Random blue screen when I press spacebar?

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Neon Knight

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Joined: 28th Oct 2006

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Posted: 27th Apr 2007 23:41

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Right, I've posted this in the dbpro forum, but my problem has not as of yet been solved, so I thought I'd see what the people in the 2D forum make of it.

Right, I've currently been working on a top-down-tank shooter in DB pro.

I have the tank driving and turning with the arrow keys, and space bar to shoot. The problem I have, is that whenever I press the spacebar, the tank shoots alright, but instead of the black background I had before, I get a blue one. When I let go of spacebar, it returns to a black background.

Does anybody know how to solve this? thanks.

Here's my code:
(it's kinda spaghetti-coded, and not commented, Sorry...)

cls

Set display mode 1024, 768, 32

Load image "Bitmap.bmp", 1
load image "sprite.jpg", 2
load image "tank1.bmp", 3
load image "tank2.bmp", 4
load image "bullet.bmp", 6
Load music "menu.mid", 1
set image colorkey 0,0,0

play music 1
do
Gosub menu

loop

menu:

rem #############################
rem MENUCODE IN  HERE

rem EDITED FOR POST
rem ###############################
gosub begingame

return

begingame:
sprite 3, 100, 200, 6
hide sprite 3

stop music 1
create animated sprite 2, "tanks.bmp", 2, 1, 5
delete sprite 1
cls
set image colorkey 0,0,0

sprite 2, 100, 200, 6

do

if escapekey() = 1 then end
cls
if upkey() = 1
   move sprite 2, 0.5
   move sprite 3, 0.5
endif

if downkey() = 1
   move sprite 2, -0.5
   move sprite 3, -0.5
endif

if rightkey() = 1
    rotate sprite 2, angle#
    rotate sprite 3, angle#
    angle# = angle# + 0.1
endif

if leftkey() = 1
    rotate sprite 2, angle#
    rotate sprite 3, angle#
    angle# = angle# - 0.1
endif

if spacekey() = 1

show sprite 3

thing:
   move sprite 3, 2

if sprite x(3) > 1024 then goto break1
   if sprite x(3) < 1 then goto break1

if sprite y(3) > 768 then goto break1
   if sprite y(3) < 1 then goto break1
   goto thing

endif

if sprite y(3) > 768
        if sprite x(3) < 0 then goto break1

rem   if a# = 100 then goto break1
rem   loop
break1:
delete sprite 3
sprite 3, sprite x (2), sprite y (2), 6
rotate sprite 3, angle#
hide sprite 3
endif
loop

end

+ Code Snippet


cls

Set display mode 1024, 768, 32

Load image "Bitmap.bmp", 1
load image "sprite.jpg", 2
load image "tank1.bmp", 3
load image "tank2.bmp", 4
load image "bullet.bmp", 6
Load music "menu.mid", 1
set image colorkey 0,0,0

play music 1
do
Gosub menu


loop



menu:

rem #############################
rem MENUCODE IN  HERE

rem EDITED FOR POST
rem ###############################
gosub begingame 

return



begingame:
sprite 3, 100, 200, 6
hide sprite 3

stop music 1
create animated sprite 2, "tanks.bmp", 2, 1, 5
delete sprite 1
cls
set image colorkey 0,0,0


sprite 2, 100, 200, 6

do

if escapekey() = 1 then end
cls
if upkey() = 1
   move sprite 2, 0.5
   move sprite 3, 0.5
endif

if downkey() = 1
   move sprite 2, -0.5
   move sprite 3, -0.5
endif

if rightkey() = 1
    rotate sprite 2, angle#
    rotate sprite 3, angle#
    angle# = angle# + 0.1
endif

if leftkey() = 1
    rotate sprite 2, angle#
    rotate sprite 3, angle#
    angle# = angle# - 0.1
endif

if spacekey() = 1

   show sprite 3

   thing:
   move sprite 3, 2

   if sprite x(3) > 1024 then goto break1
   if sprite x(3) < 1 then goto break1

   if sprite y(3) > 768 then goto break1
   if sprite y(3) < 1 then goto break1
   goto thing



   endif

   if sprite y(3) > 768
        if sprite x(3) < 0 then goto break1

   rem   if a# = 100 then goto break1
rem   loop
break1:
delete sprite 3
sprite 3, sprite x (2), sprite y (2), 6
rotate sprite 3, angle#
hide sprite 3
endif
loop

end

Thanks for any help you can give.

Also, another issue I've been having, is with the "rotate sprite" command. The problem is, the axle of rotation is in the top left hand corner, which is really annoying when driving my tank around because it kinda slides around. Is there any chance of setting the axle of rotation to the centre of the image?

Thank you very much for any help you can give in this matter.

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zenassem

22

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User Offline

Joined: 10th Mar 2003

Location: Long Island, NY

Posted: 28th Apr 2007 01:24 Edited at: 28th Apr 2007 01:32

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The second question is easier to answer:
Look at the Offset sprite command. you should be able to match the center with the anchor point with some trial and error.

