RenderMan & RISpec, noisysmoke and light visibility

1. 2 questions are back :) (lighting and visibility)

2 questions are back :) (lighting and visibility)


1. I have a problem with computing tanget space for meshes (loaded from
x-files), it fails for polygons near

the creases. Rich suggestes using adjacency array, but I have no idea how :)
To calculate tangent space from

other geometry I used only 3 vertices that create polygon, I didn't bother
neighbours. It works fine. If I use
my "step-by-step" method form meshes it fails exacly same as
D3DXComputeTangent(). Help ! :)

2. I wanted to create halo(flare?) effect for lights, but in a bit diffent
way that it is normally done. In

most cases it is rendered as an object, with z-testeing. It doesn't give
good effect in every case. I want to

do this like this: render whole scene and in the end render halo without
z-testing - it wont clip ad objects

near to it and it won't hide behind objects closer to camera, but it wont
work if I won't be able to check if

light is visible to camera or not (light totaly hidden behind object will
still produce halo). How to chcek

visibility as fast as possible (doesn't have to be extreme accurate). Is it
posible without calculating every

polygon in the view frustrum?

2. volumetric lighting ( light shafts or light volumes)

3. Problem mixing lit and non-lit

Hi,

I have a DX9 application that draws many different things to the same 
backbuffer, but calling Clear() between each thing that is drawn.  Some 
of these things are meshes, and the draw call looks like so:


   g_device->SetRenderState(D3DRS_LIGHTING, TRUE);

   // Set up all the transforms, create a light, set it's colors,
   // create a material, etc...

   g_device->SetLight(0, &light);
   g_device->LightEnable(0, TRUE);
   g_device->SetRenderState(D3DRS_AMBIENT, 0x00505050);

   g_device->SetMaterial(mat);
   g_device->SetTexture(0, texture);

   pMesh->DrawSubset(0);

   Present(NULL, NULL, NULL, NULL);


Everything there works as expected, and the mesh is drawn and lit 
correctly.  However, I have other things (line-strips) which are pre-lit 
and pre-transformed, and they are drawn like so:


   g_device->SetRenderState(D3DRS_LIGHTING, FALSE);
   g_device->SetFVF(D3DFVF_XYZRHW | D3DFVF_DIFFUSE);
   g_device->DrawPrimitiveUP(D3DPT_LINESTRIP, num_points, points,
                             sizeof(my_point));

   Present(NULL, NULL, NULL, NULL);


These "things" are created and drawn based on what the user does.  
Therefore, the application doesn't control the order in which all these 
things are drawn.

What I've found is that the line-strip objects draw correctly only until 
the first mesh object is drawn.  After that, the line-strips are always 
black.

Is there a problem with turing D3DRS_LIGHTING on and off frequently like 
this?  Or is something wrong with the FVF I'm using for the line-strips?

Thanks,
Pat

4. Lit vertices getting affected by light colors

5. Lighting problem - model lighted from inside?

Hello

I have following problem:
when I draw model on scene, it looks as if the light source was set inside 
that object - and from outside (it looks dark) i use following schema:

gl.glEnable(GL.GL_LIGHT0);

gl.glEnable(GL.GL_LIGHTING);

gl.glEnable(GL.GL_COLOR_MATERIAL);


gl.glFrontFace(GL.GL_CCW);

gl.glDisable(GL.GL_CULL_FACE);


drawModel()

when I place faces, i compute normal vertexes and I also place them, but 
when I inverse normal vectors (place '-' before all dimension) it works 
properly. But then it breaks for models that previosly works.(i'v figured 
out that's conected with normals directed and faces)

Also i've used

gl. glLightModeli(GL.GL_LIGHT_MODEL_TWO_SIDE,2);

and now works - but i think i shouldn't use that func...

what do you think ?
Any comments welcomed

6. Maya Light -> OpenGL Light

7. Need help: under water lights reflection and "Liquid Light Show"

I'm doing some "special effects" for a production of Sweet Charity and needed 
some help/pointers for two special effects:

1) We want to project the effect of under water light sources (with a wavy 
surface) hitting the walls (how a wall next to a pool looks when the pool 
lights are on).

2) We want to project the effect of a "Liquid Light Show" (like the Grateful 
Dead used) -- traditionally (i.e. physically) this was done by having several 
overhead projects focused on one scrim each with a colored gelatin blob and a 
sheet of plexiglas.  People would then vary the pressure on the corners to get 
the blob to move around.  The colors flowed like liquid and intermingled.

-- 
+--------------------------------+---------------------------------------+
| Gerald W. Lester               | "The man who fights for his ideals is |
|  XXXX@XXXXX.COM           |  the man who is alive." -- Cervantes  |
+--------------------------------+---------------------------------------+

8. Texture visibility.