Wall drags at 45° lay slopes; diagonal tubes drawn as one pipe; no side arrow on drag ghosts (t35, t36)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/PROJECT_MAP.md

@@ -205,7 +205,7 @@ Material definitions: ids, properties and metal families. ids, and drill/tank ti
 Material tables: typed properties, casting groups, flags, parts and tool tiers. Typed property tables
 - variables: PH, DENS, KC, ICAP, CASTMETAL, METAL_TIER, SOLIDMETAL, F_NAT, F_CAST, F_BURN, P_NONE, P_TU, P_TD, P_TL, P_TR, P_GRATE, P_GOPEN, P_WHEEL, P_INTAKE, P_FILTER, P_PIPE, P_TUR, P_TDR, P_TDL, P_TUL, TUBE_PARTS, TUBE_DIRS, IS_TUBE, TDX, TDY, BIT_TIERS, TANK_TIERS, REACH
 
-### src/sim/pieces.js (158 lines)
+### src/sim/pieces.js (156 lines)
 Everything the player can build (PIECES): blocks, machines and molds, with costs and descriptions; filter settings; wall materials and their cost.
 - functions: isSlope, isWall, slopeCell, slopeCode, isPipeCode, filterable, cleanFilterCfg, filterRec, filterPassAt, filterInfo, sameFilter, wallCost
 - variables: BS, BP_WALL, BP_BELT, BP_TUBE, BP_SHAFT, BP_GRATE, BP_GATE, BP_FILTER, BP_PIPE, BP_PUMP, BP_OUTLET, BP_GRIND, BP_SAW, BP_PRESS, BP_RACK, BP_SLOPE_BL, BP_SLOPE_BR, BP_SLOPE_TL, BP_SLOPE_TR, filterCfg, WALL_OF, WALL_LIST, BAR_OF, GRAINS_PER_BAR, POWER_FREE, CASH, PIECES, PIECE_BY_ID, PIECE_BY_CODE, BELT_POWER, TUBE_POWER, FAN_POWER, WHEEL_K, ENGINE_K, MOLDS
@@ -356,9 +356,9 @@ Drawing (src/render/): browser only. This file: the renderer state R, colour tab
 Propagated coloured light from glowing and burning cells.
 - functions: builtForLight, looseForLight, computeLight
 
-### src/render/world.js (332 lines)
+### src/render/world.js (361 lines)
 Scale colour without changing the smooth-look class.
-- functions: fogColor, drawWorld
+- functions: fogColor, diagonalTubeBlock, drawWorld
 - variables: TUBE_CLASS
 
 ### src/render/machines.js (242 lines)
@@ -374,7 +374,7 @@ Smooth look: WebGL setup, texture uploads, drawing and adaptive resolution.
 - functions: smCompile, smoothAvailable, smUpload, smoothDraw, smoothPace
 - variables: SM, smBytes
 
-### src/render/smooth-shaders.js (342 lines)
+### src/render/smooth-shaders.js (348 lines)
 Smooth shaders: vertex and fragment programs for the rounded world look.
 - variables: SM_VS, SM_FS
 
@@ -430,12 +430,12 @@ Notebook blueprints: starter designs, saved library and code sharing.
 The tool hotbar and what is selected.
 - functions: renderHotbar, toolId, steering, modShift, grainAt, selectTool, bagMaterials, blowList, blowAllList, blowingAll, piece
 
-### src/ui/build-menu.js (105 lines)
+### src/ui/build-menu.js (109 lines)
 The build menu along the bottom: categories, piece tiles and their icons.
 - functions: pieceIcon, catOf, selectBuildCat, cycleBuildCat, buildVariantChips, renderBuildBar, setupBuildBar
 - variables: BUILD_CATS, BUILD_ORDER, PIECE_ICONS, lastBuildKey, lastBuildMenu
 
-### src/ui/selection.js (107 lines)
+### src/ui/selection.js (112 lines)
 Tool selection: cycling, drill tuning, piece variants and costs.
 - functions: pieceSize, pieceUsesWall, setDrillWidth, tuneUnderCursor, cycleItem, cycleWall, rotate, toggleBlow, pickFilterUnderCursor, toggleFilterMat, setBrush, pieceV, pieceExtra, filterBlockAt, chipCost, pieceCostNow, pieceCode, turnSlope
 
@@ -467,7 +467,7 @@ Gamepad input.
 - functions: padPressed, pollPad
 - variables: PAD
 
-### src/ui/previews.js (203 lines)
+### src/ui/previews.js (199 lines)
 Cursor previews: shared grid helpers, air streaks and tool preview dispatch.
 - functions: blockRectPx, drawGrid, previewColor, drawAirStreaks, drawReachCircle, drawPreviews, previewBlock