Babylon.js/src/Shaders/passCube.fragment.fx

// Samplers
varying vec2 vUV;
uniform samplerCube textureSampler;

void main(void) 
{
	vec2 uv = vUV * 2.0 - 1.0;

#ifdef POSITIVEX
	gl_FragColor = textureCube(textureSampler, vec3(1.001, uv.y, uv.x));
#endif
#ifdef NEGATIVEX
	gl_FragColor = textureCube(textureSampler, vec3(-1.001, uv.y, uv.x));
#endif
#ifdef POSITIVEY
	gl_FragColor = textureCube(textureSampler, vec3(uv.y, 1.001, uv.x));
#endif
#ifdef NEGATIVEY
	gl_FragColor = textureCube(textureSampler, vec3(uv.y, -1.001, uv.x));
#endif
#ifdef POSITIVEZ
	gl_FragColor = textureCube(textureSampler, vec3(uv, 1.001));
#endif
#ifdef NEGATIVEZ
	gl_FragColor = textureCube(textureSampler, vec3(uv, -1.001));
#endif
}