Wednesday, May 1, 2019

Rendering Lots of Blocks Efficiently in Unity

The last few weeks I've spent trying to see how many blocks I can render, while keeping everything at a nice frame rate (30-60fps) with no frame drops. A minecraft type engine has a few rendering steps, as far as I know:


1. Culling: Only process the blocks that aren't completely surrounded by other blocks with cube models. The other blocks we can't see are "culled" away

By "cube models" I mean that they have the default block model that takes up the whole space. For example, if a torch is on a wall the block it is attached to should still display, but if I replace the torch with a dirt block I no longer need to render the block the torch was attached to (assuming it isn't touching any other air blocks)

By the way, for all non-culled blocks, only rendering the block faces that are visible (and hiding faces that are against a wall) can end up almost halfing your triangle count sometimes, which really helps! I highly recommend trying it.

2. For all the non-culled blocks, convert their raw data into triangles (or some other intermediate data of some kind)

3. Move that data to the GPU

4. Tell the GPU to render it


I had initially been doing step 1 in a compute shader (running one GPU thread per block, then appending the coordinates of all blocks that aren't culled to an AppendBuffer and reading this out later). If this seems like overkill, you're right. The reason I was doing it that way was because I borrowed that code from my VR Sand project. In VR Sand, blocks are changing very frequently, so I needed this whole process to be very fast. While it was, when I tried to scale up my world sizes, suddenly the size of my ComputeBuffers needed to be very large and the cost of managing them all became slow. I also couldn't easily increase the chunk sizes to something like 64*64*64 before my compute buffers started complaining about that being too many threads.

Also, I wanted to multithread things, and Dispatch can only be ran on the main thread.

So I figured I'd try moving my code to the CPU and see how the performance fares.

It turns out that it worked very well! The reason is this:

The main overhead I had was draw calls. and moving everything to the CPU allowed me to increase chunk size, and decrease draw calls


I decided to upgrade to Unity 2019, and the profiler is much more efficient. This was very nice, because before, if let Unity deep profile record for more than 200 frames (or at the very start when the world was generating). my computer would hang for 10-20 minutes, and not let me even bring up the task manager, so I'd have to restart my computer. With 2019 improvements, this is no longer a problem, making this whole optimization process much less frustrating :)

Anyway, so after moving steps 1 and 2 to the CPU, I needed to move the data to the GPU. I had three options:

Option A: Use the Unity builtin Mesh object
Option B: Use DrawProcedural
Option C: Use a native graphics plugin and manage the VBOs myself

I figured Option A made the most sense, so I made one Mesh object per chunk, and tried it out. The performance was decent, but I kept getting these unpredictable spikes occasionally. I looked at the profiler, and it had to do with Unity "deciding" when was the right time to make VBOs, Unity trying to cull things, and related graphics things.

For those that don't do, a VBO (vertex buffer object) is the object you make when you want to pass triangle data from the CPU to the GPU. Unity has a builtin Mesh object that tries to abstract that away from you. For most purposes, this abstraction works pretty well.

However, I needed more fine grained control over exactly when the VBOs were being created and moved to the graphics engine, because these lag spikes were a big pain in the neck. I kept trying to tweak settings and fiddle with stuff to convince unity to do things the way I wanted (spread things out over multiple frames), but Unity kept being annoying.

I looked into the details, and you can get a little lower level control here (Option C) if you manage the graphics objects yourself. However, that would lose me a lot of platform portability, and I find native plugins generally a pain to use (I've had to write a few in the past for other related projects), so I decided to try Option B first.

To explain Option B: Unity has a DrawProcedural method. How this works is that you do the following:

- Create a ComputeBuffer that has your graphics data


Then in the drawing loop, you can just do this

- Give your drawing material that buffer using drawingMaterial.SetBuffer("DrawingThings", graphicsDataBuffer);
- Call drawingMaterial.SetPass(0); on a material that has a shader you wrote attached to it
- Call Graphics.DrawProcedural(MeshTopology.Triangles, numVertices);

This works well, but it has some overhead. To address this, I tried making my chunk sizes 64x128x64. (they used to be 16x16x16). Once I did this, I was suprised to find that I could render tons of chunks while keeping a very good frame rate!

