[GoD-Tony]

This is a neat idea! I tried something like this myself a while ago and ran into a few issues with a PassServerEntityFilter detour.

Using this code for example:

PHP Code:

public Action:CH_PassFilter( ent1, ent2, &bool:result )
{
    // No client-client collisions
    if (1 <= ent1 <= MaxClients && 1 <= ent2 <= MaxClients)
    {
        result = false;
        return Plugin_Handled;
    }
    
    return Plugin_Continue;
} 


This is all on CS:S, and the code above seems to crash when shooting a player.

Normally it would prevent trace weapons from hitting any player target, because the player firing is passed as pPass. So in order to differentiate player collision traces from the rest, I detoured CTraceFilterSimple::ShouldHitEntity instead which provided collisionGroup and contentsMask.

Mine ended up looking like this:
(unreleased because I thought it was an ugly workaround)

DETOUR_DECL_MEMBER2(ShouldHitEntity, bool, IHandleEntity *, pHandleEntity, int, contentsMask)
{
	IHandleEntity *m_pPassEnt = *(IHandleEntity **)((intptr_t)this + g_iPassEntOffs);
	int m_collisionGroup = *(int *)((intptr_t)this + g_iCollisionOffs);

	cell_t result = DETOUR_MEMBER_CALL(ShouldHitEntity)(pHandleEntity, contentsMask);

	if (!pHandleEntity || !m_pPassEnt || pHandleEntity == m_pPassEnt)
		return (result != 0);

	cell_t touchEnt = gamehelpers->EntityToBCompatRef((CBaseEntity *)pHandleEntity);
	cell_t passEnt = gamehelpers->EntityToBCompatRef((CBaseEntity *)m_pPassEnt);

	g_pOnShouldCollide->PushCell(touchEnt);
	g_pOnShouldCollide->PushCell(passEnt);
	g_pOnShouldCollide->PushCell(m_collisionGroup);
	g_pOnShouldCollide->PushCell(contentsMask);
	g_pOnShouldCollide->PushCellByRef(&result);
	g_pOnShouldCollide->Execute(NULL);

	return (result != 0);
}

Then in the plugin if you only wanted to work with player collisions, you could check if contentsMask == MASK_PLAYERSOLID.