Design Scripting Documentation


	Intersection Line Sphere


	Inputs:

two point of line, circle center and radius


	Outputs:

a number -> no intersection -> distance sphere line
a vertex -> tangency -> tangency point on sphere
vertices -> intersection -> two intersection points

Implementation

01  function intersect_linesphere( va, vb, cc, cr )
02    dim u: u = vector_create( va, vb )
03    dim v: v = vector_create( cc, va )
04    dim a: a = vector_dot( u, u )   * 2.0
05    dim b: b = vector_dot( u, v )   * 2.0
06    dim c: c = vector_dot( cc, cc ) + _
07               vector_dot( va, va ) - _
08               vector_dot( cc, va ) * 2.0 - cr * cr
09    dim d: d = b * b - 2.0 * a * c
10    if( abs( d ) <= NUMBER_ZERO ) then
11      intersect_linesphere = vertex_translate( va, vector_scale( u, - b / a ) )
12    else
13      if( d > 0 ) then
14        intersect_linesphere = array( _
15          vertex_translate( va, vector_scale( u, -( b + sqr( d ) ) / a ) ), _
16          vertex_translate( va, vector_scale( u, -( b - sqr( d ) ) / a ) )  _
17        )
18      else
19        intersect_linesphere = vertex_length( cc, vertex_project( va, vb, cc ) ) - cr
20      end if
21    end if
22  end function

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Page timestamp: { Feb. 2, 2006 }