为什么要解释这个参数：

在一些插件中，设置碰撞属性，比如玩家之间是否可穿越，或者说物体和其他物体之间是否可穿越，它们是这样写的

SetEntData(entity, g_offsCollisionGroup, 2, 4, true);

这里面的2，4就很奇怪，到底代表什么含义呢？

经过查询SetEntData API介绍知道：

/**
 * Peeks into an entity's object data and sets the integer value at
 * the given offset.
 *
 * @param entity        Edict index.
 * @param offset        Offset to use.
 * @param value         Value to set.
 * @param size          Number of bytes to write (valid values are 1, 2, or 4).
 * @param changeState   If true, change will be sent over the network.
 * @error               Invalid entity or offset out of reasonable bounds.
 */
native void SetEntData(int entity, int offset, any value, int size=4, bool changeState=false);

其中的数字2代表的是一个表示可以被设置的属性数值，数字4是表示这个数据的字节大小。那么问题来了，我们怎么知道到底设置什么数值？有哪些数值呢？

下面的官方源码中的enum值，给了我们最详细的解答：

官方源码：

hl2sdk-ob: public/const.h@2e2ec01be7aa (alliedmods.net)

碰撞组 - Valve 开发者社区 (valvesoftware.com)

enum Collision_Group_t
// from this website:https://hg.alliedmods.net/hl2sdks/hl2sdk-ob/file/2e2ec01be7aa/public/const.h
{
	COLLISION_GROUP_NONE  = 0,
 	COLLISION_GROUP_DEBRIS,			// Collides with nothing but world and static stuff
 	COLLISION_GROUP_DEBRIS_TRIGGER, // Same as debris, but hits triggers
 	COLLISION_GROUP_INTERACTIVE_DEBRIS,	// Collides with everything except other interactive debris or debris
 	COLLISION_GROUP_INTERACTIVE,	// Collides with everything except interactive debris or debris
	COLLISION_GROUP_PLAYER,
	COLLISION_GROUP_BREAKABLE_GLASS,
	COLLISION_GROUP_VEHICLE,
 	COLLISION_GROUP_PLAYER_MOVEMENT,  // For HL2, same as Collision_Group_Player, for
 										// TF2, this filters out other players and CBaseObjects
 	COLLISION_GROUP_NPC,			// Generic NPC group
 	COLLISION_GROUP_IN_VEHICLE,		// for any entity inside a vehicle
 	COLLISION_GROUP_WEAPON,			// for any weapons that need collision detection
 	COLLISION_GROUP_VEHICLE_CLIP,	// vehicle clip brush to restrict vehicle movement
 	COLLISION_GROUP_PROJECTILE,		// Projectiles!
 	COLLISION_GROUP_DOOR_BLOCKER,	// Blocks entities not permitted to get near moving doors
 	COLLISION_GROUP_PASSABLE_DOOR,	// Doors that the player shouldn't collide with
 	COLLISION_GROUP_DISSOLVING,		// Things that are dissolving are in this group
 	COLLISION_GROUP_PUSHAWAY,		// Nonsolid on client and server, pushaway in player code

 	COLLISION_GROUP_NPC_ACTOR,		// Used so NPCs in scripts ignore the player.
 	COLLISION_GROUP_NPC_SCRIPTED,	// USed for NPCs in scripts that should not collide with each other

	LAST_SHARED_COLLISION_GROUP
};

在SourceMod 1.11+引入了：

SetEntityCollisionGroup · sdktools_functions · SourceMod Scripting API Reference

void SetEntityCollisionGroup(int entity, int collisionGroup)

Parameters

int entity

The entity index.

int collisionGroup

Collision group to use.

也是可以达到同样的效果，函数更直观了！

参考：sdktools_functions · SourceMod Scripting API Reference

第三方WiKi介绍：

COLLISION_GROUP - Garry's Mod Wiki (facepunch.com)

相关插件：

FF2-Library/improved_saxton.sp at edited · Batfoxkid/FF2-Library (github.com)

g_offsCollisionGroup - AlliedModders (alliedmods.net)