# bug #2250
import
math, strutils
type
Meters = float
Point2[T] = tuple[x, y: T]
HexState* = enum
hsOn, hsOff
Index = uint16
HexGrid* = object
w, h: int ## Width and height of the hex grid.
radius: Meters ## Radius of circle that circumscribes a hexagon.
grid: seq[HexState] ## Information on what hexes are drawn.
HexVtxIndex = enum
hiA, hiB, hiC, hiD, hiE, hiF
HexCoord* = Point2[int]
const
HexDY = sqrt(1.0 - (0.5 * 0.5)) # dy from center to midpoint of 1-2
HexDX = sqrt(1.0 - (HexDY * HexDY)) # dx from center to midpoint of 1-5 (0.5)
let
hexOffsets : array[HexVtxIndex, Point2[float]] = [
(-1.0, 0.0),
(-HexDX, -HexDY),
(HexDX, -HexDY),
(1.0, 0.0),
(HexDX, HexDY),
(-HexDX, HexDY)]
evenSharingOffsets : array[HexVtxIndex, tuple[hc: HexCoord; idx: HexVtxIndex]] = [
((0,0), hiA),
((0,0), hiB),
((1,-1), hiA),
((1,0), hiB),
((1,0), hiA),
((0,1), hiB)]
oddSharingOffsets : array[HexVtxIndex, tuple[hc: HexCoord; idx: HexVtxIndex]] = [
((0,0), hiA),
((0,0), hiB),
((1,0), hiA),
((1,1), hiB),
((1,1), hiA),
((0,1), hiB)]
template odd*(i: int) : expr =
(i and 1) != 0
proc vidx(hg: HexGrid; col, row: int; i: HexVtxIndex) : Index =
#NOTE: this variation compiles
#var offset : type(evenSharingOffsets[i])
#
#if odd(col):
# offset = oddSharingOffsets[i]
#else:
# offset = evenSharingOffsets[i]
let
#NOTE: this line generates the bad code
offset = (if odd(col): oddSharingOffsets[i] else: evenSharingOffsets[i])
x = col + 1 + offset.hc.x
y = row + 1 + offset.hc.y
result = Index(x*2 + y * (hg.w + 2)*2 + int(offset.idx))
proc go() =
var hg : HexGrid
echo "vidx ", $vidx(hg, 1, 2, hiC)
go()