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Diffstat (limited to 'examples/almultireverb.c')
| -rw-r--r-- | examples/almultireverb.c | 696 |
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diff --git a/examples/almultireverb.c b/examples/almultireverb.c new file mode 100644 index 00000000..a2587585 --- /dev/null +++ b/examples/almultireverb.c @@ -0,0 +1,696 @@ +/* + * OpenAL Multi-Zone Reverb Example + * + * Copyright (c) 2018 by Chris Robinson <[email protected]> + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + */ + +/* This file contains an example for controlling multiple reverb zones to + * smoothly transition between reverb environments. The general concept is to + * extend single-reverb by also tracking the closest adjacent environment, and + * utilize EAX Reverb's panning vectors to position them relative to the + * listener. + */ + +#include <stdio.h> +#include <assert.h> +#include <math.h> + +#include <SDL_sound.h> + +#include "AL/al.h" +#include "AL/alc.h" +#include "AL/alext.h" +#include "AL/efx-presets.h" + +#include "common/alhelpers.h" + + +#ifndef M_PI +#define M_PI 3.14159265358979323846 +#endif + + +/* Filter object functions */ +static LPALGENFILTERS alGenFilters; +static LPALDELETEFILTERS alDeleteFilters; +static LPALISFILTER alIsFilter; +static LPALFILTERI alFilteri; +static LPALFILTERIV alFilteriv; +static LPALFILTERF alFilterf; +static LPALFILTERFV alFilterfv; +static LPALGETFILTERI alGetFilteri; +static LPALGETFILTERIV alGetFilteriv; +static LPALGETFILTERF alGetFilterf; +static LPALGETFILTERFV alGetFilterfv; + +/* Effect object functions */ +static LPALGENEFFECTS alGenEffects; +static LPALDELETEEFFECTS alDeleteEffects; +static LPALISEFFECT alIsEffect; +static LPALEFFECTI alEffecti; +static LPALEFFECTIV alEffectiv; +static LPALEFFECTF alEffectf; +static LPALEFFECTFV alEffectfv; +static LPALGETEFFECTI alGetEffecti; +static LPALGETEFFECTIV alGetEffectiv; +static LPALGETEFFECTF alGetEffectf; +static LPALGETEFFECTFV alGetEffectfv; + +/* Auxiliary Effect Slot object functions */ +static LPALGENAUXILIARYEFFECTSLOTS alGenAuxiliaryEffectSlots; +static LPALDELETEAUXILIARYEFFECTSLOTS alDeleteAuxiliaryEffectSlots; +static LPALISAUXILIARYEFFECTSLOT alIsAuxiliaryEffectSlot; +static LPALAUXILIARYEFFECTSLOTI alAuxiliaryEffectSloti; +static LPALAUXILIARYEFFECTSLOTIV alAuxiliaryEffectSlotiv; +static LPALAUXILIARYEFFECTSLOTF alAuxiliaryEffectSlotf; +static LPALAUXILIARYEFFECTSLOTFV alAuxiliaryEffectSlotfv; +static LPALGETAUXILIARYEFFECTSLOTI alGetAuxiliaryEffectSloti; +static LPALGETAUXILIARYEFFECTSLOTIV alGetAuxiliaryEffectSlotiv; +static LPALGETAUXILIARYEFFECTSLOTF alGetAuxiliaryEffectSlotf; +static LPALGETAUXILIARYEFFECTSLOTFV alGetAuxiliaryEffectSlotfv; + + +/* LoadEffect loads the given initial reverb properties into the given OpenAL + * effect object, and returns non-zero on success. + */ +static int LoadEffect(ALuint effect, const EFXEAXREVERBPROPERTIES *reverb) +{ + ALenum err; + + alGetError(); + + /* Prepare the effect for EAX Reverb (standard reverb doesn't contain + * the needed panning vectors). + */ + alEffecti(effect, AL_EFFECT_TYPE, AL_EFFECT_EAXREVERB); + if((err=alGetError()) != AL_NO_ERROR) + { + fprintf(stderr, "Failed to set EAX Reverb: %s (0x%04x)\n", alGetString(err), err); + return 0; + } + + /* Load the reverb properties. */ + alEffectf(effect, AL_EAXREVERB_DENSITY, reverb->flDensity); + alEffectf(effect, AL_EAXREVERB_DIFFUSION, reverb->flDiffusion); + alEffectf(effect, AL_EAXREVERB_GAIN, reverb->flGain); + alEffectf(effect, AL_EAXREVERB_GAINHF, reverb->flGainHF); + alEffectf(effect, AL_EAXREVERB_GAINLF, reverb->flGainLF); + alEffectf(effect, AL_EAXREVERB_DECAY_TIME, reverb->flDecayTime); + alEffectf(effect, AL_EAXREVERB_DECAY_HFRATIO, reverb->flDecayHFRatio); + alEffectf(effect, AL_EAXREVERB_DECAY_LFRATIO, reverb->flDecayLFRatio); + alEffectf(effect, AL_EAXREVERB_REFLECTIONS_GAIN, reverb->flReflectionsGain); + alEffectf(effect, AL_EAXREVERB_REFLECTIONS_DELAY, reverb->flReflectionsDelay); + alEffectfv(effect, AL_EAXREVERB_REFLECTIONS_PAN, reverb->flReflectionsPan); + alEffectf(effect, AL_EAXREVERB_LATE_REVERB_GAIN, reverb->flLateReverbGain); + alEffectf(effect, AL_EAXREVERB_LATE_REVERB_DELAY, reverb->flLateReverbDelay); + alEffectfv(effect, AL_EAXREVERB_LATE_REVERB_PAN, reverb->flLateReverbPan); + alEffectf(effect, AL_EAXREVERB_ECHO_TIME, reverb->flEchoTime); + alEffectf(effect, AL_EAXREVERB_ECHO_DEPTH, reverb->flEchoDepth); + alEffectf(effect, AL_EAXREVERB_MODULATION_TIME, reverb->flModulationTime); + alEffectf(effect, AL_EAXREVERB_MODULATION_DEPTH, reverb->flModulationDepth); + alEffectf(effect, AL_EAXREVERB_AIR_ABSORPTION_GAINHF, reverb->flAirAbsorptionGainHF); + alEffectf(effect, AL_EAXREVERB_HFREFERENCE, reverb->flHFReference); + alEffectf(effect, AL_EAXREVERB_LFREFERENCE, reverb->flLFReference); + alEffectf(effect, AL_EAXREVERB_ROOM_ROLLOFF_FACTOR, reverb->flRoomRolloffFactor); + alEffecti(effect, AL_EAXREVERB_DECAY_HFLIMIT, reverb->iDecayHFLimit); + + /* Check if an error occured, and return failure if so. */ + if((err=alGetError()) != AL_NO_ERROR) + { + fprintf(stderr, "Error setting up reverb: %s\n", alGetString(err)); + return 0; + } + + return 1; +} + + +/* LoadBuffer loads the named audio file into an OpenAL buffer object, and + * returns the new buffer ID. + */ +static ALuint LoadSound(const char *filename) +{ + Sound_Sample *sample; + ALenum err, format; + ALuint buffer; + Uint32 slen; + + /* Open the audio file */ + sample = Sound_NewSampleFromFile(filename, NULL, 65536); + if(!sample) + { + fprintf(stderr, "Could not open audio in %s\n", filename); + return 0; + } + + /* Get the sound format, and figure out the OpenAL format */ + if(sample->actual.channels == 1) + { + if(sample->actual.format == AUDIO_U8) + format = AL_FORMAT_MONO8; + else if(sample->actual.format == AUDIO_S16SYS) + format = AL_FORMAT_MONO16; + else + { + fprintf(stderr, "Unsupported sample format: 0x%04x\n", sample->actual.format); + Sound_FreeSample(sample); + return 0; + } + } + else if(sample->actual.channels == 2) + { + if(sample->actual.format == AUDIO_U8) + format = AL_FORMAT_STEREO8; + else if(sample->actual.format == AUDIO_S16SYS) + format = AL_FORMAT_STEREO16; + else + { + fprintf(stderr, "Unsupported sample format: 0x%04x\n", sample->actual.format); + Sound_FreeSample(sample); + return 0; + } + } + else + { + fprintf(stderr, "Unsupported channel count: %d\n", sample->actual.channels); + Sound_FreeSample(sample); + return 0; + } + + /* Decode the whole audio stream to a buffer. */ + slen = Sound_DecodeAll(sample); + if(!sample->buffer || slen == 0) + { + fprintf(stderr, "Failed to read audio from %s\n", filename); + Sound_FreeSample(sample); + return 