occlusion

type OcclusionData struct {
	Flags     int32
	FirstPoly int32
	PolyCount int32
	Mins      mgl32.Vec3
	Maxs      mgl32.Vec3
	Area      int32
}

type OcclusionPolyData struct {
	FirstVertexIndex int32
	VertexCount      int32
	PlaneNum         int32
}