Author Topic: Bullet Coding (Read 5821 times)

hellninjas · « **on:** October 19, 2011, 02:43:10 pm »

OK I need help with adding a code into my source for shooting bullets out of a ship on the screen using the 2nd button... Help please!

shmibs · « **Reply #1 on:** October 19, 2011, 02:55:03 pm »

what language are you using?

hellninjas · « **Reply #2 on:** October 19, 2011, 02:55:33 pm »

chattahippie · « **Reply #3 on:** October 19, 2011, 03:00:45 pm »

To create an array of say, 30 bullets, use

Code: [Select]

For(A,0,29)
0->{L1+A}->{L1+1+A}->{L1+2+A}->{L1+3+A}
End

This creates thirty bullets with x,y of 0,0 and are not moving
Then, you can store better coordinates to the x,y, and the x and y velocities

To move them, simply add the x velocity, whether or not it is negative, to the x coordinate, and the same for the y

Code: [Select]

For(A,0,29)
{L1+A}+{L1+2+A}->{L1+A}
{L1+1+A}+{L1+3+A}->{L1+1+A}
End

Hope this helps, and be warned, while messing around with this, you may crash your calc, so archive stuff you don't want deleted

Keoni29 · « **Reply #4 on:** October 19, 2011, 03:11:34 pm »

create bullet

Code: [Select]

:Lbl CREATE
:For(r3,0,9  //maximum of 10bullets on screen
:!If {r3*3+L1}
:1->{r3*3+L1}
:r1->{r3*3+L1+1}
:r2->{r3*3+L1+2}
:10->r3       //escape from loop
:End
:End

destroy bullet

Code: [Select]

:Lbl DESTR
:0->{r1+L1}

update

Code: [Select]

:Lbl UPDAT
:For(r1,0,9
:If {r1*3+L1}
:{r1*3+L1+1}++  //when it moves horizontally
:If 96          //outside the screen borders
:Sub(DESTR,r1
:End
:End
:End

You will have to come up with your own collision code since we are no magicians.

Darl181 · « **Reply #5 on:** October 19, 2011, 03:27:27 pm »

What's kind of tricky about bullets in general is removing them from the array safely--when a bullet in the middle of the array needs to be removed. What I ended up doing for Essence was a Copy() to bring the data for the bullets after the one being deleted. Also you'll probably want some sort of variable to tell how many bullets there are.
I'm not the best at explaining things

There's some code that does it here and a tutorial explaining a different method which is pretty helpful to read through here and here.
Hope this helps

Yeong · « **Reply #6 on:** October 19, 2011, 03:33:28 pm »

I thought DT had a tutorial for this

Darl181 · « **Reply #7 on:** October 19, 2011, 03:34:05 pm »

Both of the tutorials are his

calc84maniac · « **Reply #8 on:** October 19, 2011, 03:46:00 pm »

Quote from: Darl181 on October 19, 2011, 03:27:27 pm

What's kind of tricky about bullets in general is removing them from the array safely--when a bullet in the middle of the array needs to be removed. What I ended up doing for Essence was a Copy() to bring the data for the bullets after the one being deleted.

Actually, it's a lot easier to copy the final bullet into the position of the deleted bullet and then decrease the bullet count

Deep Toaster · « **Reply #9 on:** October 19, 2011, 03:51:23 pm »

Moved to the correct forum.

And calc84maniac, that would make the code smaller and faster, but if you're currently looping through the array for other purposes, it could cause problems. On the other hand all you would have to do would be to stay at the same position in the array after copying the last element back, but honestly I didn't think of that

AngelFish · « **Reply #10 on:** October 19, 2011, 04:12:41 pm »

Here's another way to do bullets in Axe. I assumed that the array would be stored in L1, but L1 can be changed to the pointer of your choice pretty trivially. Note that 0,0 is assumed to be an impossible coordinate. That can likewise be changed to -1 or something if it conflicts with your program.

Initialize array:

Code: [Select]

:Lbl INI
:Fill({L1},2*<max number of bullets>+1,0)

Add bullet

Code: [Select]

:Lbl ADD
:!If {L1}-10 
:.10 is max number of bullets
:X->{L1+{L1}+1}
:Y->{L1+{L1}+2}
:End

Destroy bullet

Code: [Select]

:Lbl DESTR
:Copy(L1+{L1},Ptr to cell,2)
:{L1+{L1}}-1->{L1}
:Return

Update bullet array and print bullets onscreen.

Code: [Select]

:Lbl UPD
:.Store X Increment in U
.Y increment in V
:For(A,1,{L1}
:{L1+A}+U->{L1+A}
:{L1+A+1}+V->{L1+A+1}
:Pt-ON({L1+A},{L1+A+1},<Sprite data>)
:End
:DispGraph^rr
:Return

LincolnB · « **Reply #11 on:** October 19, 2011, 04:44:22 pm »

Quote from: Darl181 on October 19, 2011, 03:27:27 pm

What's kind of tricky about bullets in general is removing them from the array safely--when a bullet in the middle of the array needs to be removed.

What I do is just go ahead and remove it, regardless where it is in the array. Then, when the user presses [2ND], I search through the array and put a new one wherever it fits. So every iteration of the main game loop, I move the bullets and display them and do collision checks with objects and such.

Deep Toaster · « **Reply #12 on:** October 19, 2011, 05:21:22 pm »

Yeah, there are several ways to do an array in Axe.

Builderboy · « **Reply #13 on:** October 19, 2011, 05:53:29 pm »

Quote from: buttsfredkin on October 19, 2011, 04:44:22 pm

Quote from: Darl181 on October 19, 2011, 03:27:27 pm
What's kind of tricky about bullets in general is removing them from the array safely--when a bullet in the middle of the array needs to be removed.

What I do is just go ahead and remove it, regardless where it is in the array. Then, when the user presses [2ND], I search through the array and put a new one wherever it fits. So every iteration of the main game loop, I move the bullets and display them and do collision checks with objects and such.

This is also very very useful if you use the address of the bullets elsewhere, since with this method the address of the bullets never change

calc84maniac · « **Reply #14 on:** October 19, 2011, 07:31:45 pm »

Quote from: Builderboy on October 19, 2011, 05:53:29 pm

Quote from: buttsfredkin on October 19, 2011, 04:44:22 pm
Quote from: Darl181 on October 19, 2011, 03:27:27 pm
What's kind of tricky about bullets in general is removing them from the array safely--when a bullet in the middle of the array needs to be removed.

What I do is just go ahead and remove it, regardless where it is in the array. Then, when the user presses [2ND], I search through the array and put a new one wherever it fits. So every iteration of the main game loop, I move the bullets and display them and do collision checks with objects and such.

This is also very very useful if you use the address of the bullets elsewhere, since with this method the address of the bullets never change

Same with my method

Edit: Wait a second, never mind. The bullet at the end of the list moves.

Author Topic: Bullet Coding (Read 5821 times)

hellninjas

Bullet Coding

shmibs

Re: Bullet Coding

hellninjas

Re: Bullet Coding

chattahippie

Re: Bullet Coding

Keoni29

Re: Bullet Coding

Darl181

Re: Bullet Coding

Yeong

Re: Bullet Coding

Darl181

Re: Bullet Coding

calc84maniac

Re: Bullet Coding

Deep Toaster

Re: Bullet Coding

AngelFish

Re: Bullet Coding

LincolnB

Re: Bullet Coding

Deep Toaster

Re: Bullet Coding

Builderboy

Re: Bullet Coding

calc84maniac

Re: Bullet Coding