Fix weird pelvis rotation on certain avatars

nicoco007 · Oct 4, 2024 · 43097bf · 43097bf
1 parent b6d858e
commit 43097bf
Showing 1 changed file with 106 additions and 0 deletions.
diff --git a/Source/CustomAvatar/Patches/IKSolverVR_Spine.cs b/Source/CustomAvatar/Patches/IKSolverVR_Spine.cs
@@ -0,0 +1,106 @@
+extern alias BeatSaberFinalIK;
+
+using System.Collections.Generic;
+using System.Reflection;
+using System.Reflection.Emit;
+using BeatSaberFinalIK::RootMotion.FinalIK;
+using HarmonyLib;
+
+namespace CustomAvatar.Patches
+{
+    /// <summary>
+    /// Patch <see cref="IKSolverVR.Spine.SolvePelvis"/> so it has the pelvis bending fix from FinalIK v2.0+.
+    /// </summary>
+    [HarmonyPatch(typeof(IKSolverVR.Spine), nameof(IKSolverVR.Spine.SolvePelvis))]
+    internal static class IKSolverVR_Spine
+    {
+        private static readonly FieldInfo kBonesField = AccessTools.DeclaredField(typeof(IKSolverVR.BodyPart), nameof(IKSolverVR.BodyPart.bones));
+        private static readonly FieldInfo kPelvisIndexField = AccessTools.DeclaredField(typeof(IKSolverVR.Spine), nameof(IKSolverVR.Spine.pelvisIndex));
+        private static readonly FieldInfo kSpineIndexField = AccessTools.DeclaredField(typeof(IKSolverVR.Spine), nameof(IKSolverVR.Spine.spineIndex));
+        private static readonly FieldInfo kChestIndexField = AccessTools.DeclaredField(typeof(IKSolverVR.Spine), nameof(IKSolverVR.Spine.chestIndex));
+        private static readonly FieldInfo kHeadIndexField = AccessTools.DeclaredField(typeof(IKSolverVR.Spine), nameof(IKSolverVR.Spine.headIndex));
+        private static readonly FieldInfo kHeadPositionField = AccessTools.DeclaredField(typeof(IKSolverVR.Spine), nameof(IKSolverVR.Spine.headPosition));
+        private static readonly FieldInfo kPelvisPositionWeightField = AccessTools.DeclaredField(typeof(IKSolverVR.Spine), nameof(IKSolverVR.Spine.pelvisPositionWeight));
+        private static readonly MethodInfo kSolveTrigonometricMethod = AccessTools.DeclaredMethod(typeof(IKSolverVR.VirtualBone), nameof(IKSolverVR.VirtualBone.SolveTrigonometric));
+
+        public static IEnumerable<CodeInstruction> Transpiler(IEnumerable<CodeInstruction> instructions)
+        {
+            CodeMatcher codeMatcher = new(instructions);
+
+            // fully remove VirtualBone.SolveTrigonometric(bones, pelvisIndex, spineIndex, headIndex, headPosition, bendNormal, pelvisPositionWeight * <whatever>);
+            while (codeMatcher.MatchForward(
+                false,
+                new CodeMatch(OpCodes.Ldarg_0),
+                new CodeMatch(i => i.LoadsField(kBonesField)),
+                new CodeMatch(OpCodes.Ldarg_0),
+                new CodeMatch(i => i.LoadsField(kPelvisIndexField)),
+                new CodeMatch(OpCodes.Ldarg_0),
+                new CodeMatch(i => i.LoadsField(kSpineIndexField)),
+                new CodeMatch(OpCodes.Ldarg_0),
+                new CodeMatch(i => i.LoadsField(kHeadIndexField)),
+                new CodeMatch(OpCodes.Ldarg_0),
+                new CodeMatch(i => i.LoadsField(kHeadPositionField)),
+                new CodeMatch(OpCodes.Ldloc_2),
+                new CodeMatch(OpCodes.Ldarg_0),
+                new CodeMatch(i => i.LoadsField(kPelvisPositionWeightField)),
+                new CodeMatch(OpCodes.Ldc_R4),
+                new CodeMatch(OpCodes.Mul),
+                new CodeMatch(i => i.Calls(kSolveTrigonometricMethod))).IsValid)
+            {
+                codeMatcher.RemoveInstructions(16);
+            }
+
+            codeMatcher.Start();
+
+            // replace pelvisIndex with spineIndex (hasChest && hasNeck)
+            codeMatcher
+                .MatchForward(
+                    false,
+                    new CodeMatch(OpCodes.Ldarg_0),
+                    new CodeMatch(i => i.LoadsField(kPelvisIndexField)))
+                .Advance(1)
+                .SetOperandAndAdvance(kSpineIndexField);
+
+            // replace `* 0.6f` with `* 0.9f`
+            codeMatcher.MatchForward(false, new CodeMatch(OpCodes.Ldc_R4), new CodeMatch(OpCodes.Mul)).SetOperandAndAdvance(0.9f);
+
+            // replace pelvisIndex with chestIndex (hasChest && hasNeck)
+            codeMatcher
+                .MatchForward(
+                    false,
+                    new CodeMatch(OpCodes.Ldarg_0),
+                    new CodeMatch(i => i.LoadsField(kPelvisIndexField)))
+                .Advance(1)
+                .SetOperandAndAdvance(kChestIndexField);
+
+            // remove unnecessary multiplication
+            codeMatcher.MatchForward(false, new CodeMatch(OpCodes.Ldc_R4), new CodeMatch(OpCodes.Mul)).RemoveInstructions(2);
+
+            // replace pelvisIndex with spineIndex (hasChest && !hasNeck)
+            codeMatcher
+                .MatchForward(
+                    false,
+                    new CodeMatch(OpCodes.Ldarg_0),
+                    new CodeMatch(i => i.LoadsField(kPelvisIndexField)))
+                .Advance(1)
+                .SetOperandAndAdvance(kSpineIndexField);
+
+            // remove unnecessary multiplication
+            codeMatcher.MatchForward(false, new CodeMatch(OpCodes.Ldc_R4), new CodeMatch(OpCodes.Mul)).RemoveInstructions(2);
+
+            // replace pelvisIndex with spineIndex (!hasChest && hasNeck)
+            codeMatcher
+                .MatchForward(
+                    false,
+                    new CodeMatch(OpCodes.Ldarg_0),
+                    new CodeMatch(i => i.LoadsField(kPelvisIndexField)))
+                .Advance(1)
+                .SetOperandAndAdvance(kSpineIndexField);
+
+            // remove unnecessary multiplication
+            codeMatcher.MatchForward(false, new CodeMatch(OpCodes.Ldc_R4), new CodeMatch(OpCodes.Mul)).RemoveInstructions(2);
+
+            return codeMatcher.Instructions();
+        }
+    }
+}