Filled polygons

[Rod]

Does anyone have code for drawing filled polygons? Andy has code in the archives where we can find if a point is in a polygon but that would be longwinded compared to just drawing the polygon.

Say a triangle

x1=350:y1=350
x2=500:y2=350
x3=500:y3=100

[tsh73]

Search on my HD got me this

nomainwin
open "filledTriangle" for graphics_nsb as #main
#main, "down; color green"
call filledTriangle "#main", 10, 10, 5, 70, 34, 16, 1
#main, "color blue"
call filledTriangle "#main", 10, 110, 5, 170, 34, 116, 0.05
#main, "color red"
call filledTriangle "#main", 10, 210, 5, 270, 34, 216, 2
#main, "color darkgreen"
call filledTriangle "#main", 100, 10, 70, 110, 130, 110, 1
'call filledTriangle "#main", 200, 100, 300, 70, 300, 130, 1 'This doesn't work: last two points must not have the same x position
#main, "trapclose [quit]"
wait

[quit]
   close #main
   end

sub filledTriangle handle$, X0, Y0, X1, Y1, X2, Y2, density
   a = (Y1 - Y2) / (X1 - X2)
   b = Y1 - a * X1
   if X1 < X2 then itX = X1 : endX = X2 else itX = X2 : endX = X1
   while itX <= endX
       #handle$, "line "; X0; " "; Y0; " "; int(itX); " "; int(a*itX + b)
       itX = itX + density
   wend
end sub

I remember seeing demo there poligin is divided into trangles and triangles fast filled
I even used triangle fast fill on my torch demo
but I cannot find any of these yet

[tsh73]

in one of other my programs
=====================================================
'     Title: Filled Triangle Sub
'Programmer: JB port by Andy Amaya
'     Date: 2010.10.27
'http://justbasic.conforums.com/index.cgi?board=shared&action=display&num=1307312447
Sub fillTriangle h$,x1, y1, x2, y2, x3, y3
   'triangle coordinates must be ordered: where x1 < x2 < x3
   If x2 < x1 Then x  = x2 : y  = y2 : x2 = x1 : y2 = y1 : x1 = x  : y1 = y
   'swap x1, y1, with x3, y3
   If x3 < x1 Then x  = x3 : y  = y3 : x3 = x1 : y3 = y1 : x1 = x  : y1 = y
   'swap x2, y2 with x3, y3
   If x3 < x2 Then x  = x3 : y  = y3 : x3 = x2 : y3 = y2 : x2 = x  : y2 = y
   If x1 <> x3 Then slope1 = (y3-y1)/(x3-x1)
   'draw the first half of the triangle
   length = x2 - x1
   If length <> 0 Then
       slope2 = (y2-y1)/(x2-x1)
       For x = 0 To length
           #h$ "Line ";Int(x+x1);" ";Int(x*slope1+y1);" ";Int(x+x1);" ";Int(x*slope2+y1)
       Next
   End If
   'draw the second half of the triangle
   y = length*slope1+y1 : length = x3-x2
   If length <> 0 Then
       slope3 = (y3-y2)/(x3-x2)
       For x = 0 To length
           #h$ "Line ";Int(x+x2);" ";Int(x*slope1+y);" ";Int(x+x2);" ";Int(x*slope3+y2)
       Next
   End If
End Sub


[B+]

I even used triangle fast fill on my torch demo
but I cannot find any of these yet

I found your lovely torch in my files:

'triangle torch
'tsh73 May 2017
nomainwin

UpperLeftX=1
UpperLeftY=1

open "flame" for graphics_nsb_nf as #gr
print #gr, "trapclose [quit]"
print #gr, "home ; down ; posxy cx cy"
print #gr, "trapclose [quit]"
 width = 2*cx : height = 2*cy
 cxx=cx
print #gr, "when leftButtonUp [quit]"

'torch handle
#gr "fill black"
r=30
for x=0-r to r
   y=sqr(r^2-x^2)/5
   c=((1-(x/r)^2)*150+50)/1.5
   #gr "color ";c;" ";c;" ";c
   #gr "place ";cx+x/1.5;" ";cy+y
   #gr "goto ";cx+x/6;" ";cy+y+130
next

for x=0-r to r
   y=sqr(r^2-x^2)/5
   c=(1-(x/r)^2)*150+50
   #gr "color ";c;" ";c;" ";c
   #gr "place ";cx+x;" ";cy+y
   #gr "go -30"

