Some plumbing for upcoming fake compute shaders

scripts/loaders/snes/music.gd

@@ -120,6 +120,11 @@ var EVENT_MAP: Dictionary
 var NOTE_DURATIONS: PoolByteArray  # This might need to be made untyped if a future addition uses PoolIntArray instead
 var REFERENCE_NOTE: int
 
+const LOGGING_LEVEL_INFO: bool = false
+func print_info(s: String) -> void:
+	if LOGGING_LEVEL_INFO:
+		print(s)
+
 # These would be static methods if NOTE_DURATIONS and EVENT_MAP could be static
 func translate_instruction(buffer: StreamPeer) -> Array:
 	var instruction := buffer.get_u8()
@@ -189,7 +194,7 @@ func unroll_track(buffer: StreamPeerBuffer, bgm_start_pos: int, track_start_pos:
 					var break_pos := loop_break_positions[loop_level]
 					var jump_pos := loop_break_targets[loop_level]
 					if jump_pos - pos != 1:  # This happens once on track 68:06 FFV SNES BGM
-						print('LOOP_END at 0x%06X would break instead from 0x%06X to 0x%06X (%d past end)' % [pos, break_pos, jump_pos, jump_pos-pos])
+						print_debug('LOOP_END at 0x%06X would break instead from 0x%06X to 0x%06X (%d past end)' % [pos, break_pos, jump_pos, jump_pos-pos])
 					buffer.seek(jump_pos)
 					var loop_events := events.slice(rom_address_to_event_index[loop_positions[loop_level]], -1)
 					var partial_loop_events := events.slice(rom_address_to_event_index[loop_positions[loop_level]], rom_address_to_event_index[break_pos]-1)
@@ -211,7 +216,7 @@ func unroll_track(buffer: StreamPeerBuffer, bgm_start_pos: int, track_start_pos:
 					loop_level -= 1
 				else:
 					# Infinite loop, convert it to a GOTO and return
-					print('ended with infinite loop')
+					print_info('ended with infinite loop')
 					events.append([EventType.GOTO, rom_address_to_event_index[loop_break_targets[loop_level]]])
 					loop_level -= 1
 					break
@@ -225,10 +230,10 @@ func unroll_track(buffer: StreamPeerBuffer, bgm_start_pos: int, track_start_pos:
 				loop_break_positions[loop_level] = pos
 				loop_break_targets[loop_level] = target_pos
 				if on_loop != loop_counts[loop_level]:
-					print('LOOP_BREAK found in track %s at 0x%06X:0x%06X:0x%06X: 0x%06X to 0x%06X on loop %d of %d' % [bgm_id, bgm_start_pos, track_start_pos, bgm_end_pos, pos, target_pos, on_loop, loop_counts[loop_level]])
+					print_info('LOOP_BREAK found in track %s at 0x%06X:0x%06X:0x%06X: 0x%06X to 0x%06X on loop %d of %d' % [bgm_id, bgm_start_pos, track_start_pos, bgm_end_pos, pos, target_pos, on_loop, loop_counts[loop_level]])
 					loop_counts[loop_level] = on_loop
 				else:
-					print('LOOP_BREAK found in track %s at 0x%06X:0x%06X:0x%06X: 0x%06X to 0x%06X on last loop' % [bgm_id, bgm_start_pos, track_start_pos, bgm_end_pos, pos, target_pos])
+					print_info('LOOP_BREAK found in track %s at 0x%06X:0x%06X:0x%06X: 0x%06X to 0x%06X on last loop' % [bgm_id, bgm_start_pos, track_start_pos, bgm_end_pos, pos, target_pos])
 				if target_pos in rom_address_to_event_index:
 					print_debug('LOOP_BREAK is a past address, this is either malformed or an infinite loop')
 					break
@@ -242,7 +247,7 @@ func unroll_track(buffer: StreamPeerBuffer, bgm_start_pos: int, track_start_pos:
 					target_pos += 0x010000
 				var event_num = rom_address_to_event_index.get(target_pos, -1)
 				if event_num >= 0:
-					print('Infinite GOTO found in track %s at 0x%06X:0x%06X:0x%06X: 0x%06X to 0x%06X (event number %d)' % [bgm_id, bgm_start_pos, track_start_pos, bgm_end_pos, pos, target_pos, event_num])
+					print_info('Infinite GOTO found in track %s at 0x%06X:0x%06X:0x%06X: 0x%06X to 0x%06X (event number %d)' % [bgm_id, bgm_start_pos, track_start_pos, bgm_end_pos, pos, target_pos, event_num])
 					events.append([EventType.GOTO, rom_address_to_event_index[target_pos]])
 					break
 				else:
@@ -253,10 +258,10 @@ func unroll_track(buffer: StreamPeerBuffer, bgm_start_pos: int, track_start_pos:
 				event_idx += 1
 	# DEBUG: Report if track doesn't end all the contained loops
 	if loop_level >= 0:
-		print('track %s ended on loop_level %d (0x%06X)' % [bgm_id, loop_level, loop_positions[loop_level]])
+		print_info('track %s ended on loop_level %d (0x%06X)' % [bgm_id, loop_level, loop_positions[loop_level]])
 	# DEBUG: Report total note duration and repeat note duration
 	if events:
-		print('%d events' % len(events))
+		print_info('%d events' % len(events))
 		var total_note_dur := 0
 		var total_notes := 0
 		var total_rests := 0
@@ -272,7 +277,7 @@ func unroll_track(buffer: StreamPeerBuffer, bgm_start_pos: int, track_start_pos:
 			for e in events.slice(events[-1][1], -1):
 				if e[0] == EventType.NOTE:
 					repeat_note_dur += e[2]
-			print('track %s has duration %d and repeat duration %d (intro %d) - %d notes %d rests' % [bgm_id, total_note_dur, repeat_note_dur, total_note_dur-repeat_note_dur, total_notes, total_rests])
+			print_info('track %s has duration %d and repeat duration %d (intro %d) - %d notes %d rests' % [bgm_id, total_note_dur, repeat_note_dur, total_note_dur-repeat_note_dur, total_notes, total_rests])
 		else:
-			print('track %s has duration %d - %d notes %d rests' % [bgm_id, total_note_dur, total_notes, total_rests])
+			print_info('track %s has duration %d - %d notes %d rests' % [bgm_id, total_note_dur, total_notes, total_rests])
 	return events

