UnityURP-InfiniteGrass

Fully Procedural and Dynamic Grass for Unity URP. This repository is structured as a Unity Package (UPM).

It meant to be a fast to implement grass system that doesn't need any baking or having any static environemnt.
Just enable it, give it the LayerMask of the objects where you want it to be, and everything gets drawn procedurally.

Preview Video

Tested on RTX 3060: https://youtu.be/NwVtPIxUuCY

How to Use

Install this repository as a Git package through the Unity Package Manager then add the "GrassDataRendererFeature" to your URP Renderer.
From there choose the LayerMask of your Terrain mesh.
Assign the Material and the ComputeShader (included in the package).

Next, in your scene, make an empty object and add the "InfiniteGrassRenderer" script to it.
Assign the Grass Material (included in the package) and play with the settings until you get what you want.

Features

Fully Procedural:

You don't need to have a HeightMap or use the Unity Terrain, you can put grass on anything just by changing the LayerMask of it.
Also it doesn't require generating a big buffer of positions of the whole world, it generates just the necessary amout of positions around the camera so the Memory isn't a big concern.

Frustum Culling and Smooth Density Falloff:

Grass density now fades out smoothly from the camera position to the draw distance. Each cell uses a stable random threshold so blades disappear only once as you move, preventing flickering in the distance and giving a natural transition. Use the Density Falloff Exponent parameter on the InfiniteGrassRenderer component to control how gradual the fade is.

Dynamic Color Modifier:

It allows you to modify the color of the grass blades using any object or texture you want.
To make you own color modifier, create a new material from "InfiniteGrass/Modifiers/GrassColoringShader", give the material a texture and a color.
Finally, add a quad mesh to your scene and apply the material to it, you can then place the object wherever you want with any scale or rotation like a Decal.
There is no problem also in using Particle Systems with that shader like the waves in the preview video.

Dynamic Mask and Density:

Just like the color modifier, just make a material from "InfiniteGrass/Modifiers/GrassMaskShader" and apply it to a quad or any other mesh.
Just note that the usual meaning of "mask" here isn't what it's used, White means the grass will fully be cutout, Black means full density.
You can also instead of fully cutting out the grass make the density decrease by making the material "Opacity" property lower.
(The Red Channel of the VertexColor of your meshes also occludes the grass).

Dynamic Slope:

By "Slope" I mean the inclination of the grass blade.
It's just a simple modifier like others, just make a material and apply it to a quad, but this time the color will describe the direction where the grass blade will be directed to.
Red controls how much the grass is inclined to the X axis (0: it will go to the -x, 1: it will go to the x, 0.5: it will stay upward).
Green controls how much the grass is inclined to the Z axis (0: it will go to the -z, 1: it will go to the z, 0.5: it will stay upward).
There is no need to use the blue channel cause the grass can't be inclined to the Y axis (it just mean it's upward).
This is usefull if you want to make Custom Wind effects, Explosions, Stepping on grass ...
There is an example of each of these in the Sample Scene.

Wind System:

Wind from texture, similar to the "Dynamic Slope" but just applied to the whole grass field.

Stylized Billboard Grass:

The grass blades are always (atleast trying) to look to the camera from all angles.
The material includes a lot of parameters to customize the look. Increasing Expand Distant Grass Width helps the thin distant blades blend more smoothly before they fade out.

Performance Optimizations

Tip	Why it helps
Update the height/mask/ color/ slope textures only when the camera has moved farther than Texture Update Threshold	Skips the four raster passes on frames where nothing in view has changed.
Dispatch the compute shader at half-rate (e.g. every second frame) on high-end GPUs	The grass position buffer often stays valid for two frames without artefacts, halving compute cost.
Quantise the camera-space centre to the grass cell size	Ensures cache-friendly reuse of generated cells and avoids frequent buffer resets.
Use UNITY_VERTEX_OUTPUT_STEREO only when XR is enabled	Removes the extra instancing overhead for mono rendering.
Pack the height and mask into a single R16G16 texture	Reduces tile memory pressure compared with two separate resources.
Early-out in the fragment shader when the blade normal faces away from the light by more than 120 °	Saves ALU on back-lit blades that will be alpha-faded anyway.
Switch distant blades to an unlit material variant once they cross the half draw-distance	Removes per-pixel lighting for the majority of on-screen grass while keeping near blades fully shaded.
Use MaterialPropertyBlock to push per-camera wind parameters	Avoids creating material instances and keeps SRP batching intact.
Batch GraphicsBuffer.CopyCounterValue calls together	Minimises command-buffer stalls caused by counter queries.
Enable Hi-Z culling in the compute shader (sample the depth pyramid before appending a position)	Prevents blades that are fully occluded by terrain or large objects from ever being generated.
Strip shader variants that keep unused colour or slope channels	Shrinks build size and slashes shader warm-up time at launch.

Visual Optimizations

• Use an alpha value to fade out distant blades instead of fully cutting them out.
• Nearby grass should blend smoothly into the terrain texture.