High Speed Graphics Pt. 2

[Tyrone W. Lee]

Ok Guys.. Check this out.. I wrote this code using PB1.1 cause its all
I had here but I think my results were pretty amazing..

I first created an optimized line (ray trace) routine without
using distance formulas or Single Point Variables.

Hence this routine..

Sub FastRay (ByVal x1 as Long, ByVal y1 as Long, ByVal x2 as Long, ByVal y2 as Long)
Dim xchange as Long, ychange as Long
Dim xp as Long, yp as Long, ray as Long, ray_seg as Long
Dim x as Long, y as Long
Dim ray_xchange as Long, ray_ychange as Long
Dim count as long, lowest_change as Long
Dim x_Step as Long, y_Step as Long

ray_xchange = x2 - x1
x_step = Sgn(ray_xchange)
ray_ychange = y2 - y1
y_step = Sgn(ray_ychange)

xp = x1
yp = y1


If ray_xchange < ray_ychange Then
lowest_change = Abs(ray_xchange)
Select Case lowest_change
Case 0
ray_seg = Abs(ray_ychange)
Case Else
ray_seg = Abs(ray_ychange / lowest_change)
End SELECT

For ray = 1 to lowest_change
For count = 1 to ray_Seg
Screen(xp,yp) = 0
yp = yp + y_step
Next count
xp = xp + x_step
Next ray

Else
lowest_change = Abs(ray_ychange)
Select Case lowest_change
Case 0
ray_seg = Abs(ray_xchange)
Case Else
ray_seg = Abs(ray_xchange / lowest_change)
End SELECT

For ray = 1 to lowest_change
For count = 1 to ray_Seg
Screen(xp,yp) = 0
xp = xp + x_step
Next count
yp = yp + y_step
Next ray
End if
End Sub


I think took this code an placed it in a loop to fill an area 1024 x 768.
I am running this routine on a Pentium III 1Ghz so my frame rates
are high. I wanted to know what people with lower machine speeds
recieve from this little routine.


Sub CompleteTest () EXPORT
Dim x1 as Long, y1 as Long, x2 as Long, y2 as Long
Dim yl as Long, xloop as Long


'Actual Ray Variables
Dim xchange as Long, ychange as Long
Dim xp as Long, yp as Long, ray as Long, ray_seg as Long, ray_height as Long
Dim x as Long, y as Long, h as Long
Dim ray_xchange as Long, ray_ychange as Long
Dim count as long, lowest_change as Long
Dim x_Step as Long, y_Step as Long


For xloop = 1 to 80
For yl = 0 to 1024
x1 = 0 : y1 = y
x2 = 768: y2 = y


'Actual Ray Cast Routine
ray_xchange = x2 - x1
x_step = Sgn(ray_xchange)
ray_ychange = y2 - y1
y_step = Sgn(ray_ychange)

xp = x1
yp = y1


If ray_xchange < ray_ychange Then
lowest_change = Abs(ray_xchange)
Select Case lowest_change
Case 0
ray_seg = Abs(ray_ychange)
Case Else
ray_seg = Abs(ray_ychange / lowest_change)
End SELECT

For ray = 0 to lowest_change
For count = 1 to ray_Seg
Screen(xp,yp) = 0
'Screen(xp,yp+1) = 0
'Screen(xp+1,yp) = 0
'Screen(xp+1,yp+1) = 0
yp = yp + y_step
Next count
xp = xp + x_step
Next ray

Else
lowest_change = Abs(ray_ychange)
Select Case lowest_change
Case 0
ray_seg = Abs(ray_xchange)
Case Else
ray_seg = Abs(ray_xchange / lowest_change)
End SELECT

For ray = 0 to lowest_change
For count = 1 to ray_Seg
Screen(xp,yp) = 0
'Screen(xp,yp+1) = 0
'Screen(xp+1,yp) = 0
'Screen(xp+1,yp+1) = 0
xp = xp + x_step
Next count
yp = yp + y_step
Next ray
End if
'End of Ray Cast Routine

Next yl
Next xloop
End Sub

With this Pentium III 1Ghz machine I got 80 frames in under a second
1024x768. You will see some commented lines where I tried to double
the frame rate by simply deviding my itterations 1/2 and doubling
the Screen variable set routine. In most cases this would speed
up routines, but I found that this slowed my code down. (This is 16bit
compiled code but I used Longs throughout.)

Tell me if there are some areas that need optimization or should
I keep this routine.. I would like to get 160fps on a 1Ghz machine
though.. Because I'm sure the frame rate will drop considerably
once I add color affects and stuff..

Thanks a bunch to all who helped in this design..

------------------
Explorations v3.0 RPG Development System
http://www.explore-rpg.com

[Tyrone W. Lee]

Sorry for the double post but I'm soo excited right now I had to share this..

I am home now, and working on my AMD380Mhz machine. I took the
above code and replaced the reference to Screen(x,y) with
ptrScreen WORD PTR.

All references to arrays are @ptrScreen[xp * 768 + xp] = value
And was able to crank out 1024x768x80 in WELL less than a second.
Pointers are awesome!!

And thats 16bit PowerBasic 2.0!

I just changed the outer most loop to 200 (yea 200 fps) And I'm still
under 1 second! - I wonder if this thing is really working.. ha!

I will double check the logic and get back to you..


The obvious bottleneck for the code is storing into variables. Its
MUCH faster to store a value via a pointer than to store a value
via a VARIABLE of any type - Long, WORD, DWORD etc..



------------------
Explorations v3.0 RPG Development System
http://www.explore-rpg.com