* Clean up

* Update screenshot

* MeshPhysicalMaterial: Fix refraction

* Update screenshot

* Add specularStrength and specular to MeshPhysicalMaterial

* GLTFLoader: Add KHR_materials_specular support

* Add specularStrength and specular to GUI in webgl_materials_physical_transmission example

* Update webgl_loader_gltf_transmission example

* Update example screenshot

* MeshPhysicalMaterial: Rename specularStrength and specular to specularIntensity and specularTint

* Add 4 eye charts to demonstrate the effects of mipmaps on text.
* Add a GUI to demonstrate interacting with layers.
* Improve info text and add more comments.
* Add a preview screenshot.

Tested:
  * Oculus Quest 2 shows layers properly.
  * Chrome on Windows shows error message.
Co-authored-by: NSameer Padala <sameer@padalas.net>

* WebGLRenderer: Integrate PMREM

* Examples: Update screenshot.

* GLTFLoader: Add KHR_materials_volume and KHR_materials_ior extensions support

* Update example screenshot

* Add preliminary support for WebXR Layers

* WebXR Layers: rename sample

* Resolve merge conflicts for WebXR Layers

* Update WebXRManager.js

Clean up.

* Update webxr_vr_layers.html

Correct title.
Co-authored-by: NRik Cabanier <cabanier@fb.com>
Co-authored-by: NMichael Herzog <michael.herzog@human-interactive.org>

* TransformControls: Redesigned translation/scale modes and increased line thickness

* Editor: Pass devicePixelRatio to TransformControls

* Examples: Pass devicePixelRatio to TransformControls

* Examples: Clean up

* TransformControls: Fixed lineGeometry2

* Revert "Editor: Pass devicePixelRatio to TransformControls"

This reverts commit 8d8a26bdc739f3ba8902f6a571371fa98d5735de.

* Revert "Examples: Pass devicePixelRatio to TransformControls"

* TransformControls: "Backwards compatible" size

* Updated example screenshots

* Clean up

* Update screenshot

* Clean up

* Update screenshot

* Clean up

* Update screenshot

* Improve MeshPhysicalMaterial transmission

* Update screenshots

* WebGLRenderer: Use HalfFloatType for transmissionRenderTarget

* Update screenshots

* WebGLRenderer: Render doublesided in two calls

* Examples: Updated webgl_buffergeometry_instancing screenshot

* WebGLRenderer: Only draw transparent doublesided with two calls.

* Add prototype of MMDToonMaterial.

* Try to use ShaderMaterial to simulate MeshToonMaterial.

* Done simulate MeshToonMaterial with ShaderMaterial.

* Clean up MMDToonMaterial.

* Add envMap uniforms.

* Enable merge gradient map with phong material but got warning.

* Enable specular and shininess in MMDToonMaterial.

* Done combining Phong/Toon/Matcap materials.

* Pre PR chores.

* fix typos.

* Set color to diffuse uniform.

* Update e2e test screenshots.

* Set .shininess to original and cut half irradiance.

* Remove dotNL from irradiance and update screenshots.

* Fix with PR comments.

* Modify maps file name storing position.

* Clean extra code.

* Update comment and use setter/getters to improve compatibility.

* Simplify defineProterties with defineProterty.

* Improve exposing property pattern.

* Simplify defineProterties with defineProterty.

* Updated puppeteer to 10.0.0

* Updated webgl2_multisampled_renderbuffers screenshot.

* e2e: Ignore webgl_loader_imagebitmap

* e2e: Ignore webgpu_lights_custom

* e2e: Updated webgl_video_panorama_equirectangular screenshot.

* Add Kooima's Generalized Projection Matrix Formulation

Addresses Issue #5381

This PR adds an implementation for Kooima's Generalized Projection Matrix Formulation, better known as "the way CAVE rendering works".

In a nutshell, it sets the `projectionMatrix` frustum to exactly frame an arbitrary rectangle.   This is a key operation in rendering portals, CAVEs, and certain kinds of projection based effects.

I find myself porting and reporting this function wherever I go because it's so darn useful.   I'm not certain that this is the right place in the codebase for it, but I'd really love for three.js to have a working implementation for people to use.

Here's a video I made years ago that utilizes the formulation:
https://www.youtube.com/watch?v=90kHhOUzeQc&t=1s

* Switch to const

* Add Portal Example

* Improve Metallic Transmission shader

* Update example screenshots

* Imptove MeshPhysicalMaterial transmission support

* Add webgl_loader_gltf_transmission example

* Update webgl_materials_physical_transmission screenshot

* Dispose transmissionRenderTarget in WebGLRenderer.dispose()

* Remove _transmissionSamplerMap from MeshPhysicalMaterial

* Fix transmissionMap

* Remove unnecessary sRGB-Linear conversion from transmission shader

* Improve transmission shaders

* Add more parameters to webgl_materials_physical_transmission example

* Update screenshot

* WebGPURenderer: Add support for alphaTest.

* Examples: Update screenshot.

* WebGPUUniformsGroup: Fix alignment bug.

* Adding advanced hand examples

* Update samples with ECSY implementation

* Fix hands examples broken by the recent oculus WebXR Hands API change

* Replace fbx hand models with glb

* Generate screenshots for new examples

* Clean up in Text2D.js

* Clean up in Text2D.js

* Update XRHandModelFactory and OculusHandModel to fetch hand model from webxr input profile cdn

* MRT clean up

* Updated files.json

* Added mrt tag for webgl2_multiple_rendertargets

* MRT Support

* Add MRT example

* Rename AttachnemtsNum to NumAttachments

* Reflect the review comments to webgl2_mrt.html

* Define texture parameter via WebGLMultiRenderTarget constructor in MRT example

* Minor clean up

* Fix setupFrameBufferTextre(). Use texture.format/type instead of renderTarget.texture's

* Use module in MRT example

* Replace var with let or const

* Replace ShaderMaterial with RawShaderMaterial for MRT example

* Fix formatting

* Fix for lint

* Add MRT example screenshot

* Reflect the review comments for WebGLMultiRenderTarget

* Rename .textures to .texture in WebGLMultiRenderTarget

* WebGLMultiRenderTarget: Remove setCount()

* WebGLMultiRenderTarget: Method chain

* WebGLMultiRenderTarget: More proper setTexture() and copy()

* WebGLCapabilities: Use extensions.has() instead of .get()

* WebGLMultiRenderTarget: Remove setTexture()

* Rename WebGLMultiRenderTarget to WebGLMultipleRenderTargets

* Examples: Slightly refactor FXAA demo.

* Update screenshot.