About as bad as it can be

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VB Code:

Public Sub Collision()
 
 
 
For X = 1 To MaxBullets
    With Bullet(X)
        'makes sure it is visible, has moved, and can move
        If .Visible = True And .Moved = True And .Move = True Then
            'Gets rid of bullets outside of the arena (move to collision
            If .Left > ArenaWidth Then
                BulletCollideEffects (X), ArenaWidth - .Width, .Top, plat(1), True
            ElseIf .Left < 0 Then
                BulletCollideEffects (X), 0, .Top, plat(1), True
            ElseIf .Top < 0 Then
                BulletCollideEffects (X), .Left, 0, plat(1), False
            ElseIf .Top > ArenaHeight Then
                BulletCollideEffects (X), .Left, ArenaHeight - .Height, plat(1), False
            End If
        
            If .Xinertia = 0 Then .Xinertia = 1 'prevent divide by 0
            M = .Yinertia / .Xinertia 'find slope
            If M = 0 Then M = 0.001 'prevent divide by 0
            'y intercept for top left (b) and bottom right(bb)
            B = (.Top - .Yinertia) - (M * (.Left - .Xinertia))
            BB = ((.Top + .Height) - .Yinertia) - (M * ((.Left + .Width) - .Xinertia))
            
            For Y = 1 To PlatCount
                
                If plat(Y).Visible Then
                    'finds the point where it passes each side
                    Ty = plat(Y).Top
                    Tx = (B - Ty) / -M
                    Tbx = (BB - Ty) / -M
                    
                    Hy = plat(Y).Top + plat(Y).Height
                    Hx = (B - Hy) / -M
                    Hbx = (BB - Hy) / -M
                    
                    Lx = plat(Y).Left
                    Ly = M * Lx + B
                    Lby = M * Lx + BB
                    
                    Wx = plat(Y).Left + plat(Y).Width
                    Wy = M * Wx + B
                    Wby = M * Wx + BB
                    
                    'makes sure that it crosses the line inside the block
                    If Ly >= plat(Y).Top And Ly <= plat(Y).Top + plat(Y).Height And .Left >= Lx And .Left - .Xinertia <= Lx Then
                            BulletCollideEffects (X), Lx - .Width, (Ly), plat(Y), True
                            
                    ElseIf Wy >= plat(Y).Top And Wy <= plat(Y).Top + plat(Y).Height And .Left <= Wx And .Left - .Xinertia >= Wx Then
                        BulletCollideEffects (X), (Wx), (Wy), plat(Y), True
                        
                    ElseIf Lby >= plat(Y).Top And Lby <= plat(Y).Top + plat(Y).Height And .Left >= Lx And .Left - .Xinertia <= Lx Then
                            BulletCollideEffects (X), Lx - .Width, Lby - .Height, plat(Y), True
                            
                    ElseIf Wby >= plat(Y).Top And Wby <= plat(Y).Top + plat(Y).Height And .Left <= Wx And .Left - .Xinertia >= Wx Then
                        BulletCollideEffects (X), (Wx), Wby - .Height, plat(Y), True
                        
                    End If
                        
                    
                            
                    If Tx >= plat(Y).Left And Tx <= plat(Y).Left + plat(Y).Width And .Top >= Ty And .Top - .Yinertia <= Ty Then
                            BulletCollideEffects (X), (Tx), Ty - .Height, plat(Y), False
                            
                    ElseIf Hx >= plat(Y).Left And Hx <= plat(Y).Left + plat(Y).Width And .Top <= Hy And .Top - .Yinertia >= Hy Then
                        BulletCollideEffects (X), (Hx), (Hy), plat(Y), False
                        
                    ElseIf Tbx >= plat(Y).Left And Tbx <= plat(Y).Left + plat(Y).Width And .Top >= Ty And .Top - .Yinertia <= Ty Then
                            BulletCollideEffects (X), Tbx - .Width, Ty - .Height, plat(Y), False
                            
                    ElseIf Hbx >= plat(Y).Left And Hbx <= plat(Y).Left + plat(Y).Width And .Top <= Hy And .Top - .Yinertia >= Hy Then
                        BulletCollideEffects (X), Hbx - .Width, (Hy), plat(Y), False
                        
