Standard
Class Standard_MappingShapeEgg

Object
  common:Generic
      common:MappingShape
          Standard:Standard_MappingShapeEgg

class 
MappingShape:Standard_MappingShapeEgg

Implements the Egg shape (radius 0.5..0.667) from 3D Mapping in Standard.uxf.

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 class Standard_MappingShapeEgg(common.ulb:MappingShape) {
 ; Implements the Egg shape (radius 0.5..0.667) from 3D Mapping in Standard.uxf.
 public:
   bool func GetTextureCoordinates(float sx, float sy, float sz, float dx, \
                                   float dy, float dz, complex &result)
     ; This must be solved:
     ; [ sx ]          [ dx ]   [ x ]
     ; [ sy ] + lambda [ dy ] = [ y ]
     ; [ sz ]          [ dz ]   [ z ]
     ; and
     ; 1) x^2 + (6/7 * y)^2 + z^2 = radius^2
     ; or
     ; 2) x^2 + (24/35 * y)^2 + z^2 - radius^2
     ;
     ; If y > 0, equation 2 is the right one, otherwise equation 1.
 
     float lambda
     float x = 0
     float y = 0
     float z = 0
     float x1 = 0
     float y1 = 0
     float z1 = 0
     float x2 = 0
     float y2 = 0
     float z2 = 0
     bool solid = false
     bool solid1 = false
     bool solid2 = false
 
     ; First perform hit test for equation 1; store coordinates
     ; in (x1, y1, z1)
 
     sy = sy * 6/7
     dy = dy * 6/7
 
     float a = sqr(dx) + sqr(dy) + sqr(dz)
     float b = 2 * sx * dx + 2 * sy * dy + 2 * sz * dz
     float c = sqr(sx) + sqr(sy) + sqr(sz) - 0.25
     float d = sqr(b) - 4 * a * c
 
     if d < 0
       ; No roots exist.
       solid1 = true
     else
       ; One or two roots: select smallest.
       if a > 0
         lambda = (-b - sqrt(d)) / (2 * a)
       else
         lambda = (-b + sqrt(d)) / (2 * a)
       endif
 
       if lambda <= 0
         ; Intersection point is behind the screen.
         solid1 = true
       else
         x1 = sx + lambda * dx
         y1 = sy + lambda * dy
         z1 = sz + lambda * dz
       endif
     endif
 
     ; Now perform hit test for equation 2; store coordinates
     ; in (x2, y2, z2)
 
     sy = sy * 4/5
     dy = dy * 4/5
 
     float a = sqr(dx) + sqr(dy) + sqr(dz)
     float b = 2 * sx * dx + 2 * sy * dy + 2 * sz * dz
     float c = sqr(sx) + sqr(sy) + sqr(sz) - 0.25
     float d = sqr(b) - 4 * a * c
 
     if d < 0
       ; No roots exist.
       solid2 = true
     else
       ; One or two roots: select smallest.
       if a > 0
         lambda = (-b - sqrt(d)) / (2 * a)
       else
         lambda = (-b + sqrt(d)) / (2 * a)
       endif
 
       if lambda <= 0
         ; Intersection point is behind the screen.
         solid2 = true
       else
         x2 = sx + lambda * dx
         y2 = sy + lambda * dy
         z2 = sz + lambda * dz
       endif
     endif
 
     ; Now select proper coordinates (either set 1 or set 2)
 
     if solid1
       if y2 < 0
         solid = true
       else
         x = x2
         y = y2
         z = z2
         solid = solid2
       endif
     else
       if y2 > 0
         x = x2
         y = y2
         z = z2
       else
         x = x1
         y = y1
         z = z1
       endif
     endif
 
     if !solid
       if z == 0
         if x > 0
           result = 2
         else
           result = -2
         endif
       else
         result = (4 / #pi) * atan(x / abs(z))
       endif
       result = result + flip((4 / #pi) * atan(y / sqrt(sqr(x) + sqr(z))))
       return true
     else
       return false
     endif
   endfunc
 
 default:
   title = "Egg"
 }
 

Constructor Summary

Standard_MappingShapeEgg()

Method Summary

boolean

GetTextureCoordinates(float sx, float sy, float sz, float dx, float dy, float dz, complex result) GetTextureCoordinates tests a ray against the mapping shape.

Methods inherited from class common:Generic

GetParent

Methods inherited from class Object

Constructor Detail

Standard_MappingShapeEgg

public Standard_MappingShapeEgg()

Method Detail

GetTextureCoordinates

public boolean GetTextureCoordinates(float sx,
                                     float sy,
                                     float sz,
                                     float dx,
                                     float dy,
                                     float dz,
                                     complex result)

Description copied from class: MappingShape

GetTextureCoordinates tests a ray against the mapping shape. If the ray intersects the shape, it returns true, and returns the coordinates of the point on the shape that intersects the ray in the result argument. If the shape does not intersect the ray, returns false.

A concrete shape descendant should override this function to define the mapping shape.

The ray is defined as:
[ sx ] [ dx ]
[ sy ] + lambda [ dy ]
[ sz ] [ dz ]

Overrides:

GetTextureCoordinates in class MappingShape

Parameters:

sx - X coordinate of point in space that the ray passes through.

sy - Y coordinate of point in space that the ray passes through.

sz - Z coordinate of point in space that the ray passes through.

dx - Relative movement of the line along the X axis.

dy - Relative movement of the line along the Y axis.

dz - Relative movement of the line along the Z axis.

result - Receives the texture coordinates if the function returns true.

Returns:

True if the ray intersects the shape, false otherwise.