MeshDepthMaterial: Fix broken depthPacking. (#23801)

* MeshDepthMaterial: Fix broken depthPacking.

* Clean up.

src/renderers/webgl/WebGLProgram.js

@@ -683,7 +683,7 @@ function WebGLProgram( renderer, cacheKey, parameters, bindingStates ) {
 			ShaderChunk[ 'encodings_pars_fragment' ], // this code is required here because it is used by the various encoding/decoding function defined below
 			getTexelEncodingFunction( 'linearToOutputTexel', parameters.outputEncoding ),
 
-			parameters.depthPacking ? '#define DEPTH_PACKING ' + parameters.depthPacking : '',
+			parameters.useDepthPacking ? '#define DEPTH_PACKING ' + parameters.depthPacking : '',
 
 			'\n'
 

src/renderers/webgl/WebGLPrograms.js

@@ -259,7 +259,8 @@ function WebGLPrograms( renderer, cubemaps, cubeuvmaps, extensions, capabilities
 			doubleSided: material.side === DoubleSide,
 			flipSided: material.side === BackSide,
 
-			depthPacking: ( material.depthPacking !== undefined ) ? material.depthPacking : false,
+			useDepthPacking: !! material.depthPacking,
+			depthPacking: material.depthPacking || 0,
 
 			index0AttributeName: material.index0AttributeName,
 
@@ -345,6 +346,7 @@ function WebGLPrograms( renderer, cubemaps, cubeuvmaps, extensions, capabilities
 		array.push( parameters.toneMapping );
 		array.push( parameters.numClippingPlanes );
 		array.push( parameters.numClipIntersection );
+		array.push( parameters.depthPacking );
 
 	}
 
@@ -444,7 +446,7 @@ function WebGLPrograms( renderer, cubemaps, cubeuvmaps, extensions, capabilities
 			_programLayers.enable( 11 );
 		if ( parameters.flipSided )
 			_programLayers.enable( 12 );
-		if ( parameters.depthPacking )
+		if ( parameters.useDepthPacking )
 			_programLayers.enable( 13 );
 		if ( parameters.dithering )
 			_programLayers.enable( 14 );