[examples] Add `audio_stream_callback` (#5638)

* Add audio_raw_stream_callback.c

* Update audio_raw_stream_callback.c to more closely follow raylib coding conventions

* Remove spaces before asterisks in comments in audio_raw_stream_callback.c

* Put SetTargetFPS(30) before while(!WindowShouldClose()) in audio_raw_stream_callback.c

* Add audio_stream_callback.c

* Delete examples/audio/audio_raw_stream_callback.c

* Delete examples/audio/audio_raw_stream_callback.png

* Update audio_raw_stream.c to more closely follow raylib coding conventions

Drawing code wasn't tabbed in

* Remove screenshot code in audio_stream_callback.c

* Update raylib version and copyright year in audio_raw_stream.c

* Update audio_stream_callback.c

Used if instead of switch to compact code; seemed more readable in this case.

examples/audio/audio_raw_stream.c

@@ -4,14 +4,14 @@
 *
 *   Example complexity rating: [★★★☆] 3/4
 *
-*   Example originally created with raylib 1.6, last time updated with raylib 4.2
+*   Example originally created with raylib 1.6, last time updated with raylib 6.0
 *
 *   Example created by Ramon Santamaria (@raysan5) and reviewed by James Hofmann (@triplefox)
 *
 *   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) 2015-2025 Ramon Santamaria (@raysan5) and James Hofmann (@triplefox)
+*   Copyright (c) 2015-2026 Ramon Santamaria (@raysan5) and James Hofmann (@triplefox)
 *
 ********************************************************************************************/
 
@@ -109,26 +109,26 @@ int main(void)
         // Draw
         //----------------------------------------------------------------------------------
         BeginDrawing();
-        ClearBackground(RAYWHITE);
-
-        DrawText(TextFormat("sine frequency: %i", sineFrequency), screenWidth - 220, 10, 20, RED);
-        DrawText(TextFormat("pan: %.2f", pan), screenWidth - 220, 30, 20, RED);
-        DrawText("Up/down to change frequency", 10, 10, 20, DARKGRAY);
-        DrawText("Left/right to pan", 10, 30, 20, DARKGRAY);
-
-        int windowStart = (GetTime() - sineStartTime)*SAMPLE_RATE;
-        int windowSize = 0.1f*SAMPLE_RATE;
-        int wavelength = SAMPLE_RATE/sineFrequency;
-
-        // Draw a sine wave with the same frequency as the one being sent to the audio stream
-        for (int i = 0; i < screenWidth; i++)
-        {
-            int t0 = windowStart + i*windowSize/screenWidth;
-            int t1 = windowStart + (i + 1)*windowSize/screenWidth;
-            Vector2 startPos = { i, 250 + 50*sin(2*PI*t0/wavelength) };
-            Vector2 endPos = { i + 1, 250 + 50*sin(2*PI*t1/wavelength) };
-            DrawLineV(startPos, endPos, RED);
-        }
+            ClearBackground(RAYWHITE);
+    
+            DrawText(TextFormat("sine frequency: %i", sineFrequency), screenWidth - 220, 10, 20, RED);
+            DrawText(TextFormat("pan: %.2f", pan), screenWidth - 220, 30, 20, RED);
+            DrawText("Up/down to change frequency", 10, 10, 20, DARKGRAY);
+            DrawText("Left/right to pan", 10, 30, 20, DARKGRAY);
+    
+            int windowStart = (GetTime() - sineStartTime)*SAMPLE_RATE;
+            int windowSize = 0.1f*SAMPLE_RATE;
+            int wavelength = SAMPLE_RATE/sineFrequency;
+    
+            // Draw a sine wave with the same frequency as the one being sent to the audio stream
+            for (int i = 0; i < screenWidth; i++)
+            {
+                int t0 = windowStart + i*windowSize/screenWidth;
+                int t1 = windowStart + (i + 1)*windowSize/screenWidth;
+                Vector2 startPos = { i, 250 + 50*sin(2*PI*t0/wavelength) };
+                Vector2 endPos = { i + 1, 250 + 50*sin(2*PI*t1/wavelength) };
+                DrawLineV(startPos, endPos, RED);
+            }
 
