scene:snapshot

(scene:snapshot v)

One frame of an offscreen viewer, as its pixels: width * height * 4 bytes, BGRA, row 0 at the top (see metal:pixels). The frame is drawn through scene:refresh like every other frame, so what comes back is what a window would show. Signals on a viewer that has a window, which has no texture to read. Part of the scene package: macOS only, never a .wasm. See scene:offscreen.

CL-USER> (defvar *v* (scene:offscreen :width 64 :height 64))
CL-USER> (scene:grid *v* :extent nil)
CL-USER> (defvar *px* (scene:snapshot *v*))
CL-USER> (list (aref *px* 0) (aref *px* 1) (aref *px* 2))
(23 17 14)