Classical old school fire effect

examples/fire.nim

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+#? replace(sub = "\t", by = " ")
+
+# import std/lenientops
+import std/random
+import std/tables
+import nico
+
+# https://gist.github.com/emanuel-sanabria-developer/5793377
+# Converts an HSL color value to RGB. Conversion formula
+# adapted from http://en.wikipedia.org/wiki/HSL_color_space.
+proc hsl2rgb( h8, s8, l8: int ): tuple =
+	let h = h8 / 255
+	let s = s8 / 255
+	let l = l8 / 255
+	var r, g, b: float
+
+	if s == 0:
+		r = l; g = l; b = l # achromatic
+	else:
+		proc hue2rgb( p, q, t: float ): float =
+			var t = t
+			if t < 0: t += 1
+			if t > 1: t -= 1
+			if t < 1 / 6: return p + ( q - p ) * 6 * t
+			if t < 1 / 2: return q
+			if t < 2 / 3: return p + ( q - p ) * ( 2 / 3 - t ) * 6
+			return p
+
+		let q = if l < 0.5: l * (1 + s) else: l + s - l * s
+		let p = 2 * l - q
+		r = hue2rgb( p, q, h + 1 / 3 )
+		g = hue2rgb( p, q, h)
+		b = hue2rgb( p, q, h - 1 / 3 )
+
+	return ( r * 255, g * 255, b * 255 )
+
+proc loadPaletteFire( color: range[ 0 .. 4 ] ): Palette =
+	proc transferFunc( value: int ): int =
+		return min( 255, value * 2 )
+		# return int( sqrt( value / 255 ) * 255 )
+
+	var offset {.global.} = 0
+	var r, g, b: float
+	for i in 0 .. 255:
+		case color
+		of 0: # white - yellow - red
+			( r, g, b ) = hsl2rgb( int( i / 3 ), 255, transferFunc( i ) )
+		of 1: # white - yellow - green
+			( r, g, b ) = hsl2rgb( int( 1 * 255 / 3 - i / 3 ), 255, transferFunc( i ) )
+		of 2: # white - turquoise - blue
+			( r, g, b ) = hsl2rgb( int( 2 * 255 / 3 - i / 3 ), 255, transferFunc( i ) )
+		of 3: # white - magenta - red
+			( r, g, b ) = hsl2rgb( int( 3 * 255 / 3 - i / 3 ), 255, transferFunc( i ) )
+		of 4: # color cycle
+			# ( r, g, b ) = hsl2rgb( int( ( i + offset ) / 3 ) mod 256, 255, transferFunc( i ) )
+			( r, g, b ) = hsl2rgb( int( offset / 3 ) mod 256, 255, transferFunc( i ) )
+		result.data[ i ] = ( r.uint8, g.uint8, b.uint8 )
+	result.size = 256
+	offset += 1
+
+proc keyPressed( keycode: Keycode ): bool =
+	var previousKeys {.global.} = initTable[ Keycode, bool ]()
+	let isKeyPressed = key( keycode )
+	result = isKeyPressed and not previousKeys.getOrDefault( keycode )
+	previousKeys[ keycode ] = isKeyPressed
+
+proc gameInit() =
+	# setVSync( false )
+	# echo getVSync()
+	# cls()
+	fps( 20 )
+	setPalette( loadPaletteFire( 0 ) )
+	loadMusic( 0, "fire_1.ogg" )
+	music( 15, 0 ) # Needs to be rendered at 60 fps with the default audioBufferSize.
+	setAudioBufferSize( 1024 * 2 * 60 div fps() ) # So we adjust it to our needs.
+	setColor( 255 )
+	printc( "KEYS:", screenWidth / 2, screenHeight / 3, 5 )
+	printc( "S C M P", screenWidth / 2, 2 * screenHeight / 3, 5 )
+
+proc gameUpdate( dt: Pfloat ) =
+	discard
+
+const
+	width = 160
+	# width = 1200
+	height = 90
+	# height = 125
+	scale = 3
+
+proc gameDraw() =
+	var frame {.global.}: int32 = -1
+	var fireArray {.global.}: array[ width, uint8 ]
+	var randomizeFire {.global.}: bool = true
+
+	frame += 1
+
+	# Toggle sound playback with s key:
+	if keyPressed( K_s ):
+		if getMusic( 15 ) == -1:
+			music( 15, 0 )
+			printc( "SND ON", screenWidth / 2, screenHeight / 2, 5 )
+		else:
+			music( 15, -1 )
+			printc( "SND OFF", screenWidth / 2, screenHeight / 2, 5 )
+
+	# Cycle fire color with c key:
+	var fireColor {.global.} = 0
+	if keyPressed( K_c ):
+		fireColor = ( fireColor + 1 ) mod 5
+		setPalette( loadPaletteFire( fireColor ) )
+		const colors = [ "ORANGE", "GREEN", "BLUE", "MAGENTA", "CYCLE" ]
+		printc( colors[ fireColor ], screenWidth / 2, screenHeight / 2, 5 )
+
+	if fireColor == 4:
+		setPalette( loadPaletteFire( 4 ) )
+
+	# Toggle message displaying with m key:
+	var showMessage {.global.}:bool = false
+	if keyPressed( K_m ):
+		showMessage = not showMessage
+
+	# Randomize fire every other frame.
+	if randomizeFire:
+		randomizeFire = false
+		for x in 0 ..< screenWidth:
+			fireArray[ x ] = rand( 255 ).uint8
+	else:
+		randomizeFire = not key( K_p ) # Pause fire with p key.
+
+	const border = 5
+
+	for x in border ..< screenWidth - border:
+		pset( x, screenHeight - 2, fireArray[ x ] )
+		pset( x, screenHeight - 1, fireArray[ x ] )
+
+	if showMessage:
+		const message = [ "", "", "HAPPY", "NEW", "YEAR", "2024", ":-)", ]
+		if frame mod ( fps() * 2 ) == 0:
+			setColor( 255 )
+			printc( message[ ( frame div ( fps() * 2 ) ) mod len( message ) ],
+				screenWidth / 2, screenHeight / 2, 5 )
+
+	# https://lodev.org/cgtutor/fire.html
+	for y in 0 ..< screenHeight - 2:
+		for x in 1 ..< screenWidth - 1:
+			let color = ( pget( x - 1, y + 1 ) + pget( x, y + 1 )  + pget( x + 1, y + 1 ) +
+				pget( x, y + 2 ) ) / 4.1
+			pset( x, y, color.int )
+
+	for x in border ..< screenWidth - border:
+		pset( x, screenHeight - 2, 255 )
+		pset( x, screenHeight - 1, 0 )
+
+nico.init( "nico", "test" )
+
+fixedSize( true )
+integerScale( true )
+nico.createWindow( "fire", width, height + 2, scale )
+nico.run( gameInit, gameUpdate, gameDraw )