Timer&Collision

[Peter]

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[attachment deleted by admin]

[Charles Pegge]

Thanks Peter.

I had a few ideas for more efficient collision detection. It only makes a small difference.

But if there are large numbers of objects I would then adopt a zone mapping strategy to avoid exponential increases in collision tests.

Code: [Select]

/*  Circle Collision by Peter  o5/o4/2011  */

  indexbase 0
  include "wFunc.h"

  OpenWindow "Circle Collison",800,600,ws_overlapped
  SetFont 16,16,0,0
  Long xCir1,yCir1,rCir1,xCir2,yCir2,rCir2,color,px,jx
  Long xBox1,yBox1,xBox2,yBox2

  Function CircleCollision(long xd, long yd,long rp) as long
  '=========================================================
  iF xd*xd+yd*yd < rp*rp
    return 1
  End iF
  End Function

  Function BoxCollision(long xd, long yd,long rp) as long
  '======================================================
  iF abs(yd) < rp
    iF abs(xd) < rp then return 1
  end if
  End Function

  xCir1 =0   : yCir1=300 : rCir1=20
  xCir2 =800 : yCir2=300 : rCir2=30
  xBox1=0 : yBox1=200
  xBox1=0 : yBox2=220

  '====
  'MAIN
  '====

  While WinExit=0

  ClearBuffer color
  Text "Collision " + Str(px) + "/" + Str(jx),312,32,RGB(255,255,255)
  color=0
  Circle xCir1,yCir1,rCir1,RGB(255,255,255)
  Circle xCir2,yCir2,rCir2,RGB(255,255,255)
  xCir1 +=1: xCir2 -=2
  iF xCir1 >=800 Then xCir1 =0
  iF xCir2 <=0   Then xCir2 =800
  px = CircleCollision xCir2-xCir1,yCir2-yCir1, rCir1+rCir2
  iF px Then color = RGB(Rand(24,200),Rand(24,200),Rand(24,200))
  Box xBox1,yBox1,40,40,RGB(255,255,255)
  Box xBox2,yBox2,20,20,RGB(255,255,255)
  xBox1 +=2: xBox2 -=2
  iF xBox1 >=800 Then xBox1 =0
  iF xBox2 <=0   Then xBox2 =840
  jx = BoxCollision xBox2-xBox1,yBox2-yBox1,30
  iF jx Then color or=255
  DoEvents
  FlipBuffer
  WaitFrames 80

  Wend
  WinEnd

Charles

[Charles Pegge]

Hi Peter,

My collision test procedure for circles reduced the load by about 25% by eliminating some parameters and one nested subtraction.

Global and static variables are all referenced from the EBX register. This prevented you from using the ebx register and these variables at the same time. Similarly DLL procedure addresses (& other vectored calls) are also mapped to offsets  of the EBX register. Local variables use this EBP register.

BYREF long/sys is the default for prototypes.

If you would like to adopt this convention with BYVAL params then all you have to do is use the #byval directive.

Code: [Select]


#byval 'default byval params

function f(a,b,c,d) as long
  d*=10
  function=a*10
end function

long a=1,b=2,c=3,d=4

print f a,b,c,d
print d

#byref 'default byref params


Charles

[Charles Pegge]

Another more recent innovation

You can apply a type to a whole group of parameters.

Code: [Select]


'These have params BYVAL
'=======================

function f(single a,b,c,d) as single
  d*=10
  function=b*10
end function

single f(single a,b,c,d)
{
  d*=10
  function=b*10
}

'These have params BYREF
'=======================

function f(single* a,b,c,d) as single
  d*=10
  function=b*10
end function

single f(single* a,b,c,d)
{
  d*=10
  function=b*10
}

single a=1.25,b=2.25,c=3.25,d=4.25

print f a,b,c,d
print d

Charles

[Charles Pegge]

Before this program gets out of control I thought I had better post it now

This is collision detection with zone proximity testing. It also has some elementary elastic collision physics.

The OOP helps to keep it all well encapsulated.

Charles



[attachment deleted by admin]

[Charles Pegge]

Hi Peter,

Glad you liked it. I hope the class syntax might be useful for managing game objects. I am still working on the best way to make objects interact. This is my best scheme so far.

FS and GS are reserved names along with a number of other specialised CPU registers. There are so many of them that they often interfere with the variable name space and cause inconvenience to the programmer. I should be able to make Oxygen a bit smarter and interpret these as registers only when used as Assembler operands. But maybe keep the main 32/64 bit registers reserved and available in Basic  expressions: EAX, ECX etc

Charles

[kryton9]

Nice example guys, thanks.