Shapes

The Eradiate kernel provides two shape plugins:

• arectangle — an axis-aligned rectangle shape, equivalent to Mitsuba’s rectangle but with additional support for Eradiate’s atmospheric scene geometry conventions.

• instancelist — efficiently instantiates a large collection of identical subsets of a scene geometry (e.g. a canopy of identical trees) by referencing a shared shape group with many per-instance transforms.

Analytical rectangle (arectangle)

Parameter	Type	Description	Flags
flip_normals	boolean	Is the rectangle inverted, i.e. should the normal vectors be flipped? (Default: false)
to_world	transform	Specifies a linear object-to-world transformation. (Default: none (i.e. object space = world space))	P, ∂, D
silhouette_sampling_weight	float	Weight associated with this shape when sampling silhouettes in the scene. (Default: 1)	P

Basic example¶

A textured rectangle with the default parameterization¶

This shape plugin describes a simple rectangular shape primitive. It is mainly provided as a convenience for those cases when creating and loading an external mesh with two triangles is simply too tedious, e.g. when an area light source or a simple ground plane are needed. By default, the rectangle covers the XY-range \([-1,1]\times[-1,1]\) and has a surface normal that points into the positive Z-direction. To change the rectangle scale, rotation, or translation, use the to_world parameter.

The following XML snippet showcases a simple example of a textured rectangle:

XMLPython

<shape type="rectangle">
    <bsdf type="diffuse">
        <texture name="reflectance" type="checkerboard">
            <transform name="to_uv">
                <scale x="5" y="5" />
            </transform>
        </texture>
    </bsdf>
</shape>

InstanceList (instancelist)

Parameter	Type	Description	Flags
(Nested plugin)	shapegroup	A reference to a shape group that should be instantiated.
transforms	tensor	Specifies a buffer of object-to-world transformations of shape [N,4,4] with N being the number of instances.	P

This is utility plugins allows to create multiple instances of a shape group from a buffer of object-to-world transforms. For details on how to create instances, refer to the shapegroup and instance plugins from Mitsuba’s core plugin library.