Patreon Peeks 42: A Transforming Mario Kart! (Patreon)

Hello everyone! I'd like to show a bit about the April Fool's Day joke video I made this year, since it was conceived less as a joke and more as animation and look-development practice in Blender. I'm considering making a video about this later, but for now I'll show you how it worked!

First the idea was just to design a new Standard Kart as though for a new Mario Kart game. The general shape is always pretty similar and based off of real go-karts, designed to look more functional than thematic. But playing some Mario Kart games to research the kart design, I also got an idea for a "new" gimmick for Mario Kart: enhancing the glider feature of Mario Kart 7/8 into a full-fledged aircraft transformation, a la Diddy Kong Racing or Sega All-Stars Racing Transformed. And like Sega's game, the kart would work the ability to transform into its design (yet still in a cartoony Mario-ish way). Here was the initial sketch for the "Standard Kart Aero Model," as I would come to call it:

From initial sketches and measurements, I started modeling the kart from scratch in Blender, using the wheels as a reference for the size of everything else. Some major changes included bringing the front sheets of the kart together with only a seam in between them, to make the propeller emerging more of a surprise; turning a regular steering wheel into something made of pistons that could snap between a full steering wheel and a flight yoke; and removing the rear rudder.

I also created a rig for this model that could open the front to reveal the propeller (and spring out the propeller's blades) and unfold the kart's sides into wings that reveal turbine engines. The steering wheel switched between shape keys instead of using rig bones.

But once the kart model was done, there were still a few systems to set up to get animation running smoothly without having to set everything by hand. I created a track for it to run on, using the same system I've used in the Mario Kart Doppler Effect video (and the same road model!): creating a Bezier curve object, and using an Array and then a Curve modifier on a piece of road to extend it along the contour of the curve. This would also allow me to have the kart and several cameras follow the curve over time, while retaining control over their local position/rotation to hand-animate things like steering and drifting.

Before I animated everything, I wanted to craft a unique look for what was becoming a concept trailer for this kart. I wanted it to look pretty realistic, but have a certain cel-shaded style to it that made it pop even more than Mario Kart already does. For this, I imported Mario's Mario Kart 8 model with a cel-shaded look, and I designed a few custom shaders for various parts of the kart:

For the car paint and all other metal/plastic surfaces, I made different variations of this format: take a metallic shader, extract just color information from that shader (this requires Blender's Eevee renderer to work), plug that into emission strength on another shader, and develop that shader for whatever color and specularity you desire (here, I used vertex painting to choose between red and black paint, for when I needed to make the turbine engines look deeper than they really are).

The tire shader is even more complicated. Most of it is about creating a procedural tire track pattern that I could sculpt to how I desired, but the part I'm happiest about it what I've circled in red here:

The circled part is the rim lighting on the tires. It takes color information from a diffuse shader, multiplies it by a Fresnel function (in which the value increases from 0 to 1 as the viewing angle gets more parallel with the surface) and plugged that into emission strength of white light. This means that, no matter which angle you view the tires, the edge of them that is facing the major light source (a sun lamp and HDR global illumination) will glow. Combined with the tire tracks also serving as a bump map, the result looks extremely comic-booky. I'm really happy with it.

And finally, I had to set up a few more systems, like invisible objects that the front tires could turn to face, an invisible object Mario could look at, an object to take over tire rotation once the scene turns slow-motion, and a modifier on all Mario's movements to make them only move every 4 frames, making him more stylized still. The rest was hand-animated and each camera hand-set up.

And after all that, a few more effects were added in post. While all the motion blur in this is Blender-native, I did redo one shot adding some x-axis displacement to Mario's model itself, creating some nonphysical, cartoony smear frames.

You'll also notice from this shot and the final video that I drew some comic-booky motion lines over the tires. I should have done this with Blender's Grease Pencil, but this was a late idea only a little bit before April 1st, so I opted for drawing over the frames in After Effects instead. The same process allowed me to enhance some motion-blurry shots during the kart transformation scenes.

The last step was making some energetic music to sell this video as a trailer. As the kart launches into the air and the name is revealed, the music references a tune from Mario Kart: Double Dash!!, when you are awarded a new kart! And that's the story of how this idea and the animation came to be.

And now that I have the original kart and its transformation animation, time to make an original karting game to go with it, someday maybe...!