This operator generates anti-aliased (fractional brownian motion) noise by using the derivative information of the incoming position to compute band-limited noise. This type of noise is ideal for shading.
The roughness parameter determines the coarseness of the noise. The maxoctaves parameter limits the noise to a fixed number of iterations.
The amplitude parameter is a scale factor on the resulting noise. The default output range of noise is -0.5 to 0.5.
Make sure at least the Position (
pos) input is connected in order to
notice any noise. The easiest way to accomplish this is to pipe the
P into the
pos input. However, the global variable
is in camera space, so noise will move through the surface.
Connect the noise output to the Color Mix bias or to Displace Along Normal to obtain interesting results. The options are boundless.
The following examples include this node.
This example demonstrates how to diffuse the density of a smoke simulation using the Gas Diffuse DOP.
This example simulates grass being pushed down by an RBD object. Fur Objects are used to represent the blades of grass and Wire Objects are used to simulate the motion. When a single Fur Object is used to represent the grass, neighbouring blades of grass will have similar motion. Additional objects with different stiffness values can be used to make the motion less uniform. When "Complex Mode" is enabled, two objects are used to represent the grass. The stiffness of each set of curves can be controlled by adjusting the "Angular Spring Constant" and "Linear Spring Constant" parameters on the corresponding Wire Objects.
This example uses static object nodes in an RBD simulation of a grid falling and bouncing off three spheres before it hits the ground.
In this file we create a downhill lava flow with crust gathering and hardening at the base of the slope. All of the animation is achieved through the shader itself, and all of the geometry is completely static.
Most of the parameters for the lava material are overridden by point attributes created in the surface nodes.
No geometry is animated in this file. All animation is achieved by animating the textures
Flames are grids so that UV textures can easily be applied, they are then warped around a metaball using a magnet SOP. The flames are then assigned to either a yellow or blue Flames texture. The Flames' opacity mask wrap is set to Decal to prevent the texture from repeating and showing a single pixel ring at the top of the flame geometry. I'm also using a mask file named
flameOpacMap.jpg to enhance the flames' shape at the top. The noise offset has been animated over
$T with an greater emphasis on the Y axis so that the flames look like they are rising. This is the same reason the Noise jitter is larger for the Y axis as well.
The coals are spheres that have been copy stamped onto a deformed grid. Using Attribute Create surface nodes I am able to override and copy stamp the lava texture’s parameters at the SOP level so that local variables, such as
$BBY, can be used to animate the texture. This way the texture’s crust and its crust values can be used only to form the tops of the coals. This reserves the lava aspect of the texture to be used on the bottoms of the coals. The lava intensity (
Kd attribute) is then stamped and animated to create the look of embers on the bottom of coals glowing.
This example shows how to render an isosurface defined by a cvex shader using mantra’s volume rendering capabilities. A noise field is generated by a cvex shader, which is attached to the VEX Volume Procedural. The volume is shaded by finding the surface where the density crosses 0, and then shading using a simple surface shader that shows the normals.
This example demonstrates how the Fur SOP builds hair-like curves based on guide curves and skin geometry.
This example demonstrates how the Fur SOP and Mantra Fur Procedural can be applied to an animated skin geometry. CVEX shaders are used to apply a custom look to the hairs based upon attributes assigned to the geometry.