diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/SMAPI/Framework/Content/AssetDataForImage.cs | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/src/SMAPI/Framework/Content/AssetDataForImage.cs b/src/SMAPI/Framework/Content/AssetDataForImage.cs index cd372948..a8ec79a8 100644 --- a/src/SMAPI/Framework/Content/AssetDataForImage.cs +++ b/src/SMAPI/Framework/Content/AssetDataForImage.cs @@ -84,13 +84,13 @@ namespace StardewModdingAPI.Framework.Content // merge pixels // This performs a conventional alpha blend for the pixels, which are already - // premultiplied by the content pipeline. - float alphaAbove = above.A / 255f; - float alphaBelow = (255 - above.A) / 255f; + // premultiplied by the content pipeline. The formula is derived from + // https://blogs.msdn.microsoft.com/shawnhar/2009/11/06/premultiplied-alpha/. + float alphaBelow = 1 - (above.A / 255f); newData[i] = new Color( - r: (int)((above.R * alphaAbove) + (below.R * alphaBelow)), - g: (int)((above.G * alphaAbove) + (below.G * alphaBelow)), - b: (int)((above.B * alphaAbove) + (below.B * alphaBelow)), + r: (int)(above.R + (below.R * alphaBelow)), + g: (int)(above.G + (below.G * alphaBelow)), + b: (int)(above.B + (below.B * alphaBelow)), a: Math.Max(above.A, below.A) ); } |