Enhancing Unity Game Performance with Universal Render Pipeline (URP)

The Universal Render Pipeline (URP) is a powerful tool that can significantly improve the performance of your Unity game. By leveraging its features and implementing optimisation techniques, you can create a smoother and more responsive gaming experience. In this article, we’ll explore key strategies for performance tuning in Unity games using the URP pipeline. When I started using unity, I had no idea what it was that I was missing, so to help you get started, here are a list of things any Unity developer should know about, and look up.

Utilise GPU Instancing

GPU instancing allows multiple objects with the same material to be rendered in a single draw call. This reduces the overhead associated with making separate draw calls for each object.

void Start()
{
    Renderer renderer = GetComponent<Renderer>();
    if (renderer != null)
    {
        renderer.material.enableInstancing = true;
    }
}

Optimise Shaders

URP offers a Shader Graph that allows for visually designing shaders. Keep these tips in mind:

• Simplify Shaders: Avoid complex operations in shaders, especially within fragment shaders.
• Use LODs for Shaders: Employ Level of Detail techniques for shaders to reduce complexity for distant objects.

Texture Compression and Atlasing

Optimise textures to reduce memory usage and enhance rendering performance:

• Use compressed texture formats like ASTC, BC7, or ETC2.
• Combine multiple textures into atlases to reduce draw calls
  • Generate or Collect Textures: Gather the individual textures you want to include in the atlas.
  • Create Atlas Texture: Use a graphics editing tool (e.g., Photoshop) to create a new image file, which will serve as the atlas.
  • Arrange Textures: Place the individual textures within the atlas, organizing them to minimize wasted space.
  • Import into Unity: Import the atlas texture into your Unity project.
  • Apply Atlas to Materials: Modify materials to use the atlas texture instead of individual textures.
  • Adjust UV Mapping: Ensure that UV mapping for the objects corresponds correctly to the atlas.

Implement Occlusion Culling

Occlusion culling prevents the rendering of objects that are not visible to the camera. This reduces GPU workload.

Level of Detail (LOD)

LOD techniques involve using lower-polygon models or simplified textures for distant objects. URP provides tools for LOD implementation.

Prepare LOD Models

• Create simplified versions of your object with fewer polygons for varying distances.

Add LOD Group

• Select the object in the Hierarchy.
• Add the LOD Group component.

Assign LOD Levels

• In the LOD Group, add LOD levels and assign corresponding models.
• Set Screen Relative Transition Height for each level.

Test and Adjust

• Enter Play mode to observe LOD switching.
• Fine-tune transition distances if needed.

Optimise LOD Models

• Ensure LOD models are well-optimised for performance.

Verify Performance

• Test on different devices to ensure desired performance improvements.

LOD is effective for objects like terrain, foliage, and complex structures. Apply it to objects with a significant impact on performance.

Particle System Optimisation

Efficiently managing particle systems is crucial for performance:

• Limit the number of particles emitted at a time.
• Use GPU simulation if suitable for your project.

Minimise Overdraw

Overdraw occurs when multiple transparent objects are rendered on top of each other. This can be mitigated with techniques such as:

• Sorting objects by depth to minimise overdraw.
• Utilizing techniques like depth pre-pass.

Optimise Post-Processing Effects

Post-processing effects can be resource-intensive. Consider:

• Disabling or reducing the intensity of non-essential effects.
• Using URP’s built-in optimisations for post-processing.

GPU-Driven Rendering

URP leverages GPU for various rendering tasks. Maximize its potential by utilizing Compute Shaders and other GPU-driven techniques.

Test on Target Hardware

Always test your game on the actual target hardware to ensure optimal performance. This allows you to uncover platform-specific issues and fine-tune accordingly.

Conclusion

Leveraging the Universal Render Pipeline in Unity provides a powerful set of tools for optimising game performance. By utilizing GPU instancing, optimising shaders, managing textures efficiently, and implementing various other techniques, you can create a high-performing game across a range of devices. Remember, continuous testing and iteration are crucial for achieving the best possible performance.