POV-Ray : Newsgroups : povray.binaries.images : bbox macro to help bounding. Server Time
2 Aug 2024 18:11:51 EDT (-0400)
  bbox macro to help bounding. (Message 1 to 1 of 1)  
From: Bruno Cabasson
Subject: bbox macro to help bounding.
Date: 27 Mar 2007 08:40:01
Message: <web.46091dfb8c694744f5fba6ef0@news.povray.org>
Hi everybody!!

At lunch time today I made this little macro that may help to better bound
some objects. The macro is embeded in a sample scene. Perhaps it can be of
some convenience ...

    Regards

        Bruno


// Persistence of Vision Ray Tracer Scene Description File
// File: bbox.pov
// Vers: 3.5
// Desc: bbox macro sample scene
// Date: March 2007
// Auth: Bruno Cabasson
//

#version 3.5;

#include "colors.inc"
#include "functions.inc"

global_settings {
  assumed_gamma 1.0
}

// ----------------------------------------

camera {
  location  <0.0, 2, -4.0>
  direction 1.5*z
  right     x*image_width/image_height
  look_at   <0.0, 0.5,  0.0>
}

sky_sphere {
  pigment {
    gradient y
    color_map {
      [0.0 rgb <0.6,0.7,1.0>]
      [0.7 rgb <0.0,0.1,0.8>]
    }
  }
}

light_source {
  <0, 0, 0>            // light's position (translated below)
  color rgb <1, 1, 1>  // light's color
  translate <-30, 30, -30>*100
}


//
----------------------------------------------------------------------------
// bbox(_object, _corner_type, _corner_color, _edge_color, _face_color,
_draw_faces)
//
// Purpose: Draw the bounding box of an object. May help tuning bounded_by{}
for objects
// and for contained_by{} for isosurfaces.
//
// Parameters:
//
// _object: a #declared object you want to draw the bounding_box of
// _corner_type: shape og the corners: BBOX_CORNER_TYPE_SPHERE |
BBOX_CORNER_TYPE_SQUARE | BBOX_CORNER_TYPE_DIAMOND
// _corner_color: the color of the corners of the bounding box, normally
without transmit
// _corner_color: the color of the corners of the bounding box, normally
without transmit
// _edge_color: the color of the edges of the bounding box, normally without
transmit
// _face_color: the color of the faces of the bounding box, normally with
transmit
// _draw_faces: true if the faces are to be drawn, false otherwise
//
// Usage: For the object(s) under tuning, perform like the following
//
// Instead of: object {myThing transform {myTransform}} // myThing was
#decalre'd earlier
//
// Write     : union
//             {
//                 object {myThing}
//                 bbox(MyThing, BBOX_CORNER_TYPE_DIAMOND, Red, Green, color
Blue transmit 0.7, true)
//                 transform {myTransform}
//             }
//
#declare BBOX_CORNER_TYPE_SPHERE = 0;
#declare BBOX_CORNER_TYPE_SQUARE = 1;
#declare BBOX_CORNER_TYPE_DIAMOND = 2;

#macro bbox(_object, _corner_type, _corner_color, _edge_color, _face_color,
_draw_faces)
    #local _ret = union
    {
        #local _min = min_extent(_object);
        #local _max = max_extent(_object);
        #local _v = _max - _min;
        #local _vx = _v.x;
        #local _vy = _v.y;
        #local _vz = _v.z;
        #local _p = array[8];
        #local _p[0] = _min;
        #local _p[1] = _min + <_vx, 0, 0>;
        #local _p[2] = _min + <_vx, 0, _vz>;
        #local _p[3] = _min + <0, 0, _vz>;
        #local _p[4] = _min + <0, _vy, 0>;
        #local _p[5] = _min + <_vx, _vy, 0>;
        #local _p[6] = _max;
        #local _p[7] = _min + <0, _vy, _vz>;

        // 8 corners
        #local _d1 = max(max(_vx, _vy), max(_vy, _vz))/40;
        #switch (_corner_type)
            #case (BBOX_CORNER_TYPE_SPHERE)
                #local _base_corner = sphere {0, _d1}
                #break
            #case (BBOX_CORNER_TYPE_SQUARE)
                #local _base_corner = box {-_d1, _d1}
                #break
            #case (BBOX_CORNER_TYPE_DIAMOND)
                #local _base_corner = isosurface {function
{abs(x)+abs(y)+abs(z) - _d1} max_gradient 4 contained_by {box{-1.05*_d1,
1.05*_d1}} scale sqrt(2)}
                #break
            #else
                #local _base_corner = isosurface {function
{abs(x)+abs(y)+abs(z) - _d1} max_gradient 4 contained_by {box{-1.05*_d1,
1.05*_d1}} scale sqrt(2)}
                #break
        #end

        #local i=0;
        #while (i<dimension_size(_p, 1))
            object {_base_corner pigment {color _corner_color} translate
_p[i]}
            #local i=i+1;
        #end

