Text Only | Text with Attachments

QB64.org Forum

Active Forums => Programs => Topic started by: Zeppelin on November 25, 2019, 11:11:36 pm

Title: Drawing Polygons
Post by: Zeppelin on November 25, 2019, 11:11:36 pm
Hey all,
I've been trying to make a program that can draw any polygon (pentagon, octagon, pentacontagon, etc...), although I can't get it to work.

Code: QB64: [Select]
  1. SCREEN _NEWIMAGE(800, 600, 32)
  2. l = 100
  3. s = 8
  4.  
  5. angle = (360 / s)
  6. lx = (_WIDTH / 2) + ((COS(angle)) * l)
  7. ly = (_HEIGHT / 2) + ((SIN(angle)) * l)
  8.  
  9. FOR n = 1 TO s
  10.     x = (_WIDTH / 2) + ((COS(angle)) * l)
  11.     y = (_HEIGHT / 2) + ((SIN(angle)) * l)
  12.  
  13.     LINE (lx, ly)-(x, y), _RGB(255, 255, 255)
  14.  
  15.     lx = x
  16.     ly = y
  17.  
  18.     angle = (360 / s) * n
  19.     PRINT angle
  21.  

l is the length of each line
s is the amount of sides i want.

No matter what I do either the shape doesnt line up or it overlaps.

Thanks,
Zep
Title: Re: Drawing Polygons
Post by: bplus on November 25, 2019, 11:28:05 pm
Man you are so close! Give me a sec...
Code: QB64: [Select]
  1. SCREEN _NEWIMAGE(800, 600, 32)
  2. l = 100
  3. s = 8
  4.  
  5. angle = (360 / s)
  6. lx = _WIDTH / 2 + COS(_D2R(angle)) * l
  7. ly = _HEIGHT / 2 + SIN(_D2R(angle)) * l
  8. FOR n = 0 TO s
  9.  
  10.     x = _WIDTH / 2 + COS(_D2R(n * angle)) * l
  11.     y = _HEIGHT / 2 + SIN(_D2R(n * angle)) * l
  12.  
  13.     LINE (lx, ly)-(x, y), _RGB(255, 255, 255)
  14.  
  15.     lx = x
  16.     ly = y
  17.  
  18.  
  19.     PRINT n * angle
  21.  

SIN and COS use radians not degrees 2*PI = 360 degrees, so we had to convert the angles from degree to radians
_D2R() function.

Then n*angle under SIN and COS function, you had that I think, then  to go full circle you have to do the first point again, I just start a 0 and go to n sides of poly.

Code: QB64: [Select]
  1. SCREEN _NEWIMAGE(800, 600, 32)
  2. l = 100
  3. FOR s = 3 TO 12
  4.     CLS
  5.     angle = (360 / s)
  6.     lx = _WIDTH / 2 + COS(_D2R(0)) * l
  7.     ly = _HEIGHT / 2 + SIN(_D2R(0)) * l
  8.     FOR n = 1 TO s
  9.         x = _WIDTH / 2 + COS(_D2R(n * angle)) * l
  10.         y = _HEIGHT / 2 + SIN(_D2R(n * angle)) * l
  11.         LINE (lx, ly)-(x, y), _RGB(255, 255, 255)
  12.         lx = x
  13.         ly = y
  14.         PRINT n * angle
  15.     NEXT n
  16.     _DELAY 1
Title: Re: Drawing Polygons
Post by: bplus on November 25, 2019, 11:50:50 pm
Subtract 90 degrees in the _D2R() to get them all to start drawing (pointing North or UP):
Code: QB64: [Select]
  1. SCREEN _NEWIMAGE(800, 600, 32)
  2. l = 100
  3. FOR s = 3 TO 12
  4.     CLS
  5.     angle = (360 / s)
  6.     lx = _WIDTH / 2 + COS(_D2R(0 - 90)) * l
  7.     ly = _HEIGHT / 2 + SIN(_D2R(0 - 90)) * l
  8.     FOR n = 1 TO s
  9.         x = _WIDTH / 2 + COS(_D2R(n * angle - 90)) * l
  10.         y = _HEIGHT / 2 + SIN(_D2R(n * angle - 90)) * l
  11.         LINE (lx, ly)-(x, y), _RGB(255, 255, 255)
  12.         lx = x
  13.         ly = y
  14.         PRINT n * angle
  15.     NEXT n
  16.     _DELAY 1
  18.  
Title: Re: Drawing Polygons
Post by: Zeppelin on November 26, 2019, 04:47:45 am
Thanks bPlus,
It's always a small issue that underpins what could've been :D

