PreviewRenderUtility

class in UnityEditor Source

Description

Used to render Assets to GUI or to Texture. It can be considered an advanced version of AssetPreview.GetAssetPreview(GameObject). Providing a virtual scene you arrange and render objects in.

Remarks

It's important to call PreviewRenderUtility.Cleanup() is essential to keep it working for long periods of time. The instances will accumulate across compilations and after you hit 64 instances the utility will stop working and you have to restart the editor to continue. (You will get "Preview scene could not be created" errors and the object is never initialized). You only ever need to use 1 instance.

You need to clean up your GameObjects by yourself if you plan on doing multiple renders.

Example

Draws a cube to a 128x128 RenderTexture and displays it OnGUI upscaled to 300x300

using UnityEditor;
using UnityEngine;

public class PreviewRenderUtilityExample : EditorWindow
{
    [MenuItem("Window/PreviewRenderUtilityExample")]
    private static void CreateWindow() {
        var win = GetWindow<PreviewRenderUtilityExample>();
        win.Show();
    }

    private PreviewRenderUtility _previewRenderUtility;
    private Texture _outputTexture;

    private void OnEnable() {
        if (_previewRenderUtility != null)
            _previewRenderUtility.Cleanup();
        _previewRenderUtility = new PreviewRenderUtility(true);
        System.GC.SuppressFinalize(_previewRenderUtility);
        var camera = _previewRenderUtility.camera;
        camera.fieldOfView = 30f;
        camera.nearClipPlane = 0.3f;
        camera.farClipPlane = 1000;
        camera.transform.position = new Vector3(2.5f, 1f, -2.5f);
        camera.transform.LookAt(Vector3.zero);

        var obj = GameObject.CreatePrimitive(PrimitiveType.Cube);
        _outputTexture = CreatePreviewTexture(obj);
        DestroyImmediate(obj);
    }

    private RenderTexture CreatePreviewTexture(GameObject obj) {
        _previewRenderUtility.BeginPreview(new Rect(0, 0, 128, 128), GUIStyle.none);

        _previewRenderUtility.lights[0].transform.localEulerAngles = new Vector3(30, 30, 0);
        _previewRenderUtility.lights[0].intensity = 2;
        _previewRenderUtility.AddSingleGO(obj);
        _previewRenderUtility.camera.Render();

        return (RenderTexture)_previewRenderUtility.EndPreview();
    }

    private void OnGUI() {
        if (_previewRenderUtility != null || _outputTexture != null)
            GUI.DrawTexture(new Rect(0,0, 300, 300), _outputTexture);
    }

    private void OnDisable() {
        _previewRenderUtility.Cleanup();
    }
}

Properties

Name	Description
cameraFieldOfView	Shortcut for camera.fieldOfView
camera	Camera of the virtual scene
ambientColor	Ambient color of the virtual scene
lights	Read only collection of lights in the virtual scene

Constructors

Name	Description
PreviewRenderUtility	Creates an instance of the class

Public Methods

Name	Description
AddSingleGO	Adds a GameObject to the virtual scene
BeginPreviewHDR	TBA
BeginPreview	Begin rendering context, with style for background
BeginPreviewHDR	TBA
BeginStaticPreview	Begins rendering context to output a static Texture2D
BeginStaticPreviewHDR	TBA
Cleanup	Clean up the Utility. Call this OnDisable or suffer the consequences
EndAndDrawPreview	Ends the rendering and draws the image on Rect
EndPreview	Ends the rendering context and returns the RenderTexture
EndStaticPreview	Ends the rendering context and returns the Texture2D
GetScaleFactor	TBA
InstantiatePrefabInScene	Instanite the GameObject and return the instance
Render	Camera.Render() with extras
DrawMesh	TBA

Static Methods

Name	Description
CreateLight	Creates a GameObject with a light component attached