0; + } + + /* Buffer the audio data into a new buffer object, then free the data and + * close the file. */ + buffer = 0; + alGenBuffers(1, &buffer); + alBufferData(buffer, format, sample->buffer, slen, sample->actual.rate); + Sound_FreeSample(sample); + + /* Check if an error occured, and clean up if so. */ + err = alGetError(); + if(err != AL_NO_ERROR) + { + fprintf(stderr, "OpenAL Error: %s\n", alGetString(err)); + if(buffer && alIsBuffer(buffer)) + alDeleteBuffers(1, &buffer); + return 0; + } + + return buffer; +} + + +/* Helper to calculate the dot-product of the two given vectors. */ +static ALfloat dot_product(const ALfloat vec0[3], const ALfloat vec1[3]) +{ + return vec0[0]*vec1[0] + vec0[1]*vec1[1] + vec0[2]*vec1[2]; +} + +/* Helper to normalize a given vector. */ +static void normalize(ALfloat vec[3]) +{ + ALfloat mag = sqrtf(dot_product(vec, vec)); + if(mag > 0.00001f) + { + vec[0] /= mag; + vec[1] /= mag; + vec[2] /= mag; + } + else + { + vec[0] = 0.0f; + vec[1] = 0.0f; + vec[2] = 0.0f; + } +} + + +/* The main update function to update the listener and environment effects. */ +static void UpdateListenerAndEffects(float timediff, const ALuint slots[2], const ALuint effects[2], const EFXEAXREVERBPROPERTIES reverbs[2]) +{ + static const ALfloat listener_move_scale = 10.0f; + /* Individual reverb zones are connected via "portals". Each portal has a + * position (center point of the connecting area), a normal (facing + * direction), and a radius (approximate size of the connecting area). + */ + const ALfloat portal_pos[3] = { 0.0f, 0.0f, 0.0f }; + const ALfloat portal_norm[3] = { sqrtf(0.5f), 0.0f, -sqrtf(0.5f) }; + const ALfloat portal_radius = 2.5f; + ALfloat other_dir[3], this_dir[3]; + ALfloat listener_pos[3]; + ALfloat local_norm[3]; + ALfloat local_dir[3]; + ALfloat near_edge[3]; + ALfloat far_edge[3]; + ALfloat dist, edist; + + /* Update the listener position for the amount of time passed. This uses a + * simple triangular LFO to offset the position (moves along the X axis + * between -listener_move_scale and +listener_move_scale for each + * transition). + */ + listener_pos[0] = (fabsf(2.0f - timediff/2.0f) - 1.0f) * listener_move_scale; + listener_pos[1] = 0.0f; + listener_pos[2] = 0.0f; + alListenerfv(AL_POSITION, listener_pos); + + /* Calculate local_dir, which represents the listener-relative point to the + * adjacent zone (should also include orientation). Because EAX Reverb uses + * left-handed coordinates instead of right-handed like the rest of OpenAL, + * negate Z for the local values. + */ + local_dir[0] = portal_pos[0] - listener_pos[0]; + local_dir[1] = portal_pos[1] - listener_pos[1]; + local_dir[2] = -(portal_pos[2] - listener_pos[2]); + /* A normal application would also rotate the portal's normal given the + * listener orientation, to get the listener-relative normal. + */ + local_norm[0] = portal_norm[0]; + local_norm[1] = portal_norm[1]; + local_norm[2] = -portal_norm[2]; + + /* Calculate the distance from the listener to the portal, and ensure it's + * far enough away to not suffer severe floating-point precision issues. + */ + dist = sqrtf(dot_product(local_dir, local_dir)); + if(dist > 0.00001f) + { + const EFXEAXREVERBPROPERTIES *other_reverb, *this_reverb; + ALuint other_effect, this_effect; + ALfloat magnitude, dir_dot_norm; + + /* Normalize the direction