MonoGame/MonoGame

GraphicsDevice.SetVertexBuffers generating garbage every frame due to params option

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#6,728 opened on May 4, 2019

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Description

I came across this issue when I decided to profile my (in progress) game and discovered I was generating a ton of VertexBufferBinding[] arrays during the Draw() call.

It appears as though the API GraphicsDevice.SetVertexBuffers(params VertexBufferBinding[] vertexBuffers) is generating garbage every frame due to the params option.

An example of using this API would be instancing viz.

SetVertexBuffers(vertexBinding, instanceBinding);

The params option generates a new array on every call which then needs to be garbage collected.

There is currently a workaround i.e. creating a static array and passing that to the API e.g.

VertexBufferBinding[] bindings = new VertexBufferBinding[2]; bindings[0] = blah; bindings[1] = blah;

SetVertexBuffers(bindings);

However, it's pretty easy to miss this issue, so it would probably be best to clean up the APIs to remove the params option and have a couple different API signatures e.g. one that takes a statically defined array and one that takes in both 1 VertexBufferBinding and 2 VertexBufferBindings, since those would be the most common use cases.

What version of MonoGame does the bug occur on:

  • MonoGame 3.7.1

What operating system are you using:

  • Windows

What MonoGame platform are you using:

  • DesktopGL, WindowsDX

Contributor guide

Tech stack
csharp
Domain
performance
Issue type
performance
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
C#MonoGamegarbage collectiongraphics API
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
The issue is about the `SetVertexBuffers` method in the `GraphicsDevice` class generating garbage due to the `params` keyword. The fix involves removing the `params` overload and adding explicit overloads for common cases (e.g., one or two bindings). Look at the relevant source files like `GraphicsDevice.cs` in the MonoGame repository. Check the existing overloads and ensure backward compatibility. Comments in the issue may provide additional insights on implementation.