direct.glsl

    float sdPlane(vec3 p, vec4 n) {
        // n must be normalized
        return dot(p, n.xyz) + n.w;
    }

    vec3 opTx(mat4 m, vec3 p) {
        vec4 q = m * vec4(p, 1.0);
        return q.xyz;
    }

    float opU(float d1, float d2) {
        return min(d1, d2);
    }

    void main(){
        vec2 uv = gl_FragCoord.xy/viewport;

        vec4 eye_data = vec4(
            texture2D(eye_normal, uv).rgb,
            unpack16f(texture2D(eye_depth, uv).rg));
        vec4 eye_data_floor = vec4(
            texture2D(eye_normal_floor, uv).rgb,
            unpack16f(texture2D(eye_depth_floor, uv).rg));

        if (eye_data.w == 0.0) {
          eye_data.w = 1000.0;
        }
        if (eye_data_floor.w == 0.0) {
          eye_data_floor.w = 1000.0;
        }

        vec3 normal;
        float depth;

        if (eye_data.w < eye_data_floor.w) {
          normal = eye_data.xyz;
          depth = eye_data.w;
        } else {
          normal = eye_data_floor.xyz;
          depth = eye_data_floor.w;

          const vec4 gp = vec4(0.0, 1.0, 0.0, 0.0); // ground plane
          float cps = 1.0 / (far - near);
          /* depth = sdPlane( */
          /*   normalize( */
          /*       (inv_eye_view * inv_eye_proj * vec4(clip, 1.0, cps)).xyz), */
          /*   vec4(0.0, 1.0, 0.0, 0.0)); */
          depth = sdPlane(opTx(inv_eye_view * inv_eye_proj, vec3(clip, 1.0)), gp);
          depth = depth + cps*far;
        }
        /* depth = near + (depth * (far - near)); */

        vec4 ro = inv_eye_proj * vec4(clip, 1.0, 1.0);
        vec3 rd = normalize(ro.xyz);
        vec3 eye_p = depth * rd;
        vec3 p = (inv_eye_view * vec4(eye_p, 1.0)).xyz;

        float occlusion = OcclusionVSM(p, normal);
        float lambert = clamp((light_rot * normal).z, 0.0, 1.0);
        float intensity = (occlusion*0.8+0.2) * lambert;

        gl_FragColor = vec4(vec3(depth), 1.0);
    }