This program demonstrates some of the basic features provided by the libgfx scripting package. Given a list of file names on the command line, it reads each of them in turn and executes the scripting commands contained within them.
The program begins by including the headers for the libgfx modules which it uses:
#include <gfx/gfx.h> #include <gfx/script.h> #include <gfx/vec3.h>
The main() application entry point performs a very simple task. It creates a scripting environment (class CmdEnv and registers a set of scripting commands. Once these handlers have been installed, it loops over every file name specified on the command line and executes it as a script.
main(int argc, char *argv[])
{
CmdEnv env;
env.register_command("add", proc_add);
env.register_command("avg", proc_add);
env.register_command("echo", proc_echo);
env.register_command("vec3", proc_vec3);
for(int i=1; i&argc; i++)
script_do_file(argv[i], env);
return 0;
}
Every scripting command is handled by some command procedure. The registration code above binds the actual procedures to the names of their scripting commands. Then, whenever a given command occurs in a script being processed, the corresponding handler is invoked.
The first command procedure actually implements two scripting commands: add and avg. It determines which command has been invoked by examining its name argument. It treats its command line as a whitespace-separated sequence of numbers, either adds or averages all of them, and then prints the result.
int proc_add(const CmdLine &cmd)
{
double sum = 0.0;
int count;
std::vector<double> values;
cmd.collect_as_numbers(values);
for(count=0; count<values.size(); count++)
sum += values[count];
if( cmd.opname() == "avg" && count>0 )
sum /= (double)count;
cout << sum << endl;
return SCRIPT_OK;
}
This next procedure requires precisely 3 numeric arguments, from which it constructs a 3-D vector using the Vec3 class. If the number of arguments is not 3, it returns a value indicating a syntax error occurred.
int proc_vec3(const CmdLine &cmd)
{
if( cmd.argcount() != 3 ) return SCRIPT_ERR_SYNTAX;
Vec3 v;
cmd.collect_as_numbers(v, 3);
cout << v << endl;
return SCRIPT_OK;
}
Finally, the echo procedure does not interpret its arguments at all. Instead, it simply prints the entire argument line as is.
int proc_echo(const CmdLine &cmd)
{
cout << cmd.argline() << endl;
return SCRIPT_OK;
}
To demonstrate the action of this sample program, here is a particularly simple script.
# This is a test script meant to be fed to t-script. It is not meant as an # exhaustive test, but mainly as a demonstration. echo The following sum should be 15 add 1 2 3 4 5 echo echo The following average should be 3.5 avg 3 8 2 1 echo echo The following is the vector [1 0 0] vec3 1 0 0
When given to the sample program, it produces the following output
The following sum should be 15 15 The following average should be 3.5 3.5 The following is the vector [1 0 0] 1 0 0