Fix: compute air absorption in the correct place.

Author: stechyo

src/server.cpp

@@ -49,6 +49,12 @@ void SteamAudioServer::tick() {
 		attn_model.type = IPL_DISTANCEATTENUATIONTYPE_INVERSEDISTANCE;
 		attn_model.minDistance = ls->cfg.min_attn_dist;
 
+		IPLAirAbsorptionModel absorp_model{};
+		absorp_model.type = ls->cfg.air_absorption_model_type;
+		absorp_model.coefficients[0] = ls->cfg.air_absorption_low;
+		absorp_model.coefficients[1] = ls->cfg.air_absorption_mid;
+		absorp_model.coefficients[2] = ls->cfg.air_absorption_high;
+
 		IPLCoordinateSpace3 src_coords;
 		src_coords.ahead = IPLVector3{};
 		src_coords.up = IPLVector3{};
@@ -60,8 +66,10 @@ void SteamAudioServer::tick() {
 		inputs.directFlags = static_cast<IPLDirectSimulationFlags>(
 				IPL_DIRECTSIMULATIONFLAGS_DISTANCEATTENUATION |
 				IPL_DIRECTSIMULATIONFLAGS_OCCLUSION |
-				IPL_DIRECTSIMULATIONFLAGS_TRANSMISSION);
+				IPL_DIRECTSIMULATIONFLAGS_TRANSMISSION |
+				IPL_DIRECTSIMULATIONFLAGS_AIRABSORPTION);
 		inputs.distanceAttenuationModel = attn_model;
+		inputs.airAbsorptionModel = absorp_model;
 		inputs.source = src_coords;
 		inputs.occlusionType = IPL_OCCLUSIONTYPE_VOLUMETRIC;
 		inputs.occlusionRadius = ls->cfg.occ_radius;

src/stream.cpp

@@ -76,22 +76,6 @@ int32_t SteamAudioStreamPlayback::_mix(AudioFrame *buffer, double rate_scale, in
 	}
 
 	if (ls->cfg.is_air_absorp_on) {
-		IPLAirAbsorptionModel airAbsorptionModel{};
-		airAbsorptionModel.type = ls->cfg.air_absorption_model_type;
-
-		IPLVector3 sourcePosition = ipl_vec3_from(ls->src.player->get_global_transform().origin);
-		IPLVector3 listenerPosition = gs->listener_coords.origin;
-		float airAbsorption[3];
-		airAbsorption[0] = ls->cfg.air_absorption_low;
-		airAbsorption[1] = ls->cfg.air_absorption_mid;
-		airAbsorption[2] = ls->cfg.air_absorption_high;
-
-		iplAirAbsorptionCalculate(gs->ctx, sourcePosition, listenerPosition, &airAbsorptionModel, airAbsorption);
-
-		ls->direct_outputs.airAbsorption[0] = airAbsorption[0];
-		ls->direct_outputs.airAbsorption[1] = airAbsorption[1];
-		ls->direct_outputs.airAbsorption[2] = airAbsorption[2];
-
 		ls->direct_outputs.flags = static_cast<IPLDirectEffectFlags>(
 				ls->direct_outputs.flags |
 				IPL_DIRECTEFFECTFLAGS_APPLYAIRABSORPTION);