Add High-Resolution Bloom Correction Option

Patch/Game/VideoBloomPatch.cs

@@ -0,0 +1,59 @@
+using ADOFAIRenderer.Core;
+using HarmonyLib;
+using UnityEngine;
+
+namespace ADOFAIRenderer.Patch.Game;
+
+/// <summary>
+/// Makes the game's bloom compute its blur size as if the frame were 720 pixels high
+/// ("High-Resolution Bloom Correction" option).
+/// <para>
+/// Patched member: <c>VideoBloom.OnRenderImage(RenderTexture source, RenderTexture destination)</c>. The game scales the
+/// frame down to a bloom buffer 198 pixels high (<c>scale = 198 / source.height</c>) and sets the blur radius in bloom
+/// buffer pixels to <c>KernelSize * MediumKernelScale * scale</c> (and <c>KernelSize * LargeKernelScale * scale</c>).
+/// <c>BloomBlit</c> turns the radius into the number of 5-tap blur passes and the blend amount of the last pass.
+/// </para>
+/// <para>
+/// While the render is active (<see cref="RenderManager.IsActive"/>) and <c>AdvancedConfig.HighResBloomCorrection</c> is
+/// enabled, the prefix multiplies <c>KernelSize</c> by <c>source.height / 720</c> for the duration of the call, so the
+/// radius equals <c>KernelSize * MediumKernelScale * 198 / 720</c> and the blur passes on the bloom buffer are the same
+/// as in a 720p frame. The finalizer restores the original <c>KernelSize</c>. The bloom buffer size and the downscale
+/// from the source frame keep the game's behavior.
+/// </para>
+/// </summary>
+[HarmonyPatch(typeof(VideoBloom))]
+public class VideoBloomPatch
+{
+    /// <summary>Frame height in pixels the blur size is computed for.</summary>
+    private const float ReferenceHeight = 720f;
+
+    /// <summary>Prefix of <c>VideoBloom.OnRenderImage</c>.</summary>
+    /// <param name="__instance">The bloom component on the game camera.</param>
+    /// <param name="source">The camera frame; its height selects the multiplier.</param>
+    /// <param name="__state">Original <c>KernelSize</c>, or null when it was not changed.</param>
+    [HarmonyPrefix]
+    [HarmonyPatch("OnRenderImage")]
+    // ReSharper disable InconsistentNaming
+    public static void ScaleKernelSize(VideoBloom __instance, RenderTexture source, out float? __state)
+    // ReSharper restore InconsistentNaming
+    {
+        __state = null;
+        if (!source || !RenderManager.IsActive || !RenderManager.Instance.Configuration.AdvancedConfig.HighResBloomCorrection)
+            return;
+
+        __state = __instance.KernelSize;
+        __instance.KernelSize *= source.height / ReferenceHeight;
+    }
+
+    /// <summary>Finalizer of <c>VideoBloom.OnRenderImage</c>: restores <c>KernelSize</c> when the prefix changed it.</summary>
+    /// <param name="__instance">The bloom component on the game camera.</param>
+    /// <param name="__state">Original <c>KernelSize</c> stored by the prefix, or null.</param>
+    [HarmonyFinalizer]
+    [HarmonyPatch("OnRenderImage")]
+    // ReSharper disable InconsistentNaming
+    public static void RestoreKernelSize(VideoBloom __instance, float? __state)
+    // ReSharper restore InconsistentNaming
+    {
+        if (__state.HasValue) __instance.KernelSize = __state.Value;
+    }
+}