Format journey

A few months ago, I had the pleasure to work with Luciano Foglia and Anrick Bregman on a visual experiment called Format Journey. The installation uses data – a series of images and a sound file – to modify the texture and the shape of a 3D object. Combined with a slight randomization it gives very nice and unpredictable results.


What can you do with Unity3d? FITC San Francisco

I’m happy to announce that I will be speaking at FITC San Francisco in August. I have been speaking at FITC events twice this year, and both times it was a fantastic experience. I’m looking forward for this one, and what really thrills me about it, is the amazing speaker lineup!


Loading 3d models at runtime in Unity3d

This post is an addition to the last series I wrote about dynamic content loading in Unity3D.

When building a dynamic application, every now and then you might need to load some 3d models at runtime. Either because there’s a database with models you want to use or just because you want someone to update the models without rebuilding the project. I actually had this situation a few weeks ago. Surprisingly, this option does not come with Unity out of the box.


Runtime objects in Unity3D

Unity3D can work with meshes created in external 3D editors, but geometry can also be created with code. And not only geometry, but materials and textures as well. To test all these options I created a simple cityscape. I got inspired by this set of awesome pictures and also by a project called Pixel City by Shamus Young.


A cinematic video player

Here’s a little piece I made after the image decomposer. This time I wanted to load videos instead of images. I had the idea to project them on a big screen so that the user can actually feel like he is in a movie theater. I started to play with it, I modeled a cinema interior, setup the lightning and I thought it’s pretty neat.


3 ways to draw 3D lines in Unity3D

Just as I was thinking about an interesting demo to play with drawing functions in Unity3D, Mrdoob published his Harmony drawing tool made with HTML5/Canvas. It looks really cool, so I though how about doing this in 3D? I only had to figure out how to draw lines.

I did some research and below I present 3 different solutions. You can grab the source of the examples discussed below here.

Drawing lines with Line Renderer [demo]

When it comes to lines, the first thing you’ll bump into in the Unity3D API is the Line Renderer component. As the name suggests, it is used to draw lines so it seems the right tool for the job. Lines in this case are defined by 2 or more points (segments), a material and a width.

It has an important limitation: the line must be continuous. So if you need two lines, you need two renderers. The other problem is that the Line Renderer acts very strangely when new points are added dynamically. The width of the line does not seem to render correctly. It’s either buggy or just wasn’t designed for such use. Because of these limitations I had to create a separate Line Renderer for each tiny bit of line I’m drawing.

It was easy to implement, but not very fast since I end up spawning lots of GameObjects each with a LineRenderer attached. It seems to be the only option if you don’t have Unity3D Pro though.

Drawing lines as a mesh using Graphics [demo]

The Graphics class allows to draw a mesh directly without the overhead of creating game objects and components to hold it. It runs much faster than Line Renderer, but you need to create the lines yourself. This is a bit more difficult but also gives you total control of the lines – their color, material, width and orientation.

Since meshes are composed of surfaces rather than lines or points, in 3D space a line is best rendered as a very thin quad. A quad is described with 4 vertices, and usually you’ll only have the start and end points and a width. Based on this data you can compute a line like this:

Vector3 normal = Vector3.Cross(start, end); Vector3 side = Vector3.Cross(normal, end-start); side.Normalize(); Vector3 a = start + side * (lineWidth / 2); Vector3 b = start + side * (lineWidth / -2); Vector3 c = end + side * (lineWidth / 2); Vector3 d = end + side * (lineWidth / -2);

First, you get the normal of the plane on which both start and end vectors lie. This will be the plane on which the line-quad will located. The cross product of the normal and of the difference between end and start vectors gives you the side vector (the “thin” side of the quad). You need to normalize it to make it a unit vector. Finally calculate all 4 points of the rectangle by adding the side vector multiplied by half width to both start and end points in both directions. In the source code all this happens in MakeQuad and AddLine methods, so take a look in there.

It wasn’t easy to implement, but once I was there it runs pretty fast.

Direct drawing with GL [demo]

No fast is fast enough! Instead of leaving this topic and live happily with the Graphics solution, I kept searching for something even better. And I found the GL class. GL is used to “issue rendering commands similar to OpenGL’s immediate mode”. This sounds like fast, doesn’t it? It is!

Being much easier to implement that the Graphics solution it is a clear winner for me, the only drawback being that you don’t have much control over the appearance of the lines. You can’t set a width and perspective does not apply (i.e. lines that are far behind look exactly the same as those that are close to the camera).


For massive & dynamic line drawing LineRenderer is not the best solution, but it is the only one available in Unity free version. It can surely be useful to draw limited amounts of static lines and this is probably what it was made for. If you do have Unity3D Pro, the solution with Graphics is reasonable and very flexible but if it is performance you’re after choose GL.