next
#gr "getbmp torch 0 0 ";width;" ";height

timer 100, [nxt]
while 1
   scan
   #gr "discard"
   '#gr "fill black"
   #gr "drawbmp torch 0 0"
   for i = 1 to 7
       cx = cxx+randR(-7,7)
       x1=cx-randR(0,20)
       y1=cy-randR(50,100)
       x2=cx+randR(0,20)
       'y2=cy-randR(0,100)
       y2=(cy+y1)/2
       if rnd(0)<.5 then
           tmp=y1:y1=y2:y2=tmp
       end if
       #gr "color ";randR(128,255);" ";randR(0,128);" 64"
       #gr "place ";cx;" ";cy
       #gr "goto ";x1;" ";y1
       #gr "goto ";x2;" ";y2
       #gr "goto ";cx;" ";cy
       for x=x1 to x2 step .5
           y = y1+(y2-y1)*(x-x1)/(x2-x1)
       #gr "line ";cx;" ";cy;" ";x;" ";y
       next
   next
   wait
[nxt]
wend

wait

[quit]
   timer 0
   close #gr
   end

function randR(min, max)
   randR=min+(max-min)*rnd(0)
end function




[B+]

Here is alternate to Andy's:

SUB filledTriangle handle$, X0, Y0, X1, Y1, X2, Y2
   if X1 <> X2 then
       a = (Y1 - Y2) / (X1 - X2)
       b = Y1 - a * X1
       IF X1 < X2 THEN itX = X1: endX = X2 ELSE itX = X2: endX = X1
       WHILE itX <= endX
           #handle$ "line "; X0; " "; Y0; " "; int(itX); " "; int(a*itX + b)
           itX = itX + .25
       WEND
   end if
   if X1 <> X0 then
       a = (Y1 - Y0) / (X1 - X0)
       b = Y1 - a * X1
       IF X1 < X0 THEN itX = X1: endX = X0 ELSE itX = X0: endX = X1
       WHILE itX <= endX
           #handle$ "line "; X2; " "; Y2; " "; int(itX); " "; int(a*itX + b)
           itX = itX + .25
       WEND
   end if
   if X0 <> X2 then
       a = (Y0 - Y2) / (X0 - X2)
       b = Y0 - a * X0
       IF X0 < X2 THEN itX = X0: endX = X2 ELSE itX = X2: endX = X0
       WHILE itX <= endX
           #handle$ "line "; X1; " "; Y1; " "; int(itX); " "; int(a*itX + b)
           itX = itX + .25
       WEND
   end if
END SUB


Tested in modified tsh73 codes above:

'triangle torch mod B+ 2020-04-05 to test filledTriangle Sub
'tsh73 May 2017


nomainwin

UpperLeftX=1
UpperLeftY=1

open "flame" for graphics_nsb_nf as #gr
print #gr, "trapclose [quit]"
print #gr, "home ; down ; posxy cx cy"
print #gr, "trapclose [quit]"
 width = 2*cx : height = 2*cy
 cxx=cx
print #gr, "when leftButtonUp [quit]"

'torch handle
#gr "fill black"
r=30
for x=0-r to r
   y=sqr(r^2-x^2)/5
   c=((1-(x/r)^2)*150+50)/1.5
   #gr "color ";c;" ";c;" ";c
   #gr "place ";cx+x/1.5;" ";cy+y
   #gr "goto ";cx+x/6;" ";cy+y+130
next

for x=0-r to r
   y=sqr(r^2-x^2)/5
   c=(1-(x/r)^2)*150+50
   #gr "color ";c;" ";c;" ";c
   #gr "place ";cx+x;" ";cy+y
   #gr "go -30"

next
#gr "getbmp torch 0 0 ";width;" ";height

timer 100, [nxt]
while 1
   scan
   #gr "discard"
   '#gr "fill black"
   #gr "drawbmp torch 0 0"
   for i = 1 to 7
       cx = cxx+randR(-7,7)
       x1=cx-randR(0,20)
       y1=cy-randR(50,100)
       x2=cx+randR(0,20)
       'y2=cy-randR(0,100)
       y2=(cy+y1)/2
       if rnd(0)<.5 then
           tmp=y1:y1=y2:y2=tmp
       end if
       #gr "color ";randR(128,255);" ";randR(0,128);" 64"
       call filledTriangle "#gr", cx, cy, x1, y1, x2, y2
   next
   wait
[nxt]
wend

wait

[quit]
   timer 0
   close #gr
   end

function randR(min, max)
   randR=min+(max-min)*rnd(0)
end function

SUB filledTriangle handle$, X0, Y0, X1, Y1, X2, Y2
   if X1 <> X2 then
       a = (Y1 - Y2) / (X1 - X2)
       b = Y1 - a * X1
       IF X1 < X2 THEN itX = X1: endX = X2 ELSE itX = X2: endX = X1
       WHILE itX <= endX
           #handle$ "line "; X0; " "; Y0; " "; int(itX); " "; int(a*itX + b)
           itX = itX + .25
       WEND
   end if
   if X1 <> X0 then
       a = (Y1 - Y0) / (X1 - X0)
       b = Y1 - a * X1
       IF X1 < X0 THEN itX = X1: endX = X0 ELSE itX = X0: endX = X1
       WHILE itX <= endX
           #handle$ "line "; X2; " "; Y2; " "; int(itX); " "; int(a*itX + b)
           itX = itX + .25
       WEND
   end if
   if X0 <> X2 then
       a = (Y0 - Y2) / (X0 - X2)
       b = Y0 - a * X0
       IF X0 < X2 THEN itX = X0: endX = X2 ELSE itX = X2: endX = X0
       WHILE itX <= endX
           #handle$ "line "; X1; " "; Y1; " "; int(itX); " "; int(a*itX + b)
           itX = itX + .25
       WEND
   end if
END SUB


