Interesting mathmatical question and polygon extrusion opacity

Hactic · 09-17-2007, 04:31 PM

Gents,

I'm finally getting somewhere with the polygon extrusion opacity. I managed to get it to work, but unfortunately I was going down the wrong path. So I re-did it and it's almost finished :-)

In the mean time, there is an interesting mathmatical question that I would like to ask. I draw an extruded line in the air. Around the extrusion, I draw the four side. Both with linefeature. Then I draw another line that goes straight through the extruded box.

Is there any way to calculate the exact position where the line goes through the box. In other words, can I somehow determine wether the line goes through the box.

cheers,

nigel_ht · 09-19-2007, 03:25 PM

If you don't have commit privs I can insert you opacity changes.

patmurris · 09-20-2007, 08:52 AM

I didnt understand what your question is about - or more likely the geometrical setup you describe... What "four sides" ?

nigel_ht · 09-20-2007, 02:11 PM

I think he means the orange box is a linefeature with extrude to ground on so its a plane. Maybe.

To caclulate the exact point I don't know. In D3D there is a Mesh.Intersect by really all it does is loop through all the triangles and does a triangle-ray intersect.

From MSDN:

http://forums.microsoft.com/MSDN/Sho...97599&SiteID=1

Here's a sample for using Mesh.Intersect for mouse picking.

http://www.mdxinfo.com/tutorials/picking.php

You'll want to use a bounding box/sphere if you want to do a lot of these.

09-17-2007, 04:31 PM	#1
Hactic Member Join Date: May 2007 Posts: 48	Interesting mathmatical question and polygon extrusion opacity Gents, I'm finally getting somewhere with the polygon extrusion opacity. I managed to get it to work, but unfortunately I was going down the wrong path. So I re-did it and it's almost finished :-) In the mean time, there is an interesting mathmatical question that I would like to ask. I draw an extruded line in the air. Around the extrusion, I draw the four side. Both with linefeature. Then I draw another line that goes straight through the extruded box. Is there any way to calculate the exact position where the line goes through the box. In other words, can I somehow determine wether the line goes through the box. cheers,

09-20-2007, 08:52 AM	#3
patmurris WWJ Consultant Join Date: Jun 2005 Location: Saint-Paul de Vence, Alpes Maritimes, France Posts: 3,412	I didnt understand what your question is about - or more likely the geometrical setup you describe... What "four sides" ? __________________ My World Wind Java Blog & WW.net Plugins page

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09-19-2007, 03:25 PM	#2
nigel_ht Senior Member Join Date: Aug 2005 Posts: 337	If you don't have commit privs I can insert you opacity changes.

09-20-2007, 02:11 PM	#4
nigel_ht Senior Member Join Date: Aug 2005 Posts: 337	I think he means the orange box is a linefeature with extrude to ground on so its a plane. Maybe. To caclulate the exact point I don't know. In D3D there is a Mesh.Intersect by really all it does is loop through all the triangles and does a triangle-ray intersect. From MSDN: http://forums.microsoft.com/MSDN/Sho...97599&SiteID=1 Here's a sample for using Mesh.Intersect for mouse picking. http://www.mdxinfo.com/tutorials/picking.php You'll want to use a bounding box/sphere if you want to do a lot of these.

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