to the portal. */ + local_dir[0] /= dist; + local_dir[1] /= dist; + local_dir[2] /= dist; + + /* Calculate the dot product of the portal's local direction and local + * normal, which is used for angular and side checks later on. + */ + dir_dot_norm = dot_product(local_dir, local_norm); + + /* Figure out which zone we're in. */ + if(dir_dot_norm <= 0.0f) + { + /* We're in front of the portal, so we're in Zone 0. */ + this_effect = effects[0]; + other_effect = effects[1]; + this_reverb = &reverbs[0]; + other_reverb = &reverbs[1]; + } + else + { + /* We're behind the portal, so we're in Zone 1. */ + this_effect = effects[1]; + other_effect = effects[0]; + this_reverb = &reverbs[1]; + other_reverb = &reverbs[0]; + } + + /* Calculate the listener-relative extents of the portal. */ + /* First, project the listener-to-portal vector onto the portal's plane + * to get the portal-relative direction along the plane that goes away + * from the listener (toward the farthest edge of the portal). + */ + far_edge[0] = local_dir[0] - local_norm[0]*dir_dot_norm; + far_edge[1] = local_dir[1] - local_norm[1]*dir_dot_norm; + far_edge[2] = local_dir[2] - local_norm[2]*dir_dot_norm; + + edist = sqrtf(dot_product(far_edge, far_edge)); + if(edist > 0.0001f) + { + /* Rescale the portal-relative vector to be at the radius edge. */ + ALfloat mag = portal_radius / edist; + far_edge[0] *= mag; + far_edge[1] *= mag; + far_edge[2] *= mag; + + /* Calculate the closest edge of the portal by negating the + * farthest, and add an offset to make them both relative to the + * listener. + */ + near_edge[0] = local_dir[0]*dist - far_edge[0]; + near_edge[1] = local_dir[1]*dist - far_edge[1]; + near_edge[2] = local_dir[2]*dist - far_edge[2]; + far_edge[0] += local_dir[0]*dist; + far_edge[1] += local_dir[1]*dist; + far_edge[2] += local_dir[2]*dist; + + /* Normalize the listener-relative extents of the portal, then + * calculate the panning magnitude for the other zone given the + * apparent size of the opening. The panning magnitude affects the + * envelopment of the environment, with 1 being a point, 0.5 being + * half coverage around the listener, and 0 being full coverage. + */ + normalize(far_edge); + normalize(near_edge); + magnitude = 1.0f - acosf(dot_product(far_edge, near_edge))/(float)(M_PI*2.0); + + /* Recalculate the panning direction, to be directly between the + * direction of the two extents. + */ + local_dir[0] = far_edge[0] + near_edge[0]; + local_dir[1] = far_edge[1] + near_edge[1]; + local_dir[2] = far_edge[2] + near_edge[2]; + normalize(local_dir); + } + else + { + /* If we get here, the listener is directly in front of or behind + * the center of the portal, making all aperture edges effectively + * equidistant. Calculating the panning magnitude is simplified, + * using the arctangent of the radius and distance. + */ + magnitude = 1.0f - (atan2f(portal_radius, dist) / (float)M_PI); + } + + /* Scale the other zone's panning vector. */ + other_dir[0] = local_dir[0] * magnitude; + other_dir[1] = local_dir[1] * magnitude; + other_dir[2] = local_dir[2] * magnitude; + /* Pan the current zone to the opposite direction of the portal, and + * take the remaining percentage of the portal's magnitude. + */ + this_dir[0] = local_dir[0] * (magnitude-1.0f); + this_dir[1] = local_dir[1] * (magnitude-1.0f); + this_dir[2] = local_dir[2] * (magnitude-1.0f); + + /* Now