Three.js: InstancedBufferGeometry.instanceCount incorrectly

[sanddyl]

Description of the problem

When I changed InstancedBufferGeometry.instanceCount, I found that the _maxInstanceCount not changed. This will cause the InstancedBufferGeometry to display incorrectly.

Three.js version

• [ ] Dev
• [x] r117
• [ ] ...

Browser

• [x] All of them
• [ ] Chrome
• [ ] Firefox
• [ ] Internet Explorer

OS

• [x] All of them
• [ ] Windows
• [ ] macOS
• [ ] Linux
• [ ] Android
• [ ] iOS

Hardware Requirements (graphics card, VR Device, ...)

[WestLangley]

@sanddyl Can you please provide a simple, live demo to show exactly what you did to cause the issue?

[sanddyl]

@sanddyl Can you please provide a simple, live demo to show exactly what you did to cause the issue?

https://jsfiddle.net/s3xco4hk/95/

[WestLangley]

You are resizing the attribute buffer. That is not supported.

See https://threejs.org/docs/#manual/en/introduction/How-to-update-things.

/ping @Mugen87 for confirmation.

[sanddyl]

You are resizing the attribute buffer. That is not supported.

See https://threejs.org/docs/#manual/en/introduction/How-to-update-things.

/ping @Mugen87 for confirmation.

I quite agree,but when I need to modify maxInstanceCount, instanceCount can not achieve my purpose, even if this is rare. I mean, the instanceCount in version 117 is not equal to the maxInstancedCount in the previous version.

[sanddyl]

You are resizing the attribute buffer. That is not supported.

See https://threejs.org/docs/#manual/en/introduction/How-to-update-things.

/ping @Mugen87 for confirmation.

Maybe both maxInstancedCount and instanceCount are required.

[Mugen87]

Yes, buffers can't be resized. The idea is to create a sufficiently sized buffer and then control via drawRange or instanceCount (when using InstancedBufferGeometry) the rendering. This approach is demonstrated by webgl_buffergeometry_instancing.

Maybe both maxInstancedCount and instanceCount are required.

Nope. It does work by just using instanceCount. Check out how the updated fiddle controls the amount of rendered instances.

https://jsfiddle.net/brs1f5oa/

[sanddyl]

Thanks a lot ! I will avoid such problems in the future.