Reverse-Z state problem

[eXponenta]

Description

Reverse Z PR not fully correctly implement reverse-Z.

Problem in state:

three.js/src/renderers/webgl/WebGLCapabilities.js

Line 100 in 0c7cf78

ext.clipControlEXT( ext.LOWER_LEFT_EXT, ext.ZERO_TO_ONE_EXT );

This flag applied in capabilities that persistent after initialisation, that is wrong due to context sharing.

ThreeJS state can be flushed for some specific cases like a 1 contex for N-renderers or libs.
For ex: Three + PIXI, Three + WebXR emulator, Three+potree.

WebGLState has reset for that:

three.js/src/renderers/webgl/WebGLState.js

Line 1152 in 0c7cf78

function reset() {

Because clipControl is context-related three also should reset this state and change it when needed back

@CodyJasonBennett can you apply some changes and move call of clipControl into WebGLLState instead of WebGLCapabilities?

@Mugen87 what you think about that?

Reproduction steps

Code

Live example

Screenshots

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Version

r169

Device

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Browser

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OS

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[eXponenta]

Also we have state problem with clearDepth:

Reverse Z upgrade depth inside renderer:

three.js/src/renderers/WebGLRenderer.js

Line 597 in 0c7cf78

_gl.clearDepth( this.capabilities.reverseDepthBuffer ? 0 : 1 );

BUT Three has state for that:

three.js/src/renderers/webgl/WebGLState.js

Line 190 in 0c7cf78

gl.clearDepth( depth );

ReversedZ will broke state upgrade, because clear value will always 0 or 1.

[CodyJasonBennett]

This flag applied in capabilities that persistent after initialisation, that is wrong due to context sharing.

ThreeJS state can be flushed for some specific cases like a 1 contex for N-renderers or libs.
For ex: Three + PIXI, Three + WebXR emulator, Three+potree.

How could this happen? Do they have a different WebGL implementation than the browser or are still using WebGL 1?

Because clipControl is context-related three also should reset this state and change it when needed back

I can agree with this and your changes in #29579. I would much prefer if renderer.capabilities had some hint as to what the context supports. Not sure anyone is using that though since this feature is so new.

[eXponenta]

How could this happen? Do they have a different WebGL implementation than the browser or are still using WebGL 1?

Simple case:
Potree is outdated library that use parts of threejs with manual state switch, it not know about reverse-Z at all.
For potree to important use valid depth info because it use postprocess for resolve dom lighting.

https://github.com/potree/potree/blob/develop/src/materials/shaders/edl.fs#L38

But in general a reverseZ must have for BIMs ( cad system ), because BIMs have billions of near placed polygons on non-normalized space( about 10000x10000 metres with step in 10sm ). Without reverseZ we to tired use hacks that reducing z-fights.

[mrdoob]

/fyi @m-schuetz