1. example code
Someone may find this code useful, please send me a comment if you
can think of a way to improve it. I use it (among other functions) to
draw scalable text on graphs.
-- routine: CURVE
-- version: 1
-- filename: CURVE.E
-- language: Euphoria version 1.5
-- operating system: tested on MS-DOS version 6.22
-- hardware: IBM PC
-- author: Matthew McNamara <mat at iconz.co.nz>
-- short description: map 1/4 of a circle to any 2 points
-- created: 1998-08-11
include graphics.e --for test code
include get.e --for test code
constant PI=3.1415926536
global procedure curve(integer pen, object P1, object P3, object P2)
-- P1, end point, 2-atom sequence, {xpixel,ypixel}
-- P3, curving point, 2-atom sequence, {xpixel,ypixel}
-- P2, end point, 2-atom sequence, {xpixel,ypixel}
--
-- example (note angle P1 P3 P2 need not be a right angle)
-- P1
-- .
-- .
--
-- .
--
-- .
-- .
-- P3 . .P2
object temp
atom y, steps, P1P3_len, P2P3_len
sequence P3P1, P2P3
temp = P1-P3
temp = temp*temp
P1P3_len = sqrt(temp[1] + temp[2])
temp = P2-P3
temp = temp*temp
P2P3_len = sqrt(temp[1] + temp[2])
steps = P1P3_len + P2P3_len --guesstimate to avoid large gaps
P3P1 = P3-P1
P2P3 = P2-P3
if steps = 0 then return end if
for x = 0 to cos(PI/4) by 1/steps do
y = 1 - sqrt(1 - x*x)
pixel(pen, P1 + P3P1*x + P2P3*y)
pixel(pen, P1 + P3P1*(1-y) + P2P3*(1-x)) --mirror
end for
end procedure
--test code
--generate random curves between 3 colored dots
--esc to exit, any other key for a new curve
object ignore, video, x, y, a, b, c
ignore = graphics_mode(18)
ignore = {
palette(1, {63,63,63}),
palette(2, {63,00,00}),
palette(3, {63,63,00}),
palette(4, {00,00,63})
}
video = video_config()
x = video[VC_XPIXELS]
y = video[VC_YPIXELS]
while 1 do
a = {rand(x)-1, rand(y)-1}
b = {rand(x)-1, rand(y)-1}
c = {rand(x)-1, rand(y)-1}
clear_screen()
ellipse(2, 1, a-5, a+5)
ellipse(4, 1, c-5, c+5)
ellipse(3, 1, b-5, b+5)
curve(1, a, b, c)
ignore = wait_key()
if ignore = 27 then exit end if
end while
ignore = graphics_mode(-1)
-- end of test code
Matthew McNamara _
mat at iconz.co.nz o( )
The Internet Company of New Zealand / /\