         EndDrawing();
         //----------------------------------------------------------------------------------

examples/audio/audio_stream_callback.c

@@ -0,0 +1,236 @@
+/*******************************************************************************************
+*
+*   raylib [audio] example - stream callback
+*
+*   Example complexity rating: [★★★☆] 3/4
+*
+*   Example originally created with raylib 6.0, last time updated with raylib 6.0
+*
+*   Example created by Dan Hoang (@dan-hoang) and reviewed by
+*
+*   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) 2015-2026
+*
+********************************************************************************************/
+
+#include "raylib.h"
+#include <stdlib.h>
+#include <math.h>
+
+#define BUFFER_SIZE 4096
+#define SAMPLE_RATE 44100
+
+// This example sends a wave to the audio device
+// The user gets the choice of four waves: sine, square, triangle, and sawtooth
+// A stream is set up to play to the audio device
+// The stream is hooked to a callback that generates a wave
+// The callback used is determined by user choice
+typedef enum
+{
+    SINE,
+    SQUARE,
+    TRIANGLE,
+    SAWTOOTH
+} WaveType;
+
+int waveFrequency = 440;
+int newWaveFrequency = 440;
+int waveIndex = 0;
+
+// Buffer for keeping the last second of uploaded audio, part of which will be drawn on the screen
+float buffer[SAMPLE_RATE] = {};
+
+void SineCallback(void *framesOut, unsigned int frameCount)
+{
+    int wavelength = SAMPLE_RATE/waveFrequency;
+
+    // Synthesize the sine wave
+    for (int i = 0; i < frameCount; i++)
+    {
+        ((float *)framesOut)[i] = sin(2*PI*waveIndex/wavelength);
+
+        waveIndex++;
+
+        if (waveIndex >= wavelength)
+        {
+            waveFrequency = newWaveFrequency;
+            waveIndex = 0;
+        }
+    }
+
+    // Save the synthesized samples for later drawing
+    for (int i = 0; i < SAMPLE_RATE - frameCount; i++) buffer[i] = buffer[i + frameCount];
+    for (int i = 0; i < frameCount; i++) buffer[SAMPLE_RATE - frameCount + i] = ((float *)framesOut)[i];
+}
+
+void SquareCallback(void *framesOut, unsigned int frameCount)
+{
+    int wavelength = SAMPLE_RATE/waveFrequency;
+
+    // Synthesize the square wave
+    for (int i = 0; i < frameCount; i++)
+    {
+        ((float *)framesOut)[i] = (waveIndex < wavelength/2)? 1 : -1;
+        waveIndex++;
+
+        if (waveIndex >= wavelength)
+        {
+            waveFrequency = newWaveFrequency;
+            waveIndex = 0;
+        }
+    }
+
+    // Save the synthesized samples for later drawing
+    for (int i = 0; i < SAMPLE_RATE - frameCount; i++) buffer[i] = buffer[i + frameCount];
+    for (int i = 0; i < frameCount; i++) buffer[SAMPLE_RATE - frameCount + i] = ((float *)framesOut)[i];
+}
+
+void TriangleCallback(void *framesOut, unsigned int frameCount)
+{
+    int wavelength = SAMPLE_RATE/waveFrequency;
+
+    // Synthesize the triangle wave
+    for (int i = 0; i < frameCount; i++)
+    {
+        ((float *)framesOut)[i] = (waveIndex < wavelength/2)? (-1 + 2.0f*waveIndex/(wavelength/2)) : (1 - 2.0f*(waveIndex - wavelength/2)/(wavelength/2));
+        waveIndex++;
+
+        if (waveIndex >= wavelength)
+        {
+            waveFrequency = newWaveFrequency;
+            waveIndex = 0;
+        }
+    }
+
+    // Save the synthesized samples for later drawing
+    for (int i = 0; i < SAMPLE_RATE - frameCount; i++) buffer[i] = buffer[i + frameCount];
+    for (int i = 0; i < frameCount; i++) buffer[SAMPLE_RATE - frameCount + i] = ((float *)framesOut)[i];
+}
+
+void SawtoothCallback(void *framesOut, unsigned int frameCount)
+{
+    int wavelength = SAMPLE_RATE/waveFrequency;
+
+    // Synthesize the sawtooth wave
+    for (int i = 0; i < frameCount; i++)
+    {
+        ((float *)framesOut)[i] = -1 + 2.0f*waveIndex/wavelength;
+        waveIndex++;
+
+        if (waveIndex >= wavelength)
+        {
+            waveFrequency = newWaveFrequency;
+            waveIndex = 0;
+        }
+    }
+
+    // Save the synthesized samples for later drawing
+    for (int i = 0; i < SAMPLE_RATE - frameCount; i++) buffer[i] = buffer[i + frameCount];
+    for (int i = 0; i < frameCount; i++) buffer[SAMPLE_RATE - frameCount + i] = ((float *)framesOut)[i];
