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-- 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 = nil
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 RL.init()
RL.SetWindowState( RL.FLAG_WINDOW_RESIZABLE )
RL.SetWindowState( RL.FLAG_VSYNC_HINT )
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 RL.process( delta )
if gameState == STATE.GAME then -- Run game.
-- Controls.
if RL.IsKeyPressed( RL.KEY_RIGHT ) and 0 <= snake.heading[1] then
snake.control = { 1, 0 }
elseif RL.IsKeyPressed( RL.KEY_LEFT ) and snake.heading[1] <= 0 then
snake.control = { -1, 0 }
elseif RL.IsKeyPressed( RL.KEY_DOWN ) and 0 <= snake.heading[2] then
snake.control = { 0, 1 }
elseif RL.IsKeyPressed( RL.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( RL.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 }, RL.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, nextSeg )
return ( vector2IsEqual( this, { 0, -1 } ) and vector2IsEqual( nextSeg, { -1, 0 } ) )
or ( vector2IsEqual( this, { -1, 0 } ) and vector2IsEqual( nextSeg, { 0, 1 } ) )
or ( vector2IsEqual( this, { 0, 1 } ) and vector2IsEqual( nextSeg, { 1, 0 } ) )
or ( vector2IsEqual( this, { 1, 0 } ) and vector2IsEqual( nextSeg, { 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, RL.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, RL.WHITE )
end
local function drawApple()
RL.DrawTexture( appleTexture, { applePos[1] * TILE_SIZE, applePos[2] * TILE_SIZE }, RL.WHITE )
end
function RL.draw()
-- Clear the window to black.
RL.ClearBackground( RL.BLACK )
-- Draw to framebuffer.
RL.BeginTextureMode( framebuffer )
RL.ClearBackground( RL.BLACK )
drawGrass()
drawSnake()
drawApple()
if gameState == STATE.OVER then
RL.DrawText( RL.defaultFont, "Press Enter to\nrestart", { 10, 10 }, 10, 2, RL.WHITE )
end
RL.EndTextureMode()
-- Draw framebuffer to window.
RL.DrawTexturePro( RL.GetRenderTextureTexture( framebuffer ), { 0, 0, RESOLUTION[1], -RESOLUTION[2] }, { 0, 0, winSize[1], winSize[2] }, { 0, 0 }, 0.0, RL.WHITE )
end
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