Zep
Title: Re: Drawing Polygons
Post by: DANILIN on November 26, 2019, 03:13:14 pm
? where are diagonals ?

  [ This attachment cannot be displayed inline in 'Print Page' view ]  


Title: Re: Drawing Polygons
Post by: bplus on November 26, 2019, 04:40:52 pm
Hi Danlin,

Ha! nice graphics, yours?

We leave the diagonals or chords as classic exercise with polygons along with drawing N pointed stars. :D
Oh, and twirling them as they streak across the screen... :)

https://www.google.com/search?client=opera&q=my+god+it%27s+full+of+stars&sourceid=opera&ie=UTF-8&oe=UTF-8
Title: Re: Drawing Polygons
Post by: DANILIN on November 26, 2019, 05:18:01 pm
yes gif & youtube is my

in Russia task of connecting of vertices of polygon

this is a classical problem on loops and arrays

 
 
Title: Re: Drawing Polygons
Post by: bplus on November 26, 2019, 09:45:59 pm
Here is a star or two to wish upon or connect :D
Code: QB64: [Select]
  2. _TITLE "Star Worlds" 'B+ 2019-11-26
  3.  
  4. CONST xmax = 1200, ymax = 700, nS = 500
  5. TYPE starType
  6.     x AS SINGLE
  7.     y AS SINGLE
  8.     dx AS SINGLE
  9.     dy AS SINGLE
  10.     ri AS SINGLE
  11.     ro AS SINGLE
  12.     nP AS INTEGER
  13.     aOff AS SINGLE
  14.     da AS SINGLE
  15.     filled AS INTEGER
  16.     cc AS _UNSIGNED LONG
  18. DIM SHARED stars(1 TO nS) AS starType
  19.  
  21. SCREEN _NEWIMAGE(xmax, ymax, 32)
  22. _SCREENMOVE 100, 20
  24.  
  25. FOR i = 1 TO nS
  26.     newStar i
  28. WHILE _KEYDOWN(27) = 0
  29.     LINE (0, 0)-(xmax, ymax), _RGBA32(0, 0, 0, 30), BF
  30.     FOR i = 1 TO nS
  31.         drawStar i
  32.         stars(i).x = stars(i).x + stars(i).dx: stars(i).y = stars(i).y + stars(i).dy
  33.         IF stars(i).x < -50 OR stars(i).x > xmax + 50 OR stars(i).y < -50 OR stars(i).y > ymax + 50 THEN newStar i
  34.         stars(i).aOff = stars(i).aOff + stars(i).da
  35.     NEXT
  36.     _DISPLAY
  37.     _LIMIT 60
  39.  
  40. SUB newStar (i)
  41.     stars(i).x = irnd%(0, xmax)
  42.     stars(i).y = irnd%(0, ymax)
  43.     stars(i).ri = irnd%(1, 6)
  44.     stars(i).ro = stars(i).ri * (RND * 1 + 1.5)
  45.     stars(i).nP = irnd%(3, 12)
  46.     stars(i).aOff = RND * _PI(2)
  47.     IF RND < .5 THEN stars(i).da = RND * _PI / -45 ELSE stars(i).da = RND * _PI / 45
  48.     stars(i).filled = irnd%(0, 1)
  49.     stars(i).dx = irnd%(-10, 10)
  50.     stars(i).dy = irnd%(-10, 10)
  51.     stars(i).cc = _RGBA32(irnd%(128, 255), irnd%(128, 255), irnd%(128, 255), irnd%(1, 255))
  53.  
  54. FUNCTION irnd% (n1, n2) 'return an integer between 2 numbers
  55.     DIM l%, h%
  56.     IF n1 > n2 THEN l% = n2: h% = n1 ELSE l% = n1: h% = n2
