From 3144cda7fcb30beaa78e85783d0af8994484edfe Mon Sep 17 00:00:00 2001
From: Eugene Blikh <bigbes@gmail.com>
Date: Tue, 28 Apr 2026 03:54:11 +0300
Subject: [PATCH] systems-power: hoist HUD cellBottom out of inner loop

Reviewer flagged the per-iteration recomputation of cellBottom inside
drawHud's column/cell loops; the value was loop-invariant. Hoist to a
file-scope const and simplify the algebra.

systems-power
---
 render.go | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/render.go b/render.go
index 9bfa2d65398a94599213b77bd9bd95cf227b63b4..dfdf3aa2edc10b749951ea59e5318bb091176823 100644
--- a/render.go
+++ b/render.go
@@ -97,6 +97,8 @@ func drawHud(screen *ebiten.Image, sys []System) {
 	const cellW = 12
 	const cellH = 10
 	const cellGap = 2
+	// cellBottom is the y of the bottom-most cell's top edge; loop-invariant.
+	const cellBottom = VirtualH - cellGap
 	outline := color.RGBA{255, 255, 255, 255}
 
 	// Role labels in display order (index == int(RoomRole)).
@@ -112,9 +114,6 @@ func drawHud(screen *ebiten.Image, sys []System) {
 
 		// Cells stacked bottom-up. Row 0 is at the bottom of the HUD strip.
 		for j := 0; j < s.MaxLevel; j++ {
-			// Compute y so that row 0 is at the bottom. We allocate space
-			// starting below the label (label height ~12px).
-			cellBottom := HudY + (VirtualH - HudY) - cellGap
 			cy := cellBottom - (j+1)*(cellH+cellGap)
 			cx := colLeft + 4