ReplaceHueShader Material

Utils/MaterialUtils.ShaderSources.cs

@@ -0,0 +1,38 @@
+namespace STS2RitsuLib.Utils
+{
+    public static partial class MaterialUtils
+    {
+        private const string ReplaceHueShaderSource = """
+            shader_type canvas_item;
+
+            const vec3 LUMA_WEIGHTS = vec3(0.2126, 0.7152, 0.0722);
+            const float EPSILON = 1e-7;
+            const float MAX_COLOR_GAIN = 1.12;
+
+            uniform vec3 target_color : source_color = vec3(1.0);
+            uniform float brightness : hint_range(0.0, 2.0) = 1.0;
+
+            varying vec4 modulate_color;
+
+            void vertex() {
+                modulate_color = COLOR;
+            }
+
+            void fragment() {
+                vec4 col = texture(TEXTURE, UV);
+
+                float max_rgb = max(max(col.r, col.g), col.b);
+                float min_rgb = min(min(col.r, col.g), col.b);
+                float value = max_rgb * brightness;
+                float saturation = (max_rgb - min_rgb) / (max_rgb + EPSILON);
+
+                float target_value = max(max(target_color.r, target_color.g), target_color.b);
+                vec3 target_hue = target_color / max(target_value, EPSILON);
+                float color_gain = min(1.0 / max(dot(target_hue, LUMA_WEIGHTS), EPSILON), MAX_COLOR_GAIN);
+
+                vec3 final = mix(vec3(value), target_color * value * color_gain, saturation);
+                COLOR = vec4(final, col.a) * modulate_color;
+            }
+            """;
+    }
+}

Utils/MaterialUtils.cs

@@ -6,7 +6,7 @@ namespace STS2RitsuLib.Utils
     ///     Factory helpers for Godot materials that mirror vanilla game shaders.
     ///     用于镜像原版游戏着色器的 Godot 材质工厂辅助方法。
     /// </summary>
-    public static class MaterialUtils
+    public static partial class MaterialUtils
     {
         private const string HsvShaderPath = "res://shaders/hsv.gdshader";
         private const string DoomBarShaderPath = "res://scenes/combat/doom_bar.gdshader";
@@ -18,13 +18,37 @@ public static class MaterialUtils
 
         private static Shader? GameDoomBarShader => (Shader?)GD.Load<Shader>(DoomBarShaderPath)?.Duplicate();
 
+        private static Shader? _replaceHueShader;
+        private static Shader ReplaceHueShader => _replaceHueShader ??= new Shader
+        {
+            Code = ReplaceHueShaderSource,
+        };
+
         private static NoiseTexture2D VanillaDoomBarNoiseTexture =>
             _vanillaDoomBarNoiseTexture ??= CreateVanillaDoomBarNoiseTexture();
 
+        /// <summary>
+        ///     Builds a <c>ShaderMaterial</c> using a custom shader that replaces the hue of the input texture
+        ///     with a caller-specified RGB color, while preserving the original brightness and saturation.
+        ///     Suitable for replacing hues when using vanilla card frames.
+        ///     parameters r, g, b are in the range 0-1, brightness is in the range 0-2 with a default of 1.
+        ///     使用一个自定义着色器构建 <c>ShaderMaterial</c>，该着色器将输入纹理的色调替换为调用方指定的 RGB 颜色，
+        ///     同时保留原始亮度和饱和度。适用于替换色调，例如给原版卡框换色。
+        ///     参数r，g，b的范围是0-1，brightness的范围是0-2，默认值为1。
+        /// </summary>
+        public static ShaderMaterial CreateReplaceHueShaderMaterial(float r, float g, float b, float brightness = 1f)
+        {
+            var material = new ShaderMaterial { Shader = ReplaceHueShader };
+            material.SetShaderParameter("target_color", new Vector3(r, g, b));
+            material.SetShaderParameter("brightness", brightness);
+            return material;
+        }
+
         /// <summary>
         ///     Builds a <c>ShaderMaterial</c> using the game's HSV shader with the given RGB parameters.
         ///     使用游戏的 HSV 着色器和给定 RGB 参数构建 <c>ShaderMaterial</c>。
         /// </summary>
+        [Obsolete("Prefer MaterialUtils.CreateReplaceHueShaderMaterial instead.")]
         public static ShaderMaterial CreateRgbShaderMaterial(float r, float g, float b)
         {
             var max = Math.Max(r, Math.Max(g, b));