Constant Nodes

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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.

Vertex attribute interpolation

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.

Constant node reference

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.
Output

The color value.

Constant

A constant scalar value.

Output

Output: float

The scalar value.
Output

The scalar value.

2D Constant

A two-component vector constant.

Output

Output: float2

The vector value.
Output

The vector value.

3D Constant

A three-component vector constant.

Output

Output: float3

The vector value.
Output

The vector value.

4D Constant

A four-component vector constant.

Output

Output: float4

The color value.
Output

The 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