• Announcements

    • khawk

      Download the Game Design and Indie Game Marketing Freebook   07/19/17

      GameDev.net and CRC Press have teamed up to bring a free ebook of content curated from top titles published by CRC Press. The freebook, Practices of Game Design & Indie Game Marketing, includes chapters from The Art of Game Design: A Book of Lenses, A Practical Guide to Indie Game Marketing, and An Architectural Approach to Level Design. The GameDev.net FreeBook is relevant to game designers, developers, and those interested in learning more about the challenges in game development. We know game development can be a tough discipline and business, so we picked several chapters from CRC Press titles that we thought would be of interest to you, the GameDev.net audience, in your journey to design, develop, and market your next game. The free ebook is available through CRC Press by clicking here. The Curated Books The Art of Game Design: A Book of Lenses, Second Edition, by Jesse Schell Presents 100+ sets of questions, or different lenses, for viewing a game’s design, encompassing diverse fields such as psychology, architecture, music, film, software engineering, theme park design, mathematics, anthropology, and more. Written by one of the world's top game designers, this book describes the deepest and most fundamental principles of game design, demonstrating how tactics used in board, card, and athletic games also work in video games. It provides practical instruction on creating world-class games that will be played again and again. View it here. A Practical Guide to Indie Game Marketing, by Joel Dreskin Marketing is an essential but too frequently overlooked or minimized component of the release plan for indie games. A Practical Guide to Indie Game Marketing provides you with the tools needed to build visibility and sell your indie games. With special focus on those developers with small budgets and limited staff and resources, this book is packed with tangible recommendations and techniques that you can put to use immediately. As a seasoned professional of the indie game arena, author Joel Dreskin gives you insight into practical, real-world experiences of marketing numerous successful games and also provides stories of the failures. View it here. An Architectural Approach to Level Design This is one of the first books to integrate architectural and spatial design theory with the field of level design. The book presents architectural techniques and theories for level designers to use in their own work. It connects architecture and level design in different ways that address the practical elements of how designers construct space and the experiential elements of how and why humans interact with this space. Throughout the text, readers learn skills for spatial layout, evoking emotion through gamespaces, and creating better levels through architectural theory. View it here. Learn more and download the ebook by clicking here. Did you know? GameDev.net and CRC Press also recently teamed up to bring GDNet+ Members up to a 20% discount on all CRC Press books. Learn more about this and other benefits here.
Sign in to follow this  
Followers 0
Migi0027

DX11
DX11 - Instancing - The choice of method

6 posts in this topic

Hello guys!

 

As you know, Directx has a feature called 'Instancing', which is quite wonderful actually. But how to use it properly is an entirely different chapter. And that's why I'm here.

 

Imagine Crysis or some other game where high level of vegetation is needed, as grass, and you need to render that. What I would do, and what I actually do:

 

When creating the scene:

 

When Creating the scene:

  • Add all instances of grass
  • Split all instances into different patches
  • Create Instance Buffers

When Rendering the scene:

  • Do some range testing and frustum culling for all patches, and all valid are added to a list.
  • Render each individual element in the list

 

Now that method works fine for me when using static non destroyable or creatable objects, but imagine if one object has to be created? Do I recalculate the respective buffer for the bullets location.

 

Also in the Crysis Sandbox, or CryEngine 3 SDK, when placing/painting vegetation over the terrain, they appear lightning fast! If you have time, how does produceal vegetation work in a nutshell?

 

But what if we are simulating a space ship, IN SPACE! Where the space is almost unlimited, and then the player shoots, I can't have buffers for an unlimited space! (I could create buffers dynamically for where I am, but I'm not sure if that's efficient).

 

So, now, I ask you, what, if it exists, is the most efficient way of handeling instances of an object?

 

Thank You, again...

