb");
    if (!f) return;
    uint16_t id = read_uint16(f);
    uint32_t length = read_uint32(f);
    if (id != 0x4D4D) {
        fclose(f);
        return;
    }
    parse_chunk(self, f, length);
    fclose(f);
}

void three_ds_file_write(ThreeDSFile *self) {
    FILE *f = fopen(self->filepath, "wb");
    if (!f) return;
    // Write main chunk header
    fwrite("\x4D\x4D", 2, 1, f); // ID
    uint32_t total_len = 6; // Placeholder
    fwrite(&total_len, 4, 1, f);
    // Write subchunks, e.g., version
    uint16_t ver_id = 0x0002;
    uint32_t ver_len = 10;
    fwrite(&ver_id, 2, 1, f);
    fwrite(&ver_len, 4, 1, f);
    fwrite(&self->props.version, 4, 1, f);
    // Update total_len, rewind and write
    total_len = ftell(f);
    fseek(f, 2, SEEK_SET);
    fwrite(&total_len, 4, 1, f);
    fclose(f);
}