Dear list members,
trying to visualize three dimensional cloud fields, I started to work
with object graphics. I created a testcase to get the differences
between volume objects and polygon objects to decide which object to use.
What I do not understand is the attribute opacity of the volume objects.
In the code below opacity is 255 and therefor all the volumes should be
opac and have the same colour. The polygon graphic should look like the
volume graphic, or not ?
But in the areas where there are more voxels in direction of the view,
colour is a little bit more solid then in the areas where there is just
one filled voxel.
Is there something wrong in my understanding of volume objects ?
Thanks for your help in advance !
Klemens
pro cloudfield_visualization_2
oModel_vol = obj_new('IDLgrModel')
; volume
voltest = bytarr(8,8,10)
voltest(*,*,*) = 0
voltest(0:3,*,3) = 80
voltest(4:5,0,3) = 80
voltest(4:5,3:7,3) = 80
voltest(6:7,*,3) = 80
voltest(1:2,0:1,4) = 80
voltest(1,3,4) = 80
voltest(1,6,4) = 80
voltest(6,0,4) = 80
voltest(6:7,1,4) = 80
voltest(6:7,5:7,4) = 80
voltest(1,4,5) = 80
voltest(7,1,5) = 80
voltest(6:7,6:7,5) = 80
opacity = bytarr(256)
opacity[80] = 255B
opacity[0] = 0B
rgb_table0 = bytarr(256,3)
rgb_table0[80,*] = [255B,0B,0B]
rgb_table0[0,*] = [0B,255B,0B]
oVol_vol =
obj_new('IDLgrVolume',voltest,opacity_table0=opacity,rgb_tab le0=rgb_table0)
oModel_vol->add,oVol_vol
; view
oView_vol =
obj_new('IDLgrView',viewplane_rect=[-1,-1,12,12],color=[255, 255,255],zclip=[20,-20],eye=800)
oView_vol->add, oModel_vol
oModel_vol->rotate,[1,0,0],-89
oWindow_vol =
obj_new('IDLgrWindow',dimension=[400,400],renderer=1,retain= 2,title='Volume_example')
oWindow_vol->draw, oView_vol
; surface_example
cubetest = intarr(8,8,10)
cubetest(*,*,*) = 0
cubetest(0:3,*,3) = 80
cubetest(4:5,0,3) = 80
cubetest(4:5,3:7,3) = 80
cubetest(6:7,*,3) = 80
cubetest(1:2,0:1,4) = 80
cubetest(1,3,4) = 80
cubetest(1,6,4) = 80
cubetest(6,0,4) = 80
cubetest(6:7,1,4) = 80
cubetest(6:7,5:7,4) = 80
cubetest(1,4,5) = 80
cubetest(7,1,5) = 80
cubetest(6:7,6:7,5) = 80
oModel_sur = obj_new('IDLgrModel')
for i = 0, 7 do begin
for j = 0, 7 do begin
for k = 0, 9 do begin
if(cubetest(i,j,k) eq 80)then begin
;offset=[i,j,k-4]
makeCube, verts, connectivity, offset=[i,j,k]
oPoly = obj_new('IDLgrPolygon', verts,
style=1,polygons=connectivity, color=[255,0,0])
f = [255,0,0]
;vc =
[[f,f,f],[f,f,f],[f,f,f],[f,f,f],[f,f,f],[f,f,f],[f,f,f],[f, f,f]]
oPoly->setProperty, style=2, shading=0;, vert_color=vc
oModel_sur->add, oPoly
endif
endfor
endfor
endfor
oModel_sur->rotate,[1,0,0],-89
oView_sur =
obj_new('IDLgrView',viewplane_rect=[-1,-1,12,12],color=[255, 255,255],zclip=[20,-20],eye=800)
oView_sur->add, oModel_sur
oWindow_sur =
obj_new('IDLgrWindow',dimension=[400,400],renderer=1,retain= 2,title='Surface_example')
oWindow_sur-> draw, oView_sur
end
pro makeCube, verts, connectivity, scale=scale, offset=offset
; creates the vertices and faces on a unit cube
; this can be scaled and offset using the keywords
; vertices in unit coordinates
verts = $
[[0.0,0.0,0.0],[1.0,0.0,0.0],[1.0,1.0,0.0],[0.0,1.0,0.0],[0. 0,0.0,1.0],[1.0,0.0,1.0],[1.0,1.0,1.0],[0.0,1.0,1.0]]
; connectivity list for the vertices
connectivity = [4,3,0,4,7,$
4,0,1,5,4,$
4,4,5,6,7,$
4,1,2,6,5,$
4,2,3,7,6,$
4,3,2,1,0]
; if the scale keyword is set then use it.
if keyword_set(scale) then verts=verts*scale
; if the offset keyword is present then apply it
if (n_elements(offset) ne 0) then begin
verts(0,*)=verts(0,*) + offset(0)
verts(1,*)=verts(1,*) + offset(1)
verts(2,*)=verts(2,*) + offset(2)
endif
return
end
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