static cgm_vec3 lookup_marble2d(const struct texture *btex, const struct rayhit *hit);
static cgm_vec3 lookup_marble3d(const struct texture *btex, const struct rayhit *hit);
static cgm_vec3 lookup_marble2d(const struct texture *btex, const struct rayhit *hit);
static cgm_vec3 lookup_marble3d(const struct texture *btex, const struct rayhit *hit);