From 6e4fdd3b3ae4e4656e151f098c40cfe551a36e8c Mon Sep 17 00:00:00 2001
From: jussi
Date: Fri, 18 Feb 2022 18:27:10 +0200
Subject: Added initial files.

---
 examples/snake/main.lua | 219 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 219 insertions(+)
 create mode 100644 examples/snake/main.lua

(limited to 'examples/snake/main.lua')

diff --git a/examples/snake/main.lua b/examples/snake/main.lua
new file mode 100644
index 0000000..74b7191
--- /dev/null
+++ b/examples/snake/main.lua
@@ -0,0 +1,219 @@
+-- Defines
+local RESOLUTION = { 128, 128 }
+local TILE_SIZE = 8
+local LEVEL_SIZE = RESOLUTION[1] / TILE_SIZE
+local STATE = { TITLE = 0, GAME = 1, OVER = 2 } -- Enum wannabe.
+
+-- Resources
+local framebuffer = -1
+local monitor = 0
+local monitorPos = RL_GetMonitorPosition( monitor )
+local monitorSize = RL_GetMonitorSize( monitor )
+local winScale = 6
+local winSize = { RESOLUTION[1] * winScale, RESOLUTION[2] * winScale }
+local gameState = STATE.GAME
+local grassTexture = -1
+local snakeTexture = -1
+local appleTexture = -1
+local gameSpeed = 7.0
+local moveTimer = 1.0
+local snake = {}
+local applePos = {}
+
+local function setSnake()
+	snake = {
+		heading = { 1, 0 },
+		control = { 1, 0 },
+		headPos = { LEVEL_SIZE / 2, LEVEL_SIZE / 2 },
+		segments = {},
+		grow = 2,
+	}
+end
+
+local function vector2IsEqual( v1, v2 )
+	return v1[1] == v2[1] and v1[2] == v2[2]
+end
+
+local function addSegment()
+	-- If first segment, grow from head and otherwise from tail. New segments are inserted firts.
+	if #snake.segments == 0 then
+		table.insert( snake.segments, 1, { pos = snake.headPos, heading = snake.heading } )
+	else
+		table.insert( snake.segments, 1, { pos = snake.segments[ #snake.segments ].pos,
+										heading = snake.segments[ #snake.segments ].heading } )
+	end
+end
+
+local function setApplePos()
+	applePos = { math.random( 0, LEVEL_SIZE - 1 ), math.random( 0, LEVEL_SIZE - 1 ) }
+	local search = true
+
+	while search do
+		search = false
+		applePos = { math.random( 0, LEVEL_SIZE - 1 ), math.random( 0, LEVEL_SIZE - 1 ) }
+
+		for _, seg in ipairs( snake.segments ) do
+			search = vector2IsEqual( applePos, seg.pos )
+
+			if search then
+				break
+			end
+		end
+	end
+end
+
+-- Init.
+
+function init()
+	RL_SetWindowState( FLAG_WINDOW_RESIZABLE )
+	RL_SetWindowSize( winSize )
+	RL_SetWindowPosition( { monitorPos[1] + monitorSize[1] / 2 - winSize[1] / 2, monitorPos[2] + monitorSize[2] / 2 - winSize[2] / 2 } )
+	RL_SetWindowTitle( "Snake" )
+	RL_SetWindowIcon( RL_LoadImage( RL_GetBasePath().."../resources/images/apple.png" ) )
+
+	framebuffer = RL_LoadRenderTexture( RESOLUTION )
+	grassTexture = RL_LoadTexture( RL_GetBasePath().."../resources/images/grass.png" )
+	snakeTexture = RL_LoadTexture( RL_GetBasePath().."../resources/images/snake.png" )
+	appleTexture = RL_LoadTexture( RL_GetBasePath().."../resources/images/apple.png" )
+
+	setSnake()
+	setApplePos()
+end
+
+-- Process.
+
+local function moveSnake()
+	-- Check if snake has eaten and should grow.
+	if 0 < snake.grow then
+		addSegment()
+		snake.grow = snake.grow - 1
+	end
+	-- Move body.
+	for i, seg in ipairs( snake.segments ) do
+		if i < #snake.segments then
+			seg.pos = snake.segments[ i+1 ].pos
+			seg.heading = snake.segments[ i+1 ].heading
+		else
+			seg.pos = snake.headPos
+			seg.heading = snake.heading
+		end
+	end
+	-- Move head.
+	snake.heading = { snake.control[1], snake.control[2] }
+	snake.headPos = { snake.headPos[1] + snake.heading[1], snake.headPos[2] + snake.heading[2] }
+
+	-- Check appple eating.
+	if vector2IsEqual( snake.headPos, applePos ) then
+		snake.grow = snake.grow + 1
+		setApplePos()
+	end
+	-- Check if hit to body.
+	for _, seg in ipairs( snake.segments ) do
+		if vector2IsEqual( snake.headPos, seg.pos ) then
+			gameState = STATE.OVER
+		end
+	end
+	-- Check if outside or level.
