CesiumGS/cesium

Feature ID Textures ignore sampler wrap mode

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#11,574 opened on Oct 19, 2023

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category - model/gltfgood first issuetype - bug

Description

Feature ID textures are allowed to have any wrap mode, but CesiumJS incorrectly overrides this with CLAMP_TO_EDGE.

In GltfLoader there is this chunk of code for feature ID textures:

  const textureInfo = gltfFeatureIdTexture.texture;
  featureIdTexture.textureReader = loadTexture(
    loader,
    gltf,
    textureInfo,
    supportedImageFormats,
    frameState,
    Sampler.NEAREST // Feature ID textures require nearest sampling
  );

The last parameter for that function is samplerOverride, which replaces the original texture.sampler with the provided one. In Sampler.js:

Sampler.NEAREST = Object.freeze(
  new Sampler({
    wrapS: TextureWrap.CLAMP_TO_EDGE,
    wrapT: TextureWrap.CLAMP_TO_EDGE,
    minificationFilter: TextureMinificationFilter.NEAREST,
    magnificationFilter: TextureMagnificationFilter.NEAREST,
  })

Instead of completely replacing the old sampler with the new one, only the minificationFilter and magnificationFilter should be overriden.

Contributor guide

Tech stack
javascript
Domain
frontend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
under 1 hour
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Basic JavaScriptCesiumJS development setupTexture sampling concepts
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
85
Research direction
Locate the loadTexture call for feature ID textures in GltfLoader. Currently, it passes Sampler.NEAREST which overrides both filters and wrap modes. Modify it to only override minificationFilter and magnificationFilter, preserving the original wrap modes from the glTF sampler. See Sampler.js to understand the sampler structure.