Unity URP Mobile Draw Mesh Instanced Indirect Example by ColinLeung-NiloCat - 2

MobileGames & Projects

Example project to draw 1million grass instances on mobile

Unity 2019.4.15f1MIT LicenseUpdated 146 days agoCreated on July 24th, 2020
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youtube runtime demo video: https://youtu.be/A7rav4tS88s
download .apk, try it on your android phone: https://drive.google.com/file/d/185JWZXYPnVyDnA451cEZkS2H2wOYSce_/view

DrawMeshInstancedIndirect ON screenshot DrawMeshInstancedIndirect ON (grass bending) screenshot screenshot DrawMeshInstancedIndirect OFF screenshot

Why create this repository?

To demonstrate an API that can draw millions of instance -> DrawMeshInstancedIndirect(), running on mobile devices.

Can this demo runs on midrange mobile?

  • can handle 10 million instances on Samsung Galaxy A70 (GPU = adreno612, not a strong GPU), 50~60fps, performance mainly affected by visible grass count on screen(draw distance = 125)
  • can handle 10 million instances on Lenovo S5 (GPU = adreno506, a weak GPU), 30fps, performance mainly affected by visible grass count on screen(draw distance = 75)


if you want to try the pre-built .apk, your android device must support Opengles3.2 / Vulkan
download .apk: https://drive.google.com/file/d/185JWZXYPnVyDnA451cEZkS2H2wOYSce_/view

Where are the important files





This is a simplified example repository to demonstrate DrawMeshInstancedIndirect API on mobile platform.
This repository is as simple as possible, only contains a simple CPU cell frustum culling(not even a quadtree) -> minimum compute GPU frustum culling (no Acceleration Algorithms), then just 1 DrawMeshInstancedIndirect call, nothing else, code is very short.

Lighting and animation is not the main focus of this project, but ~40% of the time was spent on writing grass shader’s lighting & animation, you can have a look at InstancedIndirectGrass.shader if you are interested.

This repository also contains a RendererFeature(GrassBendingRTPrePass.cs) to render an offscreen RT(R8), which renders top down view grass bending area (by trail renderer following moving objects), it is a very simple method but the result is good enough for this demo.


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