Am I done now? No I’m not done. With a definition as general as this, pixels and voxels can appear in many different ways and we can creatively push the concepts into diverse visual looks. In particular, we’ll look at combining the 4 quadrants of raster/vector, 2D/3D. Pure 2D graphics In the old days, if you wanted to draw a 2D sprite onto the screen you would have to directly copy the bits of memory that stored the colors of the sprite into the memory that stored the colors displayed on the screen (this copying is also know as bit blit or bit BLT, which is short for bit block transfer). Today almost nobody renders 2D graphics purely like that. The fantasy console PICO-8 is a modern example as it pays homage to the good old days when blitting was the only way to go. PICO-8, Lexallofle Games (and respective authors of featured carts), 2014–present Textures in 3D graphics Nowadays most graphic engines work with vectors at the lowest level since that’s how GPUs work. The main way to make 2D images appear on the screen in this system is by drawing them on the polygons using a technique called texture mapping. Textures are 2D raster images that get placed (or mapped) onto 3D polygons. That is how the vast majority of 3D video games (and 3D images in general) are created at their simplest. For example, this is a what it looks like when we have a high-poly 3D model and we add a high-res texture to it:

“Mirror’s Edge: Catalyst” Keyart, Per Haagensen, 2016

Since we’re using smooth polygon shading and texture mapping we don’t even need that many triangles to create nice looking characters. Here is a low-poly 3D model with a high-res texture: Low Poly Peon, Mark Henriksen, 2015 When we also switch a high-resolution texture to a low-res version, we get something along the lines of this low-poly 3D model with a pixel art texture:

Drift Stage, 2014–present (work in progress)

The most prominent example of this is of course Minecraft. Although Minecraft blocks are voxels by definition (they are the smallest discrete volume units in the game), they come in a wide variety of types represented by low-poly models with pixel art textures. Even though they are blocky, many of them are not simple cubes.

Minecraft, Mojang, 2009–present

This covers all 3D model cases (there’s not much need for a high-poly 3D model with a low-res texture combination, but correct me if I’m wrong). Mirror’s Edge (top-left), Max Payne (bottom-left) and Minecraft (bottom-right) Textures in 2D graphics Onto 2D! When we apply texture mapping to 2D rectangles we get the usual modern 2D games. With today’s hardware, each 2D image (in this context often called a sprite) is displayed by being placed on a rectangle formed by 2 triangles. The two triangles (together also called a quad) get rendered with the sprite mapped onto them, making the image appear in their place.

Image parts of the character (left) get texture-mapped onto animated quads (right). Badminton, Matej ‘Retro’ Jan, 2006

Things are pretty straight-forward with high-res images …

Braid, Number None, 2008 Limbo, Playdead, 2010

… but get a bit more complicated with low-res, pixel art textures. It all depends on the display resolution we’re rendering our sprites at. Braid (top-left), Path to the Sky (top-right), Kingdom (bottom-right) We’ve seen that we can have a pixel art texture applied to a low-poly 3D model, but still render it at a very high resolution. Think Minecraft. Low-poly models, low-res 16×16 pixel textures, placed in a scene that gets rendered at something like 1920×1080 display resolution.

Minecraft, Mojang, 2009–present

The same can be done with 2D polygons. We can take a pixel art image, put it on a 2D quad and render it to a high-resolution screen so that each pixel in the source image covers multiple pixels in the display.

Hotline Miami, Dennaton Games, 2012

We call this the big pixel art style. Each sprite pixel gets rendered bigger than the pixel in the display so it appears as a bigger square in the image. Each source sprite pixel being rendered onto 3x3 display pixels, Moonman, Ben Porter, 2011–present (work in progress) Big pixel style becomes apparent when sprites get rotated or skewed: Path to the Sky, Johannes ‘Dek’ Märtterer, 2011–present (work in progress) Look at the foliage above and compare it to a rotating sprite rendered at low resolution: Kingdom, Noio & Licorice, 2015 Do you see how the pixels of the water wheel stay aligned horizontally/vertically whereas in Path to the Sky the foliage, bird, and bridge get their big pixels angled and transformed? Kingdom achieves this by rendering the whole game at low resolution and then enlarging (upscaling) only the final image to the display resolution. Path to the Sky, Hotline Miami and Moonman on the other hand render sprites directly to a high-resolution display. Back to 3D Kingdom is a 2D game, but its approach can be taken into 3D as well. We can use 3D models with pixel art textures, but render them at low-resolution to get something like this: Pixel Art Academy tech demo, Matej ‘Retro’ Jan, 2016 You can see we have correct 3D shading with projected shadows. Even though the result looks like some sort of 2D pixel art it is actually a 3D scene rendered at low-resolution using pixel art textures: Pixel Art Academy tech demo (scene view), Matej ‘Retro’ Jan, 2016 Animations that are vector based (they use a skeleton rig) can also take advantage of this. Here’s how they look in big pixel style: Animation rig with reference, Matej ‘Retro’ Jan, 2016 But when they get rendered at low resolution they appear more like pixel art, with aligned pixels similar to Kingdom above.