        // 12 edges
        #local _d2 = _d1/3;
        cylinder {_p[0], _p[1], _d2 pigment{color _edge_color}}
        cylinder {_p[1], _p[2], _d2 pigment{color _edge_color}}
        cylinder {_p[2], _p[3], _d2 pigment{color _edge_color}}
        cylinder {_p[3], _p[0], _d2 pigment{color _edge_color}}

        cylinder {_p[4], _p[5], _d2 pigment{color _edge_color}}
        cylinder {_p[5], _p[6], _d2 pigment{color _edge_color}}
        cylinder {_p[6], _p[7], _d2 pigment{color _edge_color}}
        cylinder {_p[7], _p[4], _d2 pigment{color _edge_color}}

        cylinder {_p[0], _p[4], _d2 pigment{color _edge_color}}
        cylinder {_p[1], _p[5], _d2 pigment{color _edge_color}}
        cylinder {_p[2], _p[6], _d2 pigment{color _edge_color}}
        cylinder {_p[3], _p[7], _d2 pigment{color _edge_color}}

        // 6 faces
        #if (_draw_faces)
            polygon {4, _p[0], _p[1], _p[2], _p[3] pigment {color
_face_color}}
            polygon {4, _p[4], _p[5], _p[6], _p[7] pigment {color
_face_color}}
            polygon {4, _p[0], _p[1], _p[5], _p[4] pigment {color
_face_color}}
            polygon {4, _p[1], _p[2], _p[6], _p[5] pigment {color
_face_color}}
            polygon {4, _p[1], _p[2], _p[6], _p[5] pigment {color
_face_color}}
            polygon {4, _p[3], _p[0], _p[4], _p[7] pigment {color
_face_color}}
        #end
        no_shadow
    }
    _ret // returned value is object{}-able
#end
//
----------------------------------------------------------------------------



plane {
  y, -1
  pigment { color rgb <0.7,0.5,0.3> }
}

#declare O_Sphere = sphere {
  0.0, 1
  texture {
    pigment {
      radial
      frequency 8
      color_map {
        [0.00 color rgb <1.0,0.4,0.2> ]
        [0.33 color rgb <0.2,0.4,1.0> ]
        [0.66 color rgb <0.4,1.0,0.2> ]
        [1.00 color rgb <1.0,0.4,0.2> ]
      }
    }
    finish{
      specular 0.6
    }
  }

  rotate 45*x + 30*y
}

#declare O_Box = box {
  -1, 1
  texture {
    pigment {
      agate
      color_map {
        [0.00 color rgb <1.0,0.4,0.2> ]
        [0.33 color rgb <0.2,0.4,1.0> ]
        [0.66 color rgb <0.4,1.0,0.2> ]
        [1.00 color rgb <1.0,0.4,0.2> ]
      }
    }
    finish{
      specular 0.6
    }
  }
  scale 0.5
  rotate 45*x + 30*y
}


// CSG
#declare O_SphereBox_union = union
{
    object {O_Box translate -0.4*x}
    object {O_Sphere translate 0.4*x}
    //bounded_by {box{-1,1}} // improper manual bounding, let it be
automatic.
}

#declare O_SphereBox_difference = difference
{
    object {O_Box translate -0.4*x}
    object {O_Sphere translate 0.4*x}
}

#declare O_SphereBox_intersection = intersection
{
    object {O_Box translate -0.4*x}
    object {O_Sphere translate 0.4*x}
}

// Isosurface
#declare O_IsoBox = isosurface
{
    #local _dims = <1,1/2,1/3>;
    #local _dx = _dims.x;
    #local _dy = _dims.y;
    #local _dz = _dims.z;
    function {f_rounded_box(x,y,z, 0.01, _dx/2, _dy/2, _dz/2) -
0.3*f_noise3d(x*3,y*3,z*3)}
    max_gradient 2
    contained_by {box{-2*_dims/2, 2*_dims/2}}

    pigment {wrinkles scale 0.1}
    scale 0.5
}

// Good automatic bounding
union
{
    object {O_SphereBox_union}
    bbox(O_SphereBox_union, BBOX_CORNER_TYPE_DIAMOND, Red, Green, color Red
transmit 0.8, true)
    translate 5*z+y/2-2*x
}

// Improvable automatic bounding (too large, not well centered)
union
{
    object {O_SphereBox_difference}
    bbox(O_SphereBox_difference, BBOX_CORNER_TYPE_SQUARE, Red, Green, color
Green transmit 0.8, true)
    translate 5*z+y/2+3*x
}

// Good automatic bounding
union
{
    object {O_SphereBox_intersection}
    bbox(O_SphereBox_intersection, BBOX_CORNER_TYPE_DIAMOND, Red, Green,
color Blue transmit 0.8, true)
    translate z+y/2+x/2
}

// Improvable bounding (too large in x, too small in z)
union
{
    object {O_IsoBox}
    bbox(O_IsoBox, BBOX_CORNER_TYPE_SPHERE, Red, Green, color Yellow
transmit 0.8, true)
    translate -z+y/2-0.7*x
}


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