※ Q&A/Problem Thread 5 ※ for OLD Danmakufu version (0.12m)

[Serina]

Thank you very much, guys! That's great, I'm trying to use tasks too, but at least I'm sure I can do cool stuff with MainLoop :3

[Blargel]

Hardly doubt it. Look at the code. It has a loop { } in there, it seems to loop forever as a checker. Thus, he needs dual statements

It loops forever, but it never resets any of the variables back to false after turning them true so actually, after everything is set to true, it no longer even needs to run. Thus, why I suggested my solution. It also saves a few CPU clock cycles per frame by only checking one condition per frame instead of all 3. :V

[BajaBlood]

Back again!

I'm wondering if there is a good way to have stuff happen when bullets of different types intersect (without predetermining locations where this will happen). Here's a pseudo-code attempt at it, but I imagine there's a better way to go about it than this:

function GetDistance(x1,x2,y1,y2) {return distance}

mainloop{
ascent(i in a..b){
     CreateShotA(i, 'parameters for A-type bullet')
     CreateShotA(-i, 'parameters for B-type bullet')
}
a = b+1
b = 2b-a+1
ascent(g in 1..b)
   ascent(h in 1..b)
      if (GetDistance of shot g and -h < 'too close') {
          do stuff;
      }
   }
}

Particularly since this doesn't stop checking bullets even when they don't exist anymore, and the number of calcs is on the order of b^2, I'd guess that this would cause noticeable slowdown once b gets high enough.

[Kylesky]

you'll have to use object bullets and their Obj_GetX and Obj_GetY functions (or alternately, use Obj_Obj_Collision)... so I suggest you get more familiar with objects first, before you attempt this... :3

[Drake]

You're thinking along the right lines, but you have no way of determining a bullet's position without using object bullets (go learn object bullets lol). Aside from that you're pretty much right. The best method is probably storing the objects in two global arrays for A bullets and B bullets (if your intention is to have something done when A and B collide).

let position_A = [];
let position_B = [];

//code

task objbulletA{    //similar for B, obviously
    position_A = position_A ~ [Obj_Create(OBJ_SHOT)];    //creates an object and concats into array
    let id = length(position_A) - 1;    //to track id in array if needed

    //code
}

And then you run distance checks between each A bullet to B bullet.

I guess you clean up garbage entries if the bullets are deleted but that might be a tad advanced lol. There are actually a lot of optimizations you can do with things like this but that isn't really an issue either.

[BajaBlood]

I am actually familiar with object shots, and in my scripts tasks and object shots are my preferred way of creating bullets. The reason I didn't use a similar style here was because I was worried about how to call on individual shots outside of the task in which they were created (I actually just realized how to do this though - in the past I either passed nothing or shot data into the task to create an object shot named 'obj', but if I pass an object name variable down I should be able call individual shots from anywhere in the program).

I wasn't aware of an Obj_Obj_Collision function - how does this one work, or is it something I have to write?

Even using object shots, I'm not sure how to avoid having to test every bullet against every other in every frame to get my intended result.

Edit (after seeing previous post): Oh I see, haha. I'm so used to object shots I assumed I could use GetX on any bullets I spawned. ^^'
Hmm, that many calcs every frame won't slow the program down?

[Drake]

Well if the detection radius is large enough you can stand to only calculate distances once every two frames, or you can divide the work up 50/50, stuff like that.


Are you talking garbage collection?

[BajaBlood]

Didn't know what garbage collection is - now know about what 3 minutes on wikipedia tells me. xD

I guess garbage collection isn't really my concern, though if I end up having problems with slowdown on the card I'll look into it (and actually it would probably be an interesting problem to think about as well even if it isn't necessary in this case - half the reason I'm doing danmakufu is to improve my programming skills).

I don't really have a concept for what the card will look like, but one of the things I'm planning on doing when I start mixing elements in my extra boss is having 'water' and 'fire' bullets either annihilate each other or spawn some bullets in an explosion when they meet (same with 'earth' and 'air').

Yeah, I'm sure I'd be able to check for collisions less frequently than every frame - I generally stay away from pellets and high speeds, so any overlaps should last a number of frames.

