Sin & Cos trouble

Blitz3D Forums/Blitz3D Beginners Area/Sin & Cos trouble

Pazza

(Posted 2004) [#1]

Hi All its been a while.

Line 164,188,164+Sin(angle*4)*distance,188+Cos(angle*4)*distance

im using the above to draw a line starting at 164,188 screen coordinates.

the routine draws the line at various angles and distances.

What i need to know is at which screen coordinate does the line actually end.

basically i need to find the x,y pixel coordinates at which the line stops drawing.

I thought i could just do:

x=164+Sin(angle*4)*distance
y=188+Cos(angle*4)*distance

but that doesnt work.

Any help would be greatly appreciated.

many thanks

Stevie G

(Posted 2004) [#2]

I think sin(angle*4) will be converted to an integer once multiplied by distance in this example - assuming 'distance' is defined as an integer, hence the incorrect x & y

try

x = 164 + sin(angle*4) * float( distance )

poopla

(Posted 2004) [#3]

It should work. The line command draws from x, y to x1, y1.

So the end point coordinate is x1, y1.

Pazza

(Posted 2004) [#4]

That doesnt work either just gives the same result for some reason.

Rob Farley

(Posted 2004) [#5]

Looks like a bracketting problem

try

x=164+(Sin(angle*4)*distance)
y=188+(Cos(angle*4)*distance)

Pazza

(Posted 2004) [#6]

Still doing the same thing,heres the whole code if
that helps any:

It should run ive removed the graphic loading & drawing stuff.

The function shotangle draws the line & uses sin & cos

;***fielder testing*************

Graphics 640,480,16
SetBuffer BackBuffer()
Dim field1%(2),xfield%(15,11),yfield%(15,11)
Dim game%(19,1),history%(2,5),game_results(18,1)

;Global pitch_graphic = LoadImage("pitch2.png")
;Global fielder = LoadImage("fielder.png")
Global rnd1
Global x,y,angle,distance

;***READ FIELD POSITIONS***

;Gosub readfield

;***Draw pitch*************
m=0
While m<10
Cls
;DrawBlock pitch_graphic ,0,78

;** Destination in screen coordinates**
Text 10,10,"X="+x
Text 10,20,"y="+y

For i%=1 To 11
Color 202,20,20
;PCIRCLE xfield%(n%,i%),yfield%(n%,i%),1
;Oval 2*xfield%(n%,i%),2*yfield%(n%,i%),10,10,1

;DrawImage fielder,2*xfield%(8,i%),(2*yfield%(8,i%))+26,0

Next

rand1(6)
r=rnd1

rand1(90)

shotangle(rnd1,r)

Flip
VWait
Delay 1000

m=m+1

Wend

WaitKey

End

;/***random numbers**/
Function rand1(n)
rnd1=Rand(0,n)
End Function

Function shotangle(angle%,distance%)

If distance>3 distance=distance*30
If distance<4 Then distance=distance*25

;;limit distance;;
If angle%>-1 And angle%<12 And distance%>105 Then distance%=105
If angle%>11 And angle%<18 And distance%>90 Then distance%=90
If angle%>17 And angle%<26 And distance%>82 Then distance%=82
If angle%>25 And angle%<33 And distance%>68 Then distance%=68
If angle%>32 And angle%<59 And distance%>60 Then distance%=60
If angle%>58 And angle%<63 And distance%>70 Then distance%=70

If angle%>62 And angle%<79 And distance%>92 Then distance%=92
If angle%>78 And angle%<91 And distance%>105 Then distance%=105

distance=distance*2

Color 255,255,255
Line 164,188,164+Sin(angle*4)*distance,188+Cos(angle*4)*distance
Color 200,200,200
x=164+(Sin(angle*4)*distance)
y=188+(Cos(angle*4)*distance)

End Function

;**FIELD POSITIONS**

.readfield

Restore positions

For a=1 To 15
For i=1 To 11
Read xfield(a,i),yfield(a,i)
Next
Next

.positions
;''normal 1''
Data 74,69,66,112,26,72,53,34,119,72,120,111
Data 47,144,102,142,57,60,6,113,100,42

;''normal 2''
Data 74,69,66,112,24,56,58,58,109,99,7,103
Data 126,69,90,35,116,140,35,126,77,159

;''normal 3''
Data 74,69,66,112,43,51,22,81,26,123,46,150
Data 93,36,101,93,128,59,121,144,86,139

