129 lines
5.9 KiB
Plaintext
Executable File
129 lines
5.9 KiB
Plaintext
Executable File
.. _surface :
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 _place_holder;
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> **_SURFACE_**
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Defines a boundary surface of the type specified in ibtype.
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Releases a previously defined surface.
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ibtype can be **free**, **intrface**, **reflect, intrcons **or** virtual**.
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Use **reflect **or **free** for external boundaries, **intrface** for interior
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interfaces, **intrcons** for constrained interior interfaces. Use **virtual**
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for virtual interfaces. _place_holder; Nodes on **reflect**, **intrcons**,
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or **virtual _place_holder; **interfaces will be assigned icrl values
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corresponding to the surfaces on which the nodes sit. The command **settets
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**will generate parent/child node chains (isn1) for nodes on **intrface** or
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**intrcons. **Surfaces which have different materials on either side of the
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surface virtual interfaces do not separate material regions but are intended
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to identify other structural features of a geometry. _place_holder; The
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surface is defined by a set of surface-parameters.
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istype can be **plane**, **box,** **parallel**(piped), **sphere**,
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**cylinder**, **cone**, **ellipse**(oid), **tabular** (rotated tabular
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profile), or **sheet**. Surface-parameters are specified with the surface type
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in mind.
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isurname is the name of the surface and must be unique for each surface
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defined by **surface**. FORMAT: **surface**/isurname/ibtype/istype/surface-
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parameters
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**surface**/isurname/ibtype/**sheet**/cmo-name
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**surface**/isurname/**release** EXAMPLES: **surface**/s1/**release**
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Release the previously defined surface named s1. _place_holder; Remove all
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references from the geometry data structures and remove all constraints
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associated with this surface.
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**surface**/sbox/ibtype/**box**/xmin,ymin,zmin/xmax,ymax,zmax/
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Where xmin,ymin,zmin and xmax,ymax,zmax are the coordinates of opposite
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corners of a cube, i.e bottom left and top right corners.
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**surface**/mysurf/ibtype/**cone**/x1,y1,z1/x2,y2,z2/radius/
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Where point 1 is the vertex and point 2 is the top center of the cone with
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radius from that point. A cone is finite but open. To create a closed cone cap
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the open end with a plane.
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**surface**/acyl/ibtype/**cylinder**/x1,y1,z1/x2,y2,z2/radius
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Where point 1 is the bottom center and point 2 is the top center of the
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cylinder. radius is the radius of the cylinder. Cylinders are open but
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finite. _place_holder; To create a closed cylinder cap both ends with
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planes.
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**surface**/sellip/ibtype/**ellipse**/x1,y1,z1/x2,y2,z2/x3,y3,z3/ar,br,cr/
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Where point 1 is the center of the ellipsoid and point 2 is on the a semi-axis
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(new x), point 3 is on the b semi-axis (new y), and ar, br, cr are radii on
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their respective semi-axes.
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**surface**/s2/ibtype/**parallel**/x1,y1,z1/x2,y2,z2/x3,y3,z3/x4,y4,z4/
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Where points 1, 2, 3 are the front left, front right and back left points of
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the base and point 4 is the upper left point of the front face.
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**surface**/s1/ibtype/**plane**/x1,y1,z1/x2,y2,z2/x3,y3,z3
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**surface**/top/ibtype/**planexyz**/x1,y1,z1/x2, z2/x3,y3,z3
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the direction of the normal to the plane is determined by the order of the
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points according to the right hand rule.
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**surface**/bot/ibtype/**planertz**/radius1,theta1,z1,radius2,theta2,z2,radius ,zcen/
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**surface**/s10/ibtype/**planertp**/radius1,theta1,p
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**surface**/asheet/ibtype/**sheet**/cmo_name/<
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Sheet surfaces may be input by specifying a cmo_name. The Mesh Object must be
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either a 2D quad Mesh Object or a 2D triangle Mesh Object. A discussion of
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inside and outside with respect to sheet surfaces is presented after the
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EXAMPLES section.
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**surface**/sphere1/ibtype/**sphere**/x_center,y_center,z_center,radius
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**surface**/s3/ibtype/**tabular**/x1,y1,z1/x2,y2,z2/rz|rt/&
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r1,z1 &
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r2,z2 &
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r3,z3 &
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....
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rn,zn &
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end
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or
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r1,theta1 &
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r2,theta2 &
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r3,theta3 &
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...
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rn,thetan &
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end
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Where point 1 and point 2 define the axis of rotation for the tabular profile
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with point 1 as the origin. This is followed by pairs of profile descriptors
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depending on the value of geom.Ifgeom is set to **rz**, then the r value is a
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radius normal to the axis of rotation and z is the distance along the new axis
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of rotation. If geomis set to **rt** then theta is the angle from the axis of
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rotation at point 1 andris the distance from point 1 along theta. The first
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pair must start on a new line and all lines must contain pairs of data. The
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last pair of data must be followed by end.
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**Inside/outside **with respect to** sheet surfaces** will be determined by the following algorithm: * For the point being considered, p, find the nearest sheet triangle and the closest point, q, to p that lies on that triangle.
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* Construct the vector, from q to p.
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* Construct the outward normal to the triangle, _place_holder;. The outward normal is constructed using the right hand rule and the order of the points in the sheet. Sheets may be specified as quad Mesh Object (i.e. a 2 dimensional array of points containing the coordinates of the corners of each quad). Either two triangles (divide each quad in two using point (i,j) and (i+1,j+1)) or four triangles (add a point in the center of the quad) are generated by each quad. Applying the right hand rule to the points (i,j), (i+1,j), (i+1,j+1) gives the direction of the normal for all triangles created from the quad.
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* If _place_holder;* _place_holder;< 0 then the point is inside. If _place_holder;* _place_holder;>0 the point is outside. If _place_holder;* n = 0, and if p is on the triangle then p=q and p in on the triangle.
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* If _place_holder;* = 0 and p is not on the triangle then p is outside. 
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One implication of this definition is that the concept of shadows cast by open
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sheets no longer is valid. Sheets may be considered to extend to the boundary
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of the geometry.
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