=====

The first question is a little tougher, perhaps:
Your code is a little speghetti-ish, with Gosubs that don't really have a return. Like the Gosub to begingame:

Another problem is... when you hit the spacekey if the tank isn't outside the screen boarder you get stuck in an almost infinite loop becasue of "goto thing:". That logic might be off. This would cause you to get stuck with the tank moving but outside of any sync. You basically stalled the game loop.

More than likely what's happening is your code is getting stuck without a sync, and the 3d backdrop is rearing it's head (yes sprites in DBpro invoke 3d). So the backdrop is what you are seeing.

To fix it:
You can either use a method I learned from Indi in the newcomers board to color the backdrop black, or you can use a method of turning off the backdrop with the command backdrop off. and on certain situations cls* command at the beginning of your game loop (*this will require redrawing the screen every frame). If you are redrawing the screen you then should use set sprite command to turn off restore background. For these reasons and possibly speed dependent on what you are doing, indi's method might be easier for you to implement.

I'll post a link to that discussion (Just disregard the squabling between indi & I.)

You really need to look at how you can organize your code and get rid of most of those goto's and gosubs. You also need to make sure that whatever you do inside the gameloop, that you don't prevent the code from reaching the sync and restarting the loop.

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Neon Knight

18

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Joined: 28th Oct 2006

Location:

Posted: 28th Apr 2007 12:33

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Wow, thanks for the help in explaining that, it seems to make sense now.

And yeah, considering I've been programming now over 10 years, my organisation in my code is apalling and woeful.

The thing is, my dad (experienced programmer) told me when I was learning Qbasic (I was around 6 at the time) that I should always use gosubs whenever I can, because you never know when you need to use it again, and it saves time, is easier to edit and makes the program faster.
But yeah, that's quite bad. The thing is, "Loop Until X = y" doesn't seem to work for me, "while" doesn't seem to work, so I'm stuck having to physically break each loop with a goto/gosub.

Oh, and as for changing the background colour, turning it off, or using cls at the start of each game loop..

neither worked. I still get a blue screen.

It goes blue when I press space, and stays blue until the bullet leaves the screen.

Woe is me!

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Neon Knight

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Joined: 28th Oct 2006

Location:

Posted: 28th Apr 2007 21:38

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Sorry to bump, but I really want to get this sorted...

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indi

22

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Joined: 26th Aug 2002

Location: Earth, Brisbane, Australia

Posted: 29th Apr 2007 02:28 Edited at: 29th Apr 2007 02:32

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In order to prevent your project becoming too hard to handle, lay it out neatly. Think about using REMARK statements and FUNCTIONS in order to make this much easier to handle.

You can still deploy gosubs if you want but lay it out neatly and it will be easier to read.

This example is based from your code, but Ive drastically changed the commands layout as well as remark everything.

REM -------------------------------------------------------------
REM GAMENAME
REM Author : Neon Knight
REM Sunday 29th April 2007
REM support : indi(mod)
REM VERSION : DBP 6.2
REM -------------------------------------------------------------

REM -------------------------------------------------------------
REM INIT ENVIRONMENT
REM -------------------------------------------------------------
sync on : sync rate 60
randomize timer()
Set display mode 1024, 768, 32 : backdrop on : color backdrop rgb(0,0,0)
set text size 12 : set text font "verdana"

REM -------------------------------------------------------------
REM DECLARE GLOBAL VARIABLES
REM -------------------------------------------------------------
rem the maximum amount of units used in the cleanup routines
Global MaxObjects : MaxObjects = 100

REM -------------------------------------------------------------
REM DECLARE PLAYER VARIABLES
REM -------------------------------------------------------------
Plr_Angle# = 0.0
Plr_MovSpd# = 0.0
Plr_X# = screen width()/2
Plr_Y# = screen height()/2

REM -------------------------------------------------------------
REM LOAD 2D MEDIA
REM -------------------------------------------------------------
REM disabled for testing
`load image "Bitmap.bmp", 1
`load image "sprite.jpg", 2
`load image "tank1.bmp", 3
`load image "tank2.bmp", 4
`load image "bullet.bmp", 6
`set image colorkey 0,0,0

REM make some temp shapes and colours
for i = 1 to 6
   ink rgb(rnd(255),rnd(25),rnd(255)),1
   box 0,0,32,32
   ink rgb(0,0,0),1
   text 4,4,STR$(i)
   get image i,0,0,32,32,1
next i

REM -------------------------------------------------------------
REM LOAD MUSIC
REM -------------------------------------------------------------
REM disabled for testing
`load music "menu.mid", 1 : play music 1

REM -------------------------------------------------------------
REM START MENU FUNCTION
REM -------------------------------------------------------------
cls
StartMenu()
cls

REM -------------------------------------------------------------
REM PRE MAIN LOOP
REM -------------------------------------------------------------
   REM disabled for testing
   `stop music 1

REM -------------------------------------------------------------
   REM LOAD THE PLAYER SPRITE and OFFSET ITS CENTER POINT
   REM -------------------------------------------------------------
   sprite 2,Plr_X#,Plr_Y#,2
   offset sprite 2,16,16

REM -------------------------------------------------------------
   REM LOAD THE TANK SPRITES
   REM -------------------------------------------------------------
   for e = 3 to 4
      sprite e,100*e,100*e,e
   next e