                    End If
                    
                End If
            
            Next Y
            
            For Y = 1 To PlayerCount
                
                If player(Y).Visible Then
                    'finds the point where it passes each side
                    Ty = player(Y).Top
                    Tx = (B - Ty) / -M
                    Tbx = (BB - Ty) / -M
                    
                    Hy = player(Y).Top + player(Y).Height
                    Hx = (B - Hy) / -M
                    Hbx = (BB - Hy) / -M
                    
                    Lx = player(Y).Left
                    Ly = M * Lx + B
                    Lby = M * Lx + BB
                    
                    Wx = player(Y).Left + player(Y).Width
                    Wy = M * Wx + B
                    Wby = M * Wx + BB
                    
                    'makes sure that it crosses the line inside the block
                    If Ly >= player(Y).Top And Ly <= player(Y).Top + player(Y).Height And .Left >= Lx And .Left - .Xinertia <= Lx Then
                            BulletCollideEffects (X), Lx - .Width, (Ly), player(Y), True
                            
                    ElseIf Wy >= player(Y).Top And Wy <= player(Y).Top + player(Y).Height And .Left <= Wx And .Left - .Xinertia >= Wx Then
                        BulletCollideEffects (X), (Wx), (Wy), player(Y), True
                        
                    ElseIf Lby >= player(Y).Top And Lby <= player(Y).Top + player(Y).Height And .Left >= Lx And .Left - .Xinertia <= Lx Then
                            BulletCollideEffects (X), Lx - .Width, Lby - .Height, player(Y), True
                            
                    ElseIf Wby >= player(Y).Top And Wby <= player(Y).Top + player(Y).Height And .Left <= Wx And .Left - .Xinertia >= Wx Then
                        BulletCollideEffects (X), (Wx), Wby - .Height, player(Y), True
                        
                    End If
                        
                    
                            
                    If Tx >= player(Y).Left And Tx <= player(Y).Left + player(Y).Width And .Top >= Ty And .Top - .Yinertia <= Ty Then
                            BulletCollideEffects (X), (Tx), Ty - .Height, player(Y), False
                            
                    ElseIf Hx >= player(Y).Left And Hx <= player(Y).Left + player(Y).Width And .Top <= Hy And .Top - .Yinertia >= Hy Then
                        BulletCollideEffects (X), (Hx), (Hy), player(Y), False
                        
                    ElseIf Tbx >= player(Y).Left And Tbx <= player(Y).Left + player(Y).Width And .Top >= Ty And .Top - .Yinertia <= Ty Then
                            BulletCollideEffects (X), Tbx - .Width, Ty - .Height, player(Y), False
                            
                    ElseIf Hbx >= player(Y).Left And Hbx <= player(Y).Left + player(Y).Width And .Top <= Hy And .Top - .Yinertia >= Hy Then
                        BulletCollideEffects (X), Hbx - .Width, (Hy), player(Y), False
                        
                    End If
                    
                End If
            
            Next Y
            
            
            
        End If
        
        If Bullet(X).Type = 1 Then
            For Y = 1 To PlayerCount
                If collide(Bullet(X), player(Y)) = True And Bullet(X).Belong <> (Y) And Bullet(X).Visible = True Then
                    player(Y).Xinertia = Bullet(X).Xinertia
                    player(Y).Yinertia = Bullet(X).Yinertia
                    player(Y).Life = player(Y).Life - GT(1).Power
                End If
            Next Y
        End If
        
        If .Visible And .Kiboshed Then
            For Y = 1 To PlayerCount
                If player(Y).OnFire = False And player(Y).Visible And collide(player(Y), Bullet(X)) And GT(.Type).Explode Then
                     CenterX = .Left + (.Width / 2)
                     CenterY = .Top + (.Height / 2)
                     CenterX2 = player(Y).Left + (player(Y).Width / 2)
                     CenterY2 = player(Y).Top + (player(Y).Height / 2)
                     
                     'absolute of cursor position
                    XXX = Abs(CenterX2 - CenterX)
                    YYY = Abs(CenterY - CenterY2)
                     
