From BlenderWiki
Introduction
Preview Range is a useful tool for animating (espcially on longer timelines). It allows you to only run through a limited set of frames to quickly preview the timing of a section of movement without going through the whole timeline. It means you don't have to set/reset start/end frame for previewing animation everytime you wish to only preview a region of frames.
Usage Notes
- CtrlP in IPO/Action/NLA/Timeline sets preview range. Click+drag to form selection-box defining region of frames to preview
- AltP in IPO/Action/NLA/Timeline to clear preview range
- 'Pre' button beside Start/End fields in timeline toggles whether start/end fields refer to scene or preview. (This might be replaced by some icon sometime)
- ⇧ Shift← and ⇧ Shift→ jump to start/end of preview region when it is set
- S and E set the start/end frames of preview region when it is set (just like normally) in Timeline only
Screenshots
- In IPO/Action/NLA editors, frames out of preview region are now drawn darkened when preview-region is set
Un-official 'Hacks' For the Adventurous
DISCLAIMER: these hacks mentioned here are only for those people who desperately need the following functionality. Some are known to cause problems in certain situations, thus are not officially supported. No responsibility will be taken for any damage caused by using these hacks.
OpenGL Preview Renders Respecting Preview Range
This has been removed from cvs, as it was too unstable when used in conjunction with movie-files + preview ranges greater than the normal frame range. (Note: this will cause a sort of memory-leak, even if it is tempolary).
In blender/source/blender/src/renderwin.c, function BIF_do_ogl_render: change the line that says
for(CFRA= SFRA; CFRA<=EFRA; CFRA++) {
to
for(CFRA= PSFRA; CFRA<=PEFRA; CFRA++) {