;''normal 4''
Data 74,69,66,112,59,64,98,45,128,81,120,128,85,157
Data 101,96,38,150,45,106,23,75

;''normal 5''
Data 74,69,66,112,63,60,128,74,98,37,134,121,99,149
Data 18,119,53,97,51,147,110,99

;''attack 1''
Data 74,69,66,112,63,61,53,57,55,89,99,100
Data 97,45,119,76,45,131,111,148,31,73

;''attack 2''
Data 74,69,66,112,47,95,106,96,63,61,54,58
Data 121,71,27,71,43,135,102,134,94,52

;''attack 3''
Data 74,69,66,112,64,63,56,58,99,78,115,103
Data 101,129,37,74,57,91,24,113,51,139

;''attack 4''
Data 74,69,66,112,63,61,58,83,88,82,104,60
Data 26,70,25,103,44,133,119,104,96,144

;''attack 5''
Data 74,69,66,112,62,62,40,79,49,103,100,77
Data 88,97,129,121,51,138,100,142,98,52

;''defend 1''
Data 74,69,66,112,18,79,136,76,48,41,97,37
Data 14,114,30,139,126,110,100,124,64,153

;''defend 2''
Data 74,69,66,112,105,43,121,74,138,99,118,115
Data 108,152,56,138,31,118,35,74,50,48

;''defend 3''
Data 74,69,66,112,53,43,35,66,13,93,24,129
Data 55,147,118,52,129,84,102,104,102,154

;''defend 4''
Data 74,69,66,112,10,77,124,75,52,33,106,40
Data 30,105,33,143,69,162,123,107,100,136

;''defend 5''
Data 74,69,66,112,101,36,130,73,121,101,124,141
Data 88,153,38,150,16,114,23,73,51,53

Return

Rob Farley

(Posted 2004) [#7]

Can't really be arsed to look at your code, so here's something that might help...

Graphics 640,480

Repeat
	Cls

	x=Rand(0,639)
	y=Rand(0,480)

	For n=1 To 50
		angle = Rand(0,359)
		distance = Rand(0,200)
		Line x,y,x+(Sin(angle)*distance),y+(Cos(angle)*distance)
		Delay 50
	Next

Until KeyHit(1)

Regular K

(Posted 2004) [#8]

If you do Sin(45)+Cos(45) it should be equal to 1 or almost (few tenths off because of floats inprecision). So if you find the distance between x,y and x1 and y1, just multiply sin and cos by that. In theory it should work, or at least for me.

Pazza

(Posted 2004) [#9]

Thanks for trying rob,but your codes the same as mine
i still cant find the destination of the line using:

x1=x+(Sin(angle)*distance)
y1=y+(Cos(angle)*distance)

There must be an easy way of doing this?.

Stevie G

(Posted 2004) [#10]

Pazza,

It's not very clear from your code what you're trying to acheive here. If you could explain in more detail I'm sure there'll be a more elegant way of doing this. You're doing alot of messing about with 'distance', probably unecessarily - which may be you're problem.

Happy to help if you give more details :)

Rob Farley

(Posted 2004) [#11]

I really don't understand what you're trying to achieve.

x1=x+(Sin(angle)*distance)
y1=y+(Cos(angle)*distance)

x/y is the beginning of the line, x1/y1 is the end of the line.

Pazza

(Posted 2004) [#12]

all i want is the pixel coordinates for the end of the line,the line starts at the same position so i know the beggining i just cant get the end screen position.

Heres a simpler example,x1 & y1 variables should give the end point of the line in pixel coordinates,but if you run it they dont give the proper screen coordinates.

Graphics 640,480,16
SetBuffer BackBuffer()

distance=90

;***Draw pitch*************
m=0
While m<10
Cls

Text 10,10,"X1="+x1
Text 10,20,"y1="+y1

Color 202,20,20
angle=Rand(0,90)

Line 164,188,164+(Sin(angle*4)*distance),188+(Cos(angle*4)*distance)

x1=164+(Sin(angle*4)*distance)
y1=188+(Cos(angle*4)*distance)

Flip
VWait
Delay 1000

m=m+1

Wend

end

Pazza

(Posted 2004) [#13]

Doh sorry guys ive worked it out my mistake.

Thats what you get for programming whilst drinking beer last night and a megga hangover today.