• Paints an HDR studio-style equirectangular environment into a width × height Float32 RGBA buffer (row-major, top-down, alpha = 1).

    Layout:

    • Three-band gradient: zenith sky → horizon haze → ground, with a horizonBlend-wide smoothstep on either side of the horizon.
    • A bright sun disc (radiance sunIntensity) at the world-space direction sunDirection, wrapped in a soft sd^32 glow that bleeds into the surrounding sky.

    Pair with encodeRadianceHDR and pass the result to IBL.setEnvironmentHDRBuffer to drive the renderer's HDR IBL path.

    Parameters

    Returns Float32Array<any>

    Float32 RGBA pixel data, width * height * 4 floats.