x

Search in
Sort by:

Question Status:

Search help

  • Simple searches use one or more words. Separate the words with spaces (cat dog) to search cat,dog or both. Separate the words with plus signs (cat +dog) to search for items that may contain cat but must contain dog.
  • You can further refine your search on the search results page, where you can search by keywords, author, topic. These can be combined with each other. Examples
    • cat dog --matches anything with cat,dog or both
    • cat +dog --searches for cat +dog where dog is a mandatory term
    • cat -dog -- searches for cat excluding any result containing dog
    • [cats] —will restrict your search to results with topic named "cats"
    • [cats] [dogs] —will restrict your search to results with both topics, "cats", and "dogs"

Enable/disable shadow map re-rendering for movable lights?

I'd like a way to tell a movable light that it should use its shadow map but that it can (for now) stop re-rendering its shadow map.

I have a house environment with many switchable lights (controlled by lightswitches), and so you'd think stationary lights would be preferable to movable lights. However, in a realistic house environment, basically every light violates the max-of-4-overlapping-stationary-lights limitation, because their attenuation radii reach each other through walls:

alt text

So I don't think I can use stationary lights for switchable lights in a residential environment like this.

The problem with movable lights, of course, is that they need to re-render shadow maps on every frame, which gets prohibitive once you have several of them on. Once I switch on 5-10 movable lights with shadow maps, my frame rates become unacceptable.

For most of my lights, I could "lock" the shadow map most of the time, and only have it re-render the shadow map when I know something dynamic is happening nearby (eg a nearby door opening and closing). The rest of the time, the lights could consult their shadow maps but not re-render them.

Is there any concept of locking and unlocking shadow map re-rendering? One of the big benefits of shadow maps historically is that they can (often) be reused from one frame to the next, and I'd love to take advantage of that in UE4.

--Tom

Product Version: Not Selected
Tags:
img1.jpg (125.7 kB)
more ▼

asked Aug 31 '14 at 02:19 PM in Rendering

avatar image

tlokovic
21 2 3 6

(comments are locked)
10|2000 characters needed characters left
Viewable by all users

1 answer: sort voted first

This is an optimization that the engine should support but we haven't gotten around to it yet. Each movable light should cache its shadowmaps as long as it isn't moving. We could even separate static objects from ones that are moving and re-rendering the moving ones every frame, that way the 'locking' is automatic.

more ▼

answered Sep 03 '14 at 02:06 AM

avatar image

DanielW STAFF
1.9k 31 11 72

avatar image rit Apr 25 '17 at 06:49 AM

Is this optimization feature now supported in UE4?

(comments are locked)
10|2000 characters needed characters left
Viewable by all users
Your answer
toggle preview:

Up to 5 attachments (including images) can be used with a maximum of 5.2 MB each and 5.2 MB total.

Follow this question

Once you sign in you will be able to subscribe for any updates here

Answers to this question