From 24c9f784c506a2b1567080223f6e527f7e27ea34 Mon Sep 17 00:00:00 2001
From: expikr <77922942+expikr@users.noreply.github.com>
Date: Tue, 14 Jan 2025 00:58:06 +0800
Subject: [PATCH] better numerical precision for playback example

---
 examples/audio/01-simple-playback/simple-playback.c  | 10 +++++-----
 .../simple-playback-callback.c                       | 12 ++++++------
 2 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/examples/audio/01-simple-playback/simple-playback.c b/examples/audio/01-simple-playback/simple-playback.c
index a2b95bf0765ef..d550f4d1bbcc6 100644
--- a/examples/audio/01-simple-playback/simple-playback.c
+++ b/examples/audio/01-simple-playback/simple-playback.c
@@ -73,12 +73,12 @@ SDL_AppResult SDL_AppIterate(void *appstate)
         static float samples[512];  /* this will feed 512 samples each frame until we get to our maximum. */
         int i;
 
+        /* generate a 500Hz pure tone */
         for (i = 0; i < SDL_arraysize(samples); i++) {
-            /* You don't have to care about this math; we're just generating a simple sine wave as we go.
-               https://en.wikipedia.org/wiki/Sine_wave */
-            const double time = total_samples_generated / 8000.0;
-            const int sine_freq = 500;   /* run the wave at 500Hz */
-            samples[i] = (float)SDL_sin(6.283185 * sine_freq * time);
+            const int freq = 500;
+            const int cycle = freq * 8000;
+            const int phase = total_samples_generated % cycle;
+            samples[i] = (float)SDL_sin(phase * 2 * SDL_PI_D / 8000.0);
             total_samples_generated++;
         }
 
diff --git a/examples/audio/02-simple-playback-callback/simple-playback-callback.c b/examples/audio/02-simple-playback-callback/simple-playback-callback.c
index f91aaa6ee2204..fff59ee74c5cd 100644
--- a/examples/audio/02-simple-playback-callback/simple-playback-callback.c
+++ b/examples/audio/02-simple-playback-callback/simple-playback-callback.c
@@ -33,12 +33,12 @@ static void SDLCALL FeedTheAudioStreamMore(void *userdata, SDL_AudioStream *astr
         const int total = SDL_min(additional_amount, SDL_arraysize(samples));
         int i;
 
-        for (i = 0; i < total; i++) {
-            /* You don't have to care about this math; we're just generating a simple sine wave as we go.
-               https://en.wikipedia.org/wiki/Sine_wave */
-            const double time = total_samples_generated / 8000.0;
-            const int sine_freq = 500;   /* run the wave at 500Hz */
-            samples[i] = (float)SDL_sin(6.283185 * sine_freq * time);
+        /* generate a 500Hz pure tone */
+        for (i = 0; i < SDL_arraysize(samples); i++) {
+            const int freq = 500;
+            const int cycle = freq * 8000;
+            const int phase = total_samples_generated % cycle;
+            samples[i] = (float)SDL_sin(phase * 2 * SDL_PI_D / 8000.0);
             total_samples_generated++;
         }