[J.O.B]

Is someone able to make a tutorial about the nitpicky fussy things in Danmakufu?
Things such as where certain functions/tasks/variables go.
When you should put curly braces and parenthesis.
And other things like that fact that task names can't have spaces in them.
If someone were to make a tutorial for those things then it'll be greatly appreciated.

[Drake]

Is someone able to make a tutorial about the nitpicky fussy things in Danmakufu?

http://www.shrinemaiden.org/forum/index.php/topic,4155.0.html
http://www.shrinemaiden.org/forum/index.php/topic,4762.0.html
http://www.shrinemaiden.org/forum/index.php/topic,4752.0.html

Things such as where certain functions/tasks/variables go.
When you should put curly braces and parenthesis.
And other things like that fact that task names can't have spaces in them.
If someone were to make a tutorial for those things then it'll be greatly appreciated.

Uhhhhhh no. Basic syntax should be very easy to follow, and at the very least you'll learn what not to do yourself as you script and read other tutorials. These are not "nitpicky", it's being not lazy with your punctuation, grammar, etc. Nobody should have to make a tutorial going MAKE SURE YOU MATCH UP YOUR CURLY BRACKETS!!!!!1

[J.O.B]

I'm sorry then if I find that most times examples aren't enough.
Sometimes the worfing is confusing for me and I end up putting things in the wrong place.

[Drake]

It'll fix itself as you get more experienced and such.

[TheTeff007]

Two Questions: 

1.- CreateLaserB has  lengthening speed which allows the lenght of the laser to extend in "n" each frames, but what do I do if I want to change the width of the laser?

2.- Can somebody explain me how ascent/descent works in an example script? the FAQ example isn't that useful.

EDITED: Changed "CreateShotB" with "CreateLaserB"

[Chronojet ⚙ Dragon]

Two Questions: 

1.- CreateShotB has  lengthening speed which allows the lenght of the laser to extend in "n" each frames, but what do I do if I want to change the width of the laser?

CreateShotB doesn't exist.
if you mean CreateLaserB, then it doesn't work that way - you have to use object lasers and ObjLaser_SetWidth(objectid, widthinpixels);

[Blargel]

2.- Can somebody explain me how ascent/descent works in an example script? the FAQ example isn't that useful.

Code: [Select]

ascent(i in 0..20){
    CreateShot01(GetX, GetY, 3, i*18, RED01, 5);
}
is the same as

Code: [Select]

let i = 0;
while(i < 20){
    CreateShot01(GetX, GetY, 3, i*18, RED01, 5);
    i++;
}
except that in the ascent example, the variable i no longer exists after the ascent is over, but will still exist in the while example. In both cases, it's just a type of loop with a variable called i that starts at 0 and counts up by one until it reaches 20. Note that i will never actually be used when it hits 20 in the while loop. The same is true for ascents so it'll count from 0 to 19, not 0 to 20.

Descent makes i, go through the same numbers but in reverse order, so in the previous example, if we replaced ascent with descent, it'll count backwards from 19 to 0.

[rogus247]

Ok, im gonna make this one a quickie. I know the command to stop obj,bullets and hold them in place. How would i spawn like...3 bullets from that one bullet? And say if i wanted to stop THOSE bullets and make more? Would that be a Spawn command?

[Chronojet ⚙ Dragon]

That's possible with CreateShotA, but it seems you wanna use object bullets.

You'd have to make a totally new object bullet, spawned by the first object bullet.

That's all I can give - the rest anyone can figure out.

[Drake]

Ok, im gonna make this one a quickie. I know the command to stop obj,bullets and hold them in place. How would i spawn like...3 bullets from that one bullet? And say if i wanted to stop THOSE bullets and make more? Would that be a Spawn command?

task bullet(x,y,a){
    //code
    Obj_SetPosition(obj,x,y);
    Obj_SetAngle(obj,a);
    //code
    //slow down/stop
    bullet(Obj_GetX(obj),Obj_GetY(obj), a+something);
    bullet(Obj_GetX(obj),Obj_GetY(obj), a+somethingelse);
    bullet(Obj_GetX(obj),Obj_GetY(obj), a+somethingelseelse);
    //probably Obj_Delete(obj); unless you want to do something else with the stopped bullet
}

[rogus247]

http://pastebin.com/rsTUMkH0

Im...doing something wrong here...xD
Do you have to set the variables next to the bullet task?