1

Share this post


Link to post
Share on other sites

Do I recalculate the respective buffer for the bullets location.
 
i don't quite follow, how'd you get from instancing vegetation to drawing bullets? 
 
some cry3 specific thing i assume.
 
generally speaking, you'll have a model in buffers (vertex and index), and transforms for each instance in another buffer.
 
for modifiable vegetation, simply recalculate part or all of the transform buffer when required. you may also be able to do some indexing trick to only draw a range of instances in the transform buffer, and include/exclude vegetation that way.
 
although i'm not that well versed in dx11, i think you could also pass in flags in a constant buffer that could be used to determine which instances to draw.
 
it my also be possible to use some reserved value for a variable in the instance buffer that indicates "don't draw this instance".
 
it also may be possible to pass in some sort of "instance buffer" as well as the "transform buffer". the instance buffer would have a flag for each instance or perhaps work with indexes. not sure how many input buffers of what type you can use in dx11.
 
in the long run, recalculating the transform buffer, passing constant buffers, reserved values, an instance buffer (if supported), and drawing index ranges are all just different ways of telling directx which plants to draw.
 
me personally, i'd probably just recalculate the transform buffer as needed. i do a similar thing in my current title. vegetation is modifiable. terrain is drawn in chunks which are generated as needed from the various data structures that describe whats in the world. Any immobile object created in the world (a hut, landmark, storage pit, temporary shelter, or bedding) means the plants there should not be drawn. so whenever an immobile world object is created or destroyed, its "chunk" gets regenerated to add or remove the plants as needed.
 
when i generate a chunk, i basically do my own instancing to create the ground mesh for each ground texture tile. the "model" is a simple quad. a "pattern map" says which quads in the chunk's ground mesh use a given tile texture. for each quad that uses a given texture, the "model" is transformed to the correct x,z location in the chunk, procedurally height mapped in y, and added to a VB and IB. there's a VB and IB for each ground tile texture in the chunk. when its time to draw, i just set the ground texture and draw the VB for that texture, as the VB is already "pre-instanced" so to speak.
 
i still don't get the part about bullets and buffers though...    
2

Share this post


Link to post
Share on other sites

With the bullets, i mean this:

 

(Just an example)

 

Imagine thousands of spaceships, shooting lasers (or something) all the time, I would imagine that I would instance all bullets, wouldn't I? In that case I don't really see how I would split up each bullet up into a chunk, as they could go anywhere...

 

But Thanks!

1

Share this post


Link to post
Share on other sites

Procedural generation of vegetation typically means that you don't have to know / create all the instances before you need them. That is, when the vegetation block is close enough you can calculate what kind of foliage / vegetation should occupy the area. 

 

That means that you'll need to update your buffers dynamically. You should however split the problem a bit. Instancing and how to handle vegetation are two separate problems. 

 

Instancing just enables you to draw multiple meshes with same / similar parameters in one draw call. How you update / organize your data is a different matter.

 

I'm copying my instance data every frame from main memory to a generic float4 buffer object. Typically this means something like 1-3 megabytes of data per frame depending on the amount of instances and data required by one instance. The data transfer isn't a bottleneck if implemented correctly. This kind of arrangement allows me to cull objects pretty well (foliage and such in bigger blocks) and have exactly one draw call per mesh.

 

Cheers!

Edited by kauna
2

Share this post


Link to post
Share on other sites

note that if your vegetation doesn't change often, you can use static VB's and IB's. if it changes every frame or you recalculate every frame, then you'll want to go dynamic. so you can probably use static for vegetation, and dynamic for bullets. you'll have a VB and IB for your bullet or grass clump. then you'll have an instance buffer of world transforms for each instance you want to draw. the whole idea is to reduce the number of times you bind the instance buffer to a minimum. think of it this way: binding is bad. different binds have different costs: textures are highest (?).  then VB's, then IB's, then constant buffers. apparently the hit for constant buffers isn't that bad. can't recall if binding dynamic vs static buffers is more costly (i think so). all this info is available in the docs.

1

Share this post


Link to post
Share on other sites

With the bullets, i mean this:

 

(Just an example)

 

Imagine thousands of spaceships, shooting lasers (or something) all the time, I would imagine that I would instance all bullets, wouldn't I? In that case I don't really see how I would split up each bullet up into a chunk, as they could go anywhere...

 

But Thanks!

You are dealing with the problem of what objects worth drawing, One solution is keeping a buffer large enough only to draw the bullets near the camera and dynamically insert / remove the elements. You can specify the number of instances inside the buffer.

