Shader FAQ

[BlindSide]

Thanks Zak - I wasn't sure if it would be of interest to anyone else, but it does help me flesh out ideas. I actually intended itso that I could post dev. info on the demo I'm working on, but I figured I might as well use it for general R&D as well.

That said, I was wondering if I could include some of your shader tut's from the wiki in my site, full credit of course, for anyone who stumbles by =)

[Zaknafein]

Sure, if you want. But honestly I'd prefer if you linked the wiki article itself, it's simpler for you when I update it and it gives good publicity to the wiki...

[Waterman]

Sorry for arguing, but how is that a contradiction? Isn't a vector in 3D space a 3D vector?

Thanks though, you and Blind. And heck, that's an interesting blog you got there Blind.

I see you good intention but these are really fundamental conventions when describing data. Not a big deal, but:

Singleton: Data that has no dimensions.
Vector: One dimensional data, always a sequence of numbers (can be more or less than 3).
Matrix: Data with two or more dimensions, typically a table if 2 dimensions, e.g. OLAP cubes if 3 or more. Think of it: A 2-dimensional matrix actually describes data in 3D space, so by that concept we should call it a 3 dimensional matrix!

That's why a "3 dimensional vector" is a contradiction; it has always 1 dimension only. But what it describes, that's another thing.

I think that a "3D vector" sounds different, and even "3 dimension vector" (without the "al") although that's at the fuzzy border. A 3D vector it is :-).

[Zaknafein]

Aaah I see, thanks for the insight. It does make sense now.
Hm, you say "singleton" for single values... I'm used to say "scalar" because the french equivalent is "scalaire", are those two synonyms? "Singleton" sounds like the OOP concept to me

[phether]

call it a singularity  :twisted:

[Waterman]

Aaah I see, thanks for the insight. It does make sense now.
Hm, you say "singleton" for single values... I'm used to say "scalar" because the french equivalent is "scalaire", are those two synonyms? "Singleton" sounds like the OOP concept to me

Not quite, although scalar is commonly used (and that's what we want, that people understand).

A singleton is a set with exactly one element and a set is a singleton if and only if its cardinality is 1, while a scalar is a number as opposed to a character, vector, function,  object etc. But a set may also hold for example text data (or other non-numeric data) and a set may have any shape (including multidimensional), thus a singleton is a more precise definition to cover it all.

But... scalar is all ok :-). It's one number.

[CSharpDavid]

From a physics point of view

A Scalar value is one which has magnitude, but no direction

A vector is one which has both magnitude, and direction.

a vector can be described in any number of dimensions so to describe a 3D vector is both legal and descriptive.

[Dan]

Quick question. What is the correct method for cleanly removing a shader from a mesh. I am currently destroying the mesh and reapply the required non shader settings. This works for me but just wondered if an alternative exists?

[Waterman]

Mesh.SetShader [null, nothing, nil, whatever you name it]

Also works for Landscape.SetShader (i've verified) and probably everywhere as expected.

[osmcvl]

please help me, this result color WHITE, i want this result color is RED. When this error  :oops:

    Teste := Scene.CreateMeshBuilder('teste');
    Teste.CreateSphere(10,10,10);
    TesteShd := Scene.CreateShader('TesteShader');
    Testeshd.SetTechnique('TSM3');
    TesteShd.CreateFromEffectFile('c:\agua\shaders\Teste.fx');
    Teste.SetShader(TesteShd);

// teste.fx
float4x4 matViewProjection : ViewProjection;
struct VS_OUTPUT
{
   float4 Pos:     POSITION;
};
VS_OUTPUT vs_main( float4 inPos: POSITION )
{
   VS_OUTPUT Out;
   Out.Pos = mul(inPos, matViewProjection);
   return Out;
}
float4 ps_main( float4 inDiffuse: COLOR0 ) : COLOR0
{
   float4 color;
   color[0] = color[3] = 1.0;
   color[1] = color[2] = 0.0;
   return color;
}
technique TSM2 {
    pass P0 {
        VertexShader = compile vs_2_0 vs_main();
        PixelShader  = compile ps_2_0 ps_main();
    }
}
technique TSM3{
    pass P0 {
        VertexShader = compile vs_3_0 vs_main();
        PixelShader  = compile ps_3_0 ps_main();
    }
}


//DEGUG.TXT
11-19-2006 11:09:51 | DEVICE INFO : Vertex Shaders 3.0 supported in hardware.
11-19-2006 11:09:51 | DEVICE INFO : Pixel Shaders 3.0 supported in hardware.
SHADER MANAGER : Shader 'TesteShader' successfully created.

[Zarkow]

------------------------------------------------------------------------------
Is there an example of a full screen shader?

Thanks to Sylvain, yes there is:

http://www.shelter7.com/FullscreenShader.fx

05-10-2007 05:50:05 | SHADER MANAGER : Error : error X3507: 'VS_Main': function must return a value
D:\[removed]\data\shaders\FullscreenShader.fx(76): ID3DXEffectCompiler::CompileEffect: There was an error compiling expression
ID3DXEffectCompiler: Compilation failed

[Zaknafein]

It's a no-brainer... just add "return output;" to the vertex shader.

[Zarkow]

Yeah, I know and I did when I looked at it, but the file should be updated.