+	if snake.headPos[1] < 0 or LEVEL_SIZE <= snake.headPos[1] or snake.headPos[2] < 0 or LEVEL_SIZE <= snake.headPos[2] then
+		gameState = STATE.OVER
+	end
+
+	moveTimer = moveTimer + 1.0
+end
+
+function process( delta )
+	if gameState == STATE.GAME then -- Run game.
+		-- Controls.
+		if RL_IsKeyPressed( KEY_RIGHT ) and 0 <= snake.heading[1] then
+			snake.control = { 1, 0 }
+		elseif RL_IsKeyPressed( KEY_LEFT ) and snake.heading[1] <= 0 then
+			snake.control = { -1, 0 }
+		elseif RL_IsKeyPressed( KEY_DOWN ) and 0 <= snake.heading[2] then
+			snake.control = { 0, 1 }
+		elseif RL_IsKeyPressed( KEY_UP ) and snake.heading[2] <= 0 then
+			snake.control = { 0, -1 }
+		end
+	
+		moveTimer = moveTimer - gameSpeed * delta
+	
+		if moveTimer <= 0.0 then
+			moveSnake()
+		end
+	elseif gameState == STATE.OVER and RL_IsKeyPressed( KEY_ENTER ) then -- Reset game.
+		setSnake()
+		setApplePos()
+		gameState = STATE.GAME
+	end
+end
+
+-- Drawing.
+
+local function drawGrass()
+	for y = 0, LEVEL_SIZE - 1 do
+		for x = 0, LEVEL_SIZE - 1 do
+			RL_DrawTexture( grassTexture, { x * TILE_SIZE, y * TILE_SIZE }, WHITE )
+		end
+	end
+end
+
+--[[ Check if next segment is on left side. There are more mathematically elegant solution to this, but there is
+only four possibilities so we can just check them all. ]]--
+local function onLeft( this, next )
+	return ( vector2IsEqual( this, { 0, -1 } ) and vector2IsEqual( next, { -1, 0 } ) )
+		or ( vector2IsEqual( this, { -1, 0 } ) and vector2IsEqual( next, { 0, 1 } ) )
+		or ( vector2IsEqual( this, { 0, 1 } ) and vector2IsEqual( next, { 1, 0 } ) )
+		or ( vector2IsEqual( this, { 1, 0 } ) and vector2IsEqual( next, { 0, -1 } ) )
+end
+
+local function drawSnake()
+	for i, seg in ipairs( snake.segments ) do
+		local angle = math.deg( RL_Vector2Angle( { 0, 0 }, seg.heading ) )
+		local source = { 16, 0, 8, 8 }
+
+		if i == 1 then -- Tail segment. Yes tail is actually the 'first' segment.
+			source[1] = 8
+
+			if 1 < #snake.segments then
+				angle = math.deg( RL_Vector2Angle( { 0, 0 }, snake.segments[ 2 ].heading ) )
+			end
+		elseif i < #snake.segments and not vector2IsEqual( seg.heading, snake.segments[ i+1 ].heading ) then -- Turned middle segments.
+			source[1] = 0
+			-- Mirror turned segment to other way.
+			if onLeft( seg.heading, snake.segments[ i+1 ].heading ) then
+				source[4] = -8
+			end
+		elseif i == #snake.segments and not vector2IsEqual( seg.heading, snake.heading ) then -- Turned segment before head.
+			source[1] = 0
+
+			if onLeft( seg.heading, snake.heading ) then
+				source[4] = -8
+			end
+		end
+		-- Notice that we set the origin to center { 4, 4 } that acts as pivot point. We also have to adjust our dest position by 4.
+		RL_DrawTexturePro( snakeTexture, source, { seg.pos[1] * TILE_SIZE + 4, seg.pos[2] * TILE_SIZE + 4, 8, 8 }, { 4, 4 }, angle, WHITE )
+	end
+	-- Let's draw the head last to keep it on top.
+	local angle = math.deg( RL_Vector2Angle( { 0, 0 }, snake.heading ) )
+	RL_DrawTexturePro( snakeTexture, { 24, 0, 8, 8 }, { snake.headPos[1] * TILE_SIZE + 4, snake.headPos[2] * TILE_SIZE + 4, 8, 8 }, { 4, 4 }, angle, WHITE )
+end
+
+local function drawApple()
+	RL_DrawTexture( appleTexture, { applePos[1] * TILE_SIZE, applePos[2] * TILE_SIZE }, WHITE )
+end
+
+function draw()
+	-- Clear the window to black.
+	RL_ClearBackground( BLACK )
+	-- Draw to framebuffer.
+	RL_BeginTextureMode( framebuffer )
+		RL_ClearBackground( BLACK )
+		drawGrass()
+		drawSnake()
+		drawApple()
+	RL_EndTextureMode()
+
+	-- Draw framebuffer to window.
+	RL_SetTextureSource( TEXTURE_SOURCE_RENDER_TEXTURE )
+	RL_DrawTexturePro( framebuffer, { 0, 0, RESOLUTION[1], -RESOLUTION[2] }, { 0, 0, winSize[1], winSize[2] }, { 0, 0 }, 0.0, WHITE )
+	RL_SetTextureSource( TEXTURE_SOURCE_TEXTURE )
+end
-- 
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