[Kylesky]

Code: [Select]

task bullet(x,y,a){
        //code
        Obj_SetPosition(obj,GetEnemyX,GetEnemyY);
        Obj_SetAngle(obj,dir);
        //code
        //slow down/stop
        bullet(Obj_GetX(obj),Obj_GetY(obj), a+3);
        bullet(Obj_GetX(obj),Obj_GetY(obj), a+6);
        bullet(Obj_GetX(obj),Obj_GetY(obj), a+9);
        //probably Obj_Delete(obj); unless you want to do something else with the stopped bullet
        }
is this seriously what's in your code? the thing drake posted was just a general outline :V you have to fix it and make it fit whatever you want it to do...

EDIT: Given what you have in your pastebin

Code: [Select]

bullet(GetEnemyX,GetEnemyY,1,dir,ORANGE32,0);
I'm guessing you'll want something like this:

Code: [Select]

task bullet(x,y,v,a,g,d){
    let counter=0;
    let obj=Obj_Create(OBJ_SHOT);
    Obj_SetPosition(obj,x,y);
    Obj_SetAngle(obj,dir);
    Obj_SetSpeed(obj,v);
    ObjShot_SetGraphic(obj,g);
    ObjShot_SetDelay(obj,d);
    while(!Obj_BeDeleted(obj){
        counter++;
        if(counter==*insert whatever value you want*){Obj_SetSpeed(obj,0);}
        if(counter==*insert whatever other value you want*){
            bullet(Obj_GetX(obj),Obj_GetY(obj),1,a+3,ORANGE32,0); //Change values to whatever you want
            bullet(Obj_GetX(obj),Obj_GetY(obj),1,a+6,ORANGE32,0);
            bullet(Obj_GetX(obj),Obj_GetY(obj),1,a+9,ORANGE32,0);
            Obj_Delete(obj);
        }
    }
}


[Drake]

why

[BajaBlood]

Two questions:

1.) In one of my scripts I'm looking to use a couple global shot id's on object shots, as I need to compare their location to other object shots created by a different task. These shots are being created by a task called in MainLoop.

Is there a good way to pass a variable down to this task such that I don't need to break the task by cases? i.e. can I pass a variable to the task that lets me reference one of two shot id's

2.) With Object Shots not moving straight up or down, is there a simple way to apply a constant downward acceleration, or will I need to write some trigonometric functions to adjust the angle and speed based on the current angle and speed? (answered on IRC - thanks Ginko)

[rogus247]

http://pastebin.com/LWq0bZSn

yeah...i got the same error with the whole (wait) thing again....i think i should get some new eyes, cause i sure as hell cant! DX I should get a professional pro to come over to my house, and just...give me a 20 hour lecture on danmakufu.....

But yeah, all variables are set, but like most my problems, the thing comes up by the wait command, so...what has rogus done wrong this time? xD

[Drake]

I actually read over this a few times too. Didn't catch it for a while.

while(!Obj_BeDeleted(obj)){

[rogus247]

that solved the (wait problem...) but now i get a (dir) problem...i need to set it to 0, right?

[Ginko]

Code: [Select]

task bullet(x,y,v,a,g,d){
    let counter=0;
    let obj=Obj_Create(OBJ_SHOT);
    Obj_SetPosition(obj,GetEnemyX,GetEnemyY);
    Obj_SetAngle(obj,dir);
    Obj_SetSpeed(obj,3);
    ObjShot_SetGraphic(obj,ORANGE32);
    ObjShot_SetDelay(obj,20);
    while(!Obj_BeDeleted(obj){
        counter++;
        if(counter==2){Obj_SetSpeed(obj,0);}
        if(counter==4){
            bullet(Obj_GetX(obj),Obj_GetY(obj),1,a+3,ORANGE32,0); //Change values to whatever you want
            bullet(Obj_GetX(obj),Obj_GetY(obj),2,a+6,ORANGE32,0);
            bullet(Obj_GetX(obj),Obj_GetY(obj),3,a+9,ORANGE32,0);
            Obj_Delete(obj);
        }
    }
}       
Two things :

