R3DoA3(obj, mth, p1, p2, p3);

Up to three fixed parameters can be passed to a method, which are named 'p1', 'p2', 'p3'. The number and type of parameters depend on the method in question.

Again, the public class header file tells you which methods the class in question supports.

Many methods use the last parameter 'p3' to pass varying tag list parameter. Just like one can pass a tag list to a R3SetAttrs() or R3New() functions, one pass a tag list to a method by calling:

    R3Do3(obj, methodid, p1, p2, ...);

function.

In fact, R3SetAttrs() and R3New() functions described earlier are just shields to R3RM_SET and R3RM_CREATE methods. To set object attributes, you might as well call:

    R3FLOAT rad = 0.1;
    R3Do3(sphere, R3RM_SET, NULL, NULL, 
          R3RA_Name, "new name",
          R3SPHA_Radius, &rad,
          R3TAG_END);