64 lines
2.6 KiB
Markdown
64 lines
2.6 KiB
Markdown
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# Screen Position Node
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## Description
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Provides access to the screen position of the mesh vertex or fragment. The X and Y values represent the horizontal and vertical positions respectively. Use the **Mode** dropdown control to select the mode of the output value. The available modes are as follows:
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- **Default** - Returns X and Y values that represent the normalized **Screen Position**. The normalized **Screen Position** is the **Screen Position** divided by the clip space position W component. The X and Y value ranges are between 0 and 1 with position `float2(0,0)` at the lower left corner of the screen. The Z and W values aren't used in this mode, so they're always 0.
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- **Raw** - Returns the raw **Screen Position** values, which are the **Screen Position** values before the clip space position W component is divided out. Position `float2(0,0)` is at the lower left corner of the screen. This mode is useful for projection.
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- **Center** - Returns X and Y values that represent the normalized **Screen Position** offset so position `float2(0,0)` is at the center of the screen. The range of the X and Y values is –1 to 1. The Z and W values aren't used in this mode, so they're always 0.
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- **Tiled** - Returns **Screen Position** offset so position `float2(0,0)` is at the center of the screen and tiled using `frac`.
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- **Pixel** - Returns **Screen Position** in terms of the actual pixel width and height values of the screen. In this mode, position `float2(0,0)` is at the lower left corner of the screen. Whereas the range of Default mode is always 0 to 1, the range of Pixel mode depends on the screen resolution. The Z and W values aren't used in this mode, so they're always 0.
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## Ports
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| Name | Direction | Type | Binding | Description |
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|:------------|:--------------------|:---------|:--------|:------------|
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| Out | Output | Vector 4 | None | Get the **Screen Position** of the mesh. |
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## Controls
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| Name | Type | Options | Description |
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|:------|:---------|:---------|:------------|
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| Mode | Dropdown | Default, Raw, Center, Tiled, Pixel | Select which coordinate space to use for the **Screen Position** output. |
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## Generated Code Example
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The following code examples represent one possible outcome for each mode.
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**Default**
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```
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float4 Out = float4(IN.NDCPosition.xy, 0, 0);
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```
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**Raw**
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```
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float4 Out = IN.ScreenPosition;
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```
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**Center**
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```
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float4 Out = float4(IN.NDCPosition.xy * 2 - 1, 0, 0);
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```
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**Tiled**
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```
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float4 Out = frac(float4((IN.NDCPosition.x * 2 - 1) * _ScreenParams.x / _ScreenParams.y, IN.{0}.y * 2 - 1, 0, 0));
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```
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**Pixel**
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```
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float4 Out = float4(IN.PixelPosition.xy, 0, 0);
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```
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