Pixel Art Academy animation test, Matej ‘Retro’ Jan, 2016

It’s far from lovely hand-crafted, frame-by-frame animations, but hold a certain aesthetic nonetheless, reminiscent of rotoscoped animations of the 90s. Prince of Persia, Jordan Mechner, 1989 3D effects Back at high resolution, one game that takes full advantage of being 3D is The Last Night by Odd Tales. The Last Night, Odd Tales, 2014–present (work in progress) Their art assets are essentially 2D, but are layered out into a 3D world with all the modern graphics effects you can think of (dynamic lighting, bloom, depth of field, cinematic camera angles, reflections …). WIP scene from The Last Night, Tim Soret, 2016 In this way they are constructing a very much three-dimensional world that you look at from different sides. 3D scene construction in The Last Night, Tim Soret, 2016 Another example of dynamic 3D lighting was the beautifully atmospheric, but ill-fated Confederate Express:

Confederate Express, Maksym Pashanin, 2013–2014 (unreleased)

While the art assets are still only 2D, they also include images of shading from multiple directions. These get processed by a tool such as Sprite Lamp and produce smooth illumination of sprites from any position of the light source. Pixel art from voxels The problem with the above approach is that only the shading of the sprites can be done precisely while the shadows that they cast lack the necessary 3D geometry to be produced correctly. To do that you eventually have to have volume information. Enter voxels! A great example of this approach is the recently announced Pathway: Pathway, Robotality, 2016 (work in progress) Graphics look completely like they’re using pixel art sprites, but the information behind them is actually volumetric. Unlike the voxel engines from the 90s that tried to look as modern and realistic as possible, developers at Robotality don’t have to go further than matching voxels to the size of display pixels. This creates a clever disguise of looking like pixel art, but behind the scenes they have all the 3D information with which to create completely correct dynamic lighting. The use of voxel geometry to produce pixel art isn’t completely new though. The pioneer here was FEZ with its so-called trixels (3d pixels). Trixels are just voxels that get combined into 16×16×16 triles (3d tiles).

Development screenshots from FEZ, Polytron, 2007

When a FEZ scene gets rendered in-game it is mostly seen with a 2D orthogonal projection, which is how they achieve the traditional pixel art look but allow for FEZ’s trademark view rotation. FEZ GDC ’09 trailer, Polytron Corporation, 2009 FEZ, Polytron Corporation, 2012 Pure voxels Finally, since we’ve arrived full circle back to voxel geometry we can leave the world of pixel art behind and just render pure, discrete voxels in 3D space (using the cube approach without any textures). Lexallofle’s Voxatron is the name of the game in this space.

Voxatron, Lexallofle Games, 2010–present (work in progress)

Do you notice a theme in Lexallofle’s virtual consoles? Pico-8 has a pure 2D graphics engine while Voxatron does the same for 3D voxels. They are the perfect companions.

Voxatron, Lexallofle Games, 2010–present (work in progress)

Voxatron is one of the few examples (if not the only) that stay true to the pure discrete division of 3D space. But its close cousin—the analog to the big pixel style—found its place in many games, especially in the mobile space.

Crossy Road, Hipster Whale, 2014

Shooty Skies, Mighty Games, 2016

PAC-MAN 256, Hipster Whale, 2015

We come full-circle back to Sir Carma. After rising to one of the most well known voxel artists, he’s now using Unity to push the voxels-only aesthetic to further heights with numerous visual effects, similar to what Odd Tales are doing for pixel art. The Way Back, Sir Carma, 2016 (work in progress) The Way Back, Sir Carma, 2016 (work in progress) Voxel Zelda/Atic Atac anyone?

The Way Back, Sir Carma, 2016 (work in progress)