three.js/src/renderers/shaders/ShaderChunk/skinning_pars_vertex.glsl.js

export default /* glsl */`
#ifdef USE_SKINNING

	uniform mat4 bindMatrix;
	uniform mat4 bindMatrixInverse;

	uniform highp sampler2D boneTexture;

	mat4 getBoneMatrix( const in float i ) {

		int size = textureSize( boneTexture, 0 ).x;
		int j = int( i ) * 4;
		int x = j % size;
		int y = j / size;
		vec4 v1 = texelFetch( boneTexture, ivec2( x, y ), 0 );
		vec4 v2 = texelFetch( boneTexture, ivec2( x + 1, y ), 0 );
		vec4 v3 = texelFetch( boneTexture, ivec2( x + 2, y ), 0 );
		vec4 v4 = texelFetch( boneTexture, ivec2( x + 3, y ), 0 );

		return mat4( v1, v2, v3, v4 );

	}

#endif
`;