REM -------------------------------------------------------------
REM MAIN LOOP
REM -------------------------------------------------------------
disable escapekey : while escapekey()=0

REM -------------------------------------------------------------
      REM PLAYER CONTROL DETECTION
      REM -------------------------------------------------------------
      if upkey() = 1
         Plr_MovSpd# = 0.5
         else
         if upkey()=0
            Plr_MovSpd# = 0.0
         endif
      endif

if downkey() = 1
         Plr_MovSpd# = -0.3
      endif

if rightkey() = 1
          Plr_Angle# = Plr_Angle# + 0.5
      endif

if leftkey() = 1
          Plr_Angle# = Plr_Angle# - 0.5
      endif

if spacekey() = 1

endif

REM -------------------------------------------------------------
      REM PLAYER CONTROL MOVMENT
      REM -------------------------------------------------------------
      move sprite 2,Plr_MovSpd#
      rotate sprite 2,wrapvalue(Plr_Angle#)

REM TANK AI

REM GAME WORLD UPDATES HERE

REM TEXT TO SCREEN HERE
      text 1,1,"Fps:"+STR$(screen fps())

sync : endwhile

REM -------------------------------------------------------------
REM CLEANUP / DELETE MEDIA
REM -------------------------------------------------------------

for i = 1 to MaxObjects
   if sprite exist(i) = 1
      delete sprite i
   endif
next i

for i = 1 to MaxObjects
   if image exist(i) = 1
      delete image i
   endif
next i

for i = 1 to MaxObjects
   if music exist(i) = 1
      delete music i
   endif
next i

end

REM -------------------------------------------------------------
REM FUNCTIONS
REM -------------------------------------------------------------

function StartMenu()
ink rgb(255,255,255),1
disable escapekey : while spacekey()=0
center text screen width()/2,screen height()/2,"press spacebar to start"
sync : endwhile
exit
endfunction

+ Code Snippet

REM -------------------------------------------------------------
REM GAMENAME
REM Author : Neon Knight
REM Sunday 29th April 2007
REM support : indi(mod)
REM VERSION : DBP 6.2
REM -------------------------------------------------------------

REM -------------------------------------------------------------
REM INIT ENVIRONMENT
REM -------------------------------------------------------------
sync on : sync rate 60
randomize timer()
Set display mode 1024, 768, 32 : backdrop on : color backdrop rgb(0,0,0)
set text size 12 : set text font "verdana"

REM -------------------------------------------------------------
REM DECLARE GLOBAL VARIABLES
REM -------------------------------------------------------------
rem the maximum amount of units used in the cleanup routines
Global MaxObjects : MaxObjects = 100

REM -------------------------------------------------------------
REM DECLARE PLAYER VARIABLES
REM -------------------------------------------------------------
Plr_Angle# = 0.0
Plr_MovSpd# = 0.0
Plr_X# = screen width()/2
Plr_Y# = screen height()/2

REM -------------------------------------------------------------
REM LOAD 2D MEDIA
REM -------------------------------------------------------------
REM disabled for testing
`load image "Bitmap.bmp", 1
`load image "sprite.jpg", 2
`load image "tank1.bmp", 3
`load image "tank2.bmp", 4
`load image "bullet.bmp", 6
`set image colorkey 0,0,0

REM make some temp shapes and colours
for i = 1 to 6
   ink rgb(rnd(255),rnd(25),rnd(255)),1
   box 0,0,32,32
   ink rgb(0,0,0),1
   text 4,4,STR$(i)
   get image i,0,0,32,32,1
next i

REM -------------------------------------------------------------
REM LOAD MUSIC
REM -------------------------------------------------------------
REM disabled for testing
`load music "menu.mid", 1 : play music 1

REM -------------------------------------------------------------
REM START MENU FUNCTION
REM -------------------------------------------------------------
cls
StartMenu()
cls

REM -------------------------------------------------------------
REM PRE MAIN LOOP
REM -------------------------------------------------------------
   REM disabled for testing
   `stop music 1

   REM -------------------------------------------------------------
   REM LOAD THE PLAYER SPRITE and OFFSET ITS CENTER POINT
   REM -------------------------------------------------------------
   sprite 2,Plr_X#,Plr_Y#,2
   offset sprite 2,16,16

   REM -------------------------------------------------------------
   REM LOAD THE TANK SPRITES
   REM -------------------------------------------------------------
   for e = 3 to 4
      sprite e,100*e,100*e,e
   next e

REM -------------------------------------------------------------
REM MAIN LOOP
REM -------------------------------------------------------------
disable escapekey : while escapekey()=0

      REM -------------------------------------------------------------
      REM PLAYER CONTROL DETECTION
      REM -------------------------------------------------------------
      if upkey() = 1
         Plr_MovSpd# = 0.5
         else
         if upkey()=0
            Plr_MovSpd# = 0.0
         endif
      endif

      if downkey() = 1
         Plr_MovSpd# = -0.3
      endif

      if rightkey() = 1
          Plr_Angle# = Plr_Angle# + 0.5
      endif

      if leftkey() = 1
          Plr_Angle# = Plr_Angle# - 0.5
      endif

      if spacekey() = 1

      endif


      REM -------------------------------------------------------------
      REM PLAYER CONTROL MOVMENT
      REM -------------------------------------------------------------
      move sprite 2,Plr_MovSpd#
      rotate sprite 2,wrapvalue(Plr_Angle#)

