updated

programs/roulette.lua

@@ -44,12 +44,25 @@ end
 
 local function makeGpuBackend(gpu)
     gpu.refreshSize()
-    -- Per-block pixel resolution. 32 gives a nice balance between
+    -- Try a high per-block resolution; older/cheaper GPU tiers may cap
-    -- pocket density and per-pixel performance on multi-block screens.
+    -- this so fall back if it errors.
-    gpu.setSize(32)
+    local trySizes = { 64, 32, 16, 8 }
+    for _, s in ipairs(trySizes) do
+        if pcall(gpu.setSize, s) then break end
+    end
+
     local pw, ph = gpu.getSize()
-    -- Pocket cell size in pixels. Bigger = chunkier pockets.
+    print(("[roulette] GPU pixel size: %sx%s"):format(tostring(pw), tostring(ph)))
-    local cell = 16
+
+    if not pw or not ph or pw < 8 or ph < 8 then
+        error(("GPU reports unusable pixel size %sx%s. Place at least one screen block adjacent to the GPU.")
+            :format(tostring(pw), tostring(ph)))
+    end
+
+    -- Pick a cell size that gives at least 16x16 cells, capped at 16 px.
+    local cell = math.max(2, math.min(16, math.floor(math.min(pw, ph) / 16)))
+    print(("[roulette] Using cell size: %d px -> %dx%d cells"):format(
+        cell, math.floor(pw / cell), math.floor(ph / cell)))
 
     return {
         kind = "gpu",
@@ -69,10 +82,9 @@ local function makeGpuBackend(gpu)
             local px = (x - 1) * cell + 1
             local py = (y - 1) * cell + 1
             -- drawText(x, y, text, textColor, bgColor, size, padding)
-            gpu.drawText(px, py, str, fg, bg, 1, 0)
+            pcall(gpu.drawText, px, py, str, fg, bg, 1, 0)
         end,
         clear = function(col)
-            -- gpu.fill() with no args clears to black; with a color clears to that color.
             if col then gpu.fill(col) else gpu.fill() end
         end,
         sync = function()
@@ -269,8 +281,9 @@ local function start()
     math.randomseed(os.epoch("utc"))
     gfx = initBackend()
     W, H = gfx.size()
-    if W < 4 or H < 4 then
+    print(("[roulette] Wheel grid: %dx%d cells"):format(W, H))
-        error(("Screen too small: %dx%d cells"):format(W, H))
+    if W < 3 or H < 3 then
+        error(("Screen too small: %dx%d cells. Add more screen blocks."):format(W, H))
     end
     buildPerimeter()
     ballIndex = 1