| Re: OVERLAYING IMAGES [message #24692] |
Tue, 17 April 2001 12:48 |
Rick Towler
Messages: 821
Registered: August 1998
|
Senior Member |
|
|
The point of my post was that you can't do it "directly" in direct graphics.
You have to either manipulate your data to fake a sort of transparency or
you have to use object graphics to display the output.
Your best bet is to look into David Fanning's example program "Image_Blend"
found near the bottom of this page:
http://www.dfanning.com/documents/programs.html
90% of the code you need would be in there. Then, with my pointers, you
should be able to quickly code the rest. His code is top notch. Easy to
read, and well commented.
Good Luck!
-Rick
"Mark Chan" <chanm@cadvision.com> wrote in message
news:9b7ksn$c9$1@news3.cadvision.com...
> Rick,
>
> I have been avoiding object graphic so far.
>
> I am interested in the real way, not the fake way.
>
> Will you, or know where I can find some direct graphic example code of
this
> nature?
>
> Thanks,
> Mark Chan
>
> "Rick Towler" <rtowler@u.washington.edu> wrote in message
> news:AQlB6.8137$%o2.664880@news1.sttls1.wa.home.com...
>> If you literally want to control the opacity of your plots (vs. doing
>> something with your data before contouring to fake it) you could try
>> something like this:
>>
>>
>> 1.plot your contour. This could be done in object graphics, or direct.
>>
>>
>> 2.draw the plot to a buffer, read the buffer and you'll get an image
> object.
>> If you plotted with direct graphics you'll read the device you plotted
to
> to
>> get the image data, then create an image object with that data.
>>
>>
>> 3.add a 4th (alpha) channel to the image object like so:
>>
>> image -> GetProperty, data = imagedata
>> imagedims = size(imagedata)
>> newimage=make_array(imagedims[1]+1,imagedims[2],imagedims[3] , $
>> /byte, /nozero)
>> newimage[0:2,*,*] = imagedata
>> newimage[3,*,*] = 255 (see note below)
>> image -> SetProperty, data = newimage
>>
>> the value you set the alpha channel to will determine the opacity.
Your
>> range is 0 (completely translucent) to 255 (opaque).
>>
>>
>> 4.repeat 1-3 for the second plot.
>>
>>
>> 5.create two idlgrpolygon objects, one on top of the other, and texture
> map
>> your images on them.
>>
>>
>> 6.by changing the alpha value of your image objects you can fade them in
> and
>> out.
>>
>>
>> If you are familiar with object graphics and have played around with the
>> polygon object and have done some texturing then this is fairly easy.
If
>> not, plan to spend some time with the documentation. Everything is
there,
>> you'll just have to experiment a little. Then encourage David to write
> this
>> Object Graphics book he has been threatening to write. Speaking of
David,
> I
>> think he has a program demonstrating this alpha channel stuff on his web
>> site. I would check that out. It may even be a drop in solution.
>>
>> -Rick Towler
>>
>>
>>
>> "Mark Chan" <chanm@cadvision.com> wrote in message
>> news:9b38m8$f0f$1@news3.cadvision.com...
>>> 1) plot some contour, using contour fill
>>>
>>> 2) oplot it with a different contour fill
>>>
>>> You get: only (2) appears (the other has been covered).
>>>
>>> Is there a way to make (2) translucent so that one can see both images
> at
>>> the same time?
>>>
>>> Thanks,
>>> Mark
>>>
>>>
>>
>>
>
>
|
|
|
|
| Re: OVERLAYING IMAGES [message #24723 is a reply to message #24692] |
Fri, 13 April 2001 12:46  |
Mark Chan
Messages: 24
Registered: November 2000
|
Junior Member |
|
|
Rick,
I have been avoiding object graphic so far.
I am interested in the real way, not the fake way.
Will you, or know where I can find some direct graphic example code of this
nature?
Thanks,
Mark Chan
"Rick Towler" <rtowler@u.washington.edu> wrote in message
news:AQlB6.8137$%o2.664880@news1.sttls1.wa.home.com...
