Unity technical manual - preliminary performance optimization

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Premise

This is what Xiao Kong insisted on writing Unity Novice series , Welcome to taste .

Xiao Kong, for the convenience of more people （ Novice ） See through , Chinese characters used , Try to use English rules for real projects .

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The particle section is a series of articles , And the introduction was very detailed , Suggest Collection .

Practice process

Why can cross platform ？ Why is the package released so big ？

because Unity Built in Mono virtual machine , The reason why she can cross platform is because you wrote Unity The procedure is in Mono Running on a virtual machine . Virtual machines are cross platform . While being convenient, it will also increase resources , This may lead to subsequent worries about the operation card .

for instance ： If you don't wear clothes , Do you just stay at home and don't go out ？ At this time, you weigh so little , But you suddenly put on your clothes , At this time, you can go to any place outside , Correspondingly, you gained a little weight when you weighed .

Xiaozhi ： What is? Draw call？
She is CPU The call of graphic drawing interface ,CPU By calling the graphics library （DirectX、OpenGL） Interface , command GPU Render , therefore Drawcall The greater the number of times, the greater the performance consumption .
So what is the reason for the consumption ？
In this era of parallelism ,CPU and GPU It is also an independent and independent parallel work , Maintain a queue through a buffer ,CPU Give orders ,GPU Carry out orders . The difference lies in ：
CPU Calling DrawCall front , It takes a series of physical labor to prepare .
GPU Her own computing ability is her strong point （ Artificial intelligence training is widely used GPU The calculation verifies this point ）- So the rendering task is completed very quickly .
It's like printing with a printer , You need to prepare the contents to be printed in advance （ This is time-consuming ）, Then just send the pages to be printed to the printer , The printer will handle the printing itself .CPU Just as you prepare the printed content DrawCall The content of , then CPU Will be ready to draw “ page ” Pass to GPU
So it will cause a strange phenomenon ：
GPU： come quick , come quick , I'm too busy , I also want , I'm ready to absorb , Let it go .
CPU： no way , no way , I'm so tired , Too much work , A little empty .

Xiaozhi ： How to optimize the ？
Now that we know it is CPU under pressure , And what causes stress is DrawCall On the preparation of , So the starting point of optimization is to reduce DrawCall.
Will be made of the same material , Same map , Same as shader Try to merge the meshes of
Avoid using a large number of small meshes , if necessary , Consider merging
Avoid using too many materials , Try to share
Consolidation is also a cost , Try not to merge at run time
Mesh merge vertices have an upper bound

Xiaozhi ： Elder brother , I know everything , But the key is how to operate , How about something practical .

Xiaozhi ： Is this really the case ？
Xiaokong ： Otherwise it is , Reduce DrawCall It's a more general statement .
Xiaozhi ： Then you farted for a long time .
Xiaokong ： Although lower DrawCall It works , but drawcall It's not unity A direct measure of efficiency is actually ,drawcall Of itself call The process consumption is relatively low , The high cost is drawcall The change process of the object set and the processing process of each object in the set , such as dynamicbatch and staticbatch identical drawcall The performance varies greatly .
stay Unity The statistics box of has a 【SetPass calls】 Of , It is more accurate to use this to measure performance .

author ： Xiaokong and Xiaozhi Xiaokong

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