-  'dir' doesn't even exist, how exactly did you expect the script to work ? You have to initialize if you want to use a string as a variable. Then again, if you want the angle to be 0, why exactly don't you just put 0 ?
- What are those x,y,v,g and d arguments doing in your task ? They don't intervene anywhere ... it will work correctly but that's just pointless :O

[Drake]

He wants the x and y, only his initial call is supposed to spawn on the enemy. In which case,

bullet(GetEnemyX,GetEnemyY,1,anactualnumber,ORANGE32,0);

//...

task bullet(x,y,v,a,g,d){
    let counter=0;
    let obj=Obj_Create(OBJ_SHOT);
    Obj_SetPosition(obj,x,y);
    Obj_SetAngle(obj,a);
    Obj_SetSpeed(obj,3);
    ObjShot_SetGraphic(obj,ORANGE32);
    ObjShot_SetDelay(obj,20);
    while(!Obj_BeDeleted(obj){
        counter++;
        if(counter==2){Obj_SetSpeed(obj,0);}
        if(counter==4){
            bullet(Obj_GetX(obj),Obj_GetY(obj),1,a+3,ORANGE32,0); //Change values to whatever you want
            bullet(Obj_GetX(obj),Obj_GetY(obj),2,a+6,ORANGE32,0);
            bullet(Obj_GetX(obj),Obj_GetY(obj),3,a+9,ORANGE32,0);
            Obj_Delete(obj);
        }
    }

[rogus247]

http://pastebin.com/2a6nqdjb

ok...it would work, but it freezes my Comp. I have yields in all places...but it still freezes. Why?

[Naut]

task bullet(x,y,v,a,g,d){
    let counter=0;
    let obj=Obj_Create(OBJ_SHOT);
    Obj_SetPosition(obj,GetEnemyX,GetEnemyY);
    Obj_SetAngle(obj,a);
    Obj_SetSpeed(obj,3);
    ObjShot_SetGraphic(obj,ORANGE32);
    ObjShot_SetDelay(obj,20);
    while(!Obj_BeDeleted(obj)){
        counter++;
        if(counter==2){Obj_SetSpeed(obj,0);}
        if(counter==4){
            bullet(Obj_GetX(obj),Obj_GetY(obj),1,a+3,ORANGE32,0); //Change values to whatever you want
            bullet(Obj_GetX(obj),Obj_GetY(obj),2,a+6,ORANGE32,0);
            bullet(Obj_GetX(obj),Obj_GetY(obj),3,a+9,ORANGE32,0);
            Obj_Delete(obj);
      yield;
        }
    }
}   

change to

task bullet(x,y,v,a,g,d){
    let counter=0;
    let obj=Obj_Create(OBJ_SHOT);
    Obj_SetPosition(obj,GetEnemyX,GetEnemyY);
    Obj_SetAngle(obj,a);
    Obj_SetSpeed(obj,3);
    ObjShot_SetGraphic(obj,ORANGE32);
    ObjShot_SetDelay(obj,20);
    while(!Obj_BeDeleted(obj)){
        counter++;
        if(counter==2){Obj_SetSpeed(obj,0);}
        if(counter==4){
            bullet(Obj_GetX(obj),Obj_GetY(obj),1,a+3,ORANGE32,0); //Change values to whatever you want
            bullet(Obj_GetX(obj),Obj_GetY(obj),2,a+6,ORANGE32,0);
            bullet(Obj_GetX(obj),Obj_GetY(obj),3,a+9,ORANGE32,0);
            Obj_Delete(obj);
        }
   yield;
    }
}   

[Azure Lazuline]

In addition, even once that's fixed: Every bullet waits 4 frames, then creates 3 new bullets. Each of those waits 4 frames, then creates 3 new bullets. Each of those waits 4 frames, then creates 3 new bullets. Do you see the problem here? You need to have some limit on how many times they can split. Give the bullet task another parameter called "maxsplit" or something, and every time you create a child bullet, create it with maxsplit-1 instead. If it's zero, don't create any more bullets, so your processor will stop screaming.