      REM TANK AI

      REM GAME WORLD UPDATES HERE


      REM TEXT TO SCREEN HERE
      text 1,1,"Fps:"+STR$(screen fps())

sync : endwhile

REM -------------------------------------------------------------
REM CLEANUP / DELETE MEDIA
REM -------------------------------------------------------------

for i = 1 to MaxObjects
   if sprite exist(i) = 1
      delete sprite i
   endif
next i

for i = 1 to MaxObjects
   if image exist(i) = 1
      delete image i
   endif
next i

for i = 1 to MaxObjects
   if music exist(i) = 1
      delete music i
   endif
next i


end


REM -------------------------------------------------------------
REM FUNCTIONS
REM -------------------------------------------------------------

function StartMenu()
ink rgb(255,255,255),1
disable escapekey : while spacekey()=0
center text screen width()/2,screen height()/2,"press spacebar to start"
sync : endwhile
exit
endfunction

you forgot to setup the background colours etc.
On this line at the very top is this.

+ Code Snippet

Set display mode 1024, 768, 32 : backdrop on : color backdrop rgb(0,0,0)

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Neon Knight

18

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Joined: 28th Oct 2006

Location:

Posted: 29th Apr 2007 14:00 Edited at: 29th Apr 2007 14:30

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Okay, I've commented my whole code through and rearranged some bits of it..

I've tried to get it as well laid out as possible.

cls

REM set the display mode

Set display mode 1024, 768, 32 : backdrop on : color backdrop rgb(0,0,0)

REM load media

Load image "Bitmap.bmp", 1
load image "sprite.jpg", 2
load image "tank1.bmp", 3
load image "tank2.bmp", 4
load image "bullet.bmp", 6
Load music "menu.mid", 1

REM setup graphics and backdrops

set image colorkey 0,0,0
color backdrop 0
backdrop off

REM play music

play music 1

REM ############################################
REM MAIN MENU LOOP
REM ############################################

menu:
REM set x pos for menu selector (it only moves up and down)
x# = 90

load bitmap "Bitmap.bmp"

REM set start y pos for menu selector

y# = 215

REM set integer for menu selection (the first one)
menuint = 1

do
   REM gosub the routine that displays the appropriate backdrop and selection images and sprites
   gosub displaymenuimages
   REM   if a key is pressed then goto the subroutine that checks the input from keyboard
   if scancode() <> 0 then gosub checkkeymenu

loop

if ESCAPEKEY() = 1 then end

return

REM   #######################################
REM   subroutine that moves the selector down
REM   #######################################
movedown:

menuint = menuint + 1
do

y# = y# + 2
   a# = a# + 2
   paste image 1, 0, 0
     sprite 1, 90, y#, 2

REM sets a timer condition so it only goes down a certain amount each time
   if a# > 70
      a# = 0
      return
   endif
loop

return

REM  #####################################
REM  subroutine that moves the selector up
REM  #####################################
moveup:

menuint = menuint - 1

do

y# = y# - 2
   a# = a# + 2
   paste image 1, 0, 0

sprite 1, 90, y#, 2
   if a# > 70
      a# = 0
      return
   endif
loop

return

REM   -------------------------------------------------------

REM #########################################################
REM #                 MAIN GAME LOOP      !!!               #
REM #########################################################

begingame:
REM clear the screen from all menu sprites and images
cls

REM create the bullet sprite
sprite 3, 100, 200, 6
REM hide it
hide sprite 3

REM stop the menu music
stop music 1

REM create the tank sprite
create animated sprite 2, "tanks.bmp", 2, 1, 5

REM delete previous meny sprite
delete sprite 1

REM set transparent colour for images to black
set image colorkey 0,0,0

REM create the tank sprite
sprite 2, 100, 200, 6

do

if escapekey() = 1 then end

cls
   color backdrop 0

gosub checkkey

REM   if space bar is pressed,
   if spacekey() = 1
   REM   show the bullet sprite that's been following the tank around
      show sprite 3
   REM   a# = 0
   REM   do
   REM   a# = a# +1
      thing:

color backdrop 0

REM move the bullet sprite in the direction it's facing
         move sprite 3, 2
         REM    ##############################################################
         REM    if the sprite leaves the screen area, then break from the loop
         REM    ##############################################################

if sprite x(3) > 1024 then goto break1
         if sprite x(3) < 1 then goto break1

if sprite y(3) > 768 then goto break1
         if sprite y(3) < 1 then goto break1

REM allow the tank to move while the bullet is on the screen

gosub checkkey
         goto thing

endif

if sprite y(3) > 768
         if sprite x(3) < 0 then goto break1

REM   if a# = 100 then goto break1
   REM   loop
   break1:
      delete sprite 3
      sprite 3, sprite x (2), sprite y (2), 6
      rotate sprite 3, angle#
      hide sprite 3
   endif

loop

end

REM    ----------------------------------------------------------

REM ############################################################
REM ############################################################
REM ##        END OF MAIN GAME LOOP, START OF SUBROUTINES     ##
REM ##                                                        ##
REM ############################################################
REM ############################################################

