greg michael wrote:
> I'd be very interested to take a look at your meshing routines
Here it is... I don't have time to generalize it but it is fairly
straightforward. You should be able to work up a front end that takes
your data and reforms it into a 3xN array required for meshing/display.
Currently this meshes from 0,0 in rows from far to near (you can
actually use the location keyword to modify this). You'll need to
change the order of meshing by playing around with v1 and v2 to change
the corner that meshing starts and its direction.
You could also use a combination of rotations to your data, specifying
the location to the meshing routine, and transformations afterwards to
get the same effect. In practice you would have 4 sets of vertices with
4 transform matrices which you would use to render the object as viewed
from the 4 directions. I included just that starting bits of this for
you below in the demo. The first surface renders correctly head on, the
second renders correctly after you rotate it 180 degrees. What isn't
apparent is that these surfaces are in different positions in world
space. That is where the transformation would come in.
Hope this helps.
-Rick
depth_data (input) is a 2d array of surface elevations
data (output) is the array that will receive the vertex data
polygons (output) is the array that will receive the polygon
connectivity data
location (optional in) defines the, ummm..., location of the far
left corner in world space? And the surface size. Yeah,
something like that :) [X,Z,extent in X,extent in Z]
nTriangles (optional out) returns the output of MESH_NUMTRIANGLES
use_triangles (optional in) set this keyword to create a
mesh comprised of triangles. Default is quads (quads render
faster on my hardware)
pro mesh_surface, depth_data, $
data, $
polygons, $
location=location, $
nTriangles=nTriangles, $
use_triangles=useTriangles
compile_opt idl2
dims = SIZE(depth_data)
useTriangles = (N_ELEMENTS(useTriangles) eq 0) ? 0 : $
KEYWORD_SET(useTriangles)
if (N_ELEMENTS(location) ne 4) then location=[0,0,dims[1],dims[2]]
;convert 2d data to 3xN
data = FLTARR(3,dims[4], /nozero)
for n = 0L, dims[2] - 1L do begin
s = n * dims[1]
e = s + dims[1] - 1L
data[0,s:e] = FINDGEN(dims[1]) * ((location[2]-location[0]) / $
(dims[1] - 1)) + location[0]
data[1,s:e] = depth_data[*,n]
data[2,s:e] = n * ((location[3]-location[1]) / $
(dims[2] - 1)) + location[1]
endfor
;create the surface mesh
if (useTriangles) then begin
;create triangle strip mesh
nconn = (dims[2] - 1L) * (8L * (dims[1] - 1L))
nstrip = (8L * (dims[1] - 1L))
polygons = FLTARR(nconn, /nozero)
v1 = 0L
v2 = LONG(dims[1])
np = 0L
while (np lt nconn-1) do begin
for ns = 0L, nstrip-1, 8L do begin
n = ns + np
polygons[n:n+3L] = [3, v1, v1+1L, v2]
polygons[n+4L:n+7L] = [3, v2, v1+1L, v2+1L]
v1 = v1 + 1L
v2 = v2 + 1L
endfor
np = np + nstrip
if (np lt nconn-1) then begin
;mesh back row
v1 = v1 + (2L * dims[1])
for ns = 0L, nstrip-1, 8L do begin
n = ns + np
polygons[n:n+3L] = [3, v2-1L, v2, v1]
polygons[n+4L:n+7L] = [3, v2-1L, v1, v1-1L]
v1 = v1 - 1L
v2 = v2 - 1L
endfor
v2 = v2 + (2L * dims[1])
np = np + nstrip
endif
endwhile
endif else begin
; Create quad strip mesh
nconn = (dims[2] - 1) * (5 * (dims[1] -1))
nstrip = (5L * (dims[1] - 1L))
polygons = FLTARR(nconn, /nozero)
v1 = 0L
v2 = LONG(dims[1])
np = 0L
while (np lt nconn-1) do begin
for ns = 0L, nstrip-1, 5L do begin
n = ns + np
polygons[n:n+4L] = [4, v1, v1+1L, v2+1, v2]
v1 = v1 + 1L
v2 = v2 + 1L
endfor
np = np + nstrip
if (np lt nconn-1) then begin
; Mesh back row
v1 = v1 + (2L * dims[1])
for ns = 0L, nstrip-1, 5L do begin
n = ns + np
polygons[n:n+4L] = [4, v2-1L, v2, v1, v1-1L]
v1 = v1 - 1L
v2 = v2 - 1L
endfor
v2 = v2 + (2L * dims[1])
np = np + nstrip
endif
endwhile
endelse
nTriangles = MESH_NUMTRIANGLES(polygons)
end
pro mesh_example
data = READ_IMAGE(!dir + '\examples\data\rbcells.jpg')
data = CONGRID(data, 256,256) / 64.
dDims = SIZE(data, /DIMENSIONS)
mesh_surface, data, verts, polys, LOCATION=[0,0,dDims[0], dDims[1]]
oPolygon = OBJ_NEW('IDLgrPolygon', verts, POLYGONS=polys, $
COLOR=[200,200,200], ALPHA=0.3)
oModel = OBJ_NEW('IDLgrModel')
oModel -> Add, oPolygon
XOBJVIEW, oModel, /BLOCK
data = ROTATE(data, -90)
mesh_surface, data, verts, polys, $
LOCATION=[dDims[0], dDims[1], -dDims[0], -dDims[1]]
oPolygon -> SetProperty, DATA=verts
XOBJVIEW, oModel, /BLOCK
OBJ_DESTROY, oModel
end
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