Sutherland-Hodgman polygon clipping: Difference between revisions

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=={{header|Phix}}==

<lang Phix>-- demo\rosetta\Sutherland_Hodgman_polygon_clipping.exw

You can run this online [http://phix.x10.mx/p2js/shpc.htm here].

enum X,Y

--

function inside(sequence cp1, sequence cp2, sequence p)

-- demo\rosetta\Sutherland_Hodgman_polygon_clipping.exw

return (cp2[X]-cp1[X])*(p[Y]-cp1[Y])>(cp2[Y]-cp1[Y])*(p[X]-cp1[X])

-- ====================================================

end function

--

with javascript_semantics

function intersection(sequence cp1, sequence cp2, sequence s, sequence e)

enum X,Y

atom {dcx,dcy} = {cp1[X]-cp2[X],cp1[Y]-cp2[Y]},

{dpx,dpy} = {s[X]-e[X],s[Y]-e[Y]},

function inside(sequence cp1, cp2, p)

n1 = cp1[X]*cp2[Y]-cp1[Y]*cp2[X],

return (cp2[X]-cp1[X])*(p[Y]-cp1[Y])>(cp2[Y]-cp1[Y])*(p[X]-cp1[X])

n2 = s[X]*e[Y]-s[Y]*e[X],

end function

n3 = 1/(dcx*dpy-dcy*dpx)

return {(n1*dpx-n2*dcx)*n3,(n1*dpy-n2*dcy)*n3}

function intersect(sequence cp1, cp2, s, e)

end function

atom {dcx,dcy} = {cp1[X]-cp2[X],cp1[Y]-cp2[Y]},

{dpx,dpy} = {s[X]-e[X],s[Y]-e[Y]},

function sutherland_hodgman(sequence subjectPolygon, sequence clipPolygon)

n1 = cp1[X]*cp2[Y]-cp1[Y]*cp2[X],

sequence cp1, cp2, s, e, inputList, outputList = subjectPolygon

n2 = s[X]*e[Y]-s[Y]*e[X],

cp1 = clipPolygon[$]

n3 = 1/(dcx*dpy-dcy*dpx)

for i=1 to length(clipPolygon) do

return {(n1*dpx-n2*dcx)*n3,(n1*dpy-n2*dcy)*n3}

cp2 = clipPolygon[i]

end function

inputList = outputList

outputList = {}

function sutherland_hodgman(sequence subjectPolygon, clipPolygon)

s = inputList[$]

sequence cp1 = clipPolygon[$],

for j=1 to length(inputList) do

outputList = subjectPolygon

e = inputList[j]

for i=1 to length(clipPolygon) do

if inside(cp1,cp2,e) then

sequence cp2 = clipPolygon[i],

if not inside(cp1,cp2,s) then

inputList = outputList,

outputList = append(outputList,intersection(cp1,cp2,s,e))

s = inputList[$]

end if

outputList = {}

outputList = append(outputList,e)

for j=1 to length(inputList) do

elsif inside(cp1,cp2,s) then

sequence e = inputList[j]

outputList = append(outputList,intersection(cp1,cp2,s,e))

if inside(cp1,cp2,e) then

end if

if not inside(cp1,cp2,s) then

s = e

outputList = append(outputList,intersect(cp1,cp2,s,e))

end for

end if

cp1 = cp2

outputList = append(outputList,e)

end for

elsif inside(cp1,cp2,s) then

return outputList

outputList = append(outputList,intersect(cp1,cp2,s,e))

end function

end if

s = e

constant subjectPolygon = {{50, 150}, {200, 50}, {350, 150}, {350, 300},

end for

{250, 300}, {200, 250}, {150, 350}, {100, 250},

cp1 = cp2

{100, 200}},

end for

clipPolygon = {{100, 100}, {300, 100}, {300, 300}, {100, 300}}

return outputList

end function

sequence clippedPolygon = sutherland_hodgman(subjectPolygon,clipPolygon)

constant subjectPolygon = {{50, 150}, {200, 50}, {350, 150}, {350, 300},

include pGUI.e

{250, 300}, {200, 250}, {150, 350}, {100, 250},

{100, 200}},

Ihandle dlg, canvas

clipPolygon = {{100, 100}, {300, 100}, {300, 300}, {100, 300}}

cdCanvas cddbuffer, cdcanvas

sequence clippedPolygon = sutherland_hodgman(subjectPolygon,clipPolygon)

procedure draw_poly(sequence poly)

cdCanvasBegin(cddbuffer,CD_FILL)

include pGUI.e

for i=1 to length(poly) do

atom {x,y} = poly[i]