set the effects' panning vectors and gain. Energy is shared + * between environments, so attenuate according to each zone's + * contribution (note: gain^2 = energy). + */ + alEffectf(this_effect, AL_EAXREVERB_REFLECTIONS_GAIN, this_reverb->flReflectionsGain * sqrtf(magnitude)); + alEffectf(this_effect, AL_EAXREVERB_LATE_REVERB_GAIN, this_reverb->flLateReverbGain * sqrtf(magnitude)); + alEffectfv(this_effect, AL_EAXREVERB_REFLECTIONS_PAN, this_dir); + alEffectfv(this_effect, AL_EAXREVERB_LATE_REVERB_PAN, this_dir); + + alEffectf(other_effect, AL_EAXREVERB_REFLECTIONS_GAIN, other_reverb->flReflectionsGain * sqrtf(1.0f-magnitude)); + alEffectf(other_effect, AL_EAXREVERB_LATE_REVERB_GAIN, other_reverb->flLateReverbGain * sqrtf(1.0f-magnitude)); + alEffectfv(other_effect, AL_EAXREVERB_REFLECTIONS_PAN, other_dir); + alEffectfv(other_effect, AL_EAXREVERB_LATE_REVERB_PAN, other_dir); + } + else + { + /* We're practically in the center of the portal. Give the panning + * vectors a 50/50 split, with Zone 0 covering the half in front of + * the normal, and Zone 1 covering the half behind. + */ + this_dir[0] = local_norm[0] / 2.0f; + this_dir[1] = local_norm[1] / 2.0f; + this_dir[2] = local_norm[2] / 2.0f; + + other_dir[0] = local_norm[0] / -2.0f; + other_dir[1] = local_norm[1] / -2.0f; + other_dir[2] = local_norm[2] / -2.0f; + + alEffectf(effects[0], AL_EAXREVERB_REFLECTIONS_GAIN, reverbs[0].flReflectionsGain * sqrtf(0.5f)); + alEffectf(effects[0], AL_EAXREVERB_LATE_REVERB_GAIN, reverbs[0].flLateReverbGain * sqrtf(0.5f)); + alEffectfv(effects[0], AL_EAXREVERB_REFLECTIONS_PAN, this_dir); + alEffectfv(effects[0], AL_EAXREVERB_LATE_REVERB_PAN, this_dir); + + alEffectf(effects[1], AL_EAXREVERB_REFLECTIONS_GAIN, reverbs[1].flReflectionsGain * sqrtf(0.5f)); + alEffectf(effects[1], AL_EAXREVERB_LATE_REVERB_GAIN, reverbs[1].flLateReverbGain * sqrtf(0.5f)); + alEffectfv(effects[1], AL_EAXREVERB_REFLECTIONS_PAN, other_dir); + alEffectfv(effects[1], AL_EAXREVERB_LATE_REVERB_PAN, other_dir); + } + + /* Finally, update the effect slots with the updated effect parameters. */ + alAuxiliaryEffectSloti(slots[0], AL_EFFECTSLOT_EFFECT, effects[0]); + alAuxiliaryEffectSloti(slots[1], AL_EFFECTSLOT_EFFECT, effects[1]); +} + + +int main(int argc, char **argv) +{ + static const int MaxTransitions = 8; + EFXEAXREVERBPROPERTIES reverbs[2] = { + EFX_REVERB_PRESET_CARPETEDHALLWAY, + EFX_REVERB_PRESET_BATHROOM + }; + struct timespec basetime; + ALCdevice *device = NULL; + ALCcontext *context = NULL; + ALuint effects[2] = { 0, 0 }; + ALuint slots[2] = { 0, 0 }; + ALuint direct_filter = 0; + ALuint buffer = 0; + ALuint source = 0; + ALCint num_sends = 0; + ALenum state = AL_INITIAL; + ALfloat direct_gain = 1.0f; + int loops = 0; + + /* Print out usage if no arguments were specified */ + if(argc < 2) + { + fprintf(stderr, "Usage: %s [-device <name>] [options] <filename>\n\n" + "Options:\n" + "\t-nodirect\tSilence direct path output (easier to hear reverb)\n\n", + argv[0]); + return 1; + } + + /* Initialize OpenAL, and check for EFX support with at least 2 auxiliary + * sends (if multiple sends are supported, 2 are provided by default; if + * you want more, you have to request it through alcCreateContext). + */ + argv++; argc--; + if(InitAL(&argv, &argc) != 0) + return 1; + + while(argc > 0) + { + if(strcmp(argv[0], "-nodirect") == 0) + direct_gain = 0.0f; + else + break; + argv++; + argc--; + } + if(argc < 1) + { + fprintf(stderr, "No filename spacified.