1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0

  • Similar Content

    • By Holy Fuzz
      I am working on a game (shameless plug: Cosmoteer) that is written in a custom game engine on top of Direct3D 11. (It's written in C# using SharpDX, though I think that's immaterial to the problem at hand.)
      The problem I'm having is that a small but understandably-frustrated percentage of my players (about 1.5% of about 10K players/day) are getting frequent device hangs. Specifically, the call to IDXGISwapChain::Present() is failing with DXGI_ERROR_DEVICE_REMOVED, and calling GetDeviceRemovedReason() returns DXGI_ERROR_DEVICE_HUNG. I'm not ready to dismiss the errors as unsolveable driver issues because these players claim to not be having problems with any other games, and there are more complaints on my own forums about this issue than there are for games with orders of magnitude more players.
      My first debugging step was, of course, to turn on the Direct3D debug layer and look for any errors/warnings in the output. Locally, the game runs 100% free of any errors or warnings. (And yes, I verified that I'm actually getting debug output by deliberately causing a warning.) I've also had several players run the game with the debug layer turned on, and they are also 100% free of errors/warnings, except for the actual hung device:
      [MessageIdDeviceRemovalProcessAtFault] [Error] [Execution] : ID3D11Device::RemoveDevice: Device removal has been triggered for the following reason (DXGI_ERROR_DEVICE_HUNG: The Device took an unreasonable amount of time to execute its commands, or the hardware crashed/hung. As a result, the TDR (Timeout Detection and Recovery) mechanism has been triggered. The current Device Context was executing commands when the hang occurred. The application may want to respawn and fallback to less aggressive use of the display hardware). So something my game is doing is causing the device to hang and the TDR to be triggered for a small percentage of players. The latest update of my game measures the time spent in IDXGISwapChain::Present(), and indeed in every case of a hung device, it spends more than 2 seconds in Present() before returning the error. AFAIK my game isn't doing anything particularly "aggressive" with the display hardware, and logs report that average FPS for the few seconds before the hang is usually 60+.
      So now I'm pretty stumped! I have zero clues about what specifically could be causing the hung device for these players, and I can only debug post-mortem since I can't reproduce the issue locally. Are there any additional ways to figure out what could be causing a hung device? Are there any common causes of this?
      Here's my remarkably un-interesting Present() call:
      SwapChain.Present(_vsyncIn ? 1 : 0, PresentFlags.None); I'd be happy to share any other code that might be relevant, though I don't myself know what that might be. (And if anyone is feeling especially generous with their time and wants to look at my full code, I can give you read access to my Git repo on Bitbucket.)
      Some additional clues and things I've already investigated:
      1. The errors happen on all OS'es my game supports (Windows 7, 8, 10, both 32-bit and 64-bit), GPU vendors (Intel, Nvidia, AMD), and driver versions. I've been unable to discern any patterns with the game hanging on specific hardware or drivers.
      2. For the most part, the hang seems to happen at random. Some individual players report it crashes in somewhat consistent places (such as on startup or when doing a certain action in the game), but there is no consistency between players.
      3. Many players have reported that turning on V-Sync significantly reduces (but does not eliminate) the errors.
      4. I have assured that my code never makes calls to the immediate context or DXGI on multiple threads at the same time by wrapping literally every call to the immediate context and DXGI in a mutex region (C# lock statement). (My code *does* sometimes make calls to the immediate context off the main thread to create resources, but these calls are always synchronized with the main thread.) I also tried synchronizing all calls to the D3D device as well, even though that's supposed to be thread-safe. (Which did not solve *this* problem, but did, curiously, fix another crash a few players were having.)
      5. The handful of places where my game accesses memory through pointers (it's written in C#, so it's pretty rare to use raw pointers) are done through a special SafePtr that guards against out-of-bounds access and checks to make sure the memory hasn't been deallocated/unmapped. So I'm 99% sure I'm not writing to memory I shouldn't be writing to.
      6. None of my shaders use any loops.
      Thanks for any clues or insights you can provide. I know there's not a lot to go on here, which is part of my problem. I'm coming to you all because I'm out of ideas for what do investigate next, and I'm hoping someone else here has ideas for possible causes I can investigate.
      Thanks again!
       
