Reducing draw calls for sprites in a 3D scene

Hey all,

Curious what the workflow is for optimizing sprites in a 3D scene. Obviously when it comes to 3D objects in a scene you have options like batch groups, lower amounts of materials, frustum culling etc…

What should I be doing for animated sprites that are in a 3D scene? I’m using sprites to simulate a crowd in stadium seating and am pasting the same sprites around a lot. It’s not using an insane amount of draw calls for a pretty good effect but was just curious if there is any optimization I should/could be doing since this is for low-end mobile devices

You can use hardware instancing for a crowd effect like this.

Hardware Instancing | Learn PlayCanvas and engine example:

Let’s assume there are 3 frames for the animation and 300 crowd people.

You would have 100 instances of frame 1 as a plane with a material, 100 instances of frame 2 and 100 instances of frame 3.

Then you would swap them around to simulate sprite animation. ie move frame 2 instance positions to where frame 1 instances are, frame 3 to frame 2 and frame 1 to frame 2.


Thanks for the response. I’ll try to implement this.

In the documentation you linked it says:

“Each instance of the mesh can have a different limited amount of state (for example, position or color).”

It gives the example of position and color as attributes that can differ between objects. Is there a complete list of what can differ between meshes?

Also in your example… would that shake out to 3 draw calls added to the scene? 1 per frame?

Thanks again!

With hardware instancing you can have unique position, rotation and scale per instance just by filling the array buffer showed in the example.

There is also space for a 4th attribute without adding a new vertex buffer, but still you will need to write a custom shader to use that (e.g. for diffuse color). If you are determined to have more attributes, that’s doable with a custom vertex buffer.

Here is a related post about custom colors per instance using HW instancing:


In theory, yes

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