#pragma once
//###########################################################################
//
//	L4AUDEFX.h -- OpenAL EFX bridge for the authored filter/reverb chains
//	(docs/SOUND.md, findings F9 and F11).
//
//	The original drove the AWE32's initial-filter-cutoff NRPN (21) every frame
//	-- brightness x the distance high-frequency rolloff -- and sent CC91 reverb
//	on the 3D channels (global_reverb_scale=0.35 in RP's AUDIO.INI) while
//	keeping the cockpit DirectPatch channels dry.  The OpenAL port computed
//	both and applied neither: GetHighFreqCutoffScale() had no callers at all
//	and every CC91 send site sat inside a comment block, so RP played
//	spectrally full-bright at every distance and bone-dry everywhere.
//
//	This bridge reproduces both through OpenAL Soft's EFX extension: one
//	EAXReverb auxiliary slot plus a scratch AL_FILTER_LOWPASS whose parameters
//	are copied at attach time.  Without ALC_EXT_EFX it stays inert and every
//	entry point below is a no-op, so the game still runs on a bare OpenAL.
//
//###########################################################################

#include "openal/al.h"

//
// Load the EFX entry points, create the reverb slot (gain = the authored
// global_reverb_scale) and the scratch lowpass.  Call once, with the AL
// context current.  Returns false (and stays inert) without ALC_EXT_EFX.
//
bool EFX_Initialize(float global_reverb_scale);

bool EFX_Available();

//
// Per-frame direct-path filter: gainhf is the linear high-frequency gain at the
// EFX 5 kHz reference, carrying the authored brightness x distance model.
// Callers map the AWE cutoff through EFX_CutoffScaleToGainHF below.
//
// At unity the filter is detached rather than attached at no-op settings.
//
// NOTE: this is a LOWPASS and can only ever be one.  The OpenAL this game ships
// (Creative's) implements no other filter type -- see L4AUDEFX.cpp -- so the
// bass trim could not ride here as a bandpass GAINLF and lives in the resource
// loader instead (RPApplyBassTrim, L4AUDRES.cpp).
//
void EFX_SetSourceLowpassGainHF(ALuint source, float gainhf);

//
// AWE NRPN 21 curve -> EFX gainhf.  cutoff_scale is [0,1] of the 100-8000 Hz
// span; approximated as the attenuation of a 2-pole lowpass at the 5 kHz
// reference.  Curve shape is approximate, endpoints exact.
//
inline float EFX_CutoffScaleToGainHF(float cutoff_scale)
{
	if (cutoff_scale < 0.0f) cutoff_scale = 0.0f;
	if (cutoff_scale > 1.0f) cutoff_scale = 1.0f;
	float cutoff_hz = 100.0f + cutoff_scale * 7900.0f;
	float g = (cutoff_hz / 5000.0f) * (cutoff_hz / 5000.0f);
	return (g > 1.0f) ? 1.0f : ((g < 0.001f) ? 0.001f : g);
}

//
// Wet-exterior routing: attach the source's auxiliary send to the reverb slot
// (Dynamic3D / Static3D).  Direct cockpit sources stay dry.
//
void EFX_AttachReverbSend(ALuint source);

//
// Drop both the direct-path filter and the reverb send.  Required when a source
// is recycled through the pool: without it a dry cockpit sound can inherit the
// wet send of the 3D source that used the name before it, and a full-bright
// source can inherit a distant source's lowpass.
//
void EFX_ClearSourceEffects(ALuint source);