REM     subroutine to check the input from the keyboard
checkkey:

REM if the upkey is pressed, gosub the routine that moves the tank forward
if upkey() = 1
   gosub moveforward
endif
REM if the downkey is pressed, gosub the routine that moves the tank backward
if downkey() = 1
   gosub movebackward
endif

REM if the right key is pressed, then turn the tank and the
REM hidden bullet by a certain degree
if rightkey() = 1
    rotate sprite 2, angle#
    rotate sprite 3, angle#
    angle# = angle# + 0.1
endif

REM if the left key is pressed, then turn the tank and the
REM hidden bullet by the opposite degree
if leftkey() = 1
    rotate sprite 2, angle#
    rotate sprite 3, angle#
    angle# = angle# - 0.1
endif
return

REM     -----------------------------------------------------------------------

REM    #######################################
REM    subroutine that moves the tank forward.
REM    #######################################

moveforward:

move sprite 2, 0.5
   move sprite 3, 0.5

return

REM   -----------------------------------------------------------------

REM  ########################################
REM  subroutine that moves the tank backward.
REM  ########################################

movebackward:

move sprite 2, -0.5
  move sprite 3, -0.5

return

REM  -----------------------------------------------------------------------

REM  ######################################################
REM  Subroutine that checks the keyboard input for the menu.
REM  ######################################################

checkkeymenu:
 REM if downkey is pressed, and y is not at the third selection down, gosub the
      REM movedown subroutine to move the selector sprite down

if downkey() = 1 and y# <355 then gosub movedown

REM if upkey is pressed and y is not at the first selection up, gosub the
      REM moveup subroutine to move the selectior sprite up

if upkey() = 1 and y# > 235 then gosub moveup

REM if escape key is pressed, end the program

if escapekey() = 1 then end

REM if the return key is pressed (one of the selections has been selected)

if returnkey() = 1

REM if the thirs selection has been selected (quit), then end.
         if menuint = 3 then end

REM if the first selection has been selected (new game), then start a new game.
         if menuint = 1 then gosub begingame

endif

REM if
      paste image 2, 90, y#

return

REM   ------------------------------------------------------------------------

displaymenuimages:

REM display the backdrop image for the menu
   paste image 1, 0, 0

REM display the menu selection sprite
   sprite 1, 90, y#, 2

return

+ Code Snippet

cls

REM set the display mode

Set display mode 1024, 768, 32 : backdrop on : color backdrop rgb(0,0,0)

REM load media

Load image "Bitmap.bmp", 1
load image "sprite.jpg", 2
load image "tank1.bmp", 3
load image "tank2.bmp", 4
load image "bullet.bmp", 6
Load music "menu.mid", 1

REM setup graphics and backdrops

set image colorkey 0,0,0
color backdrop 0
backdrop off

REM play music

play music 1

REM ############################################
REM MAIN MENU LOOP
REM ############################################


menu:
REM set x pos for menu selector (it only moves up and down)
x# = 90

load bitmap "Bitmap.bmp"

REM set start y pos for menu selector

y# = 215

REM set integer for menu selection (the first one)
menuint = 1



do
   REM gosub the routine that displays the appropriate backdrop and selection images and sprites
   gosub displaymenuimages
   REM   if a key is pressed then goto the subroutine that checks the input from keyboard
   if scancode() <> 0 then gosub checkkeymenu

loop

if ESCAPEKEY() = 1 then end

return




REM   #######################################
REM   subroutine that moves the selector down
REM   #######################################
movedown:

   menuint = menuint + 1
do

   y# = y# + 2
   a# = a# + 2
   paste image 1, 0, 0
     sprite 1, 90, y#, 2

   REM sets a timer condition so it only goes down a certain amount each time
   if a# > 70
      a# = 0
      return
   endif
loop

return

REM  #####################################
REM  subroutine that moves the selector up
REM  #####################################
moveup:

   menuint = menuint - 1

do

   y# = y# - 2
   a# = a# + 2
   paste image 1, 0, 0


   sprite 1, 90, y#, 2
   if a# > 70
      a# = 0
      return
   endif
loop

return

REM   -------------------------------------------------------


REM #########################################################
REM #                 MAIN GAME LOOP      !!!               #
REM #########################################################


begingame:
REM clear the screen from all menu sprites and images
cls

REM create the bullet sprite
sprite 3, 100, 200, 6
REM hide it
hide sprite 3

REM stop the menu music
stop music 1

REM create the tank sprite
create animated sprite 2, "tanks.bmp", 2, 1, 5

REM delete previous meny sprite
delete sprite 1

REM set transparent colour for images to black
set image colorkey 0,0,0

REM create the tank sprite
sprite 2, 100, 200, 6

do

   if escapekey() = 1 then end

   cls
   color backdrop 0

   gosub checkkey

   REM   if space bar is pressed,
   if spacekey() = 1
   REM   show the bullet sprite that's been following the tank around
      show sprite 3
   REM   a# = 0
   REM   do
   REM   a# = a# +1
      thing:

         color backdrop 0

         REM move the bullet sprite in the direction it's facing
         move sprite 3, 2
         REM    ##############################################################
         REM    if the sprite leaves the screen area, then break from the loop
         REM    ##############################################################

         if sprite x(3) > 1024 then goto break1
         if sprite x(3) < 1 then goto break1

         if sprite y(3) > 768 then goto break1
         if sprite y(3) < 1 then goto break1

