※ Danmakufu Q&A/Problem thread 3 ※

[HumanReploidJP]

Hmm... How about... a detail of implementing a code that consists a black hole that sucks/pulls the player towards it (like Utsuho/Okuu's "Artificial Sun")?

[Arcvasti]

That's pretty easy, actually. You just need a task that looks something like this.

Code: [Select]

task gravity(){
    while(!Obj_IsDeleted(bossObj)){
        ObjMove_SetPosition(GetPlayerObjectID,GetPlayerX+cos(GetAngleToPlayer(bossObj)+180),GetPlayerY+sin(GetAngleToPlayer(bossObj)+180));
        wait(2) //wait(1) might also work
    }
}


[Helepolis]

That is one way to do it, except it lacks the control over the strength of the 'gravitational pull'. Here is a snippet from my own game which is based on 'strength' (velocity)

Code: [Select]

while(!Obj_IsDeleted(bossObj)) {
x = GetPlayerX;
y = GetPlayerY;

dir = GetPointToPointAngle(GetEnemyX, GetEnemyY, GetPlayerX, GetPlayerY);
ObjMove_SetAngle(locPlayerID, dir);
vx = v * cos(dir);
vy = v * sin(dir);

ObjRender_SetPosition(locPlayerID, x + vx, y + vy, 0);

yield;
}


[IIe4eNiIIIe]

I'm trying to make bullets that bounce off the wall once and then go throught players position (boss shoots at the wall, bullet reflects to the position player was at the moment that bullet was shot) but I'm having trouble calculating the initial angle for the bullet. Can anyone help with this?

[R. P. Genocraft]

I'm trying to make bullets that bounce off the wall once and then go throught players position (boss shoots at the wall, bullet reflects to the position player was at the moment that bullet was shot) but I'm having trouble calculating the initial angle for the bullet. Can anyone help with this?

Store the player's X and Y position at the moment the bullet is fired, when it hits the wall calculate the angle between the bullet and said position: let angle= atan2(Y2-Y1,X2-X1); X2 and Y2 being the player's stored position, X1 and Y1 the bullet's current position.

[Drake]

The above is a sensible approach, I'm just wondering why phrase it as though you need an initial angle for the bullets. If the method you would be using to reflect the bullets is a static change in angle, then there is only one possible initial angle to shoot at for a given player position and wall.

[IIe4eNiIIIe]

Well, I'm not that good at english, so i probably didn't explain properly. ObjMove_SetAngle(obj, (180 - ObjMove_GetAngle(obj))); this is a formula that i use to reflect the bullets off the right and left walls. I want a bullet to reflect using that formula, but still hit the player. The problem is calculating an angle which boss has to shoot at.

But I actualy figured it out already, so nvm. Still, thanks for the help.

[tkon]

Hello, I'm currently working on stages but I'm having a problem with hitboxes.

When I try to get the position of an enemy sprite i created, the playing field is used as referential, which means that  (0, 0) is located at (32,16) on the full game screen (see SetStgFrame() default parameters).
So to get my rect hitbox right, i need to shift it by (-32,-16) in order to be centered with the rendered sprite.

I'm using a function as a fix for the moment but i'd like to know if there is way to make sure the same referential is used everywhere : full game screen or playing field only.

[Drake]

The thing is that it's done like that as a convenience for the programmer, as you probably shouldn't be doing game-relevant stuff in a context where (0, 0) is the origin, and shouldn't be doing non-game-relevant stuff in the context where (32, 16) is. There's probably an issue with how you're attempting to tackle a problem that's making this more complicated than it should be.

[tkon]

The thing is I'm setting the hitbox position just after setting the sprite position :

Code: [Select]

ObjSprite2D_SetDestCenter(objEnemy);
ObjEnemy_SetIntersectionCircleToShot(objEnemy, ObjMove_GetX(objEnemy), ObjMove_GetY(objEnemy), 32);
ObjEnemy_SetIntersectionCircleToPlayer(objEnemy, ObjMove_GetX(objEnemy), ObjMove_GetY(objEnemy), 8);

Both functions use a different referential and i don't get why it is actually the case.
Maybe I'm using the wrong function to set it up. The radius has an effect ?

[Kinedyme]

Hi,

Is there a way to change the length of a loose laser while it is moving, such that it becomes shorter?

[Sparen]

Hi,

Is there a way to change the length of a loose laser while it is moving, such that it becomes shorter?

There's ObjLaser_SetLength but you'll need to experiment a bit since I think it will shrink from the tip towards the base.

[Drake]

The thing is I'm setting the hitbox position just after setting the sprite position :

Code: [Select]

ObjSprite2D_SetDestCenter(objEnemy);
ObjEnemy_SetIntersectionCircleToShot(objEnemy, ObjMove_GetX(objEnemy), ObjMove_GetY(objEnemy), 32);
ObjEnemy_SetIntersectionCircleToPlayer(objEnemy, ObjMove_GetX(objEnemy), ObjMove_GetY(objEnemy), 8);

Both functions use a different referential and i don't get why it is actually the case.
Maybe I'm using the wrong function to set it up. The radius has an effect ?

