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Object OpenGL shadows

July 21, 2006 | 7:55 pm

Hi !

I am drawing a scene consisting only of planes in OpenGL with some gridshape objects. Is there anybody here that can explain to me how to have shadows of those planes onto other planes as I move the light ? I looked in the forum and know that it is not automatic but I did not understand how to do it simply.

Thanks.


July 21, 2006 | 8:22 pm

On Jul 21, 2006, at 12:55 PM, Laurent Ostiz wrote:

>
> I am drawing a scene consisting only of planes in OpenGL with some
> gridshape objects. Is there anybody here that can explain to me how
> to have shadows of those planes onto other planes as I move the
> light ? I looked in the forum and know that it is not automatic but
> I did not understand how to do it simply.

Sorry, but in OpenGL, there isn’t a way to do it *simply*.

We’re looking at some yet more complicated ways to get better quality
shadows in future release, but currently I would suggest the texture
approach posted by Randy Jones:

http://www.cycling74.com/forums/index.php?t=msg&goto=47810&rid=0&srch=
%22jitter+shadows%22#msg_47810

-Joshua


July 23, 2006 | 11:34 am

Hi !

I have studied this example, but it works well only when scene is static. If I move the light, and of course move at the same time the camera in the render that create the shadow texture, I do not get a realistic shadow. The shadow is not projected from the light point of view. I have read that there could be solutions with GLSL shaders. Does anyone has already tried to write one ? What about stencils ? Does Jitter 1.5.x support stencils ? Another problem with this solution is that writing a texture to a matrix, turn rendering in software mode. Is there a way to render in a texture directly in OpenGL ? I know many questions, but perhaps do you have some clues of answer ;-)

Best regards

Laurent


July 23, 2006 | 12:18 pm

Hi again

Continuing my investigations, is there a way to read the z-buffer directly in Jitter, and render it ? (method of shadow mapping described here and there on the Internet)

Best regards

Laurent


July 24, 2006 | 5:34 pm

On Jul 23, 2006, at 5:18 AM, Laurent Ostiz wrote:

> Continuing my investigations, is there a way to read the z-buffer
> directly in Jitter, and render it ? (method of shadow mapping
> described here and there on the Internet)

Not currently, but this is being actively worked on.

-Joshua


July 24, 2006 | 7:34 pm

hello

i’m trying (without any success) to build a minimal jitter-opengl
application (shown below) in a Macintel MacBookPro 2.0 GHz under WXP.

after including all needed files (cg.dll, cgGL.dll, jitlib.dll and
jitter shaders), pushing the build button in the collective editor,
choosing "Application (*.exe)" option and pushing save button in the
file browser, max window and collective editor display the following
message :

Starting Build for minjitglplato.pat-build…

But this starting process never ends …

When object jit.gl.plato and include file jitter shaders are removed,
after relaunching max, the building process ends normally

I’ve tried building some help patches of jitter objects. I get
exactly the same behavior.

Is this a known issue?

Thank you very much for any advice, even it seems trivial

jose manuel

________________

#P window setfont "Sans Serif" 9.;
#P window linecount 1;
#P newex 180 183 48 9109513 jit.gl.plato;
#P button 168 102 15 0;
#P newex 168 74 40 9109513 key;
#P newex 110 74 45 9109513 loadbang;
#P newex 110 101 54 9109513 delay 1000;
#P newex 110 150 45 9109513 t b erase;
#P newex 110 183 68 9109513 jit.gl.render v1;
#P newex 45 183 61 9109513 jit.window v1;
#P connect 5 0 6 0;
#P connect 4 0 3 0;
#P connect 2 1 1 0;
#P connect 2 0 1 0;
#P connect 6 0 2 0;
#P connect 3 0 2 0;
#P window clipboard copycount 8;

jose manuel berenguer
jmbeal@telefonica.net +34932857046 +34696538403. http://
http://www.sonoscop.net/jmb/
jmberenguer@sonoscop.net +34933064128. http://www.sonoscop.net/
caos->sonoscop. cccb. montalegre, 5. 08001 barcelona
spain


July 25, 2006 | 9:08 am


July 25, 2006 | 10:08 pm


July 26, 2006 | 10:10 am

Hi !

I have read the documentation about the new Jitter SDK 1.6.0 (thanks for this) and, wonder this : since from the C API we have a direct access to the full (yes ?) OpenGL 2.0 API, do you think now that it could be possible to implement soft shadows algorithm directly in an external that can interact with other jit.gl.* objects ? More precisely, is it possible to setup a multipass object with "private" renderings contexts to perform complex calculations ?

Thanks a lot.

Laurent


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