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int renderstate(string query, <type>&value)
int renderstate(material mat, string query, <type>&value)
Returns a non-zero value and sets value on success, or returns 0
if the renderer cannot evaluate the query.
The two-argument variations look up the property on the current object.
If you pass a material as the first argument,
the function looks up the property on the material instead of the current object.
See the list of IFD properties you can query. Use
the IFD name (e.g. image:samples),
not the Houdini name (e.g. vm_samples).
Useful properties
The following properties are commonly useful and are reproduced here for convenience, but you can query any property from the the full list of IFD properties.
image:name
(string) The name of the image being rendered.
image:pixelaspect
(float) The pixel aspect ratio (X/Y) of the image.
image:resolution
(vector) Gives the resolution as {x_res, y_res, samples_per_pixel}.
image:samples
(vector) Gives samples as {x_samples, y_samples, 0}.
image:raysamples
(vector) Gives the raytracing samples as {x_samples, y_samples, 0}.
light:name
(string) The name of the light object which is currently active in the illuminance loop.
light:shadowscope
(string) The list of objects casting shadows from a light.
object:name
(string) The name of the object being shaded. This is valid within light and shadow shaders and can be used to query which object is being lit (or shadowed) by the light source.
object:reflectscope
(string) The default reflection scope pattern for the object being shaded.
object:refractscope
(string) The default refraction scope pattern for the object being shaded.
object:reflectlimit
(float or int) The hard limit for maximum refraction bounces for the object being shaded.
object:shadingquality
(float) The shading quality for the object being shaded.
object:lightmask
(string) The object’s light mask string.
object:area
(float) The object’s surface area.
object:materialname
(string) Path to the material that’s assigned to the object being shaded. NOTE
This is for informational purpose only and has no effect on material assignment or appearance.
renderer:name
(string) The name of the renderer.
renderer:version
As a string, gives the renderer version as "major.minor.build" As a vector, gives the renderer version as {major, minor, build}.
renderer:renderengine
(string) The render method in use, such as micropoly or raytrace.
See the properties list for the full list of possible values.
shader:name
(string) The name of the current shader being run.
Packed Primitives
When mantra renders packed primitives, the geometry gets unpacked before rendering. This means primitive attributes on the packed primitive aren’t available to shaders (since they aren’t passed down to the unpacked geometry).
Before unpacking, mantra will automatically convert the primitive attributes to custom object properties (see ray_declare on the IFD file format page). The property will be named packed:ATTRIBNAME (where ATTRIBNAME is the name of the attribute). The renderstate() function can be used to access these properties, just like any other object property.
For example:
vector Cd; if (!renderstate("packed:Cd", Cd)) Cd = 1; // There was no Cd attribute on packed geometry
Examples
surface showversion() { string rname, rversion; if (!renderstate("renderer:name", rname)) rname = "Unknown renderer"; if (!renderstate("renderer:version", rversion)) rversion = "Unknown version"; printf("Image rendered by %s (%s)\n", rname, rversion); } vector mapToScreen(vector NDC_P) { // Given a point in NDC space, find out which pixel it // maps to. vector result; if (!renderstate("image:resolution", result)) result = {640, 486, 0}; return result * NDC_P; }
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