         REM allow the tank to move while the bullet is on the screen

         gosub checkkey
         goto thing



         endif

         if sprite y(3) > 768
         if sprite x(3) < 0 then goto break1

      REM   if a# = 100 then goto break1
   REM   loop
   break1:
      delete sprite 3
      sprite 3, sprite x (2), sprite y (2), 6
      rotate sprite 3, angle#
      hide sprite 3
   endif

loop

end


REM    ----------------------------------------------------------


REM ############################################################
REM ############################################################
REM ##        END OF MAIN GAME LOOP, START OF SUBROUTINES     ##
REM ##                                                        ##
REM ############################################################
REM ############################################################




REM     subroutine to check the input from the keyboard
checkkey:

REM if the upkey is pressed, gosub the routine that moves the tank forward
if upkey() = 1
   gosub moveforward
endif
REM if the downkey is pressed, gosub the routine that moves the tank backward
if downkey() = 1
   gosub movebackward
endif

REM if the right key is pressed, then turn the tank and the
REM hidden bullet by a certain degree
if rightkey() = 1
    rotate sprite 2, angle#
    rotate sprite 3, angle#
    angle# = angle# + 0.1
endif

REM if the left key is pressed, then turn the tank and the
REM hidden bullet by the opposite degree
if leftkey() = 1
    rotate sprite 2, angle#
    rotate sprite 3, angle#
    angle# = angle# - 0.1
endif
return



REM     -----------------------------------------------------------------------


REM    #######################################
REM    subroutine that moves the tank forward.
REM    #######################################

moveforward:

   move sprite 2, 0.5
   move sprite 3, 0.5

return

REM   -----------------------------------------------------------------

REM  ########################################
REM  subroutine that moves the tank backward.
REM  ########################################

movebackward:

  move sprite 2, -0.5
  move sprite 3, -0.5

return

REM  -----------------------------------------------------------------------

REM  ######################################################
REM  Subroutine that checks the keyboard input for the menu.
REM  ######################################################

checkkeymenu:
 REM if downkey is pressed, and y is not at the third selection down, gosub the
      REM movedown subroutine to move the selector sprite down

      if downkey() = 1 and y# <355 then gosub movedown

      REM if upkey is pressed and y is not at the first selection up, gosub the
      REM moveup subroutine to move the selectior sprite up

      if upkey() = 1 and y# > 235 then gosub moveup

      REM if escape key is pressed, end the program

      if escapekey() = 1 then end

      REM if the return key is pressed (one of the selections has been selected)

      if returnkey() = 1

         REM if the thirs selection has been selected (quit), then end.
         if menuint = 3 then end

         REM if the first selection has been selected (new game), then start a new game.
         if menuint = 1 then gosub begingame

      endif

      REM if
      paste image 2, 90, y#

return

REM   ------------------------------------------------------------------------

displaymenuimages:

   REM display the backdrop image for the menu
   paste image 1, 0, 0

   REM display the menu selection sprite
   sprite 1, 90, y#, 2

return

And I still have a blue screen when the bullet is on the screen.

What can I do about this?

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Profile PM

indi

22

Years of Service

User Offline

Joined: 26th Aug 2002

Location: Earth, Brisbane, Australia

Posted: 29th Apr 2007 14:50

Link

The cls at the start is a throw back to classic days and win2k refresh, not required for pro.

your switching the backdrop on and off within your code, once at the top and off again prior to your main loop.

your missing sync statements prior to the end of your loops

your adding clear screen elements to your loops, which is effectively another clear and sync of the screen.

dont try to add any gosubs for now, just align it all so its procedural to get it working.

try to be neater with your variables and declare them in one area to make life easier.

Here is a revised snippet to the above I made for you earlier.
Notice Ive changed the start button to enter or return.

And now Ive added a button trapping method to allow to see the result of the bullet sprite appearing without a blue backdrop issue. We are using scancodes and only capturing one keypress, not rapid fire.

The bullet does not offset, rotate or move away from the players sprite but you get the mechanics of what im trying to show you in action.

Your seeing the blue background if the backdrop has not been declared off which is lines 19 and 20 in your revised code.

Anyway hopefully this example will make it clearer for you.