nomainwin
open "filledTriangle" for graphics_nsb as #main
#main, "down; color green"
call filledTriangle "#main", 10, 10, 5, 70, 34, 16
#main, "color blue"
call filledTriangle "#main", 10, 110, 5, 170, 34, 116
#main, "color red"
call filledTriangle "#main", 10, 210, 5, 270, 34, 216
#main, "color darkgreen"
call filledTriangle "#main", 100, 10, 70, 110, 130, 110
call filledTriangle "#main", 200, 100, 300, 70, 300, 130 ' B+ FIXED This doesn't work: last two points must not have the same x position
#main, "trapclose [quit]"
wait

[quit]
   close #main
   end

SUB filledTriangle handle$, X0, Y0, X1, Y1, X2, Y2
   if X1 <> X2 then
       a = (Y1 - Y2) / (X1 - X2)
       b = Y1 - a * X1
       IF X1 < X2 THEN itX = X1: endX = X2 ELSE itX = X2: endX = X1
       WHILE itX <= endX
           #handle$ "line "; X0; " "; Y0; " "; int(itX); " "; int(a*itX + b)
           itX = itX + .25
       WEND
   end if
   if X1 <> X0 then
       a = (Y1 - Y0) / (X1 - X0)
       b = Y1 - a * X1
       IF X1 < X0 THEN itX = X1: endX = X0 ELSE itX = X0: endX = X1
       WHILE itX <= endX
           #handle$ "line "; X2; " "; Y2; " "; int(itX); " "; int(a*itX + b)
           itX = itX + .25
       WEND
   end if
   if X0 <> X2 then
       a = (Y0 - Y2) / (X0 - X2)
       b = Y0 - a * X0
       IF X0 < X2 THEN itX = X0: endX = X2 ELSE itX = X2: endX = X0
       WHILE itX <= endX
           #handle$ "line "; X1; " "; Y1; " "; int(itX); " "; int(a*itX + b)
           itX = itX + .25
       WEND
   end if
END SUB



[B+]

Oh my, Andy's fillTriangle is hands down better!

nomainwin
global XMAX, YMAX
XMAX = 800 : YMAX = 600
WindowWidth = XMAX + 8
WindowHeight = YMAX + 32
open "filledTriangle" for graphics_nsb as #main
#main "trapclose quit"
#main "down"
while 1
   scan
   #main "fill white"

   #main "color ";rnd(0)*255;" ";rnd(0)*255;" ";rnd(0)*255

   ' test sub below
   'call filledTriangle "#main", rnd(0)*XMAX, rnd(0)*YMAX,rnd(0)*XMAX, rnd(0)*YMAX,rnd(0)*XMAX, rnd(0)*YMAX


   'try Andy's fill>>> Oh way better!!!!!!!!!!!!!!!!
   call fillTriangle "#main", rnd(0)*XMAX, rnd(0)*YMAX,rnd(0)*XMAX, rnd(0)*YMAX,rnd(0)*XMAX, rnd(0)*YMAX

   call pause 300
wend
wait

sub quit h$
   close #main
   end
end sub

SUB filledTriangle handle$, X0, Y0, X1, Y1, X2, Y2
   if X1 <> X2 then
       a = (Y1 - Y2) / (X1 - X2)
       b = Y1 - a * X1
       IF X1 < X2 THEN itX = X1: endX = X2 ELSE itX = X2: endX = X1
       WHILE itX <= endX
           #handle$ "line "; X0; " "; Y0; " "; int(itX); " "; int(a*itX + b)
           itX = itX + .25
       WEND
   end if
   if X1 <> X0 then
       a = (Y1 - Y0) / (X1 - X0)
       b = Y1 - a * X1
       IF X1 < X0 THEN itX = X1: endX = X0 ELSE itX = X0: endX = X1
       WHILE itX <= endX
           #handle$ "line "; X2; " "; Y2; " "; int(itX); " "; int(a*itX + b)
           itX = itX + .25
       WEND
   end if
   if X0 <> X2 then
       a = (Y0 - Y2) / (X0 - X2)
       b = Y0 - a * X0
       IF X0 < X2 THEN itX = X0: endX = X2 ELSE itX = X2: endX = X0
       WHILE itX <= endX
           #handle$ "line "; X1; " "; Y1; " "; int(itX); " "; int(a*itX + b)
           itX = itX + .25
       WEND
   end if
END SUB

sub pause mil   'tsh version has scan built-in
   t0 = time$("ms")
   while time$("ms") < t0 + mil : scan : wend
end sub

