+ vec3 sph_pos = normalize(vec3(attr_pos.x, attr_pos.y - half_height, attr_pos.z));
+
+ vec3 sph_normal = sph_pos;
+ sph_pos.y += half_height;
+
+ vec3 p = mix(attr_pos, sph_pos, time.t);
+ vec3 n = mix(attr_normal, sph_normal, time.t);
+
+ gl_Position = m.mmviewproj * vec4(p, 1.0);