Reading the texture-geometry split first got a sneaker configurator from 16.7 MB to 2.4 MB

Four bytes a pixel is what the GPU asks for. The write-up puts a 2048x2048 texture at 16 MB in GPU memory no matter how small the JPEG was, because it has to be decoded to raw RGBA before the GPU can use it ^[19]. Multiply it out: 2048 x 2048 x 4 bytes is 16.78 MB, so the quoted figure is the uncompressed buffer, not an estimate ^[21]. KTX2 with Basis Universal stays compressed on the GPU, and the author says that on a mid-range phone, where GPU memory is the actual ceiling, this is often the difference between running and crashing ^[20].

The quantisation numbers are the part least likely to transfer. The command runs position at 14 bits, normals at 10, texture coordinates at 12 and colour at 8 ^[9]. At 10 bits the author reports he could not see a difference on curved surfaces under moving light ^[10]. That is one pair of eyes on one model at one orbit distance, and the post says as much: the defaults are conservative, the right values depend on your model's scale and how close the camera gets, and the method is to walk each value down until the damage is visible and then step back one ^[12]. Getting texture coordinates wrong has a signature, texture swimming at the seams ^[11].

The texture saving came out of the source assets. Every map had been authored at the resolution you would want if the camera could get arbitrarily close, and a configurator has a defined orbit distance and a maximum zoom that bound how much detail can ever reach a pixel ^[16]. Base colour is the map the eye judges and kept the most resolution; normals need resolution but tolerate compression artefacts poorly; roughness, metalness and ambient occlusion went dramatically smaller because they drive shading response and not perceived detail ^[17]. The KTX2 encode is one gltf-transform uastc call at level 4, rdo-quality 4 and zstd 18 ^[18].

Draco also moves cost to the client. DRACOLoader is pointed at a path with setDecoderPath('/draco/') and setDecoderConfig({ type: 'js' }) before the GLTFLoader gets it ^[13]. The author's warning is that the decoder is itself a download, so serve it yourself and make sure it is cached, or you have traded model bytes for decoder bytes on every cold load ^[14].

The second half of the story is an assertion. Once the file was small enough, swapping a colourway made the shoe look wrong ^[22], and the introduction promises that the obvious way to recolour a 3D model destroys the thing you built it to show ^[23]. The text as published breaks off mid-sentence at "The obvious implementation is" ^[24]. So the diagnosis-first argument is documented end to end, with commands and parameters, and the material bug is a symptom with no code under it.