#define diagonal3(m) vec3((m)[0].x, (m)[1].y, m[2].z)
#define projMAD(m, v) (diagonal3(m) * (v) + (m)[3].xyz)

vec3 ScreenToView(vec3 pos) {
    vec4 iProjDiag = vec4(gbufferProjectionInverse[0].x,
                          gbufferProjectionInverse[1].y,
                          gbufferProjectionInverse[2].zw);
    vec3 p3 = pos * 2.0 - 1.0;
    vec4 viewPos = iProjDiag * p3.xyzz + gbufferProjectionInverse[3];
    return viewPos.xyz / viewPos.w;
}

vec3 ViewToPlayer(vec3 pos) {
    return mat3(gbufferModelViewInverse) * pos + gbufferModelViewInverse[3].xyz;
}

vec3 PlayerToShadow(vec3 pos) {
    vec3 shadowpos = mat3(shadowModelView) * pos + shadowModelView[3].xyz;
    return projMAD(shadowProjection, shadowpos);
}