(GLfloat) t.cloud_height };
extensions->glVertexAttrib3fv(USR_ATTR_1, ua1 );
extensions->glVertexAttrib3fv(USR_ATTR_2, ua2 );
(GLfloat) t.cloud_height };
extensions->glVertexAttrib3fv(USR_ATTR_1, ua1 );
extensions->glVertexAttrib3fv(USR_ATTR_2, ua2 );