Overview

Crust Render reads standard USD schemas, plus its own settings as custom attributes in the crust: namespace.

The crust: namespace

A crust:* attribute is an ordinary USD custom attribute. Other applications ignore it, so you can add these attributes to a stage that is also rendered elsewhere. Declare each one with the type given in this documentation, with or without the custom keyword:

def RenderSettings "settings"
{
    int crust:samplesPerPixel = 256
    custom float crust:indirectClamp = 0
}

Types matter. Crust Render reads each attribute with its documented type:

An attribute of the wrong type is ignored, and the default is used. The crust:openpbr shader inputs are stricter; see Materials.

Time samples work. Like any USD attribute, a crust:* attribute can be animated with timeSamples. It is read at the frame given by --frame.

Where each attribute goes

Which prim holds the render settings

Crust Render looks for the render settings on:

1. the prim named by the stage's renderSettingsPrimPath metadata, or else
2. /Render/settings.

That prim should be a RenderSettings prim. Its standard resolution and camera attributes are read as well:

#usda 1.0
(
    renderSettingsPrimPath = "/Render/settings"
)

def Scope "Render"
{
    def RenderSettings "settings"
    {
        rel camera = </World/cam>
        int2 resolution = (1920, 1080)
        int crust:samplesPerPixel = 512
    }
}

Without a RenderSettings prim, every setting takes its default: 640×360, 128 samples per pixel, and so on.

Precedence

When a value is set in more than one place, the first one in this list wins:

1. the command-line flag (for example --samples),
2. the crust:* attribute on the stage,
3. the built-in default.

A few Crust attributes have a standard or third-party equivalent. When both are authored, the crust: attribute wins:

All attributes

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