# Constant Nodes

**Visual Studio 2015**

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In the Shader Designer, constant nodes represent literal values and interpolated vertex attributes in pixel-shader calculations. Because vertex attributes are interpolated—and so, are different for each pixel—each pixel-shader instance receives a different version of the constant. This gives each pixel a unique appearance.

The image of a 3-D scene in a game or app is made by mathematically transforming a number of objects—which are defined by vertices, vertex attributes, and primitive definitions—into on-screen pixels. All of the information that's required to give a pixel its unique appearance is supplied through vertex attributes, which are blended together according to the pixel's proximity to the different vertices that make up its *primitive*. A primitive is a basic rendering element; that is, a simple shape such as a point, a line, or a triangle. A pixel that's very close to just one of the vertices receives constants that are nearly identical to that vertex, but a pixel that's evenly spaced between all the vertices of a primitive receives constants that are the average of those vertices. In graphics programming, the constants that the pixels receive are said to be *interpolated*. Providing constant data to pixels in this way produces very good visual quality and at the same time reduces memory footprint and bandwidth requirements.

Although each pixel-shader instance receives only one set of constant values and cannot change these values, different pixel-shader instances receive different sets of constant data. This design enables a shader program to produce a different color output for each pixel in the primitive.

Node | Details | Properties |
---|---|---|

Camera Vector | The vector that extends from the current pixel to the camera in world space. You can use this to calculate reflections in world space. Output`Output` : `float3` The vector from the current pixel to the camera. | None |

Color Constant | A constant color value.Output`Output` : `float4` The color value. | OutputThe color value. |

Constant | A constant scalar value.Output`Output` : `float` The scalar value. | OutputThe scalar value. |

2D Constant | A two-component vector constant.Output`Output` : `float2` The vector value. | OutputThe vector value. |

3D Constant | A three-component vector constant.Output`Output` : `float3` The vector value. | OutputThe vector value. |

4D Constant | A four-component vector constant.Output`Output` : `float4` The color value. | OutputThe vector value. |

Normalized Position | The position of the current pixel, expressed in normalized device coordinates. The x-coordinate and y-coordinate have values in the range of [-1, 1], the z-coordinate has a value in the range of [0, 1], and the w component contains the point depth value in view space; w is not normalized. Output`Output` : `float4` The position of the current pixel. | None |

Point Color | The diffuse color of the current pixel, which is a combination of the material diffuse color and vertex color attributes.Output`Output` : `float4` The diffuse color of the current pixel. | None |

Point Depth | The depth of the current pixel in view space.Output`Output` : `float` The depth of the current pixel. | None |

Normalized Point Depth | The depth of the current pixel, expressed in normalized device coordinates. The result has a value in the range of [0, 1]. Output`Output` : `float` The depth of the current pixel. | None |

Screen Position | The position of the current pixel, expressed in screen coordinates. The screen coordinates are based on the current viewport. The x and y components contain the screen coordinates, the z component contains the depth normalized to a range of [0, 1], and the w component contains the depth value in view space. Output`Output` : `float4` The position of the current pixel. | None |

Surface Normal | The surface normal of the current pixel in object space. You can use this to calculate lighting contributions and reflections in object space. Output`Output` : `float3` The surface normal of the current pixel. | None |

Tangent Space Camera Vector | The vector that extends from the current pixel to the camera in tangent space. You can use this to calculate reflections in tangent space. Output`Output` : `float3` The vector from the current pixel to the camera. | None |

Tangent Space Light Direction | The vector that defines the direction in which light is cast from a light source in the tangent space of the current pixel. You can use this to calculate lighting and specular contributions in tangent space. Output:`Output` : `float3` The vector from the current pixel to a light source. | None |

World Normal | The surface normal of the current pixel in world space. You can use this to calculate lighting contributions and reflections in world space. Output`Output` : `float3` The surface normal of the current pixel. | None |

World Position | The position of the current pixel in world space.Output`Output` : `float4` The position of the current pixel. | None |