`' Another look at Trig functions.bas SmallBASIC 0.12.2 [B+=MGA] 2016-05-01`

' inspired by PeterMaria's simple code for Atan2 on Aurels' forum BasicPro

' 2017-09-23 Modified to run again on Android

' Here is another effort in a continuing series to demystify Trig functions:

' Move your mouse around the center point of the screen and see the right triangles

' created with the mouse and a horizontal line from the center

' see all the parts of the triangle expressed in numbers:

' angles to the horizontal line, lengths of the sides and hypotenuse of the right

' and the COS, SIN and TAN ratios

sub ThickArc(xCenter, yCenter, arcRadius, dAngleStart, dAngleEnd, rThick)

local rAngle, rAngleStart, rAngleEnd, x1, y1, Stepper

'draws an Arc with center at xCenter, yCenter, radius from center is arcRadius

'for SmallBASIC angle 0 degrees is due East and angle increases clockwise towards South

'THIS SUB IS SETUP TO DRAW AN ARC IN CLOCKWISE DIRECTION

'dAngleStart is where to start Angle in degrees

' so make the dAngleStart the first ray clockwise from 0 degrees that starts angle drawing clockwise

'dAngleEnd is where the arc ends going clockwise with positive degrees

' so if the arc end goes past 0 degrees clockwise from dAngleStart

' express the end angle as 360 + angle

'rThick is the radius of the many,many tiny circles this will draw to make the arc thick

' so if rThick = 2 the circles will have a radius of 2 pixels and arc will be 4 pixels thick

if arcRadius < 1 then pset xCenter, yCenter : exit func

rAngleStart = rad(dAngleStart) : rAngleEnd = rad(dAngleEnd)

if int(rthick) = 0 then Stepper = 1 / (arcRadius*pi) else Stepper = rThick / (arcRadius * pi / 2)

for rAngle = rAngleStart to rAngleEnd step Stepper

x1 = arcRadius * cos(rAngle) : y1 = arcRadius * sin(rAngle)

if int(rThick) < 1 then

pset xCenter + x1, yCenter + y1

else

circle xCenter + x1, yCenter + y1, rThick filled

fi

next

end

sub ThickLine(x1, y1, x2, y2, rThick)

local length, stepx, stepy, dx, dy, i

'x1,y1 is one endpoint of line

'x2,y2 is the other endpoint of the line

'rThick is the radius of the tiny circles that will be drawn

' from one end point to the other to create the thick line

'Yes, the line will then extend beyond the endpoints with circular ends.

stepx = x2 - x1

stepy = y2 - y1

length = (stepx ^ 2 + stepy ^ 2) ^.5

if length then

dx = stepx / length : dy = stepy / length

for i=0 to length

circle x1 + dx * i, y1 + dy * i, rThick filled

next

end if

end

'============================== Main

const thick = 2

const arc_radius = 100

const hor_color = rgb(30,30,30)

const sin_color = rgb(0,0,255)

const cos_color = rgb(255,0,0)

const hyp_color = rgb(0,192,0)

const ang_color = rgb(255,255,0)

const white = rgb(255,255,255)

cx = xmax / 2 : cy = ymax / 2

while 1

cls

'draw horizontal through center of screen

line 0, cy, xmax, cy, hor_color

'get mouse

mx = pen(4) : my = pen(5) 'get mouse location

'draw our Color Coded Trig Triangle

color cos_color

ThickLine cx, cy, mx, cy, thick

color sin_color

ThickLine mx, cy, mx, my, thick

color hyp_color

ThickLine cx, cy, mx, my, thick

stepx = abs(cx - mx) : stepy = abs(cy - my)

hyp = ( (stepx ^ 2 + stepy ^ 2) ^.5 )\1

'to draw angle need to do some math

'dAng = mouse angle to 0 degrees due East

' other Angles: StartA, EndA and reportA are for the Trig Ratios of triangle

dAng = ( deg(atan( (my - cy) / (mx - cx) ) )+.5 ) \ 1

if mx < cx then dAng = dAng + 180

if my < cy and mx > cx then dAng = dAng + 360

if dAng <= 90 then

startA = 0 : endA = dAng : reportA = dAng

elif dAng <= 180

startA = dAng : endA = 180 : reportA = 90 - (dAng - 90)

elif dAng <= 270

startA = 180 : endA = dAng : reportA = dAng - 180

elif dAng <= 360

startA = dAng : endA = 360 : reportA = 90 - (dAng - 270)

fi

color ang_color

ThickArc cx, cy, arc_radius, startA, endA, thick

'report all numbers color coded

color ang_color

locate 0, 0 : ? "yellow Angle (degrees) ~ "; reportA

color white

locate 2, 0 : ? "Lengths:"

color Hyp_Color

locate 3, 0 : ? "green Hyp ~ "; hyp

color SIN_Color

locate 4, 0 : ? " blue Opp ~ "; stepy \ 1

color COS_Color

locate 5, 0 : ? " red Adj ~ "; stepx \ 1

color white

locate 7, 0 : ? "Ratios: (if no division by 0)"

if hyp <> 0 then

color COS_Color

locate 8, 0 : ? "COS = Adj ";

color Hyp_Color

? "/ Hyp ";

color white

? "~ "; left(str(stepx / hyp), 6)

color SIN_Color

locate 9, 0 : ? "SIN = Opp ";

color Hyp_Color

? "/ Hyp ";

color white

? "~ "; left(str(stepy / hyp), 6)

fi

if stepx <> 0 then

locate 10, 0 : ? "TAN = ";

color SIN_Color

? "Opp ";

color COS_Color

? "/ Adj ";

color white

? "~ "; left(str(stepy / stepx), 6)

fi

showpage

delay 100

wend

I got this working again on my Android device by eliminating experimental exit button (like Windows) and a couple of other goofy ways to do mouse input. So now it works on my Android device almost as good as in Windows.

There is a tendency for triangle to snap back to mousex, mousey = 0, 0 when you finger is off the screen but it will tap or drag to any position you like...

So I think now all the on-line samples are working on Android devices.