[bb] Angle360 for B3D/B+ by markcw [ 1+ years ago ]

[BlitzBot]

Title : Angle360 for B3D/B+
Author : markcw
Posted : 1+ years ago

Description : Angle360() takes 4 parameters x1,y1,x2,y2 and returns a float value from 0..359 degrees.
Point 1 is assumed to be the center of a circle and point 2 is assumed to be on the edge. The top of the screen is assumed to be zero degrees. A working example is included with the function.

Code :

Code: BlitzBasic

1. ;Angle360 Example for B3D/B+
2.  
3. Graphics 640,480,0,2
4. SetBuffer BackBuffer()
5.  
6. While Not KeyDown(1)
7.  Cls
8.  
9.  ;Here the center of the screen is point 1 and the mouse is point 2
10.  angle#=Angle360(320,240,MouseX(),MouseY())
11.  Text 0,0,"angle#="+angle#
12.  
13.  ;Draw 2 points and 3 lines
14.  Rect MouseX()-2,MouseY()-2,4,4
15.  Rect 320-2,240-2,4,4
16.  Line 320,240,MouseX(),MouseY()
17.  Line 320,240,MouseX(),240
18.  Line 320,240,320,MouseY()
19.  
20.  Flip
21. Wend
22. End
23.  
24. Function Angle360b#(x1,y1,x2,y2)
25.  ;Returns a 360 degree angle between 2 points, 0..359 degrees
26.  ;Author: Snarkbait, 9 Mar 2008
27.  Return (ATan2(y2-y1,x2-x1)+450) Mod 360
28. End Function
29.  
30. Function Angle360#(x1,y1,x2,y2)
31.  ;Returns a 360 degree angle between 2 points, 0..359 degrees
32.  ;Assumes point 1 is the center and point 2 is on the edge of a circle
33.  ;Author: markcw, edited 12 Mar 2008
34.  
35.  Local adj,opp,hyp#,angle#
36.  adj=Abs(x2-x1)
37.  opp=Abs(y2-y1)
38.  hyp#=Sqr((adj*adj)+(opp*opp)) ;Pythagoras
39.  If hyp#=0 Then hyp#=1 ;Avoid divide by zero
40.  If opp<=adj : angle#=ASin(opp/hyp#) ;Sin=Opp/Hyp
41.  Else : angle#=ACos(adj/hyp#) ;Cos=Adj/Hyp
42.  EndIf
43.  If x2>x1 And y2<=y1 : angle#=90-angle# ;0..90
44.  ElseIf x2>x1 And y2>y1 : angle#=90+angle# ;90..180
45.  ElseIf x2<=x1 And y2>y1 : angle#=180+90-angle# ;180..270
46.  ElseIf x2<=x1 And y2<=y1 : angle#=180+90+angle# ;270..360
47.  EndIf
48.  If angle#=360 Then angle#=0
49.  Return angle#
50.  
51. End Function

Comments :


Snarkbait(Posted 1+ years ago)

 simpler:

Code: [Select]

Function Angle360#(x1,y1,x2,y2)
return (ATan2(y2 - y1, x2 - x1) + 450) Mod 360
End Function



Naughty Alien(Posted 1+ years ago)

 


tonyg(Posted 1+ years ago)

 I am guessing this is something to do with <a href="http://www.blitzmax.com/Community/posts.php?topic=76478#855398" target="_blank"> this [/url]


Who was John Galt?(Posted 1+ years ago)

 It appears so.


markcw(Posted 1+ years ago)

 Thanks Snarkbait. Stunning bit of code. Now I know how Atan2 works. Yours works exactly like mine so is a better version to use.tonyg: yes, I noticed there wasn't a decent entry for this in the code archives after looking at Nebula's code so I thought I'd add one. [/i]