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Hello,

I am using ATanFull() to successfully find the angle from my pointer to the player sprite, and cause the player sprite to point directly at the pointer by using the following code


pointer_loc_X = agk::GetPointerX();
pointer_loc_Y = agk::GetPointerY();

playerAngle = agk::ATanFull(	pointer_loc_X  - agk::GetSpriteX(1) , pointer_loc_Y - agk::GetSpriteY(1) );

agk::SetSpriteAngle( 3, playerAngle );

Works PERFECT...

However as soon as I start with the screen moving using SetViewOffset() .. well now it only works near the center of the screen.

Now I understand conceptually this is probably because the X/Y cordinates of either the screen, or the pointer, or the sprite are not going to match the code above.

But every way I have tried to accommodate for this does not seem to make a darn bit of difference?

So my question is once you start using SetViewOffset() how would I go about this?

See some failed examples here:

FAIL 1:


int viewX = agk::GetViewOffsetX();
int viewY = agk::GetViewOffsetY();

int viewXDiff =  0;
int viewYDiff =  0;

if ( viewX < 0 )viewXDiff = pointer_loc_X - agk::GetSpriteXByOffset(3);
if (viewX > 0 )	viewXDiff = pointer_loc_X + agk::GetSpriteXByOffset(3);
if (viewY < 0 ) viewYDiff = pointer_loc_Y - agk::GetSpriteYByOffset(3);
if (viewY > 0 ) viewYDiff = pointer_loc_Y + agk::GetSpriteYByOffset(3);

playerAngle = agk::ATanFull( viewXDiff ,  viewYDiff );

I also tried inverting the + and - on each line in case I had it backwards, no luck.

I also tried this and a few variants


int viewX = agk::GetViewOffsetX();
int viewY = agk::GetViewOffsetY();

int viewXDiff =  0;
int viewYDiff =  0;

	
if ( viewX < 0 ) viewXDiff = pointer_loc_X - agk::GetSpriteXByOffset(3) - viewX ;
if ( viewX > 0 ) viewXDiff = pointer_loc_X - agk::GetSpriteXByOffset(3) + viewX ;
if ( viewY < 0 ) viewYDiff = pointer_loc_Y - agk::GetSpriteYByOffset(3) - viewY;
if ( viewY > 0 ) viewYDiff = pointer_loc_Y - agk::GetSpriteYByOffset(3) + viewY;

playerAngle = agk::ATanFull( viewXDiff ,  viewYDiff );

Again I inverted all the + and - signs in case I had it backwards. Also no luck.

So any help appreciated, the SetViewOffset() is killing me here!

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Hodgey

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Posted: 6th Feb 2013 05:21

Quote: "However as soon as I start with the screen moving using SetViewOffset() .. well now it only works near the center of the screen."

If your player never leaves the screen you could (theoretically) simply use the WorldToScreen commands. The angle should still be the same either way.

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erebusman

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Posted: 6th Feb 2013 05:23

@Hodgey: Yeah the player is always smack dab center of the screen. Its the world that moves around him.

I'll toy with that and see if it helps. Thanks.

PS: Anyone with other ideas don't be shy, I'll take them all!

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baxslash

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Posted: 6th Feb 2013 12:05

If your player is always in the centre of the screen why not just use something like this:

cx# = getVirtualWidth()*0.5
cy# = getVirtualHeight()*0.5
dx# = getPointerX()-cx#
dy# = getPointerY()-cy#
angle# = atanfull(dx#,dy#)-90.0

this.mess = abs(sin(times#))

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erebusman

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Posted: 6th Feb 2013 16:07

@backslash: now that's a creative idea too! I think that'll work.

Was doing artwork last night so havent gotten to try either but I will definitely work on this tonight.

Thanks guys

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Van B

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Posted: 6th Feb 2013 16:38

I think you'd need to add the view offset coordinates onto your mouse pointer coords - maybe best to split your code up a little, so work out the X and Y difference and store it as a variable, rather than doing the math directly in the Atanfull call. Firstly, because it'll make it more readable when you add in the view offset adjustment, but also because you'll need that if you plan to check the distance with SQRT as well, I tend to use DX# and DY# for X/Y distances as a rule just in case.

I got a fever, and the only prescription, is more memes.

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Markus

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Posted: 6th Feb 2013 19:19 Edited at: 6th Feb 2013 19:28

i think the problem is that x from mouse is not x from sprite
if you use the viewoffset.

you can think ATanFull is the middle of a circle and x,y parameter are
one point of the circle around, the radius is unimportant because you get the same angle.

if you have two x,y coordinates you must subtract at both the x,y middle point you want. two coordinates because you will have the
delta / distance.
mx=x1 < your sprite is the middle point
x1=x1-mx
x2=x2-mx
dx=x2-x1

in theory you can trim it because x1-x1 =0,
its better if you understand your code and let the computer do
a little bit more.

try for the mouse a sprite and bring it at the same position as the pointer and use this both sprite x,y for calculating.

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erebusman

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Posted: 7th Feb 2013 05:49

Well an hour and 40 minutes of coding work later. I still have the exact same problem.

Believe I've tried all the suggestions several times over at this point

Ever feel frustrated?

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erebusman

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Posted: 7th Feb 2013 06:22

And here we are 40 minutes later this is working like so:


	int viewX = agk::GetViewOffsetX();
	int viewY = agk::GetViewOffsetY();

	int mouseX = pointer_loc_X + viewX;
	int mouseY = pointer_loc_Y  + viewY;

	int vWidth = agk::GetSpriteX(3) +16 ; // offsetting by 16 because the sprite is 32 pixels so its in the center
	int vHeight = agk::GetSpriteY(3) +16; // offsetting by 16 because the sprite is 32 pixels so its in the center

	int viewXDiff =  mouseX - vWidth ;
	int viewYDiff =  mouseY - vHeight ;
	
	 playerAngle = agk::ATanFull( viewXDiff	, viewYDiff );

Now my movement code is a tiny wonky but the angles perfect.. think I am back to progress now.

I have no idea what I really did though haha!

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erebusman

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Posted: 7th Feb 2013 06:39

And movement bug fixed.

I spent 4 days on this code and I thought it would take 2-3 hours

What is persistence?

And thank you everyone for tipping in I really appreciate it, helped me think about it in different ways!

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Markus

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Posted: 7th Feb 2013 13:05

@erebusman
this function are usefull if you want handle ae sprite at middle,
i saw you use the left,top corner + width/2 height/2

setspriteoffset(spr,getspritewidth(spr)/2,getspriteheight(spr)/2)
setspritepositionbyoffset(spr,x,y)
getspritexbyoffset(spr)
getspriteybyoffset(spr)

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baxslash

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Posted: 7th Feb 2013 13:13