I am using DeckGL with react, and i had a question about best practices considering the amount of Deck instances. One option is to add all layers in a single Deck instance, for example:
<DeckGL layers={[layerA, layerB, layerC, layerD]} />
Or to split them between diffrent instances, for example:
<DeckGL layers={[layerA, layerB]} />
<DeckGL layers={[layerC, layerD]} />
The second approach lets you incapsulate diffrent deck instances:
const RegionsLayer = () => <DeckGL layers={[layerA, layerB]} />;
const WeatherLayer = () => <DeckGL layers={[layerC, layerD]} />;
does one approach have a performance advantage compared to the other?
I did both approaches, in basic usage both work well.
Sharing the answer i got from ibgreen in the deck gl repository discussion.
"There are no practical advantages to having two DeckGL instances other than if you absolutely need to draw into two separate canvases. Not that deck.gl has a view system to let you draw multiple views into a single canvas.
You'll avoid duplicated overhead with a single deck.gl instance (= single WebGL context), both in terms of GPU and CPU memory as well as browser resources. Things like offscreen GPU buffers for picking etc add to that overhead.
The performance and memory savings of using two views in a single deck instance become more significant if you share layers between the two instances. Less pronounced if each instance shows independent data and layers..
Also be aware that browsers have a limited number of WebGL contexts, so there is a fairly small limit to how many Deck instances you can have."
Related
Is it an acceptable practice to recreate RenderPass(es) every frame?
In a maximally dynamic engine, a frame's composition could vary wildly from one frame to the next. One frame could require completely different RenderPasses/Subpasses from the one before.
Also, to implement something like the FrameGraph of the Frostbite engine, doesn't that necessitate (potentially) recreating the RenderPass every frame?
https://www.gdcvault.com/play/1024612/FrameGraph-Extensible-Rendering-Architecture-in
I'm not sure how expensive the creation of RenderPasses could be in different devices, like between Desktop and Mobile.
This question is somewhat unanswerable as stated. How to architecture your engine and which compromises you take is bit opinion-based. And every function (that is not a no op) is technically less expensive if called outside render loop, than every time inside inside render loop. It is just a matter of whether it is viable to call these outside every frame from functional and architectural concerns of your codebase.
Simply treat vkCreateRenderPass and vkCreateFramebuffer as potentially expensive operations. Those functions are two opportunites for the driver to form an optimization strategy (which can be relatively expensive). So keep them outside a hotspot, if you can. Additionally, it is possible to cache them, even when created inside a frame.
It should be somewhat less expensive for contemporary desktop GPUs, and somewhat more expensive on mobile (resp. tiler) GPUs. But that is subject to change across GPU generations, and perhaps even across driver versions.
I am in a serious need of optimization of my some Unity projects and i have so many objects which are from 3DsMax, so i am wondering if Combining the meshes would have any effect on the memory/performance or i should leave the objects Instance to each other as it would save me some space.
This arise the question that what is the difference between Combined mesh objects or Instance Objects as it will save a lot of memory and hassle if one realy knows the difference and what is better
Looking forward for some Brief information about the two
Thanks
Combining is useful if you have a lot of unique assets that only appear once or twice in a scene, e.g unique buildings in a 3D FPS, but not cloned houses in a SimCity style game. If you have a model that appears many times in a scene it's more performant to have Unity (automatically) batch them, this is Unity's default behaviour. e.g lets say your scene is in an art gallery; if the gallery contains a dozen distinct sculptures then combine them. If it contains a dozen of the same sculpture don't bother, Unity will batch them for you.
However, you should be wary of using different materials, each material adds to the draw count. So, if you had 10 of the same model but using 5 different materials it's going to be expensive. The way round this is to use a texture atlas with a single material, with different UV mapping for each models. This means you have a lot of different models, but save on render time due to the single material.
Also, be aware that transparent shaders much more expensive than opaque, if you have three semi transparent objects in front of each other that's at least 4 render passes.
As you probably know this is a complex subject with a lot of variables (many more than I can describe here) and is best judged by using the profiler.
Here are some general rules of thumb I've learned while creating a game for mobile which naturally is performance critical:
Use as few a materials as possible
Use as fewer textures as possible, share textures between materials
Recycle models as often as possible. Often a model oriented at a different angle or in a different material can look like a whole new model to the player, particularly if their attention is elsewhere in the game
Use LODS extensively
Ensure your models are clean, remove all unnecessary vertices before importing
After importing think if there's anything about the model that could be represented with less vertices
Good use of normal mapping can pay off, depending on the platform. If you can trade in 1000 verts for a 256 px normal map and 50 verts then do it, otherwise dont bother normal mapping just to save a few verts
I created a tutorial that explains draw calls, static batching, lightmapping etc.
https://www.youtube.com/watch?v=x0t2xylbTo8&t=253s
In my upcoming iPhone game different scene elements are split up into their own CCNode.
My Obstacle node contains many nodes, each representing an obstacle. Inside every obstacle node are the images that make up the obstacle (1 - 4 images), and there are only ~10 obstacles at a time. Every update my game calls the update function in the Obstacle node, which moves every obstacle to the left. But this slows down my game quite a bit.
