EditorGUI.DrawTextureAlpha 绘制纹理通道

// Load a texture, display the texture, display its alpha channel and
// show a preview of the inverted texture
//加载并这个纹理，显示其Alpha通道，并显示该纹理的反向预览

class EditorGUITextures extends EditorWindow {

	var texture : Texture2D;
	var invertedTexture : Texture2D;
	var showInverted = false;

	@MenuItem("Examples/Texture Previewer")
	static function Init() {
		var window = GetWindow(EditorGUITextures);
		window.position = Rect(0,0,400, 200);
		window.Show();
	}

	function OnGUI() {
		texture = EditorGUI.ObjectField(Rect(3,3,200,20),
		"Add a Texture:",
		texture,
		Texture);
		if(GUI.Button(Rect(208,3, position.width - 210, 20),"Process Inverted")) {
			if(invertedTexture)
				DestroyImmediate(invertedTexture);
			//Copy the new texture
			//复制新的纹理
			invertedTexture = new Texture2D(texture.width,
			texture.height,
			texture.format,
			(texture.mipmapCount != 0));
			for (var m : int = 0; m < texture.mipmapCount; m++)
				invertedTexture.SetPixels(texture.GetPixels(m), m);
				InvertColors();
			showInverted = true;
		}
		if(texture) {
			EditorGUI.PrefixLabel(Rect(25,45,100,15),0,GUIContent("Preview:"));
			EditorGUI.DrawPreviewTexture(Rect(25,60,100,100),texture);
			EditorGUI.PrefixLabel(Rect(150,45,100,15),0,GUIContent("Alpha:"));
			EditorGUI.DrawTextureAlpha(Rect(150,60,100,100),texture);
			EditorGUI.PrefixLabel(Rect(275,45,100,15),0,GUIContent("Inverted:"));
			if(showInverted)
				EditorGUI.DrawPreviewTexture(Rect(275,60,100,100),invertedTexture);
			if(GUI.Button(Rect(3,position.height - 25, position.width-6,20),"Clear texture")) {
				texture = EditorGUIUtility.whiteTexture;
				showInverted = false;
			}
		} else {
			EditorGUI.PrefixLabel(
			Rect(3,position.height - 25,position.width - 6, 20),
			0,
			GUIContent("No texture found"));
		}
	}

	function InvertColors() {
		for (var m : int = 0; m < invertedTexture.mipmapCount; m++) {
			var c : Color[] = invertedTexture.GetPixels(m);
			for (var i : int = 0 ;i < c.Length; i++) {
				c[i].r = 1 - c[i].r;
				c[i].g = 1 - c[i].g;
				c[i].b = 1 - c[i].b;
			}
			invertedTexture.SetPixels(c, m);
		}
		invertedTexture.Apply();
	}
	function OnInspectorUpdate() {
		Repaint();
	}
}