EnmMsg.md

Enemy message system

The message system allows easy communication between enemies without needing to use global variables. There are 2 basic operations - sending a message in the given channel and receiving a message from the given channel. The channel can be any number, though if you want to communicate 2 enemies (parent and child) you can use ID variable in the child enemy and LAST_ENM_ID in the parent enemy. Make sure to properly initialize channels used, as they do not get reset automatically at any point (you could actually send a message at the end of stage 6, start extra stage and receive it there). This can be done with msgResetAll instruction which resets all channels, or the msgReset instruction which resets only the specified channel. I recommend calling msgResetAll at the beginning of every stage if you use messages, in order to avoid memory leaks. In case of spawning a child that will use messages, make sure to reset the channel from the child, as child ECL code actually executes immidiately after spawning (before the instruction after enmCreate executes).

Example 1 - sending messages between 2 siblings

void sender() {
    flagSet(32);
    msgReset(42069); // reset channel 42069
    while(1) {
        msgSend(RANDF, RANDF2, RANDRAD, PLAYER_X, 42069);
        wait(60);
    } 
}

void reader() {
    flagSet(32);
    while(1) {
        int received;
        float a, b, c, d;
        msgReceive(received, a, b, c, d, 42069);
        if (received)
            printf("I got a message! a=%f, b=%f, c=%f, d=%f\n", _ff a, _ff b, _ff c, _ff d);
        else
            printf("There were no messages!\n");
        wait(50);
    }
}

void main()
{
    cls();
    enmCreate("sender", 0f, 0f, 100, 100, 0);
    enmCreate("reader", 0f, 0f, 100, 100, 0);
    while(1)
        wait(1000);
}

Example 2 - sending message from parent to child

void reader() {
    msgReset(ID);
    msgWait(ID);
    printf("Hello\n");
}

void main() {
    cls();
    enmCreate("reader", 0f, 0f, 100, 100, 0);
    int id = LAST_ENM_ID;
    wait(360);
    msgSend(0f, 0f, 0f, 0f, id);
    while(1)
        wait(1000);
}