Perspective Fill

[Rod]

Ok, still developing the sprite creator. Next task is a perspective transformation that takes say a 64x64 sprite and maps it to a perspective view. Any help much appreciated. Shout if there is confusion, my maths and trig is poor. Discount my solution, throw it away and substitute yours.

Eventually I will be able to take 64x64 flat images and do a perspective transform that will allow them to be used as floor wall or ceiling tiles. Double the size will knit together and produce a 3d view.





   nomainwin
   WindowWidth = 860
   WindowHeight = 500
   UpperLeftX = int((DisplayWidth-WindowWidth)/2)
   UpperLeftY = 10
   graphicbox #1.gb, 35, 30, 386, 386
   open "Sprite Creator" for graphics_nsb_nf as #1
   #1 "trapclose [quit]"
   #1.gb "down ; fill black "

   global pix, npix, fcol$, bcol$,frame
   pix=6
   npix=64
   null=color("255 255 0")
   dim frame$(npix,npix)
   dim back$(npix,npix)

   'frame$() is out visible drawing
   'back$() is a background copy
   'draw a yellow line round the graphicbox
   'and store it in frame$() and back$()

   for x= 0 to npix-1
       null=paint(x,0)
       back$(x,0)="255 255 0"
       null=paint(x,npix-1)
       back$(x,npix-1)="255 255 0"
   next
   for y= 0 to npix-1
       null=paint(0,y)
       back$(0,y)="255 255 0"
       null=paint(npix-1,y)
       back$(npix-1,y)="255 255 0"
   next



[perspective]
   cursor hourglass
   ocol$=fcol$
   null=perspective("floor")

   nul=color(ocol$)
   cursor normal
   wait

[quit]
   close #1
   end

function color(c$)
if c$="" then c$="0 0 0"
   fcol$=c$
   #1.gb "backcolor ";fcol$;" ; color ";fcol$
end function

function paint(x,y)
   'clips and paints pixel square to size, updating frame array
   if x>=0 and x<npix and y>=0 and y<npix then
       #1.gb "place ";x*pix;" ";y*pix
       #1.gb "boxfilled ";x*pix+pix;" ";y*pix+pix
       frame$(x,y)=fcol$
   end if
end function

'if we take a 64x64 sprite to get a perspective view that will be scaleable
'we need to take the 64x64 image and spread it.
'top line gets mapped to x=16 y= 48 to x=48 y=48
'bottom is mapped just as it is x=0 y=63 to x=63 y=63

function perspective(face$) 'floor,left,right,ceiling
   'for the moment we just want the floor perspective
   'eventually we will clear the screen before drawing
   'the perspective view, for now it just overdraws
   sx=npix/4+npix/4
   sy=npix/4*3
   sd=npix/2/npix
   yd=npix/4/npix
   xd=npix/2/npix
   for y=0 to npix-1
   xx=sx
   for x=0 to npix-1
       'get the color from the background file
       tcol$=back$(x,frame*npix+y)
       'set the pen to that color
       nul=color(tcol$)
       'paint the new location
       nul=paint(xx,sy)
       xx=xx+xd
   next
   xd=y/npix
   sx=sx-sd
   sy=sy+yd
   next

end function



[tsh73]

Ha!

I never knew JB could do that.
cursor hourglass
...
cursor normal

[Rod]

If anyone is feeling really mathematical how about mapping the 64x64 to an orb, that is next on the agenda.

[Rod]

Just to clarify my problem. The first picture is what I get now, the second picture is kinda like what I am hoping for. Take the top line it will be mapped much smaller from 64 pixels to 32 pixels. Some pixels will be lost by overwriting but it does not seem to matter too much. I do the resized import on a similar basis. So just need to get the geometry right.

[tsh73]

Have a look
I calculated xx, sy from x, y - not incrementally but each time anew, by a formula



   nomainwin
   WindowWidth = 860
   WindowHeight = 500
   UpperLeftX = int((DisplayWidth-WindowWidth)/2)
   UpperLeftY = 10
   graphicbox #1.gb, 35, 30, 386, 386
   open "Sprite Creator" for graphics_nsb_nf as #1
   #1 "trapclose [quit]"
   #1.gb "down ; fill black "

   global pix, npix, fcol$, bcol$,frame
   pix=6
   npix=64
   null=color("255 255 0")
   dim frame$(npix,npix)
   dim back$(npix,npix)

   'frame$() is out visible drawing
   'back$() is a background copy
   'draw a yellow line round the graphicbox
   'and store it in frame$() and back$()

   for x= 0 to npix-1
       null=paint(x,0)
       back$(x,0)="255 255 0"
       null=paint(x,npix-1)
       back$(x,npix-1)="255 255 0"
       'call pause 10
   next
   for y= 0 to npix-1
       null=paint(0,y)
       back$(0,y)="255 255 0"
       null=paint(npix-1,y)
       back$(npix-1,y)="255 255 0"
       'call pause 10
   next



[perspective]
   cursor hourglass
   ocol$=fcol$
   null=perspective("floor")

   nul=color(ocol$)
   cursor normal
   wait

[quit]
   close #1
   end

function color(c$)
if c$="" then c$="0 0 0"
   fcol$=c$
   #1.gb "backcolor ";fcol$;" ; color ";fcol$
end function

function paint(x,y)
   'clips and paints pixel square to size, updating frame array
   if x>=0 and x<npix and y>=0 and y<npix then
       #1.gb "place ";x*pix;" ";y*pix
       #1.gb "boxfilled ";x*pix+pix;" ";y*pix+pix
       frame$(x,y)=fcol$
   end if
end function

'if we take a 64x64 sprite to get a perspective view that will be scaleable
'we need to take the 64x64 image and spread it.
'top line gets mapped to x=16 y= 48 to x=48 y=48
'bottom is mapped just as it is x=0 y=63 to x=63 y=63

function perspective(face$) 'floor,left,right,ceiling
   'for the moment we just want the floor perspective
   'eventually we will clear the screen before drawing
   'the perspective view, for now it just overdraws
   sx=npix/4+npix/4
   sy=npix/4*3
   sd=npix/2/npix
   yd=npix/4/npix
   xd=npix/2/npix
   for y=0 to npix-1
       ''the new location
       sy = (3*npix + y)/4'to lower 1/4
   for x=0 to npix-1
       'get the color from the background file
       tcol$=back$(x,frame*npix+y)
       'set the pen to that color
       nul=color(tcol$)
       ''the new location
           xx = npix/2+(x-npix/2)*((y+npix)/(2*npix))  'depending on y/npix
       'paint the new location
       nul=paint(xx,sy)
   next
   next

end function

sub pause mil
   t = time$("ms")+mil
   while time$("ms")<t
       scan
   wend
end sub


[cundo]

This is really interesting not only for sprites creation.

[Rod]

Thank you Anatoly. I needed to set it back to integer x,y. That lost a lot of detail and line images were lost. So I tweaked it to only draw color and not to draw over black/blank. Edges are not quite right but that's because I overdraw. However overall it works really well for busy images. And they rotate as well! This is a 128x128 flat wall image in 800x600 window, perfectly useable.

[Rod]

Thank you again, a working version has been integrated to Sprite Creator and the download updated.

[cundo]

that's some 2.5D (fake 3d) mapping!