REM -------------------------------------------------------------
REM GAMENAME
REM Author : Neon Knight
REM Sunday 29th April 2007
REM support : indi(mod)
REM VERSION : DBP 6.2
REM -------------------------------------------------------------

REM -------------------------------------------------------------
REM INIT ENVIRONMENT
REM -------------------------------------------------------------
sync on : sync rate 60
randomize timer()
Set display mode 1024, 768, 32 : backdrop on : color backdrop rgb(0,0,0)
set text size 12 : set text font "verdana"

REM -------------------------------------------------------------
REM DECLARE GLOBAL VARIABLES
REM -------------------------------------------------------------
rem the maximum amount of units used in the cleanup routines
Global MaxObjects : MaxObjects = 100

REM -------------------------------------------------------------
REM DECLARE PLAYER VARIABLES
REM -------------------------------------------------------------
Plr_Angle# = 0.0
Plr_MovSpd# = 0.0
Plr_X# = screen width()/2
Plr_Y# = screen height()/2

REM PLAYER KEY SWITCH / TOGGLES
dim Yourname_Switch(1) : Yourname_Switch(1) = 0
dim Yourname_Toggle(1) : Yourname_Toggle(1) = 0

REM -------------------------------------------------------------
REM LOAD 2D MEDIA
REM -------------------------------------------------------------
REM disabled for testing
`load image "Bitmap.bmp", 1
`load image "sprite.jpg", 2
`load image "tank1.bmp", 3
`load image "tank2.bmp", 4
`load image "bullet.bmp", 6
`set image colorkey 0,0,0

REM make some temp shapes and colours
for i = 1 to 6
   ink rgb(rnd(255),rnd(25),rnd(255)),1
   box 0,0,32,32
   ink rgb(0,0,0),1
   text 4,4,STR$(i)
   get image i,0,0,32,32,1
next i

REM -------------------------------------------------------------
REM LOAD MUSIC
REM -------------------------------------------------------------
REM disabled for testing
`load music "menu.mid", 1 : play music 1

REM -------------------------------------------------------------
REM START MENU FUNCTION
REM -------------------------------------------------------------
cls
StartMenu()
cls

REM -------------------------------------------------------------
REM PRE MAIN LOOP
REM -------------------------------------------------------------
   REM disabled for testing
   `stop music 1

REM -------------------------------------------------------------
   REM LOAD THE PLAYER SPRITE and OFFSET ITS CENTER POINT
   REM -------------------------------------------------------------
   sprite 2,Plr_X#,Plr_Y#,2
   offset sprite 2,16,16

REM -------------------------------------------------------------
   REM LOAD THE TANK SPRITES
   REM -------------------------------------------------------------
   for e = 3 to 4
      sprite e,100*e,100*e,e
   next e

REM -------------------------------------------------------------
   REM MAKE AND HIDE THE PLAYERS SPRITE BULLET
   REM -------------------------------------------------------------
   sprite 6,-100,-100,6
   hide sprite 6

REM -------------------------------------------------------------
REM MAIN LOOP
REM -------------------------------------------------------------
disable escapekey : while escapekey()=0

REM -------------------------------------------------------------
      REM PLAYER CONTROL DETECTION
      REM -------------------------------------------------------------
      if upkey() = 1
         Plr_MovSpd# = 1.0
         else
         if upkey()=0
            Plr_MovSpd# = 0.0
         endif
      endif

if downkey() = 1
         Plr_MovSpd# = -0.3
      endif

if rightkey() = 1
          Plr_Angle# = Plr_Angle# + 1.5
      endif

if leftkey() = 1
          Plr_Angle# = Plr_Angle# - 1.5
      endif

rem ------------------------------------------------------------------------------------------
      rem KeyPess switch toggle action SPACEBAR
      rem ------------------------------------------------------------------------------------------
      If keystate(57)=1 and Yourname_Switch(1)=0
         Yourname_Toggle(1)=1-Yourname_Toggle(1)
         Yourname_Switch(1)=1
            sprite 6,sprite x(2),sprite y(2),6
            show sprite 6
      Endif
      If keystate(57)=0 then Yourname_Switch(1)=0
         if Yourname_Toggle(1)=1
      endif

REM -------------------------------------------------------------
      REM PLAYER CONTROL MOVMENT
      REM -------------------------------------------------------------
      move sprite 2,Plr_MovSpd#
      rotate sprite 2,wrapvalue(Plr_Angle#)

REM TANK AI

REM GAME WORLD UPDATES HERE

REM TEXT TO SCREEN HERE
      text 1,1,"Fps:"+STR$(screen fps())
      text 1,16,"scancode"+STR$(scancode())

sync : endwhile

REM -------------------------------------------------------------
REM CLEANUP / DELETE MEDIA
REM -------------------------------------------------------------

for i = 1 to MaxObjects
   if sprite exist(i) = 1
      delete sprite i
   endif
next i

for i = 1 to MaxObjects
   if image exist(i) = 1
      delete image i
   endif
next i

for i = 1 to MaxObjects
   if music exist(i) = 1
      delete music i
   endif
next i

end

REM -------------------------------------------------------------
REM FUNCTIONS
REM -------------------------------------------------------------

function StartMenu()
ink rgb(255,255,255),1
disable escapekey : while returnkey()=0
center text screen width()/2,screen height()/2,"press returnkey to start"
sync : endwhile
exit
endfunction

+ Code Snippet

REM -------------------------------------------------------------
REM GAMENAME
REM Author : Neon Knight
REM Sunday 29th April 2007
REM support : indi(mod)
REM VERSION : DBP 6.2
REM -------------------------------------------------------------

