Constant Nodes

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