shaders/audio_renderer.gdshader

@@ -0,0 +1,57 @@
+shader_type canvas_item;
+render_mode blend_premul_alpha;
+const float TEX_SIZE = 4096.0;
+const float UV_QUANTIZE = TEX_SIZE;
+// I feel like these magic numbers are a bit more intuitive in hex
+const float x00FF  = float(0x00FF);   //   255.0
+const float x0100  = float(0x0100);   //   256.0
+const float x7FFF  = float(0x7FFF);   // 32767.0
+const float x8000  = float(0x8000);   // 32768.0
+const float xFF00  = float(0xFF00);   // 65280.0
+const float xFFFF  = float(0xFFFF);   // 65535.0
+const float x10000 = float(0x10000);  // 65536.0
+
+const vec2 INT16_DOT_BE = vec2(xFF00, x00FF);
+const vec2 INT16_DOT_LE = vec2(x00FF, xFF00);
+uniform sampler2D tex : hint_normal;
+
+float unpack_int16(vec2 int16) {
+	// Convert packed 2byte integer, sampled as two [0.0, 1.0] range floats,
+	// to the original int value [-32768, 32767] or [0, 65535] but in float32
+	float unsigned = dot(int16, INT16_DOT_LE);
+	return unsigned - (unsigned < x7FFF ? 0.0 : x10000);
+}
+
+float rescale_int16(float int16) {
+	// Rescale from [-32768, 32767] to [-1.0, 1.0)
+	return int16 / x8000;
+}
+
+vec2 pack_float_to_int16(float value) {
+	// Convert a float in range [-1.0, 1.0) to a signed 2byte integer [-32768, 32767] packed into two [0.0, 1.0] floats
+	float scaled = value * x8000;
+	float unsigned = scaled + (scaled < 0.0 ? x10000 : 0.0);
+	float unsigned_div_256 = unsigned / x0100;
+	float MSB = trunc(unsigned_div_256)         / x00FF;
+	float LSB = fract(unsigned_div_256) * x0100 / x00FF;
+	return vec2(LSB, MSB);
+}
+
+vec4 test_writeback(vec2 uv) {
+	// Test importing and exporting the samples,
+	// and exporting a value derived from the UV
+	vec4 output;
+	float sample_1 = rescale_int16(unpack_int16(texture(tex, uv).xw));
+	float sample_2 = rescale_int16(dot(trunc(uv*TEX_SIZE), vec2(1.0, TEX_SIZE)));
+	output.xy = pack_float_to_int16(sample_1);
+	output.zw = pack_float_to_int16(sample_2);
+	return output;
+}
+
+void fragment() {
+	// GLES2
+	vec2 uv = vec2(UV.x, 1.0-UV.y);
+	uv = (trunc(uv*UV_QUANTIZE)+0.5)/UV_QUANTIZE;
+
+	COLOR.xyzw = test_writeback(uv);
+}

