When building structures in Minecraft I usually tend to thoroughly plan my lighting layout, with the primary focus on a seamless coverage of the whole "civilized" area in a light level of at least 8, to keep hostile mobs from spawning at night.
For this, though, the easiest way in vanilla Minecraft seems to be to employ the debug view (reached through F3), which shows both the sky light as well as the artificial block light of the block that the player's feet stand in. However, when planning the lighting layout of a more irregular structure, like a naturally generated hill, this can get rather tedious to do thoroughly.
Thus, I'd like to ask if there is an easier way to analyse the light distribution on a larger scale, without the need for manually checking the light level of each individual block surface. Preferably I'd just like to highlight all the block surfaces that are below a certain light level (effectively where monsters could spawn). And for direct and interactive lighting design it would be best for this to show it right in the running game. I'd wager (but would be happy to err on this) that this isn't possible with vanilla Minecraft but only through a mod.
(If I'm correct and this needs a mod, I'd prefer it to work in latest Minecraft (1.8.X as of now) as well as not adding a plethora of other features, as I'd prefer my normal gameplay unaltered.)
Best Answer
This is one of the features of Not Enough Items. After installing the mod, press F7 (by default) while in-game and it will render a grid of red and yellow Xs on top of nearby blocks. Red Xs mean mobs can spawn on that block at all times (assuming a player is not nearby), while yellow Xs mean that mobs can spawn on that block at night.