'     Title: Filled Triangle Sub
'Programmer: JB port by Andy Amaya
'     Date: 2010.10.27
'http://justbasic.conforums.com/index.cgi?board=shared&action=display&num=1307312447
Sub fillTriangle h$,x1, y1, x2, y2, x3, y3
   'triangle coordinates must be ordered: where x1 < x2 < x3
   If x2 < x1 Then x  = x2 : y  = y2 : x2 = x1 : y2 = y1 : x1 = x  : y1 = y
   'swap x1, y1, with x3, y3
   If x3 < x1 Then x  = x3 : y  = y3 : x3 = x1 : y3 = y1 : x1 = x  : y1 = y
   'swap x2, y2 with x3, y3
   If x3 < x2 Then x  = x3 : y  = y3 : x3 = x2 : y3 = y2 : x2 = x  : y2 = y
   If x1 <> x3 Then slope1 = (y3-y1)/(x3-x1)
   'draw the first half of the triangle
   length = x2 - x1
   If length <> 0 Then
       slope2 = (y2-y1)/(x2-x1)
       For x = 0 To length
           #h$ "Line ";Int(x+x1);" ";Int(x*slope1+y1);" ";Int(x+x1);" ";Int(x*slope2+y1)
       Next
   End If
   'draw the second half of the triangle
   y = length*slope1+y1 : length = x3-x2
   If length <> 0 Then
       slope3 = (y3-y2)/(x3-x2)
       For x = 0 To length
           #h$ "Line ";Int(x+x2);" ";Int(x*slope1+y);" ";Int(x+x2);" ";Int(x*slope3+y2)
       Next
   End If
End Sub


[bluatigro]

this is my triangle


sub tri x1 , y1 , x2 , y2 , x3 , y3 , clr$
 #m "color " ; clr$
 #m "backcolor " ; clr$
 if y1 = y2 then y1 = y1 - 1e-10
 if y2 = y3 then y3 = y3 + 1e-10
 if y1 > y3 then
   call swap y1 , y3
   call swap x1 , x3
 end if
 if y1 > y2 then
   call swap y1 , y2
   call swap x1 , x3
 end if
 if y2 > y3 then
   call swap y2 , y3
   call swap x2 , y3
 end if
 for i = y1 to y3
   a = x1 + ( x3 - x1 ) * (i-y1) / ( y3 - y1 )
   if i < y2 then
     b = x1 + ( x2 - x1 ) * (i-y1) / ( y2 - y1 )
   else
     b = x2 + ( x3 - x2 ) * (i-y2) / ( y3 - y2 )
   end if
   #m.g "down"
   #m.g "line " ; a ; " " ; i _
   ; " " ; b ; " " ; i
   #m.g "up"
 next i
 #m.g "flush"
end sub




[bluatigro]


sub swap byref a , byref b
 h = a
 a = b
 b = h
end sub


[Rod]

Thank you all, good stuff, perhaps Carl can code something native for the next refresh.

[honkytonk]

Here ->: libertybasic.fr/forum/topic-538+sprite-factory.php
There is a procedure that detects the limits of a polygon (thanks Anatoly and others)

[B+]

Apr 6, 2020 12:34:29 GMT honkytonk said:

Here ->: libertybasic.fr/forum/topic-538+sprite-factory.php
There is a procedure that detects the limits of a polygon (thanks Anatoly and others)

What do you mean "detects the limits of a polygon"? Find the box it fits in? ie get the max/min of x and y?

[Rod]

I see a flood fill routine in sprite factory but we have moved on from that. We are now drawing the polygon rather than pixel by pixel testing if we are in it. Much much faster.

[honkytonk]

Apr 6, 2020 16:54:01 GMT Rod said:

I see a flood fill routine in sprite factory but we have moved on from that. We are now drawing the polygon rather than pixel by pixel testing if we are in it. Much much faster.

Indeed, but is the quick method valid for any polygons as is the slow flood method ?

[Rod]

True, however every polygon is just a collection of triangles. The challenge would be to take Andy’s routine and combine it with a routine to find all triangles in a polygon.

[B+]

Apr 7, 2020 10:31:26 GMT Rod said:

True, however every polygon is just a collection of triangles. The challenge would be to take Andy’s routine and combine it with a routine to find all triangles in a polygon.

I have this worked out in theory as long as there are not 2 different points on any of 360 degrees) angle from an "origin" of polygon but why?