test/audio_renderer.gd

@@ -0,0 +1,70 @@
+extends Control
+
+var viewport: Viewport
+var render_queue: Array  # of PoolByteArrays
+var result_queue: Array  # of PoolByteArrays
+var current_image: Image
+var current_tex: ImageTexture  # Needed to prevent GC before draw
+var waiting_for_viewport: bool
+var done_first_draw: bool
+
+func _ready() -> void:
+	self.viewport = get_parent()
+	self.render_queue = []
+	self.result_queue = []
+	self.waiting_for_viewport = false
+	self.done_first_draw = false
+	self.current_image = Image.new()
+	self.current_tex = ImageTexture.new()
+
+func _process(_delta) -> void:
+	update()
+
+func _draw() -> void:
+	# Seems like the first one always fails
+	if not self.done_first_draw:
+		self.done_first_draw = true
+		return
+
+	if self.waiting_for_viewport:
+		# Another node later in the draw sequence can call this within the same frame,
+		# otherwise, this picks it up the following frame
+		get_result()
+
+	if not self.render_queue:
+		return
+
+	# Draw the next ImageTexture
+	var data: PoolByteArray = self.render_queue.pop_front()
+	print(data.subarray(0, 15))
+	self.current_image.create_from_data(4096, 4096, false, Image.FORMAT_LA8, data)
+	self.current_tex.create_from_image(self.current_image, Texture.FLAG_FILTER)
+	self.material.set_shader_param('tex', self.current_tex)
+	draw_texture(self.current_tex, Vector2.ZERO)
+	self.waiting_for_viewport = true  # Grab the result next draw
+
+func get_result() -> void:
+	var result_texture := self.viewport.get_texture()
+	var result_image := result_texture.get_data()
+	var result_bytes := result_image.get_data()
+
+	# Debugging: compare a sequence of all the possible 16bit integers
+	print_debug('result_image format is %d and has size'%result_image.get_format(), result_image.get_size(), result_bytes.subarray(0, 11))
+	test_readback(result_bytes)
+
+	self.result_queue.append(result_bytes)
+	self.waiting_for_viewport = false
+
+func test_readback(result_bytes: PoolByteArray):
+	# Debugging: compare a sequence of all the possible 16bit integers
+	var buff := StreamPeerBuffer.new()
+	buff.set_data_array(result_bytes)
+	var tex_readback = 0
+	var uv_readback = 0
+	for i in 0x1000:
+		tex_readback = buff.get_u16()
+		uv_readback = buff.get_u16()
+		if tex_readback != i:
+			print('tex readback %d (0x%04x) was instead %d (0x%04x)'%[i, i, tex_readback, tex_readback])
+		if uv_readback != i:
+			print('uv readback %d (0x%04x) was instead %d (0x%04x)'%[i, i, uv_readback, uv_readback])

test/audio_system.tscn

@@ -1,11 +1,31 @@
-[gd_scene load_steps=3 format=2]
+[gd_scene load_steps=6 format=2]
 
 [ext_resource path="res://test/audio_system.gd" type="Script" id=1]
 [ext_resource path="res://theme/menu_theme.tres" type="Theme" id=2]
+[ext_resource path="res://test/audio_renderer.gd" type="Script" id=3]
+[ext_resource path="res://shaders/audio_renderer.gdshader" type="Shader" id=4]
+
+[sub_resource type="ShaderMaterial" id=2]
+shader = ExtResource( 4 )
 
 [node name="audio_system" type="Node2D"]
 script = ExtResource( 1 )
 
+[node name="viewport_audio_renderer" type="Viewport" parent="."]
+size = Vector2( 4096, 4096 )
+size_override_stretch = true
+transparent_bg = true
+handle_input_locally = false
+hdr = false
+render_target_update_mode = 3
+
+[node name="audio_renderer" type="Control" parent="viewport_audio_renderer"]
+unique_name_in_owner = true
+material = SubResource( 2 )
+margin_right = 40.0
+margin_bottom = 40.0
+script = ExtResource( 3 )
+
 [node name="inst_buttons" type="ReferenceRect" parent="."]
 margin_right = 348.0
 margin_bottom = 118.0
@@ -42,4 +62,5 @@ margin_top = 192.0
 margin_right = 315.0
 margin_bottom = 216.0
 theme = ExtResource( 2 )
+pressed = true
 text = "HACK: Loop Extension"