Single Sample Seamless Tri-Planar Mapping (UE5)

Here I demonstrate a method of using temporally blended stochastic sampling to achieve tri-planar mapping and texture switching using a single texture sampler. Traditional tri-planar mapping requires a sample for each of the 3 world planes in order to achieve a seamless blend. This can be costly, especially for landscape materials with many textures. By levering frame blending used for TAA, dithering and noise we can achieve a seamless transition with just one sample for all planes. The downside is that the dithering may become momentarily visible upon disocclusion for a few frames while the blending accumulates, especially in areas of high contrast. This technique can also be used to blend samples from arrays to allow landscape materials to seamlessly transition under a single sampler.

Inspired by:
https://www.gdcvault.com/play/1025480...
Timestamps
00:00 Welcome
00:30 The issue with tri-planar mapping: 3 samples per texture
01:15 A typical tri-planar material
02:58 Comparing the methods: Virtually indistinguishable
03:30 How my method works
04:55 Watch the seam disappear
05:55 References
06:25 Animated Blue Noise Dither TAA
07:50 Applying the dithering to the tri-planar masks
10:25 DDX & DDY
11:55 The Normal Map
14:05 This can also blend array samples for totally different textures
16:30 What happens to arrays without temporal blending
17:16 Worst case is high contrast blends
17:34 An entire landscape could be constructed with 1 sample per texture type by combining these techniques
19:45 Disocclusion artifacts for a few frames in high contrast areas
20:55 TSR seems to offer slightly better results, TAA might ghost a bit more
21:40 TAA/TSR is required for full effect.