Unless the error was added as a training-step.

[Craigomatic]

How is a shader include loaded up?

A number of the shaders in the FX Composer library have this include:

Code:

#include <include\\Quad.fxh>

[GD]

Quad.fxh is just a set of few defines that make shader writing easier.
You could also make your own file with functions and defines that you want to share with your shaders.
It's best to put includes in the same path as .fx's and use #include "Quad.fxh".

[Craigomatic]

Thanks for the reply GD, what I'm mainly wanting to do is support shaders from as many different places as possible, ie: the NVIDIA shader lib.

Without going into too much detail, the shaders are all being loaded from memory via something similar to:

Code:

tvshader.CreateFromEffectString(shaderString)

So I have everything coming in as strings, including the includes. Is there a way to load the include up into the shader first? Or combine the strings (include with the shader) and put it straight into CreateFromEffectString?

[sybixsus]

Thanks for the reply GD, what I'm mainly wanting to do is support shaders from as many different places as possible, ie: the NVIDIA shader lib.

Without going into too much detail, the shaders are all being loaded from memory via something similar to:

Code:

tvshader.CreateFromEffectString(shaderString)

So I have everything coming in as strings, including the includes. Is there a way to load the include up into the shader first? Or combine the strings (include with the shader) and put it straight into CreateFromEffectString?

Write a mini-parser which parses includes, finds their location on disk, loads them and includes them into the string.

[Insomnia]

Hi there, I have trouble initializing a shader. I'm working with VB6, and when I call Scene.CreateShader it just sais "property or method unknown" for this line, though CreateShader is in the functions list of TVScene.
What's the problem here? (Same for Scene.CreateParticleSystem by the way)

Thanks for any help

[macrosii]

For those that are interested some of the Bugs of Rendermonkey are fixed.  A simple shader will now run unmodded.  You must sellect the default packing order so that the matrix packing is the same as directX expects.

Regards
Macrosii

[GosikII]

How to modify "wind.shade" from "Windy Grass" sample for work with TVMesh. It works only with minimesh.  What difference between these classes (Minimesh, Tvmesh). 

Code:

//------------------------------------------------------------------------------
// SHADE.
//----------------
// Wind Shader.
// Written By Geoff Wilson.
//---------------------------------
        float4x4 Wrld           : WORLD;
        float4x4 ViewProj       : VIEWPROJECTION;
        float4x3 WorldIT        : MINIMESH_WORLDINVERSETRANSPOSE;
        float4x3 World[52]      : MINIMESH_WORLD;
        float4   Colour[52]     : MINIMESH_COLOR;
       
        float3   Light          = float3(280, 450, 280);
        float3   LightColour    = float3(1, 0.8, 0.8);
        float    LightRange     = 75;
       
        float    Tick           : TIME;

        texture  Diffuse        : TEXTURE0;
       
        float    WindSpeed      = 2;
        float    WindPower      = 0.09;

//------------------------------
// Samplers.
//-------

        sampler2D DiffuseSampler = sampler_state
        {
                Texture          = (Diffuse);
                MIPFILTER        = LINEAR;
                MAGFILTER        = LINEAR;
                MINFILTER        = LINEAR;
        };

//------------------------------
// Structs.
//-------

        struct a2v //App->Vertex.
        {
                float4 Position : POSITION0;
                float3 Normal   : NORMAL;
                float2 UV       : TEXCOORD0;
                float2 Index    : TEXCOORD1;
        };

        struct v2p //Vertex->Pixel.
        {
                float4 Position : POSITION0;
                float2 UV       : TEXCOORD0;
                float4 Colour   : TEXCOORD1;
        };

        struct p2s //Pixel->Screen.
        {
                float4 Colour   : COLOR0;
        };

//------------------------------
// Programs.
//-------

        void vp( in a2v IN, out v2p OUT )
        {
                float4x3 cMatrix  = World[IN.Index.x];
               
                float3   Weight   = float3(IN.Position.x, 0, IN.Position.z);
                IN.Position.z    += (sin(WindSpeed * Tick) * WindPower) * distance(Weight.y, IN.Position.y);
                IN.Position.x    += (sin(WindSpeed * Tick) * WindPower) * distance(Weight.y, IN.Position.y);
               
                float3   WorldPos = mul(IN.Position, cMatrix);
               
                OUT.Position      = mul(float4(WorldPos, 1), ViewProj);
               
//Start test lighting.
                float  Att        = (Light.xyz - WorldPos.xyz);
                float3 L          = normalize(Light - WorldPos);
                float3 N          = normalize(mul(IN.Normal, (float3x3)(cMatrix)));
                float  D0         = saturate(dot(L, N)) * clamp(1 - length(Att) / LightRange, 0, 1);
                D0               += 0.15;
               
                float4 Ec         = float4(D0, D0, D0, 1);
//End test lighting.
               
                OUT.UV            = IN.UV;
               
                OUT.Colour        = Colour[IN.Index.x] * Ec;
        }

        void fp( in v2p IN, out p2s OUT )
        {
                OUT.Colour        = IN.Colour * tex2D(DiffuseSampler, IN.UV);
        }

        technique render
        {
                pass pass0
                {
                        vertexshader = compile vs_2_0 vp();
                        pixelshader  = compile ps_2_0 fp();
                }
        }