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Why reinvent the wheel? There're some handy little functions for the everyday HLSL writer. Please add your snippets in this wiki page.

## General snippets

### get clipping planes of a Perspective Projection

```float4x4 tPI: PROJECTIONINVERSE;
float FarPlane = 1 / (tPI + tPI);
float NearPlane = 1 / distance(tPI, tPI);```

### apply rotation to vertices via texture

rotation function:

```float4x4 Vrotate(float rotX,
float rotY,
float rotZ)
{
rotX *= TwoPi;
rotY *= TwoPi;
rotZ *= TwoPi;
float sx = sin(rotX);
float cx = cos(rotX);
float sy = sin(rotY);
float cy = cos(rotY);
float sz = sin(rotZ);
float cz = cos(rotZ);

return float4x4( cz*cy+sz*sx*sy, sz*cx, cz*-sy+sz*sx*cy, 0,
-sz*cy+cz*sx*sy, cz*cx, sz*sy+cz*sx*cy , 0,
cx * sy       ,-sx   , cx * cy        , 0,
0             , 0    , 0              , 1);
}```

use the function like this:

```PosO = mul(PosO, Vrotate(Sampler.r, Sampler.g, Sampler.b));
NormO = mul(NormO, Vrotate(Sampler.r, Sampler.g, Sampler.b));```

Sampler.rgb are the corresponding values from the texture

### Render to Texture/UV (useful for e.g. texture baking)

Calculate screenspace coordinates based on UV instead of object space and pass it to PS

`Out.Pos = float4((TexCd.xy-0.5)*2*float2(1,-1),0,1);`

## PixelShader snippets for Image processing

### invert

rgb-inversion

`col.rgb = 1 - col.rgb;`

### contrast

`col.rgb = ((col.rgb - 0.5) * var) + 0.5;`

if var > 1, the contrast is greater. var = 0 gives a grey picture
The 0.5 can be replaced with a variable to give a gamma or centre
point for the contrast as well, for more fine tuning...

### black&white

```const float4 lumcoeff = {0.299, 0.587, 0.114, 0};
col = dot(col, lumcoeff);```

the dot product of the color (col) and the luminace coefficients results in a correct b&w image

### lumakey

```const float4 lumcoeff = {0.299, 0.587, 0.114, 0};
float luma = length(dot(col, lumcoeff));
col.a = step(var, luma);```

var is the keying amount. the rest works like the b&w conversion.

### scene alpha

`return(tex2D(Samp, float2(IN.TexCd.xy)).wwww);`

Texture input must be in A8R8G8B8 format.

### working alpha channel in 3d

needs 2 passes so connect an iobox with 2 rows to the pass pin and fill it with 0,1

```technique workingalpha
{
pass P0
{
AlphaBlendEnable = false;

AlphaTestEnable = true;
AlphaFunc = Greater;
AlphaRef = 245;

ZEnable = true;
ZWriteEnable = true;

CullMode = None;
}
pass P1
{
AlphaBlendEnable = true;
SrcBlend = SrcAlpha;
DestBlend = InvSrcAlpha;

AlphaTestEnable = true;
AlphaFunc = LessEqual;
AlphaRef = 245;

ZEnable = true;
ZWriteEnable = false;

CullMode = None;
}
}```

### DX11 Set DepthBuffer

DepthStencilState DisableDepth
{

```    DepthEnable = FALSE;
DepthFunc = LESS_EQUAL;
```
```    StencilEnable  = FALSE;
```

};

and add this when you create the pass
SetDepthStencilState( DisableDepth, 0 );

### DX11 Access TextureArray

// declare array of N textures
Texture2D MyTextureArray[N];

// sample texture of index I from array (0 to N-1)
MyTextureArray[I].Sample(MySampler, UV);

### Will the real texture array please stand up

note that the above is an array of textures- which is NOT the same thing as a actual texture array! Example of that below:

//Control Texture Array
bool useControlMap;
Texture2DArray cTex <string uiname="Texture";>;
SamplerState sam //can be set in vvvv
{

```    Filter = MIN_MAG_MIP_LINEAR;
```

};

float controlTexSample(float2 uv, float iid)
{
float control = 1;
if (useControlMap)
{
uint d,textureCount;
cTex.GetDimensions(d,d,textureCount);
float3 coords = float3(uv, iid % textureCount); //make sure Instance ID buffer is in floats
control *= cTex.SampleLevel(sam,coords,0).r;
}
return control;
}

```pass P0 <string format="R32G32B32A32_float";>

### Defines (or pre-processor directives)

Use pre-processors as in other C inspired languages. These will actually transform the text of your code before compilation.

```#define MYDEFINE 4
float MyFunc()
{
return MYDEFINE;
}
// result: 4```

Conditional:

```#define MYCONDITION 2
float MyFunc()
{
#if MYCONDITION==2
return 2;
#else
return 0;
#endif
}
// result: 2```

Check if thing is defined:

```#define MYCONDITION 2
float MyFunc()
{
#if defined(MYCONDITION)
return 2;
#else
return 0;
#endif
}
// result: 2```

### DX11: Define from vvvv

All shader nodes in DX11 (layers, tfx and gfx) have a hidden pin called "Defines" which awaits a spread of string formatted like that:

`DEFINENAME=stuff`

Every time you change the Defines spread shader is recompiled. Example tricks:

Change tfx pass format without changing the code:

```// define a default value to avoid compilation errors
#if !defined(PASSFORMAT)
#define PASSFORMAT "R8_UNorm"
#endif

...

pass P0 <string format=PASSFORMAT;>

from vvvv:

`PASSFORMAT="R16G16B16A16_Float"`

# Shoutbox

~2d ago

~7d ago

SuperflysiNZ: Thanks

~8d ago

~10d ago

sebescudie: @Superfly : ApplicationPath

~10d ago

SuperflysiNZ: How do you get the path of the current patch in VL?

~10d ago

SuperflysiNZ: How do you get the path of the current patch in VL?

~11d ago

joreg: reminder: first #vvvv online meetup after the summer break: tomorrow, tuesday 7th, 8pm CET 13.-worldwide-vvvv-meetup