Three.js：3D对象边缘出现扭曲的原因排查求助

Hey there! Let's break down why your 3D shirt is showing distorted, blurry, or low-poly edges in Three.js when it looks perfect in PlayCanvas. The JSON mesh format could definitely be a culprit, but there are several other key factors to investigate:

Possible Causes #

1. JSON Mesh Precision Loss #

Older Three.js JSON formats (pre-r58) often had issues with data compression or simplified vertex storage. When exporting your mesh to JSON, some tools might quantize vertex coordinates, normals, or UVs to save space—this strips away precision, leading to jagged edges or flat shading that makes the model look low-poly. PlayCanvas might handle JSON imports with more leniency, or you might have used a different export preset there that preserved full precision.

2. Renderer & Material Setting Differences #

Three.js and PlayCanvas have different default rendering pipelines, so small settings can make a huge difference:

• Antialiasing: Three.js's WebGLRenderer doesn't enable antialias by default. Without it, polygon edges will look jagged and distorted.
• Texture Filtering: If your shirt uses textures, Three.js defaults to basic linear filtering. Missing anisotropic filtering can make textures (and edges) look blurry, especially at oblique angles.
• Z-Fighting/Polygon Overlap: If your mesh has overlapping faces, Three.js might not handle depth sorting as smoothly as PlayCanvas, leading to flickering or distorted edges.
• Camera Clipping Planes: A near plane that's too close or a far plane that's too far can cause depth precision issues, making edges appear distorted or "swim."

3. LOD (Level of Detail) Accidents #

It's possible that during the JSON export/import process, a low-detail LOD level was accidentally applied to your mesh. PlayCanvas might ignore or auto-disable LOD by default, while Three.js might be using the simplified version.

Fixes to Try #

• Switch to GLTF Format: Ditch the JSON mesh—GLTF is Three.js's recommended, modern format that preserves full vertex precision and has far better compatibility. Export your mesh from your modeling tool (like Blender) as GLTF and load it with GLTFLoader instead. This alone might fix the issue.
• Tweak Renderer Settings:
  • Enable antialiasing when initializing your renderer:

    const renderer = new THREE.WebGLRenderer({ antialias: true });
    

  • Add anisotropic filtering to your textures for crisper edges:

    texture.anisotropy = renderer.capabilities.getMaxAnisotropy();
    

  • If you see Z-fighting, enable polygon offset on your material:

    material.polygonOffset = true;
    material.polygonOffsetFactor = -1;
    material.polygonOffsetUnits = 1;
    

• Inspect Mesh Data: After loading your JSON mesh, log the vertex positions to check for precision loss:

  console.log(geometry.attributes.position.array);
  

  If you see rounded integers instead of precise decimals, re-export your mesh with full precision enabled in your modeling tool.
• Match PlayCanvas's Render Settings: Check PlayCanvas's project settings for antialiasing, texture filtering, and camera clip planes, then replicate those values in your Three.js code.

内容的提问来源于stack exchange，提问作者appzone_oto