                    'Makes sure you do not divide by 0
                    If XXX = 0 Then
                         Angle = 0
                    Else
                        'find angle
                         Angle = Atn(YYY / XXX)
                    End If
                    
                    'finds absolute x and y aim
                    XXX = RR * Cos(Angle)
                    YYY = RR * Sin(Angle)
                    
                    'Sets result aiming co-ordinates
                    player(Y).Xinertia = Sgn(CenterX2 - CenterX) * XXX / 20
                    player(Y).Yinertia = (Sgn(CenterY2 - CenterY) * YYY) / 20
                    
                    'other effects
                    player(Y).OnFire = True
                    player(Y).Firetime = 40
                    player(Y).Life = player(Y).Life - 10
                End If
            Next Y
        End If
    End With
Next X

This is my collision sub, it checks (almost) every collision in my game however it is VERY redundant as you can see but i cant figure out how to shrink it

also note that collide is a function elsewhere in the code for finding if two things are actually touching where the majority of this code is for objects moving over something and finding if and where they should have hit

and if you were wondering, that is the bulletcollideeffects sub

Re: About as bad as it can be

this is the bullet collide effects sub if you were wondering

VB Code:

Public Sub BulletCollideEffects(BulletNum As Integer, X As Integer, Y As Integer, WhoHit As Bltty, HitSide As Boolean)
 
With Bullet(BulletNum)
    .Top = Y
    .Left = X
    
    
    If WhoHit.Move = True Then
        WhoHit.Xinertia = WhoHit.Xinertia + (.Xinertia * GT(.Type).Weight)
        WhoHit.Yinertia = WhoHit.Yinertia + (.Yinertia * GT(.Type).Weight)
        WhoHit.Life = WhoHit.Life - GT(.Type).Power
        If .Type = 3 Then
            WhoHit.OnFire = True
            WhoHit.Firetime = 10
        End If
        KillBullet BulletNum
    ElseIf GT(.Type).Bounce = True And HitSide = True Then
        .Xinertia = .Xinertia * -1
        Moved = False
    ElseIf GT(.Type).Bounce = True Then
        .Yinertia = .Yinertia * -1
        Moved = False
    Else
        .Move = False
        KillBullet BulletNum
    End If
End With
        
 
End Sub

Re: About as bad as it can be

Show the code where you declared your variables (all of them that are in these Subs) so I can see what data types you are using.

Here is one area you can increase some speed. The Cos() and Sin() functions. Rather than using them, let's create some lookup tables. This is based on Andre Lamothe's code in my Tricks of the 3D Game Programming Gurus book written by him.
VB Code:
Public Const PI As Double = 3.14159265358979 '4 * Atn(1)
 
Public Cos_Look_Up_Table(361) As Single
Public Sin_Look_Up_Table(361) As Single
 
Public Sub Build_Sin_Cos_Tables()
 
    Dim Angle As Long
    
    For Angle = 0 To 360
    
        Dim Theta As Single
    
        Theta = Angle * PI / 180
    
        Cos_Look_Up_Table(Angle) = Cos(Theta)
        Sin_Look_Up_Table(Angle) = Sin(Theta)
    
    Next Angle
    
End Sub
 
Public Function Fast_Cos(ByVal Theta As Single) As Single
 
    Theta = Theta Mod 360
    
    If Theta < 0 Then Theta = Theta + 360
    
    Dim Theta_Integer As Long
    Dim Theta_Fraction As Single
    
    Theta_Integer = Theta
    Theta_Fraction = Theta - Theta_Integer
    
    Fast_Cos = Cos_Look_Up_Table(Theta_Integer) + Theta_Fraction * (Cos_Look_Up_Table(Theta_Integer + 1) - Cos_Look_Up_Table(Theta_Integer))
    
End Function
 
Public Function Fast_Sin(ByVal Theta As Single) As Single
 
    Theta = Theta Mod 360
    
    If Theta < 0 Then Theta = Theta + 360
 
    Dim Theta_Integer As Long
    Dim Theta_Fraction As Single
    
    Theta_Integer = Theta
    Theta_Fraction = Theta - Theta_Integer
    
    Fast_Sin = Sin_Look_Up_Table(Theta_Integer) + Theta_Fraction * (Sin_Look_Up_Table(Theta_Integer + 1) - Sin_Look_Up_Table(Theta_Integer))
    
