import gg import gx import sokol.audio struct AppState { mut: gframe int // the current graphical frame frame_0 int // offset of the current audio frames, relative to the start of the music frames [2048]f32 // a copy of the last rendered audio frames gg &gg.Context // used for drawing } fn my_audio_stream_callback(buffer &f32, num_frames int, num_channels int, mut acontext AppState) { mut soundbuffer := buffer for frame := 0; frame < num_frames; frame++ { t := int(f32(acontext.frame_0 + frame) * 0.245) // Credits for the formula below: https://www.youtube.com/watch?v=V4GfkFbDojc // "Techno" by Gabriel Miceli y := (t * (((t / 10 | 0) ^ ((t / 10 | 0) - 1280)) % 11) / 2 & 127) + (t * (((t / 640 | 0) ^ ((t / 640 | 0) - 2)) % 13) / 2 & 127) for ch := 0; ch < num_channels; ch++ { idx := frame * num_channels + ch unsafe { a := f32(byte(y) - 127) / 255.0 soundbuffer[idx] = a acontext.frames[idx & 2047] = a } } } acontext.frame_0 += num_frames } fn main() { mut state := &AppState{ gg: 0 } audio.setup({ stream_userdata_cb: my_audio_stream_callback user_data: state }) state.gg = gg.new_context({ bg_color: gx.rgb(50, 50, 50) width: 1024 height: 400 use_ortho: true create_window: true window_title: 'ByteBeat Music' frame_fn: graphics_frame user_data: state }) state.gg.run() audio.shutdown() } fn graphics_frame(mut state AppState) { state.gframe++ state.gg.begin() state.draw() state.gg.end() } [inline] fn (mut state AppState) bsample(idx int) byte { return byte(127 + state.frames[(state.gframe + idx) & 2047] * 128) } fn (mut state AppState) draw() { // first, reset and setup ortho projection for x in 0 .. 1024 { mut y := 100 * (state.frames[2 * x] + state.frames[2 * x + 1]) state.gg.draw_line(x, 200, x, 200 + y, gx.rgba(state.bsample(x), state.bsample(x + 300), state.bsample(x + 700), 255)) } }