Bitmap/Bézier curves/Cubic: Difference between revisions

=={{header|FreeBASIC}}==

{{trans|BBC BASIC}}

<lang freebasic>' version 01-11-2016

' compile with: fbc -s console

' translation from Bitmap/Bresenham's line algorithm C entry

Sub Br_line(x0 As Integer, y0 As Integer, x1 As Integer, y1 As Integer, _

Col As UInteger = &HFFFFFF)

Dim As Integer dx = Abs(x1 - x0), dy = Abs(y1 - y0)

Dim As Integer sx = IIf(x0 < x1, 1, -1)

Dim As Integer sy = IIf(y0 < y1, 1, -1)

Dim As Integer er = IIf(dx > dy, dx, -dy) \ 2, e2

Do

PSet(x0, y0), col

If (x0 = x1) And (y0 = y1) Then Exit Do

e2 = er

If e2 > -dx Then Er -= dy : x0 += sx

If e2 < dy Then Er += dx : y0 += sy

Loop

End Sub

' Bitmap/Bézier curves/Cubic BBC BASIC entry

Sub beziercubic(x1 As Double, y1 As Double, x2 As Double, y2 As Double, _

x3 As Double, y3 As Double, x4 As Double, y4 As Double, _

n As ULong, col As UInteger = &HFFFFFF)

Type point_

x As Integer

y As Integer

End Type

Dim As ULong i

Dim As Double t, t1, a, b, c, d

Dim As point_ p(n)

For i = 0 To n

t = i / n

t1 = 1 - t

a = t1 ^ 3

b = t * t1 * t1 * 3

c = t * t * t1 * 3

d = t ^ 3

p(i).x = Int(a * x1 + b * x2 + c * x3 + d * x4 + .5)

p(i).y = Int(a * y1 + b * y2 + c * y3 + d * y4 + .5)

Next

For i = 0 To n -1

Br_line(p(i).x, p(i).y, p(i +1).x, p(i +1).y, col)

Next

End Sub

' ------=< MAIN >=------

ScreenRes 250,250,32 ' 0,0 in top left corner

beziercubic(160, 150, 10, 120, 30, 0, 150, 50, 20)

' empty keyboard buffer

While Inkey <> "" : Wend

Print : Print "hit any key to end program"

Sleep

End</lang>