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Re: Is it possible a transparent image in space ??? [message #38772]

Tue, 30 March 2004 09:38

Rick Towler
Messages: 821
Registered: August 1998

Senior Member

"Antonio Santiago" wrote ...
> Mmm... i am making crazy.
>
> Just i have put an image with alpha channel in plane XY, and the same
> image as a texture map of a polygon in another plane. TRhe result is the
> image object is transparent but the polygon object (with image texture)
> no!!! argg.
>
> Do you know any example to make this ok? Am i makeing wrong anything?

Why don't you post your simple example? Then we can see what you might be
doing wrong. At this point all you want to do is texture map a polygon with
an image containing an alpha channel. Your example should only be 5 or so
lines. Use XOBJVIEW to display it.

As for examples, I don't know of any in the IDL distribution. I know this
has been covered in depth before in this group. You could use google to
search the archives.

-Rick

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Re: Is it possible a transparent image in space ??? [message #38783 is a reply to message #38772]

Mon, 29 March 2004 23:06

Antonio Santiago
Messages: 201
Registered: February 2004

Senior Member

Mmm... i am making crazy.

Just i have put an image with alpha channel in plane XY, and the same
image as a texture map of a polygon in another plane. TRhe result is the
image object is transparent but the polygon object (with image texture)
no!!! argg.

Do you know any example to make this ok? Am i makeing wrong anything?

Thanks anyway.
Antonio.

Rick Towler wrote:
> "Antonio Santiago" wrote...
>
>
>> i know it is possible to put two images in the same "plane" and make one
>> of two semi-transparent to allow see the second image.
>> My question is: Is it possible to create an image as a texture of
>> poligon and make it be transparent in the 3D space? (transparent for
>> other planes).
>
>
> Yes.
>
> Take that image with an alpha channel and apply it as a texture to a planar
> polygon. Position that polygon in space either by manipulating its vertices
> or by transforming the model that contains it.
>
> You must make sure that your objects are drawn back to front (-z to +z)
> otherwise you'll not see the far objects thru the near objects.
>
> -Rick
>
>

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Re: Is it possible a transparent image in space ??? [message #38784 is a reply to message #38783]

Mon, 29 March 2004 22:46

Antonio Santiago
Messages: 201
Registered: February 2004

Senior Member

That seems not work.
I have a program similar to d_vectrack, but i want my slices to be
semi-transparent.
I try put on a polygon an image texture (with alpha channel) as you say
but it doesnt works. The image is right visualized but it is not
transparent, it is see lika if it isn't transparent.

I'm continue trying.
Bye and thanks.

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Re: Is it possible a transparent image in space ??? [message #38794 is a reply to message #38784]

Mon, 29 March 2004 10:31

Rick Towler
Messages: 821
Registered: August 1998

Senior Member

"Antonio Santiago" wrote...

> i know it is possible to put two images in the same "plane" and make one
> of two semi-transparent to allow see the second image.
> My question is: Is it possible to create an image as a texture of
> poligon and make it be transparent in the 3D space? (transparent for
> other planes).

Yes.

Take that image with an alpha channel and apply it as a texture to a planar
polygon. Position that polygon in space either by manipulating its vertices
or by transforming the model that contains it.

You must make sure that your objects are drawn back to front (-z to +z)
otherwise you'll not see the far objects thru the near objects.

-Rick

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Re: Is it possible a transparent image in space ??? [message #38857 is a reply to message #38794]

Wed, 31 March 2004 01:02

Antonio Santiago
Messages: 201
Registered: February 2004

Senior Member

Hi Rick,

sorry to bother you another time but i just seeing some examples found
in google about texture maps transparencies and i think i am doing the same.

My code is a little big (is part of a more big program) so i put some
important lines.
(I have one IDLgrModel and put a polygon with a texture_map and a simple
IDLgrImage.)

-First i create two IDLgrImage ('oXImage' and 'ximage'. 'oXImage' will
be a texture map and 'ximage' will be a simple image put on a IDLgrModel):

Note: The first data i put into image DATA is not an alpha image. I
create later this.

;Imagen corte X
img_x_data = data_vol[0,*,*]
img_x_data = REFORM(img_x_data, sizes[1], sizes[2])
oXImage = OBJ_NEW('IDLgrImage', img_x_data, $
XCOORD_CONV=xconv, YCOORD_CONV=yconv, ZCOORD_CONV=zconv, $
PALETTE=sEstado.oPalPolygon, BLEND_FUNCTION=[3,4])
sEstado.oXSlideImage = oXImage
sEstado.oHolderTemp->Add, oXImage

ximage = OBJ_NEW('IDLgrImage', img_x_data, $
XCOORD_CONV=xconv, YCOORD_CONV=yconv, ZCOORD_CONV=zconv, $
PALETTE=sEstado.oPalPolygon, BLEND_FUNCTION=[3,4])
sEstado.oTopModelVol->Add, ximage
sEstado.ximage=ximage

-Then i create one IDLgrPolygon and assing oXImage as a texture_map:

oXSlide = OBJ_NEW('IDLgrPolygon', COLOR=[255,255,255], $
[[0,0,0],[0,y,0],[0,y,z],[0,0,z],[0,0,0]], $
THICK=2, STYLE=2, $
XCOORD_CONV=xconv, YCOORD_CONV=yconv, ZCOORD_CONV=zconv, $
TEXTURE_MAP=oXImage, TEXTURE_COORD=[[0,0], [1,0], [1,1],[0,1], [0,0]])
sEstado.oVolumeModelVol->Add, oXSlide
sEstado.oXSlide = oXSlide

-Final when i move the polygon i caught some data, convert to alpha
image and assign to both texture_map image and simple image:

...
c[*,*,0] = red(img_x_data[*,*])
c[*,*,1] = green(img_x_data[*,*])
c[*,*,2] = blue(img_x_data[*,*])
c[*,*,3] = 100

sEstado.ximage->SetProperty, DATA=c, INTERLEAVE=2, $
XCOORD_CONV=xconv, YCOORD_CONV=yconv, ZCOORD_CONV=zconv
sEstado.oXSlideImage->SetProperty, DATA=c, INTERLEAVE=2, $
XCOORD_CONV=xconv, YCOORD_CONV=yconv, ZCOORD_CONV=zconv

The result is: the simple image put on the IDLgrModel is transparent but
the texture map not.

I think it is the same as all examples.

Well, if you arrive here a lot of thanks for your patient and time :)

--------
Antonio.

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