node_modules/three/src/renderers/shaders/ShaderLib/equirect_frag.glsl.js

export default /* glsl */`
uniform sampler2D tEquirect;

varying vec3 vWorldDirection;

#include <common>

void main() {

	vec3 direction = normalize( vWorldDirection );

	vec2 sampleUV;

	sampleUV.y = asin( clamp( direction.y, - 1.0, 1.0 ) ) * RECIPROCAL_PI + 0.5;

	sampleUV.x = atan( direction.z, direction.x ) * RECIPROCAL_PI2 + 0.5;

	vec4 texColor = texture2D( tEquirect, sampleUV );

	gl_FragColor = mapTexelToLinear( texColor );

	#include <tonemapping_fragment>
	#include <encodings_fragment>

}
`;