Editing Openai/690e4c4b-5530-800d-ae72-e702400813d4 (section)

=== Assistant: Perfect — that’ll make the graph much more informative at low speeds. ===
Perfect — that’ll make the graph much more informative at low speeds.

Here’s the final version: it now auto-scales the vertical range of the velocity graph to the recent peak over the past 5 seconds. It still clamps extreme outliers for stability.

<syntaxhighlight lang="lua">-- main.lua
import "CoreLibs/graphics"
import "CoreLibs/timer"

local gfx = playdate.graphics

local W, H = 400, 240
local CX, CY = W / 2, H / 2
local RADIUS = 70

-- Crank tracking
local lastCrank = playdate.getCrankPosition()
local lastTime = playdate.getCurrentTimeMilliseconds()
local crankVelocity = 0
local displayedVelocity = 0
local direction = 0  -- 1 = clockwise, -1 = counterclockwise, 0 = still

-- Velocity history for last 5 seconds
local history = {}
local historyDuration = 5  -- seconds
local sampleRate = 30      -- samples per second (~ Playdate FPS)
local maxSamples = historyDuration * sampleRate

-- Config
local damping = 0.15
local lerpRate = 0.2
local baseMaxVel = 300 -- hard cap

-- Helper: draw dial tick marks
local function drawDial(cx, cy, radius)
    for deg = 0, 330, 30 do
        local rad = math.rad(deg)
        local x1 = cx + math.cos(rad) * (radius - 8)
        local y1 = cy + math.sin(rad) * (radius - 8)
        local x2 = cx + math.cos(rad) * radius
        local y2 = cy + math.sin(rad) * radius
        gfx.drawLine(x1, y1, x2, y2)
    end
end

local function addToHistory(value)
    table.insert(history, value)
    if #history > maxSamples then
        table.remove(history, 1)
    end
end

local function getDynamicRange()
    local maxAbs = 0
    for _, v in ipairs(history) do
        maxAbs = math.max(maxAbs, math.abs(v))
    end
    -- avoid divide-by-zero and excessive zoom
    return math.min(baseMaxVel, math.max(50, maxAbs * 1.2))
end

local function drawVelocityGraph(x, y, width, height)
    gfx.drawRect(x, y, width, height)
    local midY = y + height / 2
    gfx.setLineWidth(1)
    gfx.drawLine(x, midY, x + width, midY)

    if #history < 2 then return end

    local maxVel = getDynamicRange()
    local step = width / (maxSamples - 1)
    for i = 2, #history do
        local v1 = math.max(-baseMaxVel, math.min(baseMaxVel, history[i - 1]))
        local v2 = math.max(-baseMaxVel, math.min(baseMaxVel, history[i]))
        local y1 = midY - (v1 / maxVel) * (height / 2)
        local y2 = midY - (v2 / maxVel) * (height / 2)
        local x1 = x + (i - 2) * step
        local x2 = x + (i - 1) * step
        gfx.drawLine(x1, y1, x2, y2)
    end

    -- draw current scale indicator
    gfx.drawTextAligned(string.format("±%.0f°/s", getDynamicRange()), x + width/2, y - 14, kTextAlignment.center)
end

function playdate.update()
    gfx.clear()

    local now = playdate.getCurrentTimeMilliseconds()
    local crank = playdate.getCrankPosition()
    local deltaAngle = crank - lastCrank

    -- Handle wrap-around (359° → 0°)
    if deltaAngle > 180 then deltaAngle = deltaAngle - 360 end
    if deltaAngle < -180 then deltaAngle = deltaAngle + 360 end

    -- Time delta in seconds
    local dt = (now - lastTime) / 1000
    if dt > 0 then
        crankVelocity = deltaAngle / dt
    end

    -- Direction
    if deltaAngle > 0 then
        direction = 1
    elseif deltaAngle < 0 then
        direction = -1
    else
        direction = 0
    end

    lastCrank = crank
    lastTime = now

    -- Ease and damp velocity
    displayedVelocity = displayedVelocity + (crankVelocity - displayedVelocity) * lerpRate
    if math.abs(crankVelocity) < 2 then
        displayedVelocity = displayedVelocity * (1 - damping)
    end

    -- Add to velocity history
    addToHistory(displayedVelocity)

    -- Draw dial
    gfx.setLineWidth(2)
    gfx.drawCircleAtPoint(CX, CY, RADIUS)
    drawDial(CX, CY, RADIUS)

    -- Draw needle
    local needleAngle = math.rad(crank - 90)
    local nx = CX + math.cos(needleAngle) * (RADIUS - 12)
    local ny = CY + math.sin(needleAngle) * (RADIUS - 12)
    gfx.setLineWidth(6)
    gfx.drawLine(CX + 1, CY + 1, nx + 1, ny + 1)  -- shadow
    gfx.setLineWidth(4)
    gfx.drawLine(CX, CY, nx, ny)
    gfx.fillCircleAtPoint(CX, CY, 6)

    -- Draw velocity graph (left of dial)
    local graphX = CX - RADIUS - 80
    local graphY = CY - 50
    local graphW = 60
    local graphH = 100
    drawVelocityGraph(graphX, graphY, graphW, graphH)

    -- Text info
    local angleText = string.format("Angle: %.1f°", crank)
    local dirText = "Direction: " .. (direction == 1 and "clockwise" or (direction == -1 and "counterclockwise" or "still"))
    local velText = string.format("Velocity: %.1f°/s", displayedVelocity)

    gfx.setFont(gfx.getSystemFont())
    gfx.drawTextAligned(angleText, CX, CY + RADIUS + 10, kTextAlignment.center)
    gfx.drawTextAligned(dirText, CX, CY + RADIUS + 30, kTextAlignment.center)
    gfx.drawTextAligned(velText, CX, CY + RADIUS + 50, kTextAlignment.center)
    gfx.drawTextAligned("Turn the crank to see live velocity history", CX, 10, kTextAlignment.center)

    playdate.drawFPS(2, 2)
end

</syntaxhighlight>

===== ✅ Auto-scaling graph: =====
* The vertical scale adjusts dynamically to the largest absolute velocity in the last 5 seconds.
* Minimum range = ±50°/s; max = ±300°/s.
* The current scale (e.g. “±120°/s”) is shown above the graph.

✅ Smooth scrolling:
The line graph continuously scrolls left, showing the most recent history window.

✅ Stable performance:
Older samples are trimmed as new ones arrive, maintaining a fixed 5 s window.

Would you like me to add a faint horizontal grid and timestamps (1 s divisions) for readability?