The key here is that in a blocky type world, once you do world generation and compute lighting, blocks don't change that often. This means that it is okay for us to take the few additional milliseconds in having to recreate the triangles of an entire 64x128x64 chunk every time a single block changes. And once you are done doing that, you just need to pass that data to the GPU, and then the overhead per frame is very low! (since there are very few draw calls)

To prove this, here is a screenshot of the world. My world generation is really simple right now, and I made the variability in height much higher than normal just to see what would happen. But yea, so that's my solution to rendering lots of blocks efficiently in unity :)


7 comments:

  1. However, most presents have a minimal deposit requirement. The greatest casino bonus is the one with the very best cash worth AND the lowest wagering requirement. New customers are likely to|are inclined 바카라 to} overlook this half, however it’s truly fairly essential. The lower the wagering necessities are, the easier it is to show your bonus quantities into precise cash. Only board games, keno games, scratch cards, slots, and real-series video slots rely in the direction of|in path of} the wagering requirement. While making your deposits, you need to|you should|you have to} use the bonus codes – SS250 for the first and SS100 for the rest of|the remainder of} your deposits.

    ReplyDelete
  2. Sign up now to get the inside scoop on the 카지노 사이트 most recent bonus provides. His drive and keenness for casinos and the most well-liked games keep him in contact with the most recent information and interests to supply one of the best for his readers. JackpotCity Casino also has country-specific bonuses, birthday bonuses, and special vacation bonuses. Again, these are tailored to fit your|to properly with|swimsuit} your} nation of residence, so it’s impossible in a short area to listing all the promotions. When you enroll, ask the Jackpot City cashier about special bonuses.

    ReplyDelete
  3. The supplier's first round consists of two cards for both the Player and Banker. The five punters on the best win or lose by the cards dealt to that facet; the five others by the cards dealt to the left facet. The guidelines as to turning up with eight or 9, providing and accepting cards, and so on, are the same as Chemin de fer. Bankers are determined by the player’s third card number to obtain https://kirill-kondrashin.com/ an 먹튀폴리스 additional quantity.

    ReplyDelete
  4. Operators can select between one or more of} devoted tables or a completely devoted surroundings set- up. The objectivein Andar Bahar game is to guess on which side Andar or Bahar the card matching the Joker card on the desk will appear first. It is alleged to have originated in Bengaluru in the southern state of Karnataka, 인터넷카지노 and might be} additionally identified in Tamil as Mangatha or Ullae Veliyae, south part of of} India principally.

    ReplyDelete
  5. With your first deposit of 0.15 BTC, you’ll qualify for a 125% bonus worth up to as} 1 BTC. Additionally, you’ll obtain 100 free spins to make use of on a variety of their high-RTP reels. You also can declare four BTC in extra bonus funds along with your next three crypto deposits. It’s necessary to know that the payout percentage is predicated on the cash you have got} wagered, and not on the cash you thecasinosource.com have got} deposited.

    ReplyDelete
  6. You solely lose if a roulette wheel stops with the ball being on a quantity between 1 and 12. People like to observe the Martingale technique after they play roulette end result of|as a result of} it's the easiest betting technique on the 온라인 카지노 planet. But if all you want is an outline of the different betting strategies that can help you could have} more chances to win on roulette - right here we go. If you're be} severe about half in} roulette for cash, want to|you should|you have to} deal with your winnings as occasion that they} did not exist. I suggest you open a free account on this web site and use the free bonus to play your first on line casino games on-line.

    ReplyDelete
  7. 2/4 Card Counting While card counting is both legal, honest and may enhance 코인카지노 your edge, it’s not a surefire approach to win. Many gamers make the error of believing that counting cards will make them wealthy. One of the most important perks of taking part in} on-line video poker is you've got got} the chance to try out your chosen methods in free demos.

    ReplyDelete

Rendering Lots of Blocks Efficiently in Unity

The last few weeks I've spent trying to see how many blocks I can render, while keeping everything at a nice frame rate (30-60fps) with ...