test/Documentation/FLASHMOVE_PROTOCOL_COMPARISON.md

Flash Move Skill Protocol Comparison: C++ vs C#

Summary

Both C++ and C# send the same command ID (89) for CAST_POS_SKILL, but they use different protocol wrappers.

C++ Implementation

Log Evidence (EC.log)

[17:10:03.501] [FLASH_SKILL_PROTOCOL] c2s_SendCmdCastPosSkill: Sending protocol C2S::CAST_POS_SKILL (command ID=89), skillID=58, pos=(858.33, 60.93, -149.44), byPVPMask=0, targetCount=0
[17:10:03.501] [FLASH_SKILL_PROTOCOL] c2s_SendCmdCastPosSkill: Protocol packet size=20 bytes
[17:10:03.501] CLIENT - CAST_POS_SKILL(89)

Code Location

• File: EC_SendC2SCmds.cpp
• Function: c2s_SendCmdCastPosSkill() (line 1030-1068)
• Protocol: Sends C2S::CAST_POS_SKILL directly as protocol command
• Command ID: 89 (from enum C2S::CAST_POS_SKILL)
• Packet Structure:

  [cmd_header] + [cmd_cast_pos_skill]
  - cmd_header.cmd = C2S::CAST_POS_SKILL (89)
  - cmd_cast_pos_skill contains: skill_id, pos, force_attack, target_count, targets[]
  

C# Implementation

Log Evidence (SessionLog)

[16:58:15.286] [DISTANCE_DEBUG] CastSkill: Before sending c2s_CmdCastPosSkill (flashmove self), skillID=58, hostPos=(860.71, 59.59, -130.28), destPos=(860.62, 60.73, -145.39), flashDistance=16.00, byPVPMask=0
[16:58:15.286] [GameSession] Sending protocol: gamedatasend (Type: PROTOCOL_GAMEDATASEND) +  Type=34 - CMD_ID: CAST_POS_SKILL

Code Location

• File: C2SCommand.cs
• Enum: CommandID.CAST_POS_SKILL = 89 (line 118)
• Protocol: Wraps command in PROTOCOL_GAMEDATASEND (Type=34)
• Command ID: 89 (stored in first 2 bytes of Data field)
• Packet Structure:

  [PROTOCOL_GAMEDATASEND header] + [Data field]
  - Protocol Type = 34 (PROTOCOL_GAMEDATASEND)
  - Data[0-1] = CommandID.CAST_POS_SKILL (89) as ushort
  - Data[2+] = CMD_CastPosSkill structure (skillId, pos, pvpMask, targetCount, targets[])
  

Key Differences

Aspect	C++	C#
Protocol Type	Direct command (89)	Wrapped in PROTOCOL_GAMEDATASEND (34)
Command ID	89 (C2S::CAST_POS_SKILL)	89 (CommandID.CAST_POS_SKILL)
Packet Structure	[cmd_header][cmd_cast_pos_skill]	[PROTOCOL_GAMEDATASEND][Data with CMD_ID][CMD_CastPosSkill]
Packet Size	20 bytes (for skillID=58, no targets)	Larger (includes PROTOCOL_GAMEDATASEND wrapper)

Conclusion

✅ The command ID is the same (89) in both implementations.

⚠️ The protocol wrapper is different:

• C++ sends the command directly as protocol 89
• C# wraps it in PROTOCOL_GAMEDATASEND (34) and puts the command ID (89) in the Data field

This is a protocol architecture difference, not a bug. The C# implementation uses a unified GameDataSend protocol that wraps all game commands, while the C++ implementation sends commands directly. The server should handle both formats correctly if it recognizes:

1. Direct protocol 89 (C++ style)
2. Protocol 34 with command ID 89 in the data (C# style)

Verification

Both logs show:

• Skill ID: 58 (same flash move skill)
• Command ID: 89 (CAST_POS_SKILL)
• Position data: Present in both
• PVP Mask: 0 in both
• Target Count: 0 in both

The actual command data is identical; only the protocol wrapper differs.