Would a jump in refresh rates in your level indicate a bad block somewhere?

I have an area in my level where my fps drops from 50fps to about 37 fps. Debug shows an increase in time for refresh - see the screen shots below. You can tell from the image I have only moved the camera slightly between the two screen captures and most other statistics have stayed the same (number of polygons etc).

Would this indicate a bad block?...because I have been backing out many changes and messing around - but can not figure out what is causing the drop. Please help. Any direction for debugging this appreciated.

I have something similar and much more severe than that. 8.1 is 5 times better than what I've had. I've noticed that, in my case, it gets to 41 milliseconds. I cannot explain this myself. It happens when the camera gets into a certain position. Just a change of about 40 quants, refresh time goes from around 8 milliseconds to 40. Go back down about 40 quants and it returns to 8.... I'm baffled over it myself.

PS nice scene.

Well glad to know I am not alone (I think). Wish I understood this better...don't know if I am wasting my time trying to debug nothing. I am rechecking all the blocks to see if they are snapped. After that, if the problem persists - I am out of ideas.

PS. Congrats on finishing your beta. Saw your Showcase post. I'll check it out over Christmas holidays.

Ah, I'm referring to the "pan" value in my 3D game which gets to 43. In my abandoned project, I do recall it getting clear up to, even beyond 180 milliseconds with a pyramid-like structure of blocks. When I press the up arrow, for example, there'd be quite a long delay before anything responds. Perhaps I could try to rebuild my structure so you can see the results yourself (and perhaps make it more extreme).

Screenshot - this is with the 6.22 engine as this screenshot was taken on Sep 6, 2004, 15 months ago.

Don't go to any troubl Uli. I was just hoping for some information to understand this better and hopefully save some time - as I have been getting a little frustrated ... but there probably is no short cut. Thanks anyway.

The only clues that I have is that this seems to happen when you are close to a group of otherwise small blocks crowded close to each other, possibly intersecting.

This screenshot showing this same bunch of blocks from in WED. I just recently had to open up the old project just to see it and get this screenshot as otherwise, I have no screenshots on hand of it.

Edit: it's that pyramid that you see there that's where I'm getting the extremely high ref value.

Hey Uli
Just FYI - I did find some bad blocks, which I had unfortunately copied and pasted in a few spots. I rebuilt those blocks and the problem is now gone. I should have known - because I was having some problems with shadows in a few spots and sure enough - that is where I found the bad block.

Well, I only thought I fixed this. I improved fps in general - but I can still get this problem. After spending all morning isolating and testing entities I now understand a little better what is happening in my level.

The trees and bushes are models - but the branches are 2d planes. If I put one of these trees or bushes in a level by themselves and aim the camera straight at them the refresh times are really high. If you scale these models to a larger size - the refresh time increases what looks like proportionally. So even though these models are low polys - they demand a longer refresh time. (I am guessing it is because some of these planes are viewed edgewise).

Having said that, I don't know why they behave as well as they do in the larger level - because I have lots of these bushes and trees but its only sometimes, at some angle, that these models will drive up the refresh time.

In the shot above - I believe the culprit is the tree on the upper LHS of the screen shot - which is scaled quite large. When I removed it from the scene - I had a more difficult time reproducing the higher refresh time. However because of the pink flowered bush in the foreground (also scaled larger)- I can still get the same results standing in certain spots and viewing the scene from certain angles.

The effects on fps are significant but may well just be the price of having bushes and trees...and still I am getting reasonable fps...so I think I will just have to accept that there probably is no way to optimise this other than to be careful about the scale as it does exaggerate the problem.

It could also be the problem that many engines have with showing many sprites behind other sprites. Since your sprites seem to have a "keyed" out color, or a color that shows totally transparent, the engine has to redraw many sprites in conjunction with the other transparent sprites behind it. When I say transparent I mean by sprites that have an overlay flag on to show certain parts of the image. So when alot of these sprites/models are behind each other or bunched up, the engine has to iterate through each one, redrawing it, then redrawing whats behind it, I think this is called overdraw. And I might be wrong about this, but due to this overdraw problem, that statue with its many polygons may actually render faster than 2 large sprites that are overlapping each other in the current POV.

And I think your right, I dont think there is too much you can do about this overdraw problem, because many engines have this problem. I havent made a good growth filled level with lush plants and bushes, but I thought about using a smaller scaled version of an LOD system for plants. When a plant reaches a certain distance from the camera, it would morph into its next LOD level, but the resolution of the next LOD would be greatly smaller compared to the last one. I havent tried this out, and I dont know if it would be faster to have many low-res sprites together compared to many high-res sprites together to prevent overdraw.

That's good information. Thanks jumpman. In the shot with the problem, there are about four of these trees/bushes lined up along the LHS. I will check to see if/how much of the problem may be due to overlapping..but I think I can reproduce it with just the flowered bush in the foreground. (but I guess there would be significant overlapping even with just one bush with the way these models are designed). I'll check it out.

I haven't done anything to the models yet except add mipmaps to the skins.