Graphics Functions: Draw one or more Bezier curves.
USE IFQWIN
result = POLYBEZIERTO (ppoints,cpoints)
result = POLYBEZIERTO_W (wppoints,cpoints)
ppoints |
(Input) Derived type xycoord. Array of derived types defining the endpoints and the control points for each Bezier curve. The derived type xycoordis defined in IFQWIN.F90 as follows: |
cpoints |
(Input) INTEGER(2). Number of points in ppoints or wppoints. |
wppoints |
(Input) Derived type wxycoord. Array of derived types defining the endpoints and the control points for each Bezier curve. The derived type wxycoordis defined in IFQWIN.F90 as follows: |
The result type is INTEGER(2). The result is nonzero if anything is drawn; otherwise, 0.
A Bezier curve is based on fitting a cubic curve to four points. The first point is the starting point, the next two points are control points, and last point is the ending point. The starting point is the current graphics position as set by MOVETO for the first curve; subsequent curves use the ending point of the previous curve as their starting point. So, cpoints should contain 3 for one curve, 6 for 2 curves, 9 for 3 curves, and so forth.
POLYBEZIERTO moves the current graphics position to the ending point of the last curve drawn.
STANDARD GRAPHICS QUICKWIN GRAPHICS LIB
Program Bezier
use IFQWIN
! Shows how to use POLYBEZIER, POLYBEZIER_W,
! POLYBEZIERTO, and POLYBEZIERTO_W,
TYPE(xycoord) lppoints(31)
TYPE(wxycoord) wlppoints(31)
TYPE(xycoord) xy
TYPE(wxycoord) wxy
integer(4) i
integer(2) istat, orgx, orgy
real(8) worgx, worgy
i = setcolorrgb(Z'00FFFFFF') ! graphic to black
i = settextcolorrgb(Z'00FFFFFF') ! text to black
i = setbkcolorrgb(Z'00000000') ! background to white
call clearscreen($GCLEARSCREEN)
orgx = 20
orgy = 20
lppoints(1).xcoord = 1+orgx
lppoints(1).ycoord = 1+orgy
lppoints(2).xcoord = 30+orgx
lppoints(2).ycoord = 120+orgy
lppoints(3).xcoord = 150+orgx
lppoints(3).ycoord = 60+orgy
lppoints(4).xcoord = 180+orgx
lppoints(4).ycoord = 180+orgy
istat = PolyBezier(lppoints, 4)
! Show tangent lines
! A bezier curve is tangent to the line
! from the begin point to the first control
! point. It is also tangent to the line from
! the second control point to the end point.
do i = 1,4,2
call moveto(lppoints(i).xcoord,lppoints(i).ycoord,xy)
istat = lineto(lppoints(i+1).xcoord,lppoints(i+1).ycoord)
end do
read(*,*)
worgx = 50.0
worgy = 50.0
wlppoints(1).wx = 1.0+worgx
wlppoints(1).wy = 1.0+worgy
wlppoints(2).wx = 30.0+worgx
wlppoints(2).wy = 120.0+worgy
wlppoints(3).wx = 150.0+worgx
wlppoints(3).wy = 60.0+worgy
wlppoints(4).wx = 180.0+worgx
wlppoints(4).wy = 180.0+worgy
i = setcolorrgb(Z'000000FF') ! graphic to red
istat = PolyBezier_W(wlppoints, 4)
! Show tangent lines
! A bezier curve is tangent to the line
! from the begin point to the first control
! point. It is also tangent to the line from
! the second control point to the end point.
do i = 1,4,2
call moveto_w(wlppoints(i).wx,wlppoints(i).wy,wxy)
istat = lineto_w(wlppoints(i+1).wx,wlppoints(i+1).wy)
end do
read(*,*)
orgx = 80
orgy = 80
! POLYBEZIERTO uses the current graphics position
! as its initial starting point so we start the
! array with the first first control point.
! lppoints(1).xcoord = 1+orgx ! need to move to this
! lppoints(1).ycoord = 1+orgy
lppoints(1).xcoord = 30+orgx
lppoints(1).ycoord = 120+orgy
lppoints(2).xcoord = 150+orgx
lppoints(2).ycoord = 60+orgy
lppoints(3).xcoord = 180+orgx
lppoints(3).ycoord = 180+orgy
i = setcolorrgb(Z'0000FF00') ! graphic to green
call moveto(1+orgx,1+orgy,xy)
istat = PolyBezierTo(lppoints, 3)
! Show tangent lines
! A bezier curve is tangent to the line
! from the begin point to the first control
! point. It is also tangent to the line from
! the second control point to the end point.
call moveto(1+orgx,1+orgy,xy)
istat = lineto(lppoints(1).xcoord,lppoints(1).ycoord)
call moveto(lppoints(2).xcoord,lppoints(2).ycoord,xy)
istat = lineto(lppoints(3).xcoord,lppoints(3).ycoord)
read(*,*)
worgx = 110.0
worgy = 110.0
! wlppoints(1).wx = 1.0+worgx
! wlppoints(1).wy = 1.0+worgy
wlppoints(1).wx = 30.0+worgx
wlppoints(1).wy = 120.0+worgy
wlppoints(2).wx = 150.0+worgx
wlppoints(2).wy = 60.0+worgy
wlppoints(3).wx = 180.0+worgx
wlppoints(3).wy = 180.0+worgy
call moveto_w(1.0+worgx,1.0+worgy,wxy)
i = setcolorrgb(Z'00FF0000') ! graphic to blue
istat = PolyBezierTo_W(wlppoints, 3)
! Show tangent lines
! A bezier curve is tangent to the line
! from the begin point to the first control
! point. It is also tangent to the line from
! the second control point to the end point.
call moveto_w(1.0+worgx,1.0+worgy,wxy)
istat = lineto_w(wlppoints(1).wx,wlppoints(1).wy)
call moveto_w(wlppoints(2).wx,wlppoints(2).wy,wxy)
istat = lineto_w(wlppoints(3).wx,wlppoints(3).wy)
read(*,*)
END PROGRAM Bezier