Add the audio mixed processor example

Has issues because it relies on callbacks

examples/audio/audio_mixed_processor-broken.rb

@@ -0,0 +1,115 @@
+# ******************************************************************************************
+#
+#   raylib [audio] example - Mixed audio processing
+#
+#   Example originally created with raylib 4.2, last time updated with raylib 4.2
+#
+#   Example contributed by hkc (@hatkidchan) and reviewed by Ramon Santamaria (@raysan5)
+#
+#   Example ported to Ruby by Wilson Silva (@wilsonsilva). Works partially with Raylib 4.5
+#
+#   Example licensed under an unmodified zlib/libpng license, which is an OSI-certified,
+#   BSD-like license that allows static linking with closed source software
+#
+#   Copyright (c) 2023 hkc (@hatkidchan)
+#
+# ******************************************************************************************
+
+# FIXME: Attaching the audio mixed processor callback causes the program to slow down until the
+# music is no longer playing. Does not work even if I remove all the code from the callback.
+
+require 'bundler/setup'
+require 'raylib'
+
+# FIXME: Global variables can potentially be avoided
+
+$exponent = 1.0                     # Audio exponentiation value
+$average_volume = Array.new(400, 0) # Average volume history
+
+# ------------------------------------------------------------------------------------
+# Audio processing function
+# ------------------------------------------------------------------------------------
+
+ProcessAudio = FFI::Function.new(:void, [:pointer, :uint]) do |buffer, frames|
+  # samples = buffer.to_a
+  # average = 0.0 # Temporary average volume
+  #
+  # frames.times do |frame|
+  #   left = samples[frame * 2]
+  #   right = samples[frame * 2 + 1]
+  #
+  #   left = (left.abs ** $exponent) * (left < 0.0 ? -1.0 : 1.0)
+  #   right = (right.abs ** $exponent) * (right < 0.0 ? -1.0 : 1.0)
+  #
+  #   average += (left.abs / frames) + (right.abs / frames)
+  # end
+  #
+  # # Moving history to the left
+  # $average_volume.shift(399)
+  # $average_volume << average # Adding last average value
+end
+
+# Initialization
+# --------------------------------------------------------------------------------------
+SCREEN_WIDTH = 800
+SCREEN_HEIGHT = 450
+
+Raylib.init_window(SCREEN_WIDTH, SCREEN_HEIGHT, "raylib [audio] example - processing mixed output")
+
+Raylib.init_audio_device # Initialize audio device
+# Raylib.attach_audio_mixed_processor(ProcessAudio) # FIXME: Uncomment when callbacks are supported
+
+music = Raylib.load_music_stream(File.join(__dir__, "resources/country.mp3")) # FIXME: Should work without File.join
+sound = Raylib.load_sound(File.join(__dir__, "resources/coin.wav")) # FIXME: Should work without File.join
+
+Raylib.play_music_stream(music)
+
+Raylib.set_target_fps(60) # Set our game to run at 60 frames-per-second
+# --------------------------------------------------------------------------------------
+
+# Main game loop
+until Raylib.window_should_close # Detect window close button or ESC key
+  # Update
+  # ----------------------------------------------------------------------------------
+  Raylib.update_music_stream(music) # Update music buffer with new stream data
+
+  # Modify processing variables
+  # ----------------------------------------------------------------------------------
+  $exponent -= 0.05 if Raylib.is_key_pressed(Raylib::KEY_LEFT)
+  $exponent += 0.05 if Raylib.is_key_pressed(Raylib::KEY_RIGHT)
+
+  $exponent = 0.5 if $exponent <= 0.5
+  $exponent = 3.0 if $exponent >= 3.0
+
+  Raylib.play_sound(sound) if Raylib.is_key_pressed(Raylib::KEY_SPACE)
+
+  # Draw
+  # ----------------------------------------------------------------------------------
+  Raylib.begin_drawing
+
+  Raylib.clear_background(Raylib::RAYWHITE)
+
+  Raylib.draw_text("MUSIC SHOULD BE PLAYING!", 255, 150, 20, Raylib::LIGHTGRAY)
+  Raylib.draw_text(Raylib.text_format("EXPONENT = %.2f", :float, $exponent), 215, 180, 20, Raylib::LIGHTGRAY)
+
+  Raylib.draw_rectangle(199, 199, 402, 34, Raylib::LIGHTGRAY)
+  400.times do |i|
+    Raylib.draw_line(201 + i, 232 - $average_volume[i] * 32, 201 + i, 232, Raylib::MAROON)
+  end
+
+  Raylib.draw_rectangle_lines(199, 199, 402, 34, Raylib::GRAY)
+
+  Raylib.draw_text("PRESS SPACE TO PLAY OTHER SOUND", 200, 250, 20, Raylib::LIGHTGRAY)
+  Raylib.draw_text("USE LEFT AND RIGHT ARROWS TO ALTER DISTORTION", 140, 280, 20, Raylib::LIGHTGRAY)
+
+  Raylib.end_drawing
+  # ----------------------------------------------------------------------------------
+end
+
+# De-Initialization
+# --------------------------------------------------------------------------------------
+Raylib.unload_music_stream(music)                 # Unload music stream buffers from RAM
+# Raylib.detach_audio_mixed_processor(ProcessAudio) # Disconnect audio processor # FIXME: Uncomment when callbacks are supported
+Raylib.close_audio_device                         # Close audio device (music streaming is automatically stopped)
+Raylib.close_window                               # Close window and OpenGL context
+# --------------------------------------------------------------------------------------

examples/audio/resources/LICENSE.md

@@ -1,3 +1,4 @@
 | resource             | author      | licence | notes |
 | :------------------- | :---------: | :------ | :---- |
 | country.mp3          | [@emegeme](https://github.com/emegeme) | [CC0](https://creativecommons.org/publicdomain/zero/1.0/) | Originally created for "DART that TARGET" game |
+| coin.wav             | [@raysan5](https://github.com/raysan5) | [CC0](https://creativecommons.org/publicdomain/zero/1.0/) | Made with [rFXGen](https://raylibtech.itch.io/rfxgen) |