    • By thmfrnk
      Hello,
      I am working on a Deferred Shading Engine, which actually uses MSAA for Antialising. Apart from the big G-Buffer ressources its working fine. But the intention of my engine is not only realtime-rendering as also render Screenshots as well as Videos. In that case I've enough time to do everything to get the best results. While using 8x MSAA, some scenes might still flicker.. especially on vegetations. Unfortunately 8x seems to be the maximum on DX11 Hardware, so there is no way to get better results, even if don't prefer realtime.
      So finally I am looking for a solution, which might offer an unlimited Sample count. The first thing I thought about was to find a way to manually manipulate MSAA Sample locations, in order to be able to render multiple frames with different patterns and combining them. I found out that NVIDIA did something equal with TXAA. However, I only found a solution to use NVAPI, in order to change sample locations. https://mynameismjp.wordpress.com/2015/09/13/programmable-sample-points/
      While I am working on .NET and SlimDX I've no idea how hard it would to implement the NVIDIA API and if its possible to use it together with SlimDX. And this approach would be also limited to NV.
      Does anyone have an idea or maybe a better approach I could use?
      Thanks, Thomas
    • By matt77hias
      For vector operations which mathematically result in a single scalar f (such as XMVector3Length or XMPlaneDotCoord), which of the following extractions from an XMVECTOR is preferred:
      1. The very explicit store operation
      const XMVECTOR v = ...; float f; XMStoreFloat(&f, v); 2. A shorter but less explicit version (note that const can now be used explicitly)
      const XMVECTOR v = ...; const float f = XMVectorGetX(v);  
    • By Coelancanth
      Hi guys,
      this is a exam question regarding alpha blending, however there is no official solution, so i am wondering  whether my solution is right or not... thanks in advance...

      my idea:
      BS1:
      since BS1 with BlendEnable set as false, just write value into back buffer.
      -A : (0.4, 0.4, 0.0, 0.5)
      -B : (0.2, 0.4, 0.8, 0.5)
       
      BS2:
       
      backbuffer.RGB: = (0.4, 0.0, 0.0) * 1 + (0.0, 0.0, 0.0) * (1-0.5)      = ( 0.4, 0.0, 0.0)
      backbuffer.Alpha = 1*1 + 0*0   =1
       
      A.RGB = (0.4, 0.4, 0.0)* 0.5 + (0.4, 0.0, 0.0)* ( 1-0.5)   = (0.4,0.2,0.0)
      A.Alpha=0.5*1+1*(1-0.5) = 1
       
       
      B.RGB = (0.2, 0.4, 0.8) * 0.5 + (0.4, 0.2, 0.0) * (1-0.5)  = (0.3, 0.3, 0.4)
      B.Alpha = 0.5 * 1 + 1*(1-0.5)  = 1
       
      ==========================
      BS3:
       
      backbuffer.RGB = (0.4, 0.0, 0.0) + (0.0, 0.0, 0.0)  = (0.4, 0.0, 0.0)
      backbuffer.Alpha = 0
       
      A.RGB = (0.4, 0.4, 0.0) + (0.4, 0.0, 0.0) = (0.8, 0.4, 0.0)
      A.Alpha = 0
       
      B.RGB = (0.2, 0.4, 0.8) + (0.8, 0.4, 0.0) = (1.0, 0.8, 0.8)
      B.Alpha = 0
       
       
       
    • By lonewolff
      Hi Guys,
      I am revisiting an old DX11 framework I was creating a while back and am scratching my head with a small issue.
      I am trying to set the pixel shader resources and am getting the following error on every loop.
      As you can see in the below code, I am clearing out the shader resources as per the documentation. (Even going overboard and doing it both sides of the main PSSet call). But I just can't get rid of the error. Which results in the render target not being drawn.
      ID3D11ShaderResourceView* srv = { 0 }; d3dContext->PSSetShaderResources(0, 1, &srv); for (std::vector<RenderTarget>::iterator it = rtVector.begin(); it != rtVector.end(); ++it) { if (it->szName == name) { //std::cout << it->srv <<"\r\n"; d3dContext->PSSetShaderResources(0, 1, &it->srv); break; } } d3dContext->PSSetShaderResources(0, 1, &srv);  
      I am storing the RT's in a vector and setting them by name. I have tested the it->srv and am retrieving a valid pointer.
      At this stage I am out of ideas.
      Any help would be greatly appreciated
       
  • Popular Now