(Hacked together quickly but it semi-works on Mac, Blender 2.80 beta - there are some timers etc that might lock up Blender but it seems to run OK at the mo... )
Panel can be found under 3D View > View > Render Viewport
Will save the OpenGL viewport to a file (location and dimensions defined in render settings), every 'interval' when the Auto Render button is toggled on. Turn it off to change the frequency and then turn it back on again. Manual Render will trigger a single render.
Try TIFF with no compression (and B&W?) as a fast file format to save to, to reduce lag. Can change up to full RGBA etc if basic layout works for preview purposes.
Can use with second monitor to view 'linked' files update quickly while working on layouts in Illustrator or InDesign for example. You'll need to figure out how to switch apps quickly to force a refresh in the 'linked' app, custom shortcuts on the OS could do it, or just click other window and click back.
Maybe someway of communicating via OS Scripting to achieve refresh.
Could assign shortcut key to Manual Render to avoid UI lag.
- Multiple files, from multiple views/cameras to achieve a layered effect in layout programs
- Render from cameras only (or option View or Camera)
- Different file format and rendering settings then the actual render (although having the same settings pixel-wise makes sure render will fit external layout mockup?)
- Better handling of Timers...
- Write to tmp file and then overwrite the main file (to avoid linked programs trying to read while Blender is writing)
- More robust and better workflow - live interval change, or lock input until Auto off
- Is screenshot better/faster? https://docs.blender.org/api/master/bpy.ops.screen.html?highlight=bpy%20ops%20screen%20screenshot#bpy.ops.screen.screenshot
Blender Addon - Auto Render Viewport is released under the GNU General Public License
https://www.gnu.org/licenses/gpl-3.0.html
See Ton's (Blender Founder) blog about license - https://code.blender.org/2019/06/blender-is-free-software/