Object Explosion Generator

[jaymzjulian]

We all need to blow things up in our games, right?  This library will do that to any any object for you - i'm using the rose object i play with as a demo for this, but any LinesSprite or Lines3dSprite format object should do!  Assuming your line count is "normal", it's entirely reasonable to do this in realtime during your game - indeed, that's what the sample shows - although you could use it to generate an animation instead, with a little modification.

demos:

these are all deliberatly slow so you can see things .

explosion-demo-nobreak - explode a simple object, dont disconnect the lines
explosion-demo-break - explode a simple object, disconnect the lines
explosion-demo - explode a complex object.  Note that, for some reason, this will sometimes crash the vectrex32 hard right now .  I don't know why!  Whjich is a shame, since it looks cool!

How to use in your own stuff:

1) include explosion.bai
2) call the function "prepare_explosion" with the following params:

Code Select Expand


' Params:
' dimensions - 2 or 3
' obj - the LinesSprite format object
' world_scale - scale of the world
' point - where to explode
' x_impulse - base impulse to hit object with on the x axis
' y_impulse - base impulse to hit object with on the y axis
' x_random - additional random impulse for x
' y_random - additional random impulse for y
' break_apart - true/false - do we break the vectors?


3) call either explode2d or explode3d each frame until you're done with the explosion.

sample:

Code Select Expand


' get the object
rose_object = rose()

' prepare the object for exploding - just expanding variables here for clarity :)
world_scale = 40
x_impulse = 2.5
y_impulse = 5.0
x_random = 2.5
y_random = 5.0
rose_explosion = prepare_explosion(2, rose_object, world_scale, {0,-400}, {x_impulse, y_impulse}, {x_random, y_random}, 9.8, -400, false)

' put it on the screen
LinesSprite(rose_explosion.dest)
controls = WaitForFrame(JoystickNone, Controller1, JoystickNone)
while controls[1,3] = 0
  call explode2d(rose_explosion)
  ' wait for next frame :)
  controls = WaitForFrame(JoystickNone, Controller1, JoystickNone)
endwhile


[Vectrex32]

This is awesome! I'd love to see a video.

- Bob

[jaymzjulian]

This is awesome! I'd love to see a video.

- Bob

video: https://www.youtube.com/watch?v=f1ucBlRXVR4

updated code including this demo attached - press button 2 to explode the cycle.

also in my tools github at https://github.com/jaymzjulian/vectrex32_tools

[jaymzjulian]

Back doing vectrex stuff again, finally - when i went to integrate this into a game, i found that it could cause frame rate drops if you had complex objects (specifically, the 220 vertex cycles in vxtron) - if i exploded 1, it was fine, if i exploded 2 at once, the framerate started dropping way back.  So I added a cached mode for the ram tradeoff.

Code Select Expand


' grab 2 seconds worth of explosion - 40frams @ 20 fps                                                                  ' Note that generating more than about 10k verticies _will_ break things - for this demo, our object is
' 220 broken vertificies - this means it tkaes 220*30*4 array entries for this, or 26400 array entries for
' this precalc - so on large objects, essentially be careful!  Especially since you need to multiply that also
' out due to them being 4byte floats/ints - so after 52 frames, the v32 runs out of ram in the generation phase.
' I suspect that's also some not-so-great GC, since we use a bunch of deepcopy stuff in there, BUT... still,
' that's 183kbytes of data at that point, which DOES match with my expectations about what the v32 can handle!
'
' So the short version is, be careful about your frame rates ;)
call fill_cache(ce, 40, 20)


Then in your loop

Code Select Expand


' grab explosion based off timer
new_data = cached_explosion(ce)
' and display it!
Lines2dSprite(new_data)



It's in the vectrex32_tools github @ https://github.com/jaymzjulian/vectrex32_tools.

[Vectrex32]

If you look up "Parkinson's Law of Data", there's a picture of you. ;-)

[jaymzjulian]

If you look up "Parkinson's Law of Data", there's a picture of you. ;-)

I'm basically a toddler - if there's a limit, i can't resist pushing at it to see where it breaks!