An Unity editor extension which enables you to take screenshots of the scene view window.

editorscreenshot.cs

using System.IO;
using UnityEditor;
using UnityEngine;

/*
 * This creative work (which includes code) is under exclusive copyright by default.
 * Unless specified otherwise by Tahar Meijs, nobody else may use, copy, distribute,
 * or modify this work without being at risk of take-downs, shake-downs, or litigation.
 * 
 * Testing code does not mean you will are allowed to keep on using this codebase for
 * your own personal / commercial gain. However, it is always encouraged to use this
 * code for educational purposes
 */

public class Screenshot : EditorWindow
{
	private string m_filePath = "";

	private Camera m_sceneCamera = null;

	[MenuItem("Window/Tahars Tools/Screenshot")]
	public static void ShowWindow()
	{
		GetWindow(typeof(Screenshot));
	}

	private void OnGUI()
	{
		GUILayout.Label("Save location:");

		EditorGUILayout.BeginHorizontal();

		m_filePath = GUILayout.TextField(m_filePath);

		if (GUILayout.Button("Browse..."))
		{
			SetSaveLocation();
		}

		if (GUILayout.Button("Clear Path"))
		{
			int result = EditorUtility.DisplayDialogComplex("Clear Path", "Are you sure you want to clear the screenshot path?", "Yes.", "No.", "Cancel");

			if (0 == result)
				m_filePath = "";
		}

		EditorGUILayout.EndHorizontal();

		if (GUILayout.Button("Capture Screenshot"))
		{
			if (ValidSaveLocation())
			{
				CaptureEditorScreenshot();
			}
			else
			{
				EditorUtility.DisplayDialog("Invalid Location", "Please select a location to save your screenshots to first.", "Browse...");
				SetSaveLocation();
			}
		}
	}

	private void CaptureEditorScreenshot()
	{
		if (null == m_sceneCamera)
		{
			FindSceneCamera();
		}
		
		// Additional safety check in case the scene camera could not be found
		if (null != m_sceneCamera)
		{
			// Save the old render texture for future use
			RenderTexture oldRenderTexture = RenderTexture.active;

			// Swap the render textyre
			RenderTexture.active = m_sceneCamera.targetTexture;

			// Save the render texture data into a regular Texture2D object
			Texture2D screenshotPreview = new Texture2D(m_sceneCamera.pixelWidth, m_sceneCamera.pixelHeight);
			screenshotPreview.ReadPixels(new Rect(0.0f, 0.0f, m_sceneCamera.pixelWidth, m_sceneCamera.pixelHeight), 0, 0);
			screenshotPreview.Apply();

			// Restore the render texture
			RenderTexture.active = oldRenderTexture;

			// Write the file to the disk
			File.WriteAllBytes(m_filePath + "/" + Application.productName + System.DateTime.Now.ToString("yyyy-mm-dd-hh-mm-ss") + ".png", screenshotPreview.EncodeToPNG());
		}
	}

	private bool ValidSaveLocation()
	{
		if (0 != m_filePath.Length)
			return true;
		else
			return false;
	}

	private void SetSaveLocation()
	{
		string path = EditorUtility.OpenFolderPanel("Select save location", "", "Screenshots");

		if (0 != path.Length)
			m_filePath = path;
	}

	private void FindSceneCamera()
	{
		Camera[] cams = SceneView.GetAllSceneCameras();

		foreach (Camera cam in cams)
		{
			if ("SceneCamera" == cam.name)
			{
				// Found the scene camera
				m_sceneCamera = cam;
				return;
			}
		}

		EditorUtility.DisplayDialog("Fatal error", "Could not find the scene camera, please report this to the developer!", "Dismiss");
	}
}