End Function
Then you add the line Build_Sin_Cos_Tables in the area where you initialize everything to build a look up table, and then use Fast_Cos() and Fast_Sin() in replace of your Cos() and Sin() functions. ;)

Another area to improve is this area:
VB Code:
BulletCollideEffects(BulletNum As Integer, X As Integer, Y As Integer, WhoHit As Bltty, HitSide As Boolean)
Never use the Integer data type unless it's needed, like for example, API's. For a good speed difference, use the Long data type. Here are the reasons. 1) Don't have to worry about overflow that much. 2) Your CPU processor in your computer is 32 bit, and works with 32 bit variables faster. The Long data type is 4 bytes (32 bits) while the Integer data type is only 2 bytes (16 bits), and the processor will have to convert it in order to accomidate.

And also be sure to either include ByVal or ByRef. Leaving it blank, although by default it'll be ByRef, every time the function is called, it's somewhat slower. Using ByVal is faster. Only use ByRef if your varables in your arguements are gonna be returning a result. Only thing is though you can't use ByVal on variables that are User Defined Types, such as Blitty.

Now I got that out of the way, here is your new and improved Sub setup:
VB Code:
BulletCollideEffects(ByVal BulletNum As Long, ByVal  X As Long, ByVal Y As Long, WhoHit As Bltty, ByVal HitSide As Boolean)

Apr 3rd, 2005, 03:56 PM
notquitehere188

Re: About as bad as it can be

Quote:

"Only use ByRef if your varables in your arguements are gonna be returning a result"

???

what does byval do

Re: About as bad as it can be

ByVal variables in the arguements don't return values. If you were to do something like this:
VB Code:
Option Explicit
 
Private Sub Test(ByVal Testing As Long)
 
    Testing = 5
 
End Sub
 
Private Sub Test2(ByRef Testing As Long)
 
    Testing = 5
 
End Sub
 
Private Sub Form_Activate()
 
    Dim I As Long
    
    Test I
    
    Print I 'Returns 0
    
    Test2 I
    
    Print I 'Returns 5
 
End Sub
You would see that ByVal did not make the variable I equal 5. It stayed the same value as it was before. But when I used ByRef, it made I equal 5. Hope this helps.

Apr 4th, 2005, 06:28 PM
notquitehere188

Re: About as bad as it can be

it does indeed
Apr 12th, 2005, 01:26 PM
Maven

Re: About as bad as it can be

Quote:

Originally Posted by notquitehere188

[Highlight=VB] Public Sub Collision()
This is my collision sub, it checks (almost) every collision in my game however it is VERY redundant as you can see but i cant figure out how to shrink it

also note that collide is a function elsewhere in the code for finding if two things are actually touching where the majority of this code is for objects moving over something and finding if and where they should have hit

and if you were wondering, that is the bulletcollideeffects sub

Well the first thing I noticed is that you're using divison a lot with a variable called M. After you setup M, dividie it into 1 one time. After that use multiplication to get you're divison results.

Tx = (B - Ty) * -M
Tbx = (BB - Ty) * -M

You may have to use an extra variable but you'll be trading 8 division instructions for 8 multiplication instuctions. Should give you an instant speedup.
Apr 13th, 2005, 02:17 AM
Maven

Re: About as bad as it can be

Quote:

Originally Posted by Maven

Well the first thing I noticed is that you're using divison a lot with a variable called M. After you setup M, dividie it into 1 one time. After that use multiplication to get you're divison results.

Tx = (B - Ty) * -M
Tbx = (BB - Ty) * -M

You may have to use an extra variable but you'll be trading 8 division instructions for 8 multiplication instuctions. Should give you an instant speedup.

In fact if the following doesn't change with every iteration of the loop, then i would move it outside of the loops and setup the above suggestion outside of the loop.

M = .Yinertia / .Xinertia 'find slope
May 3rd, 2005, 04:47 PM
Dreamlax

Re: About as bad as it can be
Quote:
Originally Posted by Jacob Roman

Show the code where you declared your variables (all of them that are in these Subs) so I can see what data types you are using.