REM -------------------------------------------------------------
REM INIT ENVIRONMENT
REM -------------------------------------------------------------
sync on : sync rate 60
randomize timer()
Set display mode 1024, 768, 32 : backdrop on : color backdrop rgb(0,0,0)
set text size 12 : set text font "verdana"

REM -------------------------------------------------------------
REM DECLARE GLOBAL VARIABLES
REM -------------------------------------------------------------
rem the maximum amount of units used in the cleanup routines
Global MaxObjects : MaxObjects = 100

REM -------------------------------------------------------------
REM DECLARE PLAYER VARIABLES
REM -------------------------------------------------------------
Plr_Angle# = 0.0
Plr_MovSpd# = 0.0
Plr_X# = screen width()/2
Plr_Y# = screen height()/2


REM PLAYER KEY SWITCH / TOGGLES
dim Yourname_Switch(1) : Yourname_Switch(1) = 0
dim Yourname_Toggle(1) : Yourname_Toggle(1) = 0


REM -------------------------------------------------------------
REM LOAD 2D MEDIA
REM -------------------------------------------------------------
REM disabled for testing
`load image "Bitmap.bmp", 1
`load image "sprite.jpg", 2
`load image "tank1.bmp", 3
`load image "tank2.bmp", 4
`load image "bullet.bmp", 6
`set image colorkey 0,0,0

REM make some temp shapes and colours
for i = 1 to 6
   ink rgb(rnd(255),rnd(25),rnd(255)),1
   box 0,0,32,32
   ink rgb(0,0,0),1
   text 4,4,STR$(i)
   get image i,0,0,32,32,1
next i

REM -------------------------------------------------------------
REM LOAD MUSIC
REM -------------------------------------------------------------
REM disabled for testing
`load music "menu.mid", 1 : play music 1

REM -------------------------------------------------------------
REM START MENU FUNCTION
REM -------------------------------------------------------------
cls
StartMenu()
cls

REM -------------------------------------------------------------
REM PRE MAIN LOOP
REM -------------------------------------------------------------
   REM disabled for testing
   `stop music 1

   REM -------------------------------------------------------------
   REM LOAD THE PLAYER SPRITE and OFFSET ITS CENTER POINT
   REM -------------------------------------------------------------
   sprite 2,Plr_X#,Plr_Y#,2
   offset sprite 2,16,16

   REM -------------------------------------------------------------
   REM LOAD THE TANK SPRITES
   REM -------------------------------------------------------------
   for e = 3 to 4
      sprite e,100*e,100*e,e
   next e


   REM -------------------------------------------------------------
   REM MAKE AND HIDE THE PLAYERS SPRITE BULLET
   REM -------------------------------------------------------------
   sprite 6,-100,-100,6
   hide sprite 6


REM -------------------------------------------------------------
REM MAIN LOOP
REM -------------------------------------------------------------
disable escapekey : while escapekey()=0

      REM -------------------------------------------------------------
      REM PLAYER CONTROL DETECTION
      REM -------------------------------------------------------------
      if upkey() = 1
         Plr_MovSpd# = 1.0
         else
         if upkey()=0
            Plr_MovSpd# = 0.0
         endif
      endif

      if downkey() = 1
         Plr_MovSpd# = -0.3
      endif

      if rightkey() = 1
          Plr_Angle# = Plr_Angle# + 1.5
      endif

      if leftkey() = 1
          Plr_Angle# = Plr_Angle# - 1.5
      endif


      rem ------------------------------------------------------------------------------------------
      rem KeyPess switch toggle action SPACEBAR
      rem ------------------------------------------------------------------------------------------
      If keystate(57)=1 and Yourname_Switch(1)=0
         Yourname_Toggle(1)=1-Yourname_Toggle(1)
         Yourname_Switch(1)=1
            sprite 6,sprite x(2),sprite y(2),6
            show sprite 6
      Endif
      If keystate(57)=0 then Yourname_Switch(1)=0
         if Yourname_Toggle(1)=1
      endif




      REM -------------------------------------------------------------
      REM PLAYER CONTROL MOVMENT
      REM -------------------------------------------------------------
      move sprite 2,Plr_MovSpd#
      rotate sprite 2,wrapvalue(Plr_Angle#)

      REM TANK AI

      REM GAME WORLD UPDATES HERE


      REM TEXT TO SCREEN HERE
      text 1,1,"Fps:"+STR$(screen fps())
      text 1,16,"scancode"+STR$(scancode())

sync : endwhile

REM -------------------------------------------------------------
REM CLEANUP / DELETE MEDIA
REM -------------------------------------------------------------

for i = 1 to MaxObjects
   if sprite exist(i) = 1
      delete sprite i
   endif
next i

for i = 1 to MaxObjects
   if image exist(i) = 1
      delete image i
   endif
next i

for i = 1 to MaxObjects
   if music exist(i) = 1
      delete music i
   endif
next i


end


REM -------------------------------------------------------------
REM FUNCTIONS
REM -------------------------------------------------------------

function StartMenu()
ink rgb(255,255,255),1
disable escapekey : while returnkey()=0
center text screen width()/2,screen height()/2,"press returnkey to start"
sync : endwhile
exit
endfunction

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2D All the way! / Random blue screen when I press spacebar?