3D Sky Background

Build a sky that surrounds the world, with a readable horizon and lighting that belongs to the same atmosphere.

Choose the representation

Inspect the project's renderer, camera range, color pipeline, environment lighting, and existing assets. Use an existing licensed panorama when its cloud composition matters, a procedural sky when changing sun position matters, or a restrained hybrid. Keep the project's rendering backend and version; do not add a second renderer for the sky.

Keep three responsibilities explicit: the visible sky background, the reflection/ambient environment, and direct sun lighting. A background photograph alone does not light PBR objects. A PMREM environment does not supply a shadow-casting directional sun. See the PMREM documentation.

Build a stable surrounding sky

• Use the engine's background facility, a fullscreen direction shader, or an inward-facing dome with depth writes disabled and fog disabled. A dome must fit inside the camera's clipping range and follow camera translation; it should retain world orientation as the camera rotates.
• Derive color from the normalized viewing direction. Blend a pale warm horizon through a muted middle band into a cooler zenith. Keep the lower hemisphere compatible with the ground haze rather than leaving an exposed hard edge.
• Use a shared sun direction for the visible disk, glow, directional light, and any sky-ray pass. A broad halo and a small disk are separate terms; avoid a large white blob.
• Add distant silhouettes only when the composition needs depth. Keep them low contrast, with a hue and value close to the horizon.

Map a panorama deliberately

A true equirectangular sky wraps a full 360° horizontally and 180° vertically. Establish a consistent world-axis convention, rotate the texture so its photographed sun matches the scene sun, and inspect both the seam and zenith.