Line Cap Styling in Three.js

Based on the information available, I can provide some guidance on line cap styling in Three.js.

For materials that support wireframe rendering like MeshStandardMaterial, there is a property called wireframeLinecap that defines the appearance of line ends. This property accepts three values: 'butt', 'round', and 'square', with 'round' being the default.

However, it's important to note that this property corresponds to the 2D Canvas lineJoin property and is actually ignored by the WebGL renderer in Three.js.

For your specific case with fat lines, you have a few options:

1. If you're using a custom shader or the LineBasicMaterial, you might need to modify the shader code to implement square caps.

2. Another approach would be to use geometry manipulation - instead of relying on the material's line cap properties, you could extend your line geometry slightly to create the square cap effect manually.

3. Consider using LineDashedMaterial with specific settings, though this is more suited for dashed lines rather than changing the cap style.

If you're working with a custom fat line implementation, you'll likely need to modify the shader code or geometry generation to achieve the square caps you're looking for.

For standard Three.js line rendering, you might want to explore the various material types available:

• LineBasicMaterial
• LineDashedMaterial
• MeshBasicMaterial (with wireframe enabled)
• ShaderMaterial (for custom rendering)

Without seeing your specific implementation, it's difficult to provide exact code, but these approaches should point you in the right direction for achieving square line caps.