\n"); + CloseAL(); + return 1; + } + + context = alcGetCurrentContext(); + device = alcGetContextsDevice(context); + + if(!alcIsExtensionPresent(device, "ALC_EXT_EFX")) + { + fprintf(stderr, "Error: EFX not supported\n"); + CloseAL(); + return 1; + } + + num_sends = 0; + alcGetIntegerv(device, ALC_MAX_AUXILIARY_SENDS, 1, &num_sends); + if(alcGetError(device) != ALC_NO_ERROR || num_sends < 2) + { + fprintf(stderr, "Error: Device does not support multiple sends (got %d, need 2)\n", + num_sends); + CloseAL(); + return 1; + } + + /* Define a macro to help load the function pointers. */ +#define LOAD_PROC(x) ((x) = alGetProcAddress(#x)) + LOAD_PROC(alGenFilters); + LOAD_PROC(alDeleteFilters); + LOAD_PROC(alIsFilter); + LOAD_PROC(alFilteri); + LOAD_PROC(alFilteriv); + LOAD_PROC(alFilterf); + LOAD_PROC(alFilterfv); + LOAD_PROC(alGetFilteri); + LOAD_PROC(alGetFilteriv); + LOAD_PROC(alGetFilterf); + LOAD_PROC(alGetFilterfv); + + LOAD_PROC(alGenEffects); + LOAD_PROC(alDeleteEffects); + LOAD_PROC(alIsEffect); + LOAD_PROC(alEffecti); + LOAD_PROC(alEffectiv); + LOAD_PROC(alEffectf); + LOAD_PROC(alEffectfv); + LOAD_PROC(alGetEffecti); + LOAD_PROC(alGetEffectiv); + LOAD_PROC(alGetEffectf); + LOAD_PROC(alGetEffectfv); + + LOAD_PROC(alGenAuxiliaryEffectSlots); + LOAD_PROC(alDeleteAuxiliaryEffectSlots); + LOAD_PROC(alIsAuxiliaryEffectSlot); + LOAD_PROC(alAuxiliaryEffectSloti); + LOAD_PROC(alAuxiliaryEffectSlotiv); + LOAD_PROC(alAuxiliaryEffectSlotf); + LOAD_PROC(alAuxiliaryEffectSlotfv); + LOAD_PROC(alGetAuxiliaryEffectSloti); + LOAD_PROC(alGetAuxiliaryEffectSlotiv); + LOAD_PROC(alGetAuxiliaryEffectSlotf); + LOAD_PROC(alGetAuxiliaryEffectSlotfv); +#undef LOAD_PROC + + /* Initialize SDL_sound. */ + Sound_Init(); + + /* Load the sound into a buffer. */ + buffer = LoadSound(argv[0]); + if(!buffer) + { + CloseAL(); + Sound_Quit(); + return 1; + } + + /* Generate two effects for two "zones", and load a reverb into each one. + * Note that unlike single-zone reverb, where you can store one effect per + * preset, for multi-zone reverb you should have one effect per environment + * instance, or one per audible zone. This is because we'll be changing the + * effects' properties in real-time based on the environment instance + * relative to the listener. + */ + alGenEffects(2, effects); + if(!LoadEffect(effects[0], &reverbs[0]) || !LoadEffect(effects[1], &reverbs[1])) + { + alDeleteEffects(2, effects); + alDeleteBuffers(1, &buffer); + Sound_Quit(); + CloseAL(); + return 1; + } + + /* Create the effect slot objects, one for each "active" effect. */ + alGenAuxiliaryEffectSlots(2, slots); + + /* Tell the effect slots to use the loaded effect objects, with slot 0 for + * Zone 0 and slot 1 for Zone 1. Note that this effectively copies the + * effect properties. Modifying or deleting the effect object afterward + * won't directly affect the effect slot until they're reapplied like this. + */ + alAuxiliaryEffectSloti(slots[0], AL_EFFECTSLOT_EFFECT, effects[0]); + alAuxiliaryEffectSloti(slots[1], AL_EFFECTSLOT_EFFECT, effects[1]); + assert(alGetError()==AL_NO_ERROR && "Failed to set effect slot"); + + /* For the purposes of this example, prepare a filter that optionally + * silences