lg = love.graphics
W,H = lg.getDimensions()
local Noise = require "noise"
local DRAW_RES = love.window.toPixels(4)
local SCALE = 100
local font = lg.newFont(love.window.toPixels(24))

local decay = function(x) return .1^x end
local function rng()
    local r = love.math.newRandomGenerator(1)
    return function() return r:random() end
end
local n1 = Noise.make1d(5,rng(),decay)
local n2 = Noise.make2d(7,rng(),decay)
local n3 = Noise.make3d(11,rng(),decay)
local s1 = Noise.make1dShader(7,rng(),decay)
local s2 = Noise.make2dShader(13,rng(),decay)
local s3 = Noise.make3dShader(17,rng(),decay)

local cw,ch = W/2,H/3
local canv = lg.newCanvas(cw,ch)

function love.load()
    xOffset = 0
    yOffset = 0
    t0 = love.timer.getTime()
    love.mouse.setCursor(love.mouse.getSystemCursor("hand"))
end

function love.mousepressed()
    love.mouse.setCursor(love.mouse.getSystemCursor("sizeall"))
end

function love.mousereleased()
    love.mouse.setCursor(love.mouse.getSystemCursor("hand"))
end

function love.draw()
    lg.setColor(255,255,255)
    lg.setLineWidth(love.window.toPixels(2))
    lg.setLineJoin("none")
    local p1 = {}
    for x=0,W-H/3,DRAW_RES do
        table.insert(p1,x)
        table.insert(p1,n1(x/SCALE+xOffset)*H/3)
    end
    lg.line(p1)

    local p2 = {}
    local t = love.timer.getTime()-t0
    for x=0,W-H/3,DRAW_RES do
        table.insert(p2,x)
        table.insert(p2,(1+n2(x/SCALE+xOffset,t))*H/3)
    end
    lg.line(p2)

    for y=0,H/6*1.2,2*DRAW_RES do
        local p3 = {}
        for x=0,W-H/3,DRAW_RES do
            table.insert(p3,x)
            table.insert(p3,2/3*H+H/6*n3(x/SCALE+xOffset,y/SCALE+yOffset,t)+y)
        end
        lg.line(p3)
    end
    for x=-H/6,W-H/3,DRAW_RES*2 do
        local p3 = {}
        local slant = .5
        for y=0,H/6*1.2,2*DRAW_RES do
            local x2 = x + slant*y
            if x2 < -2*DRAW_RES then goto continue end
            table.insert(p3,x2)
            table.insert(p3,2/3*H+H/6*n3(x2/SCALE+xOffset,y/SCALE+yOffset,t)+y)
            if x2 > W/2 then break end
            ::continue::
        end
        if #p3 > 2 then
            lg.line(p3)
        end
    end

    lg.setShader(s1)
    s1:send("range_min", xOffset)
    s1:send("range_max", xOffset+cw/SCALE)
    lg.draw(canv,W-cw,0)
    lg.setShader(s2)
    s2:send("range_min", {xOffset,yOffset})
    s2:send("range_max", {xOffset+cw/SCALE,yOffset+ch/SCALE})
    lg.draw(canv,W-cw,ch)
    lg.setShader(s3)
    s3:send("range_min", {xOffset,yOffset})
    s3:send("range_max", {xOffset+cw/SCALE,yOffset+ch/SCALE})
    s3:send('z', t)
    lg.draw(canv,W-cw,2*ch)
    lg.setShader(nil)

    lg.setColor(255,200,0)
    lg.setFont(font)
    lg.printf("1D_Noise(x)", 5,5, W)
    lg.printf("2D_Noise(x,time)", 5,5+H/3, W)
    lg.printf("3D_Noise(x,y,time)", 5,5+2*H/3, W)
    lg.printf("1D_Noise_Shader(x)", 0,5, W-5, 'right')
    lg.printf("2D_Noise_Shader(x,y)", 0,5+H/3, W-5, 'right')
    lg.printf("3D_Noise_Shader(x,y,time)", 0,5+2*H/3, W-5, 'right')
end

function love.update(dt)
    local key = love.keyboard.isDown
    local dx = 400/SCALE*dt*((key('right') and 1 or 0) + (key('left') and -1 or 0))
    local dy = 400/SCALE*dt*((key('down') and 1 or 0) + (key('up') and -1 or 0))
    xOffset = xOffset + dx
    yOffset = yOffset + dy
end

function love.keypressed(key)
    if key == 'escape' then love.event.quit() end
    if key == 'r' then love.load() end
end

function love.mousemoved(x,y,dx,dy)
    if love.mouse.isDown(1) then
        xOffset = xOffset - dx/SCALE
        yOffset = yOffset - dy/SCALE
    end
end