Yes, but I'm saying that your sprite shouldn't be centered at (0, 0) of the whole window under normal circumstances. The most common reason you'd have this is if you were drawing the enemy at a render priority considered outside the bounds of gameplay, i.e. outside the range 20~80.

[Kinedyme]

There's ObjLaser_SetLength but you'll need to experiment a bit since I think it will shrink from the tip towards the base.

When I tried this before, it essentially had no visual effect. Both the sprite and the hitbox don't seem to get any shorter, or at least not at the rate that I intended.
I've sidestepped the problem by manually moving a straight laser with the same graphic and dimensions. Nonetheless, it would be nice to know how to implement it with a loose laser for future reference.

[tkon]

Yes, but I'm saying that your sprite shouldn't be centered at (0, 0) of the whole window under normal circumstances. The most common reason you'd have this is if you were drawing the enemy at a render priority considered outside the bounds of gameplay, i.e. outside the range 20~80.

Thanks, you're right it fixed it. I increased priority to keep track of mobs after they leave the screen.

I'm wondering, is there a way to reduce frame drop ? When i call the mid boss, in the middle of my stage, FPS tends to halve for few frames before coming back to normal.  Is there a way to preload the boss/mobs to reduce this effect ?

Code: [Select]

task TStage
{
    let dir = GetCurrentScriptDirectory();
    let path = dir ~ "Stage 1/Plural_midBoss.dnh";
    let idScript = LoadScriptInThread(path);
    .
    . my stage
    .
    StartScript(idScript);
    while(!IsCloseScript(idScript) && GetPlayerState() != STATE_END)
    {
        yield;
    }

    .
    . my stage again
    .

    CloseStgScene();
}


[HumanReploidJP]

Thinking about the spinning straight lasers, I wonder if there's a code that the rotation of a spinning laser is decelerated to 0 (like Yuyuko lasers during the final spell: https://youtu.be/PuU9Rxi_vyY?t=8) before it fires... If  there's one solution, then let me know.

[Gregory]

Thinking about the spinning straight lasers, I wonder if there's a code that the rotation of a spinning laser is decelerated to 0 (like Yuyuko lasers during the final spell: https://youtu.be/PuU9Rxi_vyY?t=8) before it fires... If  there's one solution, then let me know.

Non-directional laser can be spined by using ObjMove_SetPosition around of the boss
For example:

Code: [Select]

ObjMove_SetPosition(obj, ObjMove_GetX(BossObj)+r*cos(ang),ObjMove_GetY(BossObj)+r*sin(ang),ang);
ObjStLaser_SetAngle(obj, numofhowmanylasertobespined);

[Kinedyme]

I'm trying to recreate the movement of ObjMove_SetDestAtWeight(); I am using a task that sets the position of the object every frame until it reaches its destination, but I'm having trouble with one part.

It seems that the original command cancels the movement if another ObjMove operation is applied to the object in question. How can I implement this feature?

[JDude :3]

How can I make difficulties like Easy, Normal, Hard and Lunatic? (without having to make 4 plurals, since it takes too much space and time?)

[Sparen]

How can I make difficulties like Easy, Normal, Hard and Lunatic? (without having to make 4 plurals, since it takes too much space and time?)

I recommend using CommonData. Refer to https://sparen.github.io/ph3tutorials/ph3u3l24.html

[CrestedPeak9]

How can I make difficulties like Easy, Normal, Hard and Lunatic? (without having to make 4 plurals, since it takes too much space and time?)

Aside from Sparen's suggestion, I'd also advice you look at how Danmakufu fangames utilize common data to simplify difficulty implementation; I personally like BoSM's pattern difficulty which is coded with arrays containing data for bullet speed, types, shot ways, etc.

[WelshRabbit]

I have been wondering how you make aimed player shots (as in, CreatePlayerShotA1(blabla)), I have some kind of idea with GetEnemyBossObjID() (and similar) but I dont think that is enough, and I tried some stuff, it didn't work, does anybody know how to make them?


Edit: nvm I made it

[Zinochan]

Hi, how can I do the humming sound when hitting a boss?

[Sparen]

Hi, how can I do the humming sound when hitting a boss?

The boss can run a loop that keeps track of HP. If HP changes during a frame, then play the sound effect.

[Zinochan]

How can I do this effect?(the green aura)

(image taken from the kirbio's Range 15 script, Koishitale)

[AlexKerb]

How can I increase playing field's size using camera zoom without changing STG frame?

[Arcvasti]

Basically you have a task that constantly creates coloured copies of the boss sprite and then enlarges their scale and lowers their alpha, deleting them when the alpha lowers below zero. You might need to mess around with blend types a little to make the aura look nice.

[Zinochan]

Basically you have a task that constantly creates coloured copies of the boss sprite and then enlarges their scale and lowers their alpha, deleting them when the alpha lowers below zero. You might need to mess around with blend types a little to make the aura look nice.

Wouldn't it cause some good amount of lag?

[Sparen]

Wouldn't it cause some good amount of lag?

Depends on how many are in existence at any given time as well as other factors. Make sure that you test our your implementation on a proper attack so you can see what the FPS will be *with* bullets and other effects.

[Zinochan]

And which function can I use to make the alpha of the boss texture white? (I mean to make the boss all white, but with the opacity)