init

2026-09-10 10:59:37 +03:00
commit 5408d711b1
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+using System;
+using System.Collections.Generic;
+using System.Text.Json;
+
+namespace Cthangover.Live2D.Cubism.Framework
+{
+    /// <summary>
+    /// Blend mode for expression parameters.
+    /// Determines how the expression value is combined with the existing
+    /// parameter value during animation.
+    /// </summary>
+    public enum ExpressionBlendType { Additive = 0, Multiply = 1, Overwrite = 2 }
+
+    /// <summary>
+    /// A single parameter entry in an expression motion.
+    /// Targets a model parameter by ID with a specific blend type and value.
+    /// </summary>
+    public struct ExpressionParameter
+    {
+        /// <summary>Target model parameter ID.</summary>
+        public string ParameterId;
+
+        /// <summary>How to combine this value with existing parameter data.</summary>
+        public ExpressionBlendType BlendType;
+
+        /// <summary>The target value (interpretation depends on <see cref="BlendType"/>).</summary>
+        public float Value;
+    }
+
+    /// <summary>
+    /// Expression motion, parsed from a Cubism .exp3.json file.
+    /// Inherits fade and weight management from <see cref="ACubismMotion"/>.
+    /// 
+    /// Expressions are single-frame poses that transition between values using
+    /// one of three blend modes per parameter:
+    /// <list type="bullet">
+    ///   <item><see cref="ExpressionBlendType.Additive"/> — adds <c>value * weight</c></item>
+    ///   <item><see cref="ExpressionBlendType.Multiply"/> — multiplies by <c>1 + value * weight</c></item>
+    ///   <item><see cref="ExpressionBlendType.Overwrite"/> — lerps from current to target using weight</item>
+    /// </list>
+    /// 
+    /// Loaded and started by <see cref="CubismModelNode.StartExpression"/>.
+    /// </summary>
+    public class CubismExpressionMotion : ACubismMotion
+    {
+        private readonly List<ExpressionParameter> _parameters = new();
+
+        /// <summary>
+        /// Parses an .exp3.json byte buffer into an expression motion.
+        /// Reads fade-in/out times and the list of target parameters with
+        /// their blend types and values.
+        /// </summary>
+        public CubismExpressionMotion(byte[] jsonBytes)
+        {
+            var json = JsonDocument.Parse(jsonBytes);
+            var root = json.RootElement;
+
+            if (root.TryGetProperty("FadeInTime", out var fi))
+                _fadeInSeconds = fi.GetSingle();
+            if (root.TryGetProperty("FadeOutTime", out var fo))
+                _fadeOutSeconds = fo.GetSingle();
+
+            if (root.TryGetProperty("Parameters", out var paramsArr))
+            {
+                foreach (var p in paramsArr.EnumerateArray())
+                {
+                    var blend = p.TryGetProperty("Blend", out var b)
+                        ? ParseBlendType(b.GetString())
+                        : ExpressionBlendType.Additive;
+
+                    _parameters.Add(new ExpressionParameter
+                    {
+                        ParameterId = p.GetProperty("Id").GetString(),
+                        Value = p.GetProperty("Value").GetSingle(),
+                        BlendType = blend
+                    });
+                }
+            }
+        }
+
+        private static ExpressionBlendType ParseBlendType(string value) => value switch
+        {
+            "Multiply" => ExpressionBlendType.Multiply,
+            "Overwrite" => ExpressionBlendType.Overwrite,
+            _ => ExpressionBlendType.Additive
+        };
+
+        /// <summary>
+        /// Applies all expression parameters to the model using their
+        /// respective blend modes. Called every frame by the queue manager.
+        /// </summary>
+        public override unsafe void DoUpdateParameters(
+            CubismNativeModel model, float userTimeSeconds, float weight, CubismMotionQueueEntry entry)
+        {
+            var idsPtr = model.GetParameterIds();
+            var values = model.GetParameterValues();
+            var minValues = model.GetParameterMinimumValues();
+            var maxValues = model.GetParameterMaximumValues();
+            var defaultValues = model.GetParameterDefaultValues();
+
+            for (int pi = 0; pi < model.ParameterCount; pi++)
+            {
+                var pid = CubismNativeModel.ReadStringFromPtrArray(idsPtr, pi);
+                foreach (var ep in _parameters)
+                {
+                    if (ep.ParameterId != pid) continue;
+
+                    switch (ep.BlendType)
+                    {
+                        case ExpressionBlendType.Additive:
+                            values[pi] = values[pi] + ep.Value * weight;
+                            break;
+                        case ExpressionBlendType.Multiply:
+                            values[pi] = values[pi] * (1f + ep.Value * weight);
+                            break;
+                        case ExpressionBlendType.Overwrite:
+                            values[pi] = values[pi] * (1f - weight) + ep.Value * weight;
+                            break;
+                    }
+                    break;
+                }
+            }
+        }
+    }
+}