At the same time, I have a particle node that just contains images and moves them all every frame exactly the same way the Obstacle node does, but it has no noticeable effect on performance. But it has hundreds of images at a time.
My question is why do the obstacles slow it down so much but the particles don't? I have even tried replacing the images used in the obstacles with the ones in the particles and it makes no (noticeable) difference. Would it be that there is another level of child nodes?
You will dramatically increase the app's performance, run speed, frame rate and more if you put all your images in a texture atlas and rendering them once as a batch using the CCSpriteBatchNode class. If you are moving lots of objects around on the screen a lot, this makes the hardware work a lot less.
Using this class is easy. Create the class with a texture atlas that contains all your images, and then add this class as a child to your layer, just as you would a sprite.
However, when you create sprites, add them as children to this batch node, not as children to the layer.
It's very easy and will probably help you quite a lot here.
From what I recall of the Cocos2d documentation, particles are intended to be VERY lightweight so you can have many, many of them on screen at once. Nodes are heavier, require more processing between frames as they interact with the physics system and requiring node-specific rendering. The last time I looked at the render loop code, it was basically O(n) based on the number of CCnodes you had in a scene. Using NSTimers versus Cocos' built in run loop also makes quite a bit of difference in performance.
Could you provide an example of something that slows down a lot? Exactly how do you update these Obstacles?
The cocos2d documentation has some best practices that all, in one way or another, touch on performance. There's a LOT you can do to optimize your frames per second.
In general, when your code is slow, it helps to use Instruments.app to figure out where your code is spending so much time. Since you're using a framework this will be less helpful because you'll end up finding out what functions your code spends a lot of time in, and then figure out how to reduce that via the framework's best practices or other optimizations. There are a few good blog posts on improving performance, I found this one very helpful.
A colleague and I are talking about how scenes are typically rendered in complex games. He believes the world is rendered recursively in the truest object-oriented fashion, with the world's many actors each overriding a virtual function like Actor.Draw() (e.g. Koopa.Draw(), Goomba.Draw()).
By contrast, I imagined that complex games today would iterate over their scene graph, avoiding virtual function overhead and allowing more flexibility for specialized iterators (e.g. near-to-far vs. far-to-near, skipping certain objects in the tree, etc.) And my experience with OpenGL and DirectX suggested to me that they tend to draw objects in batch, and passing a batch context through a recursive call (i.e. the batch into which a class's Draw() function would draw) seemed like additional parameter-passing overhead that could be avoided with iteration.
Is one method favored over another nowadays? If so, why?
Updating parts of a scene graph might be done recursively. But drawing it is usually done via some spatial partitioning data structure and geometry/render-state batcher in order to prevent overdraw (by drawing front to back), and minimize state switches of the rendering pipeline (batching up data, draw calls that use similar resources and render states). Usually this drawing part is in a way, iterative.
You have to take into account how complex the scenes are, their composition, and how many objects are being drawn. For projects with simpler scenes or where you have certain information beforehand, sequencing your rendering (near-)optimally will not be worth the actual cost of calculating the drawing sequence or batching.
In the end the "favored" method would be project-specific.
Summary
New to iPhone programming, I'm having trouble picking the right optimization strategy to filter a set of view components in a scrollview with huge content. In what area would my app gain the most performance?
Introduction
My current iPad app-in-progress let's users explore fairly large binary tree structures. The trees contain between 30 to 900 nodes, and when drawing inside a scrollview (with limited zoom) it looks like this.
The nodes' contents are stored in a SQLite backed Core Data model. It's a binary tree and if a node has children, there are always exactly two. The x and y positions are part of the model, as are the dimensions of the node connections, shown as dotted lines.
Optimization
Only about 50 nodes fit the screen at any given time. With the largest trees containing up to 900 nodes, it's not possible to put everything in a scrollview controlled and zooming UIView, that's a recipe for crashes. So I have to do per frame filtering of the nodes.
And that's where my troubles start. I don't have the experience to make a well founded decision between the possible filtering options, and in addition I probably don't know about that really fast special magic buried deep in Objective-C or Cocoa Touch. Because the backing store is close to 200 MB in size (some 90.000 nodes in hundreds of trees), it's very time consuming to test every single tree on the iPad device. Which is why I'd like to ask you guys for advice.
For all my attempts I'm putting a filter method in the scrollViewDidScroll: and scrollViewDidZoom:. I'm also blocking the main thread with the filter, because I can't show the content without the nodes anyway. But maybe someone has an idea in that area?
Because all the positioning is present in the Core Data model, I might use NSFetchRequest to do the filtering. Is that really fast though? I have the idea it's not a very optimized method.
From what I've tried, the faulted managed objects seem to fit in memory at once, but it might be tricky for the larger trees once their contents start firing faults. Is it a good idea to loop over the NSSet of nodes and see what items should be on screen?
Are there other tricks to gain performance? Would you see ways where I could use multi threading to get the display set faster, even though the model's context was created on the main thread?
Thanks for your advice,
EP.
Ironically your binary tree could be divided using Binary Space Partitioning done in 2D so rendering will be very fast performant and a number of check close to minimum necessary.