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Post by tenochtitlanuk on Oct 22, 2020 9:52:45 GMT -5
I've posted before and linked to my website- and these tasks are still empty on Rosetta Code. I just realised I had not linked to the further example at link which are related but not on the index of my site...
The Rosetta Code tasks include- ' create a ppm file
' fill an image with a plain RGB color,
' set a given pixel with a color,
' get the color of a pixel.
' Bresenham draw line
' Convert image to grayscale;
' Compute the histogram
' Find the median: defined as the luminance such that the image has an approximately
' equal number of pixels with lesser and greater luminance.
' Replace each pixel of luminance lesser than the median to black, and others to white.
Along with the Bresenham one, which gives a particularly fun real-time display and is also already on my site, and lena, I've essentially covered all these. Fun.. |
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Post by tenochtitlanuk on Oct 27, 2020 16:19:37 GMT -5
Here's the Bezier quadratic curve- two end points and one control point, joining the control points using Bresenham's algorithm. It produces a BMP file and I will add the production of the P6 ppm file and add to my web pages. The colour changes were added just to make it easier to see the segments... 
nomainwin
' x y
dim Px( 100), Py( 100) ' up to 100 line sections..
WindowWidth = 660
WindowHeight = 680
open "display" for graphics_nsb as #wg
#wg "trapclose quit"
#wg "size 2"
for x =0 to 600 step 100
#wg "up ; goto "; x +20; " 620"
#wg "down ; goto "; x +20; " 20"
#wg "size 1"
next x
#wg "size 2"
for y =0 to 600 step 100
#wg "up ; goto 20 "; 620 -y
#wg "down ; goto 620 "; 620 -y
#wg "size 1"
next y
#wg "down ; size 2"
call bezierquad 10, 100, 250, 270, 150, 20, 40, 0, 0, 0
#wg "getbmp scr 0 0 660 660"
bmpsave "scr", "BezierQuadraticCurve.bmp"
wait ' _________________________________________________________
' P0 P1 P2 pointNum R G B
sub bezierquad x1, y1, x2, y2, x3, y3, n, r, g, b
#wg "size 10 ; color red"
#wg "set "; 20 +2 *x1; " "; 620 -2 *y1
#wg "set "; 20 +2 *x2; " "; 620 -2 *y2
#wg "set "; 20 +2 *x3; " "; 620 -2 *y3
#wg "size 2"
for i = 0 to n
t =i /n
t1 =1 -t
a =t1^2
b =2 *t *t1
c =t^2
Px( i) =int( a *x1 +b *x2 +c *x3 +0.5)
Py( i) =int( a *y1 +b *y2 +c *y3 +0.5)
next i
for i =0 to n -1
call bresenham Px( i), Py( i), Px( i +1), Py( i +1), r, g, b
R =int( i /( n -1) *255)
#wg "color "; R; " "; 80; " "; 255 -R
next i
end sub
sub bresenham x1, y1, x2, y2, r, g, b
dx =abs( x2 -x1): sx =sgn( x2 -x1)
dy =abs( y2 -y1): sy =sgn( y2 -y1)
if dx <dy then e =dx /2 else e =dy /2
do
call setpixel x1, y1, r, g, b
if x1 =x2 then if y1 =y2 then exit do
if dx >dy then
x1 =x1 +sx: e =e -dy: if e <0 then e =e +dx: y1 =y1 +sy
else
y1 =y1 +sy: e =e -dx: if e <0 then e =e +dy: x1 =x1 +sx
end if
loop until 0
end sub
sub setpixel x, y, r, g, b
'#wg "color "; str$( r); " "; str$( g); " "; str$( b)
#wg "set "; 20 +x *2; " "; 620 -y *2
end sub
sub quit h$
close #h$
end
end sub
function sgn( x)
if x>=0 then sgn =1 else sgn =0 -1
end function
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Post by tenochtitlanuk on Oct 27, 2020 16:41:10 GMT -5
... and the Bezier Cubic one.. 
nomainwin
' x y
dim Px( 100), Py( 100) ' up to 100 line sections..
WindowWidth = 660
WindowHeight = 680
open "display" for graphics_nsb as #wg
#wg "trapclose quit"
#wg "size 2"
for x =0 to 600 step 100
#wg "up ; goto "; x +20; " 620"
#wg "down ; goto "; x +20; " 20"
#wg "size 1"
next x
#wg "size 2"
for y =0 to 600 step 100
#wg "up ; goto 20 "; 620 -y
#wg "down ; goto 620 "; 620 -y
#wg "size 1"
next y
#wg "down ; size 2"
call beziercubic 160,150, 10,120, 30,0, 150,50, 20, 0,0,0
#wg "getbmp scr 0 0 660 660"
bmpsave "scr", "BezierCubicCurve.bmp"
wait ' _________________________________________________________
' P0 P1 P2 P3 pointNum R G B
sub beziercubic x1, y1, x2, y2, x3, y3, x4, y4, n, r, g, b
#wg "size 10 ; color red"
#wg "set "; 20 +2 *x1; " "; 620 -2 *y1
#wg "set "; 20 +2 *x2; " "; 620 -2 *y2
#wg "set "; 20 +2 *x3; " "; 620 -2 *y3
#wg "set "; 20 +2 *x4; " "; 620 -2 *y4
#wg "size 2"
for i = 0 to n
t =i /n
t1 =1 -t
a =t1^3
b =3 *t *t1^2
c =3 *t^2 *t1
d =t^3
Px( i) =int( a *x1 +b *x2 +c *x3 +d *x4 +0.5)
Py( i) =int( a *y1 +b *y2 +c *y3 +d *y4 +0.5)
next i
for i =0 to n -1
R =int( i /( n -1) *255)
#wg "color "; R; " "; 80; " "; 255 -R
call bresenham Px( i), Py( i), Px( i +1), Py( i +1), r, g, b
'R =int( i /( n -1) *255)
'#wg "color "; R; " "; 80; " "; 255 -R
next i
end sub
sub bresenham x1, y1, x2, y2, r, g, b
dx =abs( x2 -x1): sx =sgn( x2 -x1)
dy =abs( y2 -y1): sy =sgn( y2 -y1)
if dx <dy then e =dx /2 else e =dy /2
do
call setpixel x1, y1, r, g, b
if x1 =x2 then if y1 =y2 then exit do
if dx >dy then
x1 =x1 +sx: e =e -dy: if e <0 then e =e +dx: y1 =y1 +sy
else
y1 =y1 +sy: e =e -dx: if e <0 then e =e +dy: x1 =x1 +sx
end if
loop until 0
end sub
sub setpixel x, y, r, g, b
'#wg "color "; str$( r); " "; str$( g); " "; str$( b)
#wg "set "; 20 +x *2; " "; 620 -y *2
end sub
sub quit h$
close #h$
end
end sub
function sgn( x)
if x>=0 then sgn =1 else sgn =0 -1
end function
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