Here is one area you can increase some speed. The Cos() and Sin() functions. Rather than using them, let's create some lookup tables. This is based on Andre Lamothe's code in my Tricks of the 3D Game Programming Gurus book written by him.

VB Code:

Public Const PI As Double = 3.14159265358979 '4 * Atn(1)

Public Cos_Look_Up_Table(361) As Single
Public Sin_Look_Up_Table(361) As Single

Public Sub Build_Sin_Cos_Tables()

Dim Angle As Long

For Angle = 0 To 360

Dim Theta As Single

Theta = Angle * PI / 180

Cos_Look_Up_Table(Angle) = Cos(Theta)
Sin_Look_Up_Table(Angle) = Sin(Theta)

Next Angle

End Sub

Public Function Fast_Cos(ByVal Theta As Single) As Single

Theta = Theta Mod 360

If Theta < 0 Then Theta = Theta + 360

Dim Theta_Integer As Long
Dim Theta_Fraction As Single

Theta_Integer = Theta
Theta_Fraction = Theta - Theta_Integer

Fast_Cos = Cos_Look_Up_Table(Theta_Integer) + Theta_Fraction * (Cos_Look_Up_Table(Theta_Integer + 1) - Cos_Look_Up_Table(Theta_Integer))

End Function

Public Function Fast_Sin(ByVal Theta As Single) As Single

Theta = Theta Mod 360

If Theta < 0 Then Theta = Theta + 360

Dim Theta_Integer As Long
Dim Theta_Fraction As Single

Theta_Integer = Theta
Theta_Fraction = Theta - Theta_Integer

Fast_Sin = Sin_Look_Up_Table(Theta_Integer) + Theta_Fraction * (Sin_Look_Up_Table(Theta_Integer + 1) - Sin_Look_Up_Table(Theta_Integer))

End Function

Then you add the line Build_Sin_Cos_Tables in the area where you initialize everything to build a look up table, and then use Fast_Cos() and Fast_Sin() in replace of your Cos() and Sin() functions. ;)

Another area to improve is this area:

VB Code:

BulletCollideEffects(BulletNum As Integer, X As Integer, Y As Integer, WhoHit As Bltty, HitSide As Boolean)

Never use the Integer data type unless it's needed, like for example, API's. For a good speed difference, use the Long data type. Here are the reasons. 1) Don't have to worry about overflow that much. 2) Your CPU processor in your computer is 32 bit, and works with 32 bit variables faster. The Long data type is 4 bytes (32 bits) while the Integer data type is only 2 bytes (16 bits), and the processor will have to convert it in order to accomidate.

And also be sure to either include ByVal or ByRef. Leaving it blank, although by default it'll be ByRef, every time the function is called, it's somewhat slower. Using ByVal is faster. Only use ByRef if your varables in your arguements are gonna be returning a result. Only thing is though you can't use ByVal on variables that are User Defined Types, such as Blitty.

Now I got that out of the way, here is your new and improved Sub setup:

VB Code:

BulletCollideEffects(ByVal BulletNum As Long, ByVal X As Long, ByVal Y As Long, WhoHit As Bltty, ByVal HitSide As Boolean)
The amount of calculations (especially the conversion between integer and floating points) by far exceeds the normal amount of work done using the floating-point processor alone.

It is far wiser to stay using doubles or singles than to constantly convert between to and from integer formats. The process of loading an integer into a floating-point register is long enough; and the floating-point processor already has an instruction to calculate the sine of the value in the register. This is far more efficient than constantly converting between two types and jumping around memory, and adding latency by performing extra calculations.

Consider the following and assume x, a and b are integers:

x = 1.5 * b - a + 3

We could load all constants into the floating point registers, which would be highly inefficient, but we would still acheive results (inefficient because we would have to convert the result back to integers). Instead, we could cast the result of the floating point calculation so that it forces the remaining calculations to be done with integer operations. This is quicker than allowing all operands to be converted to floating point.

x = CLng(1.5 * b) - a + 3

Bearing this in mind, you could save on latency times, and just the tiniest improvements can go a long way in a lengthy loop.

I can see how the sine tables would improve performance on a CPU without an FPU co-processor, but even the AMD efficiency guide shows you should never use tables for sine.