+}
+
+AudioCallback waveCallbacks[] = { SineCallback, SquareCallback, TriangleCallback, SawtoothCallback };
+char *waveTypesAsString[] = { "sine", "square", "triangle", "sawtooth" };
+
+//------------------------------------------------------------------------------------
+// Program main entry point
+//------------------------------------------------------------------------------------
+int main(void)
+{
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    const int screenWidth = 800;
+    const int screenHeight = 450;
+
+    InitWindow(screenWidth, screenHeight, "raylib [audio] example - stream callback");
+
+    InitAudioDevice();
+
+    // Set the number of samples the stream will keep in memory at a time to BUFFER_SIZE
+    SetAudioStreamBufferSizeDefault(BUFFER_SIZE);
+
+    // Init raw audio stream (sample rate: 44100, sample size: 32bit-float, channels: 1-mono)
+    AudioStream stream = LoadAudioStream(SAMPLE_RATE, 32, 1);
+    PlayAudioStream(stream);
+
+    // Configure it so that waveCallbacks[waveType] is called whenever stream is out of samples
+    WaveType waveType = SINE;
+    SetAudioStreamCallback(stream, waveCallbacks[waveType]);
+
+    SetTargetFPS(30);
+    //--------------------------------------------------------------------------------------
+
+    // Main game loop
+    while (!WindowShouldClose())    // Detect window close button or ESC key
+    {
+        // Update
+        //----------------------------------------------------------------------------------
+
+        if (IsKeyDown(KEY_UP))
+        {
+            newWaveFrequency += 10;
+            if (newWaveFrequency > 12500) newWaveFrequency = 12500;
+        }
+
+        if (IsKeyDown(KEY_DOWN))
+        {
+            newWaveFrequency -= 10;
+            if (newWaveFrequency < 20) newWaveFrequency = 20;
+        }
+
+        if (IsKeyPressed(KEY_LEFT))
+        {
+            if (waveType == SINE) waveType = SAWTOOTH;
+            else if (waveType == SQUARE) waveType = SINE;
+            else if (waveType == TRIANGLE) waveType = SQUARE;
+            else waveType = TRIANGLE;
+
+            SetAudioStreamCallback(stream, waveCallbacks[waveType]);
+        }
+
+        if (IsKeyPressed(KEY_RIGHT))
+        {
+            if (waveType == SINE) waveType = SQUARE;
+            else if (waveType == SQUARE) waveType = TRIANGLE;
+            else if (waveType == TRIANGLE) waveType = SAWTOOTH;
+            else waveType = SINE;
+
+            SetAudioStreamCallback(stream, waveCallbacks[waveType]);
+        }
+
+        //----------------------------------------------------------------------------------
+
+        // Draw
+        //----------------------------------------------------------------------------------
+        BeginDrawing();
+
+            ClearBackground(RAYWHITE);
+            DrawText(TextFormat("frequency: %i", newWaveFrequency), screenWidth - 220, 10, 20, RED);
+            DrawText(TextFormat("wave type: %s", waveTypesAsString[waveType]), screenWidth - 220, 30, 20, RED);
+            DrawText("Up/down to change frequency", 10, 10, 20, DARKGRAY);
+            DrawText("Left/right to change wave type", 10, 30, 20, DARKGRAY);
+
+            // Draw the last 10 ms of uploaded audio
+            for (int i = 0; i < screenWidth; i++)
+            {
+                Vector2 startPos = { i, 250 - 50*buffer[SAMPLE_RATE - SAMPLE_RATE/100 + i*SAMPLE_RATE/100/screenWidth] };
+                Vector2 endPos = { i + 1, 250 - 50*buffer[SAMPLE_RATE - SAMPLE_RATE/100 + (i + 1)*SAMPLE_RATE/100/screenWidth] };
+                DrawLineV(startPos, endPos, RED);
+            }
+
+        EndDrawing();
+        //----------------------------------------------------------------------------------
+    }
+
+    // De-Initialization
+    //--------------------------------------------------------------------------------------
+    UnloadAudioStream(stream);   // Close raw audio stream and delete buffers from RAM
+    CloseAudioDevice();         // Close audio device (music streaming is automatically stopped)
+
+    CloseWindow();              // Close window and OpenGL context
+    //--------------------------------------------------------------------------------------
+
+    return 0;
+}