diff --git a/OpenRA.Game/Graphics/WorldRenderer.cs b/OpenRA.Game/Graphics/WorldRenderer.cs index 387f1fdb78..58b9c38c87 100644 --- a/OpenRA.Game/Graphics/WorldRenderer.cs +++ b/OpenRA.Game/Graphics/WorldRenderer.cs @@ -133,7 +133,26 @@ namespace OpenRA.Graphics foreach (var e in World.ScreenMap.RenderableEffectsInBox(Viewport.TopLeft, Viewport.BottomRight)) renderablesBuffer.AddRange(e.Render(this)); - renderablesBuffer.Sort((x, y) => RenderableZPositionComparisonKey(x).CompareTo(RenderableZPositionComparisonKey(y))); + renderablesBuffer.Sort((a, b) => + { + // Sort is an unstable sort, so elements with the same Z position may get sorted differently each frame. + // This leads to flickering when rendering several frames as the elements get swapped at random. + // To combat this, use a series of arbitrary tie-breaks to determine the "top-most" element. + // This ensures a consistent decision for which one is on top, preventing flicker. + var compared = RenderableZPositionComparisonKey(a).CompareTo(RenderableZPositionComparisonKey(b)); + if (compared != 0) + return compared; + + compared = a.Pos.X.CompareTo(b.Pos.X); + if (compared != 0) + return compared; + + compared = a.Pos.Y.CompareTo(b.Pos.Y); + if (compared != 0) + return compared; + + return a.Pos.Z.CompareTo(b.Pos.Z); + }); foreach (var renderable in renderablesBuffer) preparedRenderables.Add(renderable.PrepareRender(this));