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rewrite PNG premultiplication so mods can load PNGs during a draw cycle

This commit is contained in:
Jesse Plamondon-Willard 2018-09-03 19:32:36 -04:00
parent f921e98809
commit 047091a1a4
2 changed files with 8 additions and 53 deletions
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1
docs/release-notes.md
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@ -16,6 +16,7 @@
* Added [data API](https://stardewvalleywiki.com/Modding:Modder_Guide/APIs/Data).
* Added `IContentPack.WriteJsonFile` method.
* Added IntelliSense documentation when not using the 'for developers' version of SMAPI.
* Mods are no longer prevented from loading a PNG while the game is drawing.
* Fixed `IContentPack.ReadJsonFile` allowing non-relative paths.
* Suppressed the game's 'added crickets' debug output.
* **Breaking change:** `helper.ModRegistry` now returns `IModInfo` instead of `IManifest` directly. This lets SMAPI return more metadata about mods in future versions.

60
src/SMAPI/Framework/ContentManagers/ModContentManager.cs
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@ -165,63 +165,17 @@ namespace StardewModdingAPI.Framework.ContentManagers
return file;
}
/// <summary>Premultiply a texture's alpha values to avoid transparency issues in the game. This is only possible if the game isn't currently drawing.</summary>
/// <summary>Premultiply a texture's alpha values to avoid transparency issues in the game.</summary>
/// <param name="texture">The texture to premultiply.</param>
/// <returns>Returns a premultiplied texture.</returns>
/// <remarks>Based on <a href="https://gist.github.com/Layoric/6255384">code by Layoric</a>.</remarks>
/// <remarks>Based on <a href="https://gamedev.stackexchange.com/a/26037">code by David Gouveia</a>.</remarks>
private Texture2D PremultiplyTransparency(Texture2D texture)
{
// validate
if (Context.IsInDrawLoop)
throw new NotSupportedException("Can't load a PNG file while the game is drawing to the screen. Make sure you load content outside the draw loop.");
// process texture
SpriteBatch spriteBatch = Game1.spriteBatch;
GraphicsDevice gpu = Game1.graphics.GraphicsDevice;
using (RenderTarget2D renderTarget = new RenderTarget2D(Game1.graphics.GraphicsDevice, texture.Width, texture.Height))
{
// create blank render target to premultiply
gpu.SetRenderTarget(renderTarget);
gpu.Clear(Color.Black);
// multiply each color by the source alpha, and write just the color values into the final texture
spriteBatch.Begin(SpriteSortMode.Immediate, new BlendState
{
ColorDestinationBlend = Blend.Zero,
ColorWriteChannels = ColorWriteChannels.Red | ColorWriteChannels.Green | ColorWriteChannels.Blue,
AlphaDestinationBlend = Blend.Zero,
AlphaSourceBlend = Blend.SourceAlpha,
ColorSourceBlend = Blend.SourceAlpha
});
spriteBatch.Draw(texture, texture.Bounds, Color.White);
spriteBatch.End();
// copy the alpha values from the source texture into the final one without multiplying them
spriteBatch.Begin(SpriteSortMode.Immediate, new BlendState
{
ColorWriteChannels = ColorWriteChannels.Alpha,
AlphaDestinationBlend = Blend.Zero,
ColorDestinationBlend = Blend.Zero,
AlphaSourceBlend = Blend.One,
ColorSourceBlend = Blend.One
});
spriteBatch.Draw(texture, texture.Bounds, Color.White);
spriteBatch.End();
// release GPU
gpu.SetRenderTarget(null);
// extract premultiplied data
Color[] data = new Color[texture.Width * texture.Height];
renderTarget.GetData(data);
// unset texture from GPU to regain control
gpu.Textures[0] = null;
// update texture with premultiplied data
texture.SetData(data);
}
Color[] data = new Color[texture.Width * texture.Height];
texture.GetData(data);
for (int i = 0; i < data.Length; i++)
data[i] = Color.FromNonPremultiplied(data[i].ToVector4());
texture.SetData(data);
return texture;
}
}