Unity Performance Tips: Draw Calls

hi in today's video i'm going to tell you something i wish i knew when i started making games which will help us go from this to this without sacrificing visual quality so here we have a simple building it has three materials one for the roof windows and walls each window is a separate object let's bring it into unity and make say five thousand of them and oh dear so why does this scene run so badly well first we need to talk about draw calls a draw call tells your gpu to render a mesh if we have one mesh that's one draw call if we have three meshes that's three draw calls additional draw calls are also created for each material on each mesh if we have one mesh with two materials that's two draw calls if we have three meshes with two materials that's six it's easy to see how draw pulls can start to add up fast so why is this a problem well each call has to be processed by the cpu before being sent to the gpu imagine it like a funnel if we only have a few draw calls the cpu can get through them quickly however if we have too many the cpu takes far too long to process them which is what results in our low frame rate so what can we do to reduce the number of draw calls the first thing we can do is combine meshes in blender select everything and press ctrl j to join objects bear in mind that the last object selected will be the new origin in maya select everything and go to mesh combine you should do this for all objects in your game the only exception should be when parts need to move independently i'd recommend saving this as a separate file so it's still easy to edit later on it's worth mentioning that this only helps performance with meshes that share the same material if we jump back to unity and see how this performs now all of a sudden we're getting a pretty respectable frame rate we've gone from half an fps to about 80. so why does this happen well rather than each window being its own draw call now all windows on each building are a single draw call if we want to see the number of calls inside unity then in play mode we can click stats up the top right and look for batches we can see we've gone from 1.6 million batches down to 20 000 however we can do better which brings me to my second tip reduce the number of materials generally speaking objects should only have one material there are a couple of exceptions however if you need different shaders or tiling textures they can have their own materials here i have given our building a single material with a texture to color the different parts and if we jump back to unity we're now getting about 180 fps which is pretty impressive however there's one more thing we can do to improve performance further and that is batching batching works by combining meshes in unity into a single mesh before being sent to the gpu which significantly reduces the number of draw calls batching will only work on objects with the same material now there's two ways of batching we can control the first is static batching this can be enabled by selecting objects and ticking the static checkbox at the top right if you want to exclude these objects from navigation or bait lighting you can use the drop down this can only be used on objects that will not move in your game which brings me to my third tip if an object isn't going to move mark it as static if we take a look back at our scene with static enabled on our buildings we can see that our frame rate is now up to 210. now you might be wondering what can we do if we want to batch moving objects well we have another option called gpu instancing gpu instancing only works for objects with both the same mesh and the same material enabling it is as simple as a checkbox in the material and if we look back at our scene we're getting the same great frame rate and as an added bonus we can now make our buildings move which is our fourth tip use gpu instancing where appropriate you can't use gpu instancing at the same time as static batching in that case those objects are excluded from static batches and will just be gpu instanced so choose which one best suits your use case so to go over our tips again combine meshes in your modeling program reduce the number of materials if an object isn't going to move mark it as static and use gpu instancing where appropriate hopefully these tips will prove useful in improving the performance in your own games if you want to learn more about making the most of unity consider subscribing to the channel thank you for watching and i'll see you in the next one

Channel: Lofi Dev

Views: 23,521

Keywords: unity, game development, blender, maya, unreal, 3d, gaming, games, performance, frame rate, optimization, level design, game art

Id: IrYPkSIvpIw

Length: 4min 23sec (263 seconds)

Published: Sat Dec 26 2020