Monday, 7 January 2013

OpenTTD 32bpp Part 2 - Moving to 3D

The original OpenTTD graphics were 8-bit. This means that all the images were made up only of colours taken from a palette of 256 different colours. This image:
Is only made up from colours from this palette:

 For example you can take all the pixels from the building which are the grey shade indicated in the palette:

An 8-bit image format was used because it was much faster for older computers to display. While the images are simpler it actually makes the graphics harder to draw for a person; every single pixel has to be picked carefully. It isn't possible to use normal photoshop techniques like altering brightness or contrast or reshading the graphics which makes things difficult. Imagine having carefully drawn a brick wall. To use it on the shadowed side of the building you are forced to completely redraw it.

In contrast 32bpp images are easy to make, especially using 3D modeling and rendering. The fact that OpenTTD can now use 32bpp graphics is therefore a big advantage! Once a building is designed in 3D (modelled) the rendering process (converting it into an image) calculates all lighting, shadows, shading etc. This makes it very quick to generate a realistic looking building because the computer does a lot of the work for you.
The building as modelled in Blender, the lamps for lighting are the dotted sun-shaped objects on the right.

The rendered image with accurate shadows and shading.

In the same way that 3D modelling and rendering make lighting and shading simple they also make texturing simple.

In the old 8-bit graphics textures like brick walls had to be hand-drawn, brick by brick. With some smart texture design and 3D rendering even hard-to-draw materials can be rendered quickly and accurately. Like with lighting and shading this is far quicker than drawing the texture by hand.
Brick texture on some simple objects

Brick texture on a really complicated object!

With lighting, shading, and texturing simplified by 3D modelling and rendering this actually makes the new, high resolution graphics easier and quicker to make than the old ones. The modelling is still a bit tedious though...

Continued here: OpenTTD 32bpp Part 3 - Automation

Software used:
Blender: 3D modelling and rendering.
OpenTTD: The game!


  1. A question probably on everyone's mind after reading this: if you got all the 3D models, why not simply import the models in the game and make it simply a 3D game, with all the advantages a 3d game has?

    1. With the sheer number of vehicles, buildings, etc. most modern computers would still struggle massively with the number of polygons used to generate these graphics... You are right though; it is a great resource if OpenTTD ever gets remade in 3D in the future.

  2. you are limited by the engine

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