  57.     irnd% = INT(RND * (h% - l% + 1)) + l%
  59.  
  60. SUB fIrrPoly (arr() AS SINGLE, c AS _UNSIGNED LONG)
  61.     'this just draws a bunch of triangles according to x, y points in arr()
  62.     DIM ox AS SINGLE, oy AS SINGLE, i AS INTEGER
  63.     ox = arr(0): oy = arr(1) 'the first 2 items in arr() need to be center
  64.     FOR i = 2 TO UBOUND(arr) - 3 STEP 2
  65.         ftri ox, oy, arr(i), arr(i + 1), arr(i + 2), arr(i + 3), c
  66.     NEXT
  68.  
  69. SUB drawStar (i AS INTEGER)
  70.     ' x, y are same as for circle,
  71.     ' rInner is center circle radius
  72.     ' rOuter is the outer most point of star
  73.     ' nPoints is the number of points,
  74.     ' angleOffset = angle offset in radians
  75.     ' this is to allow us to spin the star
  76.     DIM pAngle AS SINGLE, radAngleOffset AS SINGLE, p AS INTEGER, idx AS INTEGER
  77.     DIM ar(INT(stars(i).nP) * 4 + 3) AS SINGLE 'add two for origin
  78.  
  79.     pAngle = _PI(2) / stars(i).nP: radAngleOffset = stars(i).aOff - _PI(1 / 2)
  80.     ar(0) = stars(i).x: ar(1) = stars(i).y
  81.     ar(2) = stars(i).x + stars(i).ro * COS(radAngleOffset)
  82.     ar(3) = stars(i).y + stars(i).ro * SIN(radAngleOffset)
  83.     idx = 4
  84.     FOR p = 0 TO stars(i).nP - 1
  85.         ar(idx) = stars(i).x + stars(i).ri * COS(p * pAngle + radAngleOffset + .5 * pAngle)
  86.         idx = idx + 1
  87.         ar(idx) = stars(i).y + stars(i).ri * SIN(p * pAngle + radAngleOffset + .5 * pAngle)
  88.         idx = idx + 1
  89.         ar(idx) = stars(i).x + stars(i).ro * COS((p + 1) * pAngle + radAngleOffset)
  90.         idx = idx + 1
  91.         ar(idx) = stars(i).y + stars(i).ro * SIN((p + 1) * pAngle + radAngleOffset)
  92.         idx = idx + 1
  93.     NEXT
  94.     IF stars(i).filled THEN
  95.         fIrrPoly ar(), stars(i).cc
  96.     ELSE
  97.         FOR p = 2 TO stars(i).nP * 4 + 3 STEP 2
  98.             IF p > 2 THEN LINE (ar(p - 2), ar(p - 1))-(ar(p), ar(p + 1)), stars(i).cc
  99.         NEXT
  100.     END IF
  102.  
  103. SUB ftri (x1, y1, x2, y2, x3, y3, K AS _UNSIGNED LONG)
  104.     DIM D AS LONG
  105.     STATIC a&
  106.     D = _DEST
  107.     IF a& = 0 THEN a& = _NEWIMAGE(1, 1, 32)
  108.     _DEST a&
  109.     PSET (0, 0), K
  110.     _DEST D
  111.     _MAPTRIANGLE _SEAMLESS(0, 0)-(0, 0)-(0, 0), a& TO(x1, y1)-(x2, y2)-(x3, y3)
  113.  
  114.  

Until now, I never did get around to drawing filled polygons.

Oh! I just realized, run this long enough and all the stars will become stationary, survival of the slowest.
Text Only | Text with Attachments