quote:Original post by c t o a n
...

thanks now I'm starting to understand more about this effect thing.

quote:Original post by sBibi
I was just wondering... has anyone implemented meta bouncing as Yann described it? or something similar? that is, automatic effect bouncing without any explicit links.

I have some kind of meta-bouncing... not the same as Yann described though

the shaders in my engine is broken down so that different "Effects" needs several shaders to be visible I have one shader that apply the Ambient and diffuse color of the material and another that sets the Specular and shininess if I need all four then all four are choosen, and then a third shader that applies a texture (or several) I choose them through a bit-field as an MaterialEffect description and the bit-field is set depending on what the Material has e.g. Texture etc.



EDIT:

I have been thinking.. if I create an Effect file that looks like this

--- Effects.fx ---

Effect 0
{
.description "Diffuse color"
.vertexstreams (position, normal)
.datastreams COLOR(ambient, diffuse)
}
Effect 1
{
.description "Diffuse texture"
.vertexstreams (position, normal, texcoord)
.datastreams TEXTURE(diffuse)
}
Effect 2
{
.description "Diffuse textured with lightmap"
.vertexstreams (position, normal, texcoord)
.datastreams TEXTURE(diffuse,lightmap)
}

And some material scripts that looks something like this to describe the material of the current mesh:

--- some Material scripts ---

Material "Diffuse blue"
{
.Effect "Diffuse color"

.color.ambient = 0.2 0.2 0.4
.color.diffuse = 0.4 0.4 0.8
}

Material "simple marble textured"
{
.Effect "Diffuse texture"

.texture.diffuse = "textures\marble.tga"
.texture.texcoordset = 0
}

then the egine knows when it encounter the .Effect line that the material is built from that effect..



[edited by - McZ on April 16, 2004 8:08:13 AM]

how abstract should the Effects be?

and how,when or where should I turn on the lights?

quote:Original post by McZ
how abstract should the Effects be?

What exactly do you mean by this - do you mean the balancing of effects vs adding parameters to existing effects - or the info stored in the effects?

quote:
and how,when or where should I turn on the lights?

The lights are objects within your scenegraph. You simply hold a list of the lights for the current frame - if a light isn''t on, simply don''t add it to the light pool for that frame.

quote:Original post by jamessharpe
What exactly do you mean by this - do you mean the balancing of effects vs adding parameters to existing effects - or the info stored in the effects?

I mean how much of the visual apperance is controlled by the Effect and not the Material-script

e.g.
A) here I define that the Effect controls two textures diffuse and lightmap no more no less.

--- Effects.txt ---
Effect "Diffuse and lightmap texture"
{
.description "Diffuse texture"
.vertexstreams(position,texcoord)
.datastreams TEXTURE(diffuse,lightmap)
}
--- lightmaptest.mat ---
Material "lightmaped texture"
{
.effect "Diffuse and lightmap texture"

.texture[0].name = "diffuse"
.texture[0].file = "data\textures\a.tga"
.texture[0].some_texture_operations = some_value

.texture[1].name = "lightmap"
.texture[1].file = "data\textures\a_lm.tga"
.texture[1].some_texture_operations = some_value
}

B) here in this effect I just declear that the material has textures but the number is unknown

--- Effects.txt ---
Effect "Textured"
{
.description "textured"
.vertexstreams(position,texcoords)
.datastreams(textures)
}

--- lightmaptest.mat ---
Material "lightmaped texture"
{
.effect "textured"

.texture[0].file = "data\textures\a.tga"
.texture[0].some_texture_operations = some_value

.texture[1].file = "data\textures\a_lm.tga"
.texture[1].some_texture_operations = some_value
}

quote:Original post by jamessharpe
The lights are objects within your scenegraph. You simply hold a list of the lights for the current frame - if a light isn't on, simply don't add it to the light pool for that frame.

but which shader should turn on the nearest lights to the current mesh?

my current shadersystem resolves several shaders for one material becouse the shaders either set the color of the material or the texture or somethingelse... but if all shaders are able to turn on lights then the lights would be turned on several times for each object, should have some kind of flag on the lights so the shader knows if it is on already?! or should I create a Helper shader that turns on lights if no resolved shaders has the ability to turn on the lights it self

[edited by - McZ on April 20, 2004 6:06:53 AM]

The communication between shaders is a difficult issue, however it seems most people have missed a comment made by Yann at the end of the other thread:

quote:
(2) is basically included in the facility that forwards data between shaders in different passes. A good and highly flexible way to do this, are GC-tags. I don''t remember if I explained those, if not let me know.

What I have started to implement is this tag system. Basically what I am doing is attaching a structure to each geometry chunk which contains the data that is output from the shaders. I''m not quite sure how to represent this data, but at the moment I''m thinking of either a stack based system or possibly a property map of sorts.

James