As part of my duties as Art Director at Hammer & Tong Productions, I was in charge of developing workflows and techniques to optimize our pipelines. Our art team was rather small, with only a handful of artists wearing multiple hats, which made our often fast-paced productions rather daunting. In order to make our projects feasible, I came up with some creative solutions.
Fake Shadows
Running the risk of overwhelming our modeller, I mandated that we use 2D illustrated backgrounds for the majority of our environments, only producing 3D assets where absolutely necessary. This came with the challenge of having to reintegrate the 3D elements into the compositions in a way that felt cohesive. To solve this, I created a fake Shadow shader to be used during the lighting process; when applied to geometry, the material isolates the areas receiving cast shadows, clipping everything else.
With this shader we could place primitives around the scenes, making the 3D elements appear to cast shadows on 2D backgrounds, all in realtime. I added parameters to control Transparency, Shadow Color, and Falloff, making the material conducive to faking effects like ambient occlusion.
Realtime Holdouts
To further push the integration of 3D elements into 2D compositions, we needed a way for elements to realistically occlude one another. Even with our backgrounds separated into layers, we couldn't always efficiently anticipate the variety of ways 3D elements would need to move around the compositions. To streamline this I created another material, this time using a stencil mask where needed to cut pieces of characters out and fake occlusions where needed.
This gave us cheap holdouts and saved us the trouble of rendering out several passes to be recombined in external software. That being said, a major limitation of this technique is that it falls apart if the camera moves, however it proved incredibly useful on Echoes of Chinatown, a 360 short we created where the entire set is a single Equirectangular illustration.
Painterly Post-FX
As a final way to blur the lines between 3D and 2D elements, I created a shader that added a layer of impressionism to 3D objects, allowing us to break up rigid silhouettes with noise and texture. This allowed us to blur the seams between our assets, making it harder to distinguish where the 3D stopped and the 2D began.
The effect operates in world-space with parameters to dial the Noise Intensity, Texture Scale, Opacity and Depth. The brushy texture sampled can be swapped out as well to better line up with the style of each project. I'm particularly happy with how we utilized this material on shots for one of internal projects titled The Legend of Gil Perez, created by Rene Rebora.
Overall, these small but powerful tools proved very useful, allowing us to compensate for key roles we didn't have during hectic productions.
