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fix: virtual grid-snapped tail anchor prevents corner diagonals

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Body path now goes: interp_tail → grid_tail → segment[N-2] → ... → head.
The short leg from interpolated to grid-snapped tail is always straight
(same direction), and from grid_tail onward the path strictly follows
the grid — preserving sharp corners while tail stays smooth.
This commit is contained in:
Heller
2026-06-19 10:27:42 +00:00
parent c1b9543c47
commit 90fd0f592f
1 changed files with 12 additions and 7 deletions
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19
Snake.Avalonia/Views/SnakeRenderer.cs
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@@ -135,18 +135,23 @@ public sealed class SnakeRenderer : Control
var segmentsList = Segments;
var count = segmentsList.Count;
// === Body path: from segment[Count-1] (tail) through segment[0] (head) ===
// All segments use GetVisualPosition — middle/body returns grid-snapped,
// head returns interpolated. Tail is grid-snapped, giving sharp corners
// with full body thickness.
// === Body path: from interp tail → grid tail (virtual corner anchor) → body → head ===
// The virtual grid-snapped tail prevents diagonal shortcuts at corners:
// the short leg from interp_tail to grid_tail is always straight (same direction),
// and from grid_tail onward the path strictly follows the grid.
if (count >= 2)
{
var bodyGeometry = new StreamGeometry();
using (var ctx = bodyGeometry.Open())
{
// Start at tail (last segment, grid-snapped)
var (startX, startY) = GetVisualPosition(segmentsList[count - 1], count - 1, t);
ctx.BeginFigure(new Point(startX, startY), false);
// Start at interpolated tail
var (tailX, tailY) = GetVisualPosition(segmentsList[count - 1], count - 1, t);
ctx.BeginFigure(new Point(tailX, tailY), false);
// Virtual corner anchor: grid-snapped tail position
var lastPos = segmentsList[count - 1];
var (gridTailX, gridTailY) = (lastPos.X * CellSize + CellSize * 0.5, lastPos.Y * CellSize + CellSize * 0.5);
ctx.LineTo(new Point(gridTailX, gridTailY));
// Draw through middle segments down to head
for (var i = count - 2; i >= 0; i--)