OES_fbo_render_mipmap extension is part of the WebGL API and makes it possible to attach any level of a texture to a framebuffer object.
Note: This extension is only available to WebGL 1. In WebGL2, the functionality of this extension is available in the WebGL 2 context by default.
See the sample code in the Khronos specification.
|WebGL OES_fbo_render_mipmap Extension Specification
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