the direct path which allows us to hear just the reverberation. + * A filter like this is normally used for obstruction, where the path + * directly between the listener and source is blocked (the exact + * properties depending on the type and thickness of the obstructing + * material). + */ + alGenFilters(1, &direct_filter); + alFilteri(direct_filter, AL_FILTER_TYPE, AL_FILTER_LOWPASS); + alFilterf(direct_filter, AL_LOWPASS_GAIN, direct_gain); + assert(alGetError()==AL_NO_ERROR && "Failed to set direct filter"); + + /* Create the source to play the sound with, place it in front of the + * listener's path in the left zone. + */ + source = 0; + alGenSources(1, &source); + alSourcei(source, AL_LOOPING, AL_TRUE); + alSource3f(source, AL_POSITION, -5.0f, 0.0f, -2.0f); + alSourcei(source, AL_DIRECT_FILTER, direct_filter); + alSourcei(source, AL_BUFFER, buffer); + + /* Connect the source to the effect slots. Here, we connect source send 0 + * to Zone 0's slot, and send 1 to Zone 1's slot. Filters can be specified + * to occlude the source from each zone by varying amounts; for example, a + * source within a particular zone would be unfiltered, while a source that + * can only see a zone through a window or thin wall may be attenuated for + * that zone. + */ + alSource3i(source, AL_AUXILIARY_SEND_FILTER, slots[0], 0, AL_FILTER_NULL); + alSource3i(source, AL_AUXILIARY_SEND_FILTER, slots[1], 1, AL_FILTER_NULL); + assert(alGetError()==AL_NO_ERROR && "Failed to setup sound source"); + + /* Get the current time as the base for timing in the main loop. */ + altimespec_get(&basetime, AL_TIME_UTC); + loops = 0; + printf("Transition %d of %d...\n", loops+1, MaxTransitions); + + /* Play the sound for a while. */ + alSourcePlay(source); + do { + struct timespec curtime; + ALfloat timediff; + + /* Start a batch update, to ensure all changes apply simultaneously. */ + alcSuspendContext(context); + + /* Get the current time to track the amount of time that passed. + * Convert the difference to seconds. + */ + altimespec_get(&curtime, AL_TIME_UTC); + timediff = (ALfloat)(curtime.tv_sec - basetime.tv_sec); + timediff += (ALfloat)(curtime.tv_nsec - basetime.tv_nsec) / 1000000000.0f; + + /* Avoid negative time deltas, in case of non-monotonic clocks. */ + if(timediff < 0.0f) + timediff = 0.0f; + else while(timediff >= 4.0f*((loops&1)+1)) + { + /* For this example, each transition occurs over 4 seconds, and + * there's 2 transitions per cycle. + */ + if(++loops < MaxTransitions) + printf("Transition %d of %d...\n", loops+1, MaxTransitions); + if(!(loops&1)) + { + /* Cycle completed. Decrease the delta and increase the base + * time to start a new cycle. + */ + timediff -= 8.0f; + basetime.tv_sec += 8; + } + } + + /* Update the listener and effects, and finish the batch. */ + UpdateListenerAndEffects(timediff, slots, effects, reverbs); + alcProcessContext(context); + + al_nssleep(10000000); + + alGetSourcei(source, AL_SOURCE_STATE, &state); + } while(alGetError() == AL_NO_ERROR && state == AL_PLAYING && loops < MaxTransitions); + + /* All done. Delete resources, and close down SDL_sound and OpenAL. */ + alDeleteSources(1, &source); + alDeleteAuxiliaryEffectSlots(2, slots); + alDeleteEffects(2, effects); + alDeleteFilters(1, &direct_filter); + alDeleteBuffers(1, &buffer); + + Sound_Quit(); + CloseAL(); + + return 0; +} |