* clear coat implementation.

* add physical variations to examples.

* add example file for physical materials

* adjust clearcoat range to 0-1 as original.

* switch example color to gray from yellow.

* Water grid simulation w/ ShaderMaterial cloned from MeshPhongMaterial

* Water shader works with texture heightmap

* Added GPUComputationRenderer, I'm about to test it

* GPUComputationRenderer works with water simulation

* Interaction with mouse

* Added water viscosity, simple geometry for mouse picking

* Put pass thru shaders in GPUComputationRenderer. Some minor refactoring.

* Code revisison, added comments and explanations. Inverted mouse Y coord.

* Added GUI controls for some water parameters.

* Commencing conversion of birds gpu demo to GPUComputationRenderer

* Converted gpu birds demo to GPUComputationRenderer and fixed bugs in it.

* Solved mouse bug.

* Optimized smoothWater(), renamed some GPUComputationRenderer methods.

* Substituted old bird gpu implementation. Preparing for new demo.

* Removing old SimulationRenderer

* GPU protoplanets demo started. Minor tweaks in the other demos

* Starting to implement the particle demo

* $th component of texture now is usable. It was the GPUComputationRenderer
pass-through fragment shader.
Next thing to do is use a texture that contains (vx, vy, vz, mass).

* Particles already move. Next is gravity interaction.

* Gravity interaction done. Next is particle collision and aggregation.

* Particle collision works

* Added gui

* Some minor adjustments

* Added the two new demos to the list of examples

* add unbiased mode to the MSAA render pass.

* clearer code.

* better comment.

* cleanup code.  fix bug of using "camera", instead of "this.camera"

* fix more places were "camera" is used instad of "this.camera" -- it worked because example declared "camera" as a global.

* reduce light intensity.

* add PerspectiveCamera.clearViewOffset() per @mrdoob's recommendation.

Add high quality rand() function to common.glsl and an example to show off the noise textures. (#8603)

* create procedural glsl and an example to show off the noise textures.

* add to files.js

* adopt noise procedural in PMREMGenerator.

* fix page title per @arose's suggestion.

* more adoption of procedural.glsl

* remove procedural.glsl, add a single line to common.glsl.  Update other files as needed.

* cleanup shaders to use common.glsl

* tabify.

* avoid collapsing into a single function - @WestLangley recommendations

* more adoption of tabs.

* fix tabs.

* working on depth texture

* working on depth texture

* support depth texture in webgl1 and webgl2

* fix comments

* reset build to avoid diff noise

* add check for webgl2 context

* fix depth texture example

* animation for example

* add file

* add depthTexture to WebGLRenderTarget

* ensure depth format returns correct GL parmaeter

* use null for initial depthTexture value

* add some commented out code

* special purpose materials.

* rename example from special_purpose -> channels.  Add camera controls.

* minor polish to webgl_materials_channels.

* add standard material with displacement, normal and ao to show contract with normal and depth materials.

* fix orthographic camera near/far bounds.

* remove double add of material_channels example.

* Implemented user-defined clipping planes.

* Renderer: Minor documentation update.

* Implements object-level clipping.

* Renderer: Minor cosmetic changes.

* Fixed lethal typo in normal shader.

* Let shadows respect .side of object's material.

* Fixed Plane.applyMatrix4.

- Scale denormalized but did not scale the position
- Projection is not supported (solved by documentation)
- Removed unnecessary copying to make up for the normalization
- Still arguably too heavy

* Added custom clipping example.

* Clipping: Fixed transition to disabled state.

* Improved custom clipping example.

- GUI dependency of volume visualization on Enabled state
- Larger radius for cylindrical global clipping area

* No .matrixAutoUpdate = false in clipping example.

* Let ShadowMap check renderer.localClippingEnabled.

* Added a simplified clipping example.

adds both new spotlight examples