Ihandle dlg, canvas

cdCanvasVertex(cddbuffer,x,y)

cdCanvas cddbuffer, cdcanvas

end for

cdCanvasEnd(cddbuffer)

procedure draw_poly(sequence poly)

end procedure

cdCanvasBegin(cddbuffer,CD_FILL)

for i=1 to length(poly) do

function redraw_cb(Ihandle /*ih*/, integer /*posx*/, integer /*posy*/)

atom {x,y} = poly[i]

cdCanvasActivate(cddbuffer)

cdCanvasVertex(cddbuffer,x,y)

cdCanvasClear(cddbuffer)

end for

cdCanvasSetForeground(cddbuffer, CD_CYAN)

cdCanvasEnd(cddbuffer)

draw_poly(subjectPolygon)

end procedure

cdCanvasSetForeground(cddbuffer, CD_MAGENTA)

draw_poly(clipPolygon)

function redraw_cb(Ihandle /*ih*/)

cdCanvasSetForeground(cddbuffer, CD_ORANGE)

cdCanvasActivate(cddbuffer)

draw_poly(clippedPolygon)

cdCanvasClear(cddbuffer)

cdCanvasFlush(cddbuffer)

cdCanvasSetForeground(cddbuffer, CD_CYAN)

return IUP_DEFAULT

draw_poly(subjectPolygon)

end function

cdCanvasSetForeground(cddbuffer, CD_MAGENTA)

draw_poly(clipPolygon)

function map_cb(Ihandle ih)

cdCanvasSetForeground(cddbuffer, CD_ORANGE)

cdcanvas = cdCreateCanvas(CD_IUP, ih)

draw_poly(clippedPolygon)

cddbuffer = cdCreateCanvas(CD_DBUFFER, cdcanvas)

cdCanvasFlush(cddbuffer)

cdCanvasSetBackground(cddbuffer, CD_WHITE)

return IUP_DEFAULT

cdCanvasSetForeground(cddbuffer, CD_GRAY)

end function

return IUP_DEFAULT

end function

function map_cb(Ihandle ih)

cdcanvas = cdCreateCanvas(CD_IUP, ih)

procedure main()

cddbuffer = cdCreateCanvas(CD_DBUFFER, cdcanvas)

IupOpen()

cdCanvasSetBackground(cddbuffer, CD_WHITE)

cdCanvasSetForeground(cddbuffer, CD_GRAY)

canvas = IupCanvas(NULL)

return IUP_DEFAULT

IupSetAttribute(canvas, "RASTERSIZE", "400x400")

end function

IupSetCallback(canvas, "MAP_CB", Icallback("map_cb"))

IupSetCallback(canvas, "ACTION", Icallback("redraw_cb"))

procedure main()

IupOpen()

dlg = IupDialog(canvas)

canvas = IupCanvas("RASTERSIZE=400x400")

IupSetAttribute(dlg, "TITLE", "Sutherland-Hodgman polygon clipping")

IupSetCallbacks(canvas, {"MAP_CB", Icallback("map_cb"),

IupSetAttribute(dlg, "RESIZE", "NO")

"ACTION", Icallback("redraw_cb")})

dlg = IupDialog(canvas, "RESIZE=NO")

IupShow(dlg)

IupSetAttribute(dlg, "TITLE", "Sutherland-Hodgman polygon clipping")

IupMainLoop()

IupShow(dlg)

IupClose()

if platform()!=JS then

end procedure

IupMainLoop()

IupClose()

main()</lang>

end if

end procedure

main()

=={{header|PHP}}==