> If you literally want to control the opacity of your plots (vs. doing
> something with your data before contouring to fake it) you could try
> something like this:
>
>
> 1.plot your contour. This could be done in object graphics, or direct.
>
>
> 2.draw the plot to a buffer, read the buffer and you'll get an image
object.
> If you plotted with direct graphics you'll read the device you plotted to
to
> get the image data, then create an image object with that data.
>
>
> 3.add a 4th (alpha) channel to the image object like so:
>
> image -> GetProperty, data = imagedata
> imagedims = size(imagedata)
> newimage=make_array(imagedims[1]+1,imagedims[2],imagedims[3] , $
> /byte, /nozero)
> newimage[0:2,*,*] = imagedata
> newimage[3,*,*] = 255 (see note below)
> image -> SetProperty, data = newimage
>
> the value you set the alpha channel to will determine the opacity. Your
> range is 0 (completely translucent) to 255 (opaque).
>
>
> 4.repeat 1-3 for the second plot.
>
>
> 5.create two idlgrpolygon objects, one on top of the other, and texture
map
> your images on them.
>
>
> 6.by changing the alpha value of your image objects you can fade them in
and
> out.
>
>
> If you are familiar with object graphics and have played around with the
> polygon object and have done some texturing then this is fairly easy. If
> not, plan to spend some time with the documentation. Everything is there,
> you'll just have to experiment a little. Then encourage David to write
this
> Object Graphics book he has been threatening to write. Speaking of David,
I
> think he has a program demonstrating this alpha channel stuff on his web
> site. I would check that out. It may even be a drop in solution.
>
> -Rick Towler
>
>
>
> "Mark Chan" <chanm@cadvision.com> wrote in message
> news:9b38m8$f0f$1@news3.cadvision.com...
>> 1) plot some contour, using contour fill
>>
>> 2) oplot it with a different contour fill
>>
>> You get: only (2) appears (the other has been covered).
>>
>> Is there a way to make (2) translucent so that one can see both images
at
>> the same time?
>>
>> Thanks,
>> Mark
>>
>>
>
>
|
|
|
|
| Re: OVERLAYING IMAGES [message #24749 is a reply to message #24723] |
Thu, 12 April 2001 10:45 |
Rick Towler
Messages: 821
Registered: August 1998
|
Senior Member |
|
|
If you literally want to control the opacity of your plots (vs. doing
something with your data before contouring to fake it) you could try
something like this:
1.plot your contour. This could be done in object graphics, or direct.
2.draw the plot to a buffer, read the buffer and you'll get an image object.
If you plotted with direct graphics you'll read the device you plotted to to
get the image data, then create an image object with that data.
3.add a 4th (alpha) channel to the image object like so:
image -> GetProperty, data = imagedata
imagedims = size(imagedata)
newimage=make_array(imagedims[1]+1,imagedims[2],imagedims[3] , $
/byte, /nozero)
newimage[0:2,*,*] = imagedata
newimage[3,*,*] = 255 (see note below)
image -> SetProperty, data = newimage
the value you set the alpha channel to will determine the opacity. Your
range is 0 (completely translucent) to 255 (opaque).
4.repeat 1-3 for the second plot.
5.create two idlgrpolygon objects, one on top of the other, and texture map
your images on them.
6.by changing the alpha value of your image objects you can fade them in and
out.
If you are familiar with object graphics and have played around with the
polygon object and have done some texturing then this is fairly easy. If
not, plan to spend some time with the documentation. Everything is there,
you'll just have to experiment a little. Then encourage David to write this
Object Graphics book he has been threatening to write. Speaking of David, I
think he has a program demonstrating this alpha channel stuff on his web
site. I would check that out. It may even be a drop in solution.
-Rick Towler
"Mark Chan" <chanm@cadvision.com> wrote in message
news:9b38m8$f0f$1@news3.cadvision.com...
> 1) plot some contour, using contour fill
>
> 2) oplot it with a different contour fill
>
> You get: only (2) appears (the other has been covered).
>
> Is there a way to make (2) translucent so that one can see both images at
> the same time?
>
> Thanks,
> Mark
>
>
|
|
|
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
