[Genma Saotome]

Is there any way to assess how costly shadows are?

My understanding is that any face that responds to shadowing will have every pixel of that face processed for shadowing. But what if some of those pixels are not visible? I've been told they get processed too.

Which leaves me with an issue: I have numerous faces that are partially hidden by other faces. If the view block is short and the face narrow I don't much worry about any shadowing cost. But what if the view block is longer and/or the shadowed face is larger? That would mean more pixels being processed for shadowing and at some point I assume that could degrade processing performance.

So how do I figure out when it is ok to do the run behind method vs. when it would be better to cut away that part of the face that is hidden (increasing the poly count)? Put another way my need is finding the optimal course of more polys vs. more shadowed pixels.

For example:

ALL of the horizontal faces hide behind the vertical faces. The red verticals hide behind the horizontal faces. Cutting up the horizontals so no part is hidden is a huge increase in polys. Is it still worth it... or is pixel shadowing not really much of an issue?

[superheatedsteam]

The only way to be sure is to test it yourself. Use ALT + F5 just to view the FPS and then SHIFT + ALT + F5 till the DEBUG INFORMATION is displayed which shows some of the graphics values if that helps you to fine tune the results.

I have been performing some texture vs LOD vs optimised geometry testing recently and found performance ranging from 114 FPS to 245 FPS and that is without shadows.

Note that I that I get approx 25FPS performance drop when the additional debug information SHIFT + ALT + F5 is displayed over just ALT + F5. Also, turning on dynamic shadows dropped another 55 FPS.

What have become very obvious in the testing of my models, is that the poly count is the least expensive variable when it comes to FPS hit.

It's horses for courses and there is no free lunch.

Cheers,

Marek.