#version 450
#extension GL_ARB_separate_shader_objects : enable
#extension GL_ARB_shading_language_420pack : enable
#extension GL_EXT_nonuniform_qualifier : require

layout(location = 0) out vec4 shadowMap;

void main()
{
    float depth = gl_FragCoord.z;

    float dx = dFdx(depth);
    float dy = dFdy(depth);

    float moment2 = depth * depth + 0.25f * (dx * dx + dy * dy);
    // shadowMap = vec4 (0.0f, 0.0f, gl_FragCoord.z, 1.0f);
    shadowMap = vec4 (gl_FragCoord.z, moment2, 0.0f, 1.0f);
}