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Shadow in terrain

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Thomas Freudenreich

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Sep 30, 2009, 7:03:03 AM9/30/09
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I have terrain (triangle-strips) with hills and mountains and I want to
have a shadows in it. The spotlight on the darkside of a mountain is a bit
darker as in the front but it is'nt really a shadow. I found a lot of
examples with a single object that throws a shadow. But I haven't a single
object! Does anybody know a solution for that problem ?

Thomas

scott

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Oct 7, 2009, 3:28:57 AM10/7/09
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If your light is fixed then just pre-compute the shadow and store it in a
texture.

Thomas Freudenreich

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Oct 8, 2009, 6:11:00 PM10/8/09
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It is not fixed. It should simulate the sun. And I have still no idea how
to solve it. Everything is about shadows that object throw to another, but
not on itself.

Michael Bieber

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Oct 8, 2009, 9:04:37 PM10/8/09
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> It is not fixed. It should simulate the sun. And I have still no idea how
> to solve it. Everything is about shadows that object throw to another, but
> not on itself.

To have a starting point, you could google for "Terrain Shadow Maps".
The problem has many variables, finding the best technique unfortunately
depends on many of them.
At some point in the past, I was successful with shadow volumes even for
relatively complex terrains. Sentences like "Terrain lighting", perhaps
combined with "stencil buffer" could be also helpful. At last, I think
to remember some related former SIGGRAPH papers
(http://kesen.huang.googlepages.com/)

Micha

Thomas Freudenreich

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Oct 13, 2009, 2:56:47 AM10/13/09
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Thanks Micha. I got some hints now. Do you remember if you solved ist with
shaders(GPU) or with "regular" logic (CPU) ?
Thomas

Michael Bieber

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Oct 13, 2009, 6:49:39 AM10/13/09
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> Thanks Micha. I got some hints now. Do you remember if you solved ist with
> shaders(GPU) or with "regular" logic (CPU) ?

First thing, I've to admit that I did it in OpenGL... . CPU-based,
because I had to use hardware with very limited shader support (Radeon
9600 series) at that time, utilizing the GPU didn't make sense in this
environment.

For CPU-related stuff the following articles were helpful (check the
references inside, too):

http://software.intel.com/en-us/articles/multi-threaded-shadow-volumes-on-mainstream-graphics-hardware/
http://cache-www.intel.com/cd/00/00/29/37/293752_293752.pdf

Micha

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