r132 ALPHATEST --> USE_ALPHATEST

`ALPHATEST` was previously used as a flag and a value in three.js `alphatest_fragment` chunk.
It was superseded by the `USE_ALPHATEST` flag and the `alphaTest` value passed as a uniform.
The declaration of the `alphaTest` uniform is made in the `alphatest_pars_fragment` chunk.

src/buffer/point-buffer.ts

@@ -84,7 +84,7 @@ const PointBufferParameterTypes = Object.assign({
   pointSize: { uniform: 'size' },
   sizeAttenuation: { updateShader: true },
   sortParticles: {},
-  alphaTest: { updateShader: true },
+  alphaTest: { uniform: true },
   useTexture: { updateShader: true },
   forceTransparent: {},
   edgeBleach: { uniform: true }
@@ -123,7 +123,8 @@ class PointBuffer extends Buffer {
       'size': { value: this.parameters.pointSize },
       'canvasHeight': { value: 1.0 },
       'pixelRatio': { value: 1.0 },
-      'map': { value: null }
+      'map': { value: null },
+      'alphaTest': {value: this.parameters.alphaTest}
     })
   }
 
@@ -163,7 +164,7 @@ class PointBuffer extends Buffer {
     }
 
     if (this.parameters.alphaTest > 0 && this.parameters.alphaTest <= 1) {
-      defines.ALPHATEST = this.parameters.alphaTest.toPrecision(2)
+      defines.USE_ALPHATEST = 1
     }
 
     return defines

src/shader/Point.frag

@@ -18,6 +18,7 @@ uniform float clipRadius;
     #include common
     #include color_pars_fragment
     #include fog_pars_fragment
+    #include alphatest_pars_fragment
     varying vec3 vViewPosition;
 #endif
 

src/shader/shader-utils.ts

@@ -21,7 +21,7 @@ import { ShaderRegistry } from '../globals'
 export type ShaderDefine = (
   'NEAR_CLIP'|'RADIUS_CLIP'|'PICKING'|'NOLIGHT'|'FLAT_SHADED'|'OPAQUE_BACK'|
   'DIFFUSE_INTERIOR'|'USE_INTERIOR_COLOR'|
-  'USE_SIZEATTENUATION'|'USE_MAP'|'ALPHATEST'|'SDF'|'FIXED_SIZE'|
+  'USE_SIZEATTENUATION'|'USE_MAP'|'USE_ALPHATEST'|'SDF'|'FIXED_SIZE'|
   'CUBIC_INTERPOLATION'|'BSPLINE_FILTER'|'CATMULROM_FILTER'|'MITCHELL_FILTER'
 )
 export type ShaderDefines = {