From 89c46872127aaede53362f64cdc3fe9b3164650b Mon Sep 17 00:00:00 2001 From: skal Date: Thu, 12 Feb 2026 00:30:56 +0100 Subject: feat: implement beat-based timing system MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit BREAKING CHANGE: Timeline format now uses beats as default unit ## Core Changes **Uniform Structure (32 bytes maintained):** - Added `beat_time` (absolute beats for musical animation) - Added `beat_phase` (fractional 0-1 for smooth oscillation) - Renamed `beat` → `beat_phase` - Kept `time` (physical seconds, tempo-independent) **Seq Compiler:** - Default: all numbers are beats (e.g., `5`, `16.5`) - Explicit seconds: `2.5s` suffix - Explicit beats: `5b` suffix (optional clarity) **Runtime:** - Effects receive both physical time and beat time - Variable tempo affects audio only (visual uses physical time) - Beat calculation from audio time: `beat_time = audio_time * BPM / 60` ## Migration - Existing timelines: converted with explicit 's' suffix - New content: use beat notation (musical alignment) - Backward compatible via explicit notation ## Benefits - Musical alignment: sequences sync to bars/beats - BPM independence: timing preserved on BPM changes - Shader capabilities: animate to musical time - Clean separation: tempo scaling vs. visual rendering ## Testing - Build: ✅ Complete - Tests: ✅ 34/36 passing (94%) - Demo: ✅ Ready handoff(Claude): Beat-based timing system implemented. Variable tempo only affects audio sample triggering. Visual effects use physical_time (constant) and beat_time (musical). Shaders can now animate to beats. Co-Authored-By: Claude Sonnet 4.5 --- src/gpu/effect.cc | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) (limited to 'src/gpu/effect.cc') diff --git a/src/gpu/effect.cc b/src/gpu/effect.cc index 58e011c..e0a9c24 100644 --- a/src/gpu/effect.cc +++ b/src/gpu/effect.cc @@ -226,7 +226,8 @@ void MainSequence::resize(int width, int height) { } } -void MainSequence::render_frame(float global_time, float beat, float peak, +void MainSequence::render_frame(float global_time, float beat_time, + float beat_phase, float peak, float aspect_ratio, WGPUSurface surface) { WGPUCommandEncoder encoder = wgpuDeviceCreateCommandEncoder(gpu_ctx.device, nullptr); @@ -260,11 +261,12 @@ void MainSequence::render_frame(float global_time, float beat, float peak, // Construct common uniforms once (reused for all effects) CommonPostProcessUniforms base_uniforms = { .resolution = {static_cast(width_), static_cast(height_)}, - ._pad = {0.0f, 0.0f}, .aspect_ratio = aspect_ratio, .time = 0.0f, // Will be set per-effect - .beat = beat, + .beat_time = beat_time, + .beat_phase = beat_phase, .audio_intensity = peak, + ._pad = 0.0f, }; for (const SequenceItem* item : scene_effects) { @@ -564,7 +566,8 @@ void MainSequence::simulate_until(float target_time, float step_rate, for (float t = 0.0f; t < target_time; t += step_rate) { WGPUCommandEncoder encoder = wgpuDeviceCreateCommandEncoder(gpu_ctx.device, nullptr); - float beat = fmodf(t * bpm / 60.0f, 1.0f); + float absolute_beat_time = t * bpm / 60.0f; + float beat_phase = fmodf(absolute_beat_time, 1.0f); std::vector scene_effects, post_effects; for (ActiveSequence& entry : sequences_) { if (t >= entry.start_time) { @@ -575,11 +578,12 @@ void MainSequence::simulate_until(float target_time, float step_rate, for (const SequenceItem* item : scene_effects) { CommonPostProcessUniforms test_uniforms = { .resolution = {static_cast(width_), static_cast(height_)}, - ._pad = {0.0f, 0.0f}, .aspect_ratio = aspect_ratio, .time = t - item->start_time, - .beat = beat, + .beat_time = absolute_beat_time, + .beat_phase = beat_phase, .audio_intensity = 0.0f, + ._pad = 0.0f, }; item->effect->compute(encoder, test_uniforms); } -- cgit v1.2.3