Using delsegment and redraw with a background image

[glennl]

Hi.

I have a graphics box ( #main.Map ) with a background BMP file, a aerial photo. On this graphic box I'm drawing a marker to indicate the position of a rover. 

graphicbox #main.Map, 360, 10, 640, 640
loadbmp "Map1", "Map1.bmp"
print #main.Map,"background Map1"

I can move the marker ( just a circle for now, eventually a arrow indicating direction ), but I want to remove the previous marker.  Below is part of a function that runs after receiving data from the rover

print #main.Map, "delsegment "; Seg-1
print #main.Map, "redraw"

print #main.Map, "segment Seg"
print #main.Map, "circle 10"
print #main.Map, "flush"

Its job is to remove the old marker, get the segment number of the new marker for use later, draw the circle and flush it.

problem is, seams the redraw command removes the background image.

If I remove the print #main.Map, "redraw" command, every stays, but so do the old markers.

Any suggestions?

Thanks
Glenn

[tsh73]

basically, "background" is sprite command
You probably need "drawbmp" instead.

[tsh73]

If marker is drawn frequently (so you do not need it flushed with a map), this will probably do

nomainwin

graphicbox #main.Map, 360, 10, 640, 640
''graphicbox #main.Map, 10, 10, 640, 640
open "#main" for window as #main
#main "trapclose [quit]"
#main.Map,"down"

loadbmp "Map1", "Map1.bmp"
''loadbmp "Map1", "ring54387.bmp"
print #main.Map,"background Map1"
print #main.Map,"drawbmp Map1 0 0 "
print #main.Map, "flush bg"

x=150
y=150

timer 30, [nxt]
wait

[nxt]
'I can move the marker ( just a circle for now, eventually a arrow indicating direction ), but I want to remove the previous marker.  Below is part of a function that runs after receiving data from the rover

'print #main.Map, "delsegment "; Seg-1
print #main.Map, "redraw bg"

'print #main.Map, "segment Seg"

x=x+rnd(0)*10-5
y=y+rnd(0)*10-5
print #main.Map, "place ";x;" ";y
print #main.Map, "circle 10"
'print #main.Map, "flush"

wait

[quit]
   timer 0
   close #main
   end


[Rod]

I did it this way.

graphicbox #main.Map, 360, 10, 640, 640
loadbmp "Map1", "Map1.bmp"
#main.Map "down ; drawbmp Map1 0 0"
#main.Map "flush bak"

#main.Map "discard ; redraw bak"
#main.Map "place ";x;" ";y
#main.Map "circle 10"


Since you constantly redraw the circle, no need to flush
so just the bak segment gets redrawn and the circle overlaid


[tsh73]

OK
after re-reading tutorial
alycesrestaurant.com/lbpe/Graphic%20Segments.html
I've got this:
1) your BG needs separate flush
2) since sequence starts with delsegment, we should draw/flush first set of markers (or delsegment will delete BG!)
3) "segment" command should be used after flush
'nomainwin

graphicbox #main.Map, 360, 10, 640, 640
''graphicbox #main.Map, 10, 10, 640, 640
open "#main" for window as #main
#main "trapclose [quit]"
#main.Map,"down"

loadbmp "Map1", "Map1.bmp"
''loadbmp "Map1", "ring54387.bmp"
print #main.Map,"background Map1"

print #main.Map,"drawbmp Map1 0 0 "
'needs separate flush
print #main.Map, "flush"

print #main.Map, "segment Seg"
print "bg seg", Seg

x=150
y=150

'initial segment to be deleted with delsegment
print #main.Map, "place ";x;" ";y
print #main.Map, "circle 10"
print #main.Map, "flush"
print #main.Map, "segment Seg"

print "initial  seg", Seg

timer 1500, [nxt]
wait


[nxt]
'I can move the marker ( just a circle for now, eventually a arrow indicating direction ), but I want to remove the previous marker.  Below is part of a function that runs after receiving data from the rover

print #main.Map, "delsegment "; Seg-1
print #main.Map, "redraw"

x=x+rnd(0)*10-5
y=y+rnd(0)*10-5
print #main.Map, "place ";x;" ";y
print #main.Map, "circle 10"
print #main.Map, "flush"

print #main.Map, "segment Seg"
print "current seg", Seg

wait

[quit]
   timer 0
   close #main
   end


[glennl]

Thanks guys, I'll have a play around this evening.