Monday, February 13, 2017

Take a Unity Screenshot with Alpha

This script takes a screenshot and saves it to the user desktop. It has options to use an alpha background, and also upscale the image. Useful for taking pictures of a scene or model for composition by artists.

using UnityEngine;
using System.IO;
using System;

[RequireComponent (typeof(Camera))]
public class CaptureWithAlpha : MonoBehaviour
    public int UpScale = 4;
    public bool AlphaBackground = true;

    Texture2D Screenshot ()
        var camera = GetComponent<Camera> ();
        int w = camera.pixelWidth * UpScale;
        int h = camera.pixelHeight * UpScale;
        var rt = new RenderTexture (w, h, 32);
        camera.targetTexture = rt;
        var screenShot = new Texture2D (w, h, TextureFormat.ARGB32, false);
        var clearFlags = camera.clearFlags;
        if (AlphaBackground) {
            camera.clearFlags = CameraClearFlags.SolidColor;
            camera.backgroundColor = new Color (0, 0, 0, 0);
        camera.Render (); = rt;
        screenShot.ReadPixels (new Rect (0, 0, w, h), 0, 0);
        screenShot.Apply ();
        camera.targetTexture = null; = null;
        DestroyImmediate (rt);
        camera.clearFlags = clearFlags;
        return screenShot;

    [ContextMenu ("Capture Screenshot")]
    public void SaveScreenshot ()
        var path = Environment.GetFolderPath (Environment.SpecialFolder.Desktop);
        var filename = "SS-" + DateTime.Now.ToString ("") + ".png";
        File.WriteAllBytes (Path.Combine (path, filename), Screenshot ().EncodeToPNG ());

Friday, February 03, 2017

Building fast, quality network server programs with Go.

I've been investigating and learning Go. There is a lot of high quality tools out there, for example:

- xo generates types and functions to match your SQL schema, and

- goa lets you design a REST api using a DSL, then generate the code to implement that API!

Compile time for Go is super fast, and so is the built executable. I'm using vim for the IDE, and it has excellent support for Go, including autocompletion which is great when you're learning the language.

Wednesday, January 25, 2017

A HTTP server embedded inside Unity3D.

Just 514 lines of code. Uses sockets only, no other dependencies.

Example Component:

public class FileUpload : MonoBehaviour, IWebResource
    public string path = "/upload";
    public TextAsset html;
    EmbeddedWebServerComponent server;

    void Start ()
        server = GetComponent<EmbeddedWebServerComponent>();
        server.AddResource(path, this);
    public void HandleRequest (Request request, Response response)
        response.statusCode = 200;
        response.message = "OK.";

Tuesday, January 24, 2017

A widget to list Github repositories.

<div id="github-activity"></div>
<script type="text/javascript">
window.renderGitHubWidget = function(github) {
    var html = '<div class="widget"><ul>';
    for (var i=0; i<; i++) {
        var item =[i];
        var url = item.html_url;
        if(item.fork) continue; 
        var repo = '<a href="' + url + '" target="_blank">' + + '</a>';
        html += "<li>" + repo + " <br/>" + item.description+ "</li>"
    html += '</ul></div>';
    var el = document.createElement('div');
    el.innerHTML = html;
    var URL = '';
    var script = document.createElement('script');
    script.setAttribute('type', 'text/javascript');
    script.setAttribute('src', URL);

Tuesday, January 03, 2017

Notes on the Unity3D UNET HLAPI

The NetworkManager instantiates a Player prefab. This is your Player Object.

In a two player game, your GameObjects exist conceptually in 3 places, and logically in 2 places. An object exists on each game client, and on the game server. If the game server is also a client, it is called a host, and it shares the GameObject with the client.

By default:
- only methods on components on the Player Object can have the [Command] attribute.
- you can only call [Command] methods from other methods on the Player Object.

It is hard to see which code is server code, and which is client code. I recommend using the [Server] and [Client] attributes liberally to add this information to the source code. When this attribute cannot be applied to a method (only NetworkBehaviours support this attribute) then add the attribute inside a comment.

The NetworkTransform does not provide interpolation when in Transform mode, only when using RigidBody mode. You will need to write this code yourself using [SyncVar].

For fast iterative development, keep the NetworkManager in your development scene, and add the NetworkManagerHUD component. Set this scene as your startup scene, then Build and Run, choose Host or Client from the GUI, then press Play in the editor, and choose Host or Client.

NetworkServer.Spawn only create an instance on the client, and sets it's transform component to match the server. You will have to do any other configuration on this object via a secondary [ClientRpc] call.

Less Code is Less Bugs in Less Time

Some favourite quotes from Ron Jeffries, one of the three founders of the Extreme Programming software development methodology...

Often you will be building some class and you’ll hear yourself saying “We’re going to need…”.

Resist that impulse, every time. Always implement things when you actually need them, never when you just foresee that you need them. 

And this too...

The best way to implement code quickly is to implement less of it. The best way to have fewer bugs is to implement less code.

Is the Unity3D GameObject.GetComponent method slow?

TLDR; No, not really.

Using the below test script, using GetComponent is about 3x slower than using a direct reference. Caching the return calue in a Dictionary, is slightly faster.

A typical result for me is 232 GetComponent(), 74 for private field and 201 for a dictionary lookup. If you use a builtin Unity type, like Transform, GetComponent is twice as fast.

I made sure the compiler was not optimising out my tests by putting in some fake 'xyzzy' work which is not included in the timing.

Why this simple test? I'm proving to myself it is not terribly bad to use a GetComponent call in an update loop, or keep a Dictionary cache. The call itself is so fast (0.000000232 seconds) that there is really no issue using it a few times inside an update loop.

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class GetComponentTest : MonoBehaviour {
    public int iterations = 1000000;

    GetComponentTest testComponentB, testComponentA;

    Dictionary<System.Type, Component> cache = new Dictionary<System.Type, Component>();

    void Start () {
        var sw = new System.Diagnostics.Stopwatch();
        for(var i=0; i<iterations; i++) {
            var r = GetComponent<GetComponentTest>();
            sw.Stop ();
            if( == "xyzzy") {

        testComponentB = GetComponent<GetComponentTest>();
        for(var i=0; i<iterations; i++) {
            testComponentA = testComponentB;
            sw.Stop ();
            if( == "xyzzy") {

        cache[typeof(GetComponentTest)] = GetComponent<GetComponentTest>();
        for(var i=0; i<iterations; i++) {
            testComponentA = cache[typeof(GetComponentTest)] as GetComponentTest;
            sw.Stop ();
            if( == "xyzzy") {

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