为Unity开发C++插件：首次插件开发实操咨询

Hey there! Let's get your first Unity C++ plugin working properly. I'll walk through completing your C# script, key setup checks, and troubleshooting common pitfalls.

Your incomplete C# code needs a DllImport attribute to hook into your C++ DLL. Here's the full, working version:

using UnityEngine;
using System.Runtime.InteropServices; // Required for DllImport

public class MyBehaviour : MonoBehaviour
{
    // Import the add_1 function from your DLL
    // Note: Omit the .dll suffix - Unity handles platform-specific loading
    [DllImport("FirstDLL")]
    private static extern int add_1(int number);

    void Start()
    {
        // Test the function call
        int input = 7;
        int result = add_1(input);
        Debug.Log($"add_1({input}) returned: {result}"); // Should log 8!
    }
}

Before hitting play, double-check these details to avoid headaches:

• Match Architectures: Ensure your C++ DLL is compiled for the same architecture as your Unity project. For example:
  • If you're using 64-bit Unity (most modern setups), compile your DLL as x64
  • For 32-bit Unity, compile as x86
    Mismatched architectures will cause DllNotFoundException or crashes.
• Proper DLL Placement:
  • Drop your FirstDLL.dll into Assets/Plugins
  • For multi-platform support, create subfolders like Plugins/x86_64 and Plugins/x86 to organize DLLs by architecture—Unity will auto-load the correct one.
• Keep extern "C": You already added this in your C++ code, which is crucial! It disables C++ name mangling, so Unity can find the exact function name add_1 instead of a garbled compiler-generated name.
• Static Link Runtime Libraries: In your C++ project (Visual Studio), set Project Properties > C/C++ > Code Generation > Runtime Library to Multi-threaded (/MT) (for release) or Multi-threaded Debug (/MTd) (for debug). This avoids missing VC++ runtime dependencies on target machines.

If you run into errors, here's how to fix them:

• EntryPointNotFoundException: This means Unity can't find the add_1 function. Double-check:
  • extern "C" is present in both your header and source file
  • The function name in DllImport matches exactly (case-sensitive!)
  • DLL architecture matches Unity's
• DllNotFoundException: Unity can't locate your DLL. Verify:
  • DLL is in Assets/Plugins (or the correct architecture subfolder)
  • No missing dependencies (use a tool like Dependency Walker to check if your DLL relies on other unloaded files)
• Crash When Calling the Function: Almost always an architecture mismatch or incorrect parameter types. Ensure your C++ int matches C#'s int (both are 32-bit on Windows) and architectures align.

内容的提问来源于stack exchange，提问作者user8469759