If a player is on a ladder, his move type will be fly.
Code:
// at the top of your plugin
#define IsOnLadder(%1) (entity_get_int(%1, EV_INT_movetype) == MOVETYPE_FLY)
// in your plugin
if( IsOnLadder(index) )
{
// player is on a ladder
}
That code requires the engine module.
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