Logarithmic depth buffer

#extension GL_ARB_conservative_depth : enable

float Fcoef = 2.0 / log2(4194304.0 + 1.0);

#if CRUS_VERTEX_SHADER

layout(location = nVERTEX) in vec3 inVertex;

layout(binding = nTRANSFORM, row_major) uniform TRSM {
    mat4 ProjMatrix;
    mat4 ViewMatrix;

    mat4 ViewProj;
    mat4 ModelView;
};

out float logz;

void main()
{
    gl_Position = ViewProj * vec4(inVertex, 1.0);

    logz = 1.0 + gl_Position.w;
    gl_Position.z = log2(max(1e-6, logz)) * Fcoef - 1.0;
}

#elif CRUS_FRAGMENT_SHADER

layout(binding = nMATERIAL, shared) uniform CMTS {
    vec4 Clr0;
};

layout(location = nFRAG_COLOR, index = 0) out vec4 FragColor;
layout(depth_less) out float gl_FragDepth;

in float logz;

void main()
{
    FragColor = Clr0;

    gl_FragDepth = log2(logz) * 0.5 * Fcoef;
}

#endif