Bitmap/Bézier curves/Cubic: Difference between revisions

=={{header|Fortran}}==

{{trans|C}}

This subroutine should go inside the <code>RCImagePrimitive</code> module (see [[Bresenham's line algorithm]])

<lang fortran> subroutine cubic_bezier(img, p1, p2, p3, p4, color)

type(rgbimage), intent(inout) :: img

type(point), intent(in) :: p1, p2, p3, p4

type(rgb), intent(in) :: color

integer :: i, j

real :: pts(0:N_SEG,0:1), t, a, b, c, d, x, y

do i = 0, N_SEG

t = real(i) / real(N_SEG)

a = (1.0 - t)**3.0

b = 3.0 * t * (1.0 - t)**2.0

c = 3.0 * (1.0 - t) * t**2.0

d = t**3.0

x = a * p1%x + b * p2%x + c * p3%x + d * p4%x

y = a * p1%y + b * p2%y + c * p3%y + d * p4%y

pts(i,0) = x

pts(i,1) = y

end do

do i = 0, N_SEG-1

j = i + 1

call draw_line(img, point(pts(i,0), pts(i,1)), &

point(pts(j,0), pts(j,1)), color)

end do

end subroutine cubic_bezier</lang>