Raycast on Surface¶
Dependencies¶
This node requires SciPy library to work.
Functionality¶
This node implements ray casting onto an arbitrary surface; in other words, given a point in 3D space and ray direction vector, it will find a point where this ray intersects the given surface first time.
This node uses a numerical method to find the intersection point, so it may be not very fast. If you happen to know how to find the intersection point for your specific surface by some formula, that will be faster and more precise.
Inputs¶
This node has the following inputs:
Surface. The surface to find intersection with. This input is mandatory.
Source. Source point of the ray. The default value is
(0, 0, 1).Point. The second point through which the ray goes. This input is available only when Project parameter is set to From Source.
Direction. Ray direction. The default value is
(0, 0, -1). This input is available only when Project parameter is set to Along Direction.
Parameters¶
This node has the following parameters:
Project. This defines how the direction of the ray is specified. The available options are:
Along Direction. Ray is specified by defining it’s source point in Source input, and it’s direction vector in Direction input.
From Source. Ray is specified by defining it’s source point in Source input, and a second point on the same ray in Point input.
The default option is Along Direction.
Precise. If checked, then the node will calculate precise intersection point with a numerical algorithm. Otherwise, it will return “initial guess” point, calculated by use of Blender’s “BVH raycasting” method. In this case, Samples parameter defines the precision of calculation. Checked by default.
Samples. This parameter is available in the N panel only, if Precise parameter is checked. To find the “initial guess” point for numerical method, this node evaluates the surface in points of cartesian grid, and uses Blender’s “BVH raycast” method. This input defines the number of samples for this first step. The higher this number is, the more precise the initial guess is, so the less work for numeric method; but the more time will this first step take. In most cases, you do not have to change this parameter. The default value is 10.
Method. This parameter is available in the N panel only. Type of numeric method to be used. The available options are:
Hybrd & Hybrj. Use MINPACK’s hybrd and hybrj routines (modified Powell method).
Levenberg-Marquardt. Levenberg-Marquardt algorithm.
Krylov. Krylov algorithm.
Broyden 1. Broyden1 algorithm.
Broyden 2. Broyden2 algorithm.
Anderson. Anderson algorithm.
DF-SANE. DF-SANE method.
The default option is Hybrd & Hybrj. In simple cases, you do not have to change this parameter. In more complex cases, you will have to try all of them and decide which one fits you better.
Outputs¶
This node has the following outputs:
Point. The intersection point in 3D space.
UVPoint. The point in surface’s U/V space, corresponding to the intersection point.
Example of usage¶
Along Direction (Parallel):
Generator-> Line
Generator-> Segment
Generator-> Plane
Surfaces-> Minimal Surface
Surfaces-> Evaluate Surface
Transform-> Noise Displace
Vector-> Vector Polar Input
Matrix-> Matrix In
Viz-> Viewer Draw
From Source (Conic):
Generator-> Segment
Generator-> Plane
Surfaces-> Minimal Surface
Surfaces-> Evaluate Surface
Transform-> Noise Displace
Vector-> Vector Polar Input
Matrix-> Matrix In
Viz-> Viewer Draw
Curves-> Rounded Rectangle
Curves->Curve Primitives-> Ellipse (Curve)
Curves-> Evaluate Curve
Surfaces-> Extrude Curve Along Vector
Surfaces-> Evaluate Surface
Modifiers->Modifier Make-> UV Connection
Matrix-> Matrix In
Viz-> Viewer Draw
Note that in this case we set Method parameter to Krylov.