Yet another missile silo panel widget

LuaUI/Widgets/gui_attack_aoe.lua

@@ -487,6 +487,41 @@ local function DrawAoE(tx, ty, tz, aoe, ee, alphaMult, offset, circleMode)
 	glLineWidth(1)
 end
 
+--------------------------------------------------------------------------------
+-- Shared blast-radius preview, exposed via WG so other widgets (e.g. the missile
+-- silo launch UI) draw their AoE footprint with THIS falloff code instead of
+-- duplicating it. Nested rings at (tx,ty,tz) whose alpha decays toward the edge by
+-- edgeEffectiveness `ee`. `color` (optional {r,g,b[,a]}) overrides the ring colour;
+-- `alphaMult` (optional) scales overall opacity. Line width is derived from the
+-- camera distance to the point, so callers need no per-frame setup of their own.
+--------------------------------------------------------------------------------
+local function DrawAoEPreview(tx, ty, tz, aoe, ee, color, alphaMult)
+	if not aoe or aoe <= 0 then
+		return
+	end
+	ee = ee or 1
+	local cx, cy, cz = GetCameraPosition()
+	local dx, dy, dz = cx - tx, cy - ty, cz - tz
+	local camDist = sqrt(dx*dx + dy*dy + dz*dz)
+	if camDist < 1 then
+		camDist = 1
+	end
+	local r = (color and color[1]) or aoeColor[1]
+	local g = (color and color[2]) or aoeColor[2]
+	local b = (color and color[3]) or aoeColor[3]
+	local baseAlpha = ((color and color[4]) or aoeColor[4]) * (alphaMult or 1)
+
+	glLineWidth(math.max(0.05, aoeLineWidthMult * aoe / camDist))
+	for i = 1, numAoECircles do
+		local proportion = i / (numAoECircles + 1)
+		local alpha = baseAlpha * (1 - proportion) / (1 - proportion * ee)
+		glColor(r, g, b, alpha)
+		DrawCircle(tx, ty, tz, aoe * proportion)
+	end
+	glColor(1, 1, 1, 1)
+	glLineWidth(1)
+end
+
 --------------------------------------------------------------------------------
 --dgun/noexplode
 --------------------------------------------------------------------------------
@@ -939,6 +974,39 @@ local function CalculateVlaunchImpact(info, fx, fy, fz, tx, ty, tz)
 	return false
 end
 
+--------------------------------------------------------------------------------
+-- Shared terrain-impact test, exposed via WG for the missile silo launch UI. Given a
+-- firing unit (a vlaunch missile sitting on its pad) and a target point, returns the
+-- terrain impact point (hx, hy, hz) if that unit's vlaunch trajectory is projected to
+-- strike the ground before reaching the target (a hill in the way), or nil if it
+-- reaches the target -- or has no vlaunch data, so the caller simply doesn't filter.
+-- Uses exactly the same CalculateVlaunchImpact path this widget draws (the depth line
+-- shown when force-firing), so the silo UI's "which silo can actually hit here" filter
+-- matches what a player sees.
+--------------------------------------------------------------------------------
+local function GetVlaunchTerrainImpact(unitID, tx, ty, tz)
+	local unitDefID = spGetUnitDefID(unitID)
+	local info = unitDefID and aoeDefInfo[unitDefID]
+	if not (info and info.vlaunch) or info.circleMode == "cloaker" then
+		return nil
+	end
+	local _,_,_,fx, fy, fz = GetUnitPosition(unitID, true)
+	if not fx then
+		return nil
+	end
+	if not info.mobile then
+		fy = fy + GetUnitRadius(unitID)
+	end
+	if not info.waterWeapon then
+		ty = max(0, ty)
+	end
+	local hx, hy, hz = CalculateVlaunchImpact(info, fx, fy, fz, tx, ty, tz)
+	if hx then
+		return hx, hy, hz
+	end
+	return nil
+end
+
 --------------------------------------------------------------------------------
 --Main draw
 --------------------------------------------------------------------------------
@@ -1027,10 +1095,14 @@ function widget:Initialize()
 		aoeDefInfo[unitDefID], dgunInfo[unitDefID], extraDrawRangeDefInfo[unitDefID] = SetupUnit(unitDef)
 	end
 	SetupDisplayLists()
+	WG.DrawAoEPreview = DrawAoEPreview
+	WG.GetVlaunchTerrainImpact = GetVlaunchTerrainImpact
 end
 
 function widget:Shutdown()
 	DeleteDisplayLists()
+	WG.DrawAoEPreview = nil
+	WG.GetVlaunchTerrainImpact = nil
 end
 
 function widget:DrawWorld()