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fix: Incorrect bounding box for sprites with non-default Center #3277

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fix: Incorrect bounding box for sprites with non-default Center #3277

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29 changes: 28 additions & 1 deletion sources/engine/Stride.Rendering/Rendering/Sprites/RenderSprite.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -51,6 +51,7 @@ public class RenderSprite : RenderObject
private Matrix lastWorldMatrix;
private Vector2 lastHalfSpriteSize;
private SpriteType lastSpriteType;
private Vector2 lastSpriteCenter;

public Matrix WorldMatrix;
public float RotationEulerZ;
Expand All @@ -71,7 +72,10 @@ internal void CalculateBoundingBox()
var halfSpriteSize = Sprite?.Size / 2 ?? Vector2.Zero;

// Only calculate if we've changed...
if (lastWorldMatrix != WorldMatrix || lastHalfSpriteSize != halfSpriteSize || lastSpriteType != SpriteType)
if (lastWorldMatrix != WorldMatrix || lastHalfSpriteSize != halfSpriteSize
|| lastSpriteType != SpriteType
+ || lastSpriteCenter != (Sprite?.Center ?? Vector2.Zero))

{
Vector3 halfBoxSize;
var boxWorldPosition = WorldMatrix.TranslationVector;
Expand All @@ -91,13 +95,36 @@ internal void CalculateBoundingBox()
Math.Abs(WorldMatrix.M13 * halfSpriteSize.X) + Math.Abs(WorldMatrix.M23 * halfSpriteSize.Y));
}

// Account for Sprite.Center (pivot offset) — same logic as SpriteRenderFeature.Draw()
if (Sprite != null)
{
var sourceRegion = Sprite.Region;
var normalizedCenter = new Vector2(
Sprite.Center.X / sourceRegion.Width - 0.5f,
0.5f - Sprite.Center.Y / sourceRegion.Height);

if (Sprite.Orientation == ImageOrientation.Rotated90)
{
var oldCenterX = normalizedCenter.X;
normalizedCenter.X = -normalizedCenter.Y;
normalizedCenter.Y = oldCenterX;
}

var centerOffset = Vector2.Modulate(normalizedCenter, Sprite.SizeInternal);
boxWorldPosition -= new Vector3(
centerOffset.X * WorldMatrix.M11 + centerOffset.Y * WorldMatrix.M21,
centerOffset.X * WorldMatrix.M12 + centerOffset.Y * WorldMatrix.M22,
centerOffset.X * WorldMatrix.M13 + centerOffset.Y * WorldMatrix.M23);
}

// Update bounding box
BoundingBox = new BoundingBoxExt(boxWorldPosition - halfBoxSize, boxWorldPosition + halfBoxSize);

// Save current state for next check
lastWorldMatrix = WorldMatrix;
lastHalfSpriteSize = halfSpriteSize;
lastSpriteType = SpriteType;
lastSpriteCenter = Sprite?.Center ?? Vector2.Zero;
}
}
}
Expand Down