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The Art of Poly Bridge


JavierVillalba writes:

Poly Bridge is a bridge building simulator game for PC/Mac & Linux, developed by Dry Cactus Games, and is currently available on Steam, after being in Steam Early Access since the end of June 2015.

The game has been developed in Unity, and all the art of the game has been created using Blender.

The art creation process began with the idea of building a low poly, colorful and innocent style for the game, contrasting with other bridge building games that tend to be more graphically realistic.

During the first months of development, different approaches were explored, making concept art and refining the final aesthetics with the Director Patrick Corrieri.

The main goal of the game is to build bridges that connect two pieces of terrain, allowing different types of vehicles to cross it in many creative ways.

Each of the vehicles had to be iconic and influence the gameplay with its shape, weight, speed, etc, so we went on a creative process of defining the different types of vehicles, paying attention to their silhouette and colors.

The first levels, environments and worlds were also defined, trying to find different moods and details that would make the environment enjoyable and fun, while mantaining the focus on the main action of the game.

Halfway through the development, we made a big overhaul of the game´s art. We did custom color palettes for each world, and unified the level of detail of the assets, improving the overall quality, and also giving each of the game worlds its own personality.

Blender has been heavily used in every step of the process, from the first concept art designs, to modelling and coloring of the final assets, as well as all the promotional work (merchandising, social media, Steam store material, etc)

Thanks to Blender´s flexibility, we could customize the tools for workflow we needed, even matching the appearance of the viewport shading system to the one used in Unity, or building custom asset libraries to keep everything organized. This helped to make asset creation and testing in-game faster, defining a bidirectional workflow that allows for lots of changes and improvements easily.

The modelling process for vehicles, terrains and assets that populate them, involved the use of lots of reference images and exploration to get iconic shapes and colors for the different assets. We used different modifiers regularly, like Mirror and Decimate, to reduce the final polygon count while retaining the desired shape of the objects.
Different approaches were taken for asset shading, starting with Cycles materials selections, Global Illumination and Ambient Occlusion texture baking using Cycles, and then exporting the maps for their use in Unity.

Finally, the system we used was vertex color painting, which sets data on the mesh, that is read in-game using a custom shader built for Unity, adequate to the low poly aesthetic and also beneficial for the posterior performance in the game engine.

To facilitate the process, a python script was developed to transfer, for every object in the game, their selections of material diffuse colors to its corresponding vertex RGB values. Also, a custom Ambient Occlusion shader was built, which brings more depth to the assets and improves the overall graphic quality of the game.

A constant back and forth testing between Blender and Unity helped to define each terrain and asset to adequate best to each level's gameplay.

The promotional images for merchandising and social media were all made using Cycles render, with flat materials and postproduction effects made using the Blender node graph.

Poly Bridge has been a great success since its debut as Early Access on Steam a year ago. It's been shown on various game festivals, as PAX South and GDC at San Francisco, introducing lots of improvements both on the gameplay and the art with each update.

Working on the game has been an awesome learning journey, working together with an international team from all over the world, and keeping great feedback with the players to include new ideas on the game.

Poly Bridge is now available on Steam. (Freelance 3D Artist) is the Art Director of the game.

About the Author

Avatar image for Javier Villalba
Javier Villalba

I'm a freelance 3D Artist from Spain, working on Films, TV Series & Commercials, Games & VR. Animation Mentor Alumni & BA Fine Arts graduate. I'm passionate about everything related to 3D, games and cinema, and of course Blender, which I use everyday for lots of different projects, both professional & personal.


  1. I found your post process description and the design in general both inviting and inspiring (though I have no idea how one would go about writing the code for such a game) I would be most interested in a low level tutorial regarding the python scripting porting of tools. thanks for sharing!

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