Init

07-Other/Unity/Unity通用渲染管线（URP）系列（三）——方向光（Direct Illumination）.md

@@ -0,0 +1,71 @@
+## BRDF
+案例中使用了迪士尼模型。
+
+## 混合模式
+`SrcBlend`为`One`，`DetBlend`为`OneMinusSrc`
+
+## Shader GUI
+在`Shader`{}内添加`CustomEditor“ CustomShaderGUI”`。之后添加脚本：
+```c#
+using UnityEditor;
+using UnityEngine;
+using UnityEngine.Rendering;
+
+public class CustomShaderGUI : ShaderGUI {
+	MaterialEditor editor;
+	Object[] materials;
+	MaterialProperty[] properties;
+
+	public override void OnGUI (
+		MaterialEditor materialEditor, MaterialProperty[] properties
+	) {
+		base.OnGUI(materialEditor, properties);
+		editor = materialEditor;
+		materials = materialEditor.targets;
+		this.properties = properties;
+	}
+}
+```
+之后实现
+```c#
+bool HasProperty (string name) =>
+    FindProperty(name, properties, false) != null;
+
+void SetProperty (string name, string keyword, bool value) {
+    if (SetProperty(name, value ? 1f : 0f)) {
+        SetKeyword(keyword, value);
+    }
+}
+
+bool SetProperty (string name, float value) {
+    MaterialProperty property = FindProperty(name, properties, false);
+    if (property != null) {
+        property.floatValue = value;
+        return true;
+    }
+    return false;
+}
+
+void SetKeyword (string keyword, bool enabled) {
+    if (enabled) {
+        foreach (Material m in materials) {
+            m.EnableKeyword(keyword);
+        }
+    }
+    else {
+        foreach (Material m in materials) {
+            m.DisableKeyword(keyword);
+        }
+    }
+}
+```
+就可以添加若干自定义Shader属性的`Set`函数了。添加按钮逻辑如下：
+```c#
+bool PresetButton (string name) {
+    if (GUILayout.Button(name)) {
+        editor.RegisterPropertyChangeUndo(name);
+        return true;
+    }
+    return false;
+}
+```