Shadow sampler of a cubemap array texture in GLSL

shadowmapping.glsl

uniform samplerCubeArrayShadow texture_shadowmap_cube;

/**
 * @return The fraction of the sample that is _not_ shadowed (0.0 - 1.0).
 */
float sample_shadowmap(in light_t light, in int index) {

    // the position of the fragment in light space
    vec4 position = vec4(light.model.xyz - vertex.model, 1.0);

    // the position of the fragment in normalized device coordinates (-1.0 - 1.0)
    vec4 projected = light_projection * position;

    // the position of the fragment in the light's depth map texture
    vec2 shadowmap = (projected.xy / projected.w) * 0.5 + 0.5;

    return texture(texture_shadowmap, vec4(shadowmap, index, length(position.xyz) / depth_range.y));
}