3d-tiles-renderer/src/three/plugins/batched/utilities.js

https://github.com/AnalyticalGraphicsInc/3d-tiles/tree/master/specification

// Returns whether the passed color is white or not
export function isColorWhite( color ) {

	return color.r === 1 && color.g === 1 && color.b === 1;

}

// Adjusts the given material to take an ArrayTexture for a map
export function convertMapToArrayTexture( material ) {

	material.needsUpdate = true;
	material.onBeforeCompile = shader => {

		shader.vertexShader = shader.vertexShader
			.replace(
				'#include <common>',
				/* glsl */`
				#include <common>
				varying float texture_index;
				`,
			)
			.replace(
				'#include <uv_vertex>',
				/* glsl */`
				#include <uv_vertex>
				texture_index = getIndirectIndex( gl_DrawID );
				`,
			);

		shader.fragmentShader = shader.fragmentShader
			.replace(
				'#include <map_pars_fragment>',
				/* glsl */`
				#ifdef USE_MAP
				precision highp sampler2DArray;
				uniform sampler2DArray map;
				varying float texture_index;
				#endif
				`,
			)
			.replace(
				'#include <map_fragment>',
				/* glsl */`
				#ifdef USE_MAP
					diffuseColor *= texture( map, vec3( vMapUv, texture_index ) );
				#endif
				`
			);

	};

}