# Layer Create

- Projection
- Position
- Visibility
- View

### perspective

Defines the type of projection (perspective or orthographic) used to project the layer 3D space into the screen 2D viewport. When not indicated, GAMGI uses the default. To change the default, select Layer->Config and read Help->Topics->Formats->Config->Layer.

    Example: <layer ... perspective="yes"/> (default)
    (defined in GAMGI_MESA_LAYER_PERSPECTIVE)
    Allowed values: yes, no (optional)

### top, near, far

Define the layer 3D viewing volume, before it is projected onto the 2D viewport. The top parameter measures the height from the eye-center viewing direction (at the center of the viewport) to the top and bottom limits of the 2D viewport, thus defining the lateral borders of the 3D volume (the width is automatically determined from the window dimensions, in order to preserve the ratio width/height, otherwise the objects would be distorted).

The near and far parameters define the minimum and maximum distances along the viewing direction at which objects must lie in order to be visible. near must be smaller than far.

When not indicated, GAMGI uses default values. To change the default, select Layer->Config and read Help->Topics->Formats->Config->Layer.

    Example: <layer ... near="1.0" far="1000.0" top="0.5"/> (default)
    (defined in GAMGI_MESA_LAYER_NEAR, GAMGI_MESA_LAYER_FAR
    and GAMGI_MESA_LAYER_TOP)
    Allowed values: positive real (optional)

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