User:Le Forgeron/mesh

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Access to data of mesh (including mesh2)

Returns the number of triangles in the mesh get_triangle_count( MESH )
Returns the number of vertices in the mesh get_vertex_count( MESH )
Returns the number of normal vectors in the mesh get_normal_count( MESH )
Returns the number of uv vectors in the mesh get_uv_count( MESH )
Returns the vertex vector that corresponds to the given index value (starting from 0) get_vertex( MESH, INDEX )
As get_vertex, but returns a normal vector get_normal( MESH, INDEX )
As get_vertex, but returns an uv vector (2D) get_uv( MESH, INDEX )
Returns a vector containing index values to vertices for the triangle number INDEX (starting from 0). This can be used to read the three vertices of the triangle calling get_vertex() with each vector component

get_vertex_indices( MESH, INDEX )

The same as get_vertex_indices(), but returns indices to the normal vectors of the triangle number INDEX get_normal_indices( MESH, INDEX )
The same as get_vertex_indices(), but returns indices to the uv vectors of the triangle number INDEX get_uv_indices( MESH, INDEX )
Tells whether the triangle number INDEX is smooth or not. is_smooth_triangle( MESH, INDEX )

Mesh from and to file

Loading

GTS =

A GTS file can be loaded with gts_load.

#include "colors.inc"
camera { location <3,5,-4>
	direction z
		up y
		right image_width/image_height*x
		look_at <-1/2,1/2,0>
		angle 35
}

light_source{ <-5, 20, -20>, 1}
light_source{ <0, 2, 0>, 1/2}

gts_load{ "bunny.gts"
	right
	rotate 180*y	
	scale 17
	translate -2*y
	texture { pigment { color Aquamarine}}
}

Aside from the filename of the file to load, the right keyword can be used to change the default left-handed coordinate system to a right-handed one.

gts_load can be used to create a mesh of its own or to incorporate the mesh of the file into a larger mesh, in which case a texture identifier can be applied over the loaded GTS mesh.

 mesh { ...
    gts_load { filename [right] [texture { Tid }] }
  ...
 }

OR

 gts_load { filename [right] 

 [Object_Mods...]
 }

STL

A mesh can be loaded with stl_load. Beware of I/O restrictions.

Aside from the filename of the file to load, the right keyword can be used to change the default left-handed coordinate system to a right-handed one.

stl_load is used to create a mesh of its own.

Only a binary stl file can be loaded:

text stl file format is not supported
normal and attribute are not taken into account

 stl_load { filename [right] 

 [Object_Mods...]
 }

Saving

A mesh can be saved with gts_save. Beware of I/O restrictions.

gts_save { filename, mesh_object }

GTS format saves the geometry, but neither the faked normal or the textures

Getting a new mesh from a mesh

The following method (or pseudo-object) can be used only on a mesh, whatever its origin.

Whatever the method used (it will always end as a mesh object, or inside a mesh object). there is some common parameters:

original is the mesh used as the base object (it is not updated, it is used as data source)
albinos is an option which remove all textures on the generated triangles

bend

Curve the mesh along a line, using a reference half-plane containing that line.

bend  { original Objiii 
        origin 0  
        amount 30 
        fixed z 
        direction y
        minimal -0.0
        maximal 2.0 }

bend  { original Objiii 
        origin 0  
        amount 30 
        fixed y 
        direction z
        minimal -50.0
        maximal 2.0 }

 mesh { ...
   bend {
    original mesh_object
    [albinos]  [amount float]  [direction vector]  [fixed vector]  [maximal float]  [minimal float]
    [modulation { texture_description }]  [origin vector]  [texture { Tid }]
   } 
 ...
 }

OR

 bend {
  original mesh_object
  [albinos]  [amount float]  [direction vector]  [fixed vector]  [maximal float]  [minimal float]
  [modulation { texture_description }]  [origin vector]

 [Object_Mods...]
 }

original mesh_object : the original mesh object whose data are used as source for the new mesh
albinos : do not copy the texture from the original mesh
amount float : angle of rotation (in degree) for a unit length. The rotation is proportional to the length.
direction vector : axis of the rotation, only the direction is taken into account.
fixed vector : axis of the zero-plane (origin, origin+direction & origin+fixed points are all contained inside the zero-plane: the plane with no transformation)
maximal float : when length is bigger, the transformation is limited to the float.
minimal float : when length is smaller, the transformation is limited to the float.
modulation { texture_description } : the luminosity of the colour from the texture evaluated at the vertex is used to ponder the deformation effect; full black means no transformation, white (<1,1,1>) means 100%.
origin vector : vertex used as the origin of the transformation's reference base.

displace

Move each vertex of a triangle along its normal.

Be careful: as a vertex might appears in more than one triangle, if the normal at a vertex is not the same for all the triangles sharing that vertex, the displacement would create cracks in the resulting mesh as each triangles move away.

 mesh{ ...
  displace {
    modulation { texture_description }
    original mesh_object
    [albinos]  [amount float]  [offset float] [inside_point vector] [texture { Tid } ]
  }
  ...
 }

OR
 
 displace {
  modulation { texture_description }
  original mesh_object
  [albinos] [amount float] [offset float] [inside_point vector]

 [Object_Mods...]
 }

original mesh_object : the original mesh object whose data are used as source for the new mesh
modulation { texture_description } : the luminosity of the colour from the texture evaluated at the vertex is used to ponder the deformation effect; full black means no transformation, white (<1,1,1>) means 100%.
albinos : do not copy the texture from the original mesh
amount float : length of displacement for 100%.
offset : offset applied to the luminosity. (default value is 0.5, so full black is -50% and white is 50%)
inside_point : when present, normals are flipped (for the displacement) whenever it would not be centrifuge with the vector of the position relative to the inside_point. Allow to get consistent displacement on mesh with random normal distribution.

move

Transforms the coordinates of each points.

mesh { ...
  move {
   original mesh_object
   [albinos] [modulation { texture_description } ] [move < coeff_of_matrix(12) >] [ texture { Tid } ]

} 
  ...
}

OR

move {
    original mesh_object
    [ albinos ] [modulation { texture_description } ] [ move < coeff_of_matrix(12) > ]

[Object_Mods...]
}

The starting point is used with the movematrix to produce a end point. The resulting deplacement is then modulated by the luminosity of the modulation texture to produce the final point.

The matrix is the usual transformation matrix.

#include "colors.inc"
#default { finish { ambient 0.5 specular 0.5 } }
camera { location <6,6,12> direction  -z right x up y look_at 0 angle 25 }
light_source { <-30,100,50>, 1 }

#declare tt=texture { pigment { spiral2 6 scale 2 translate -y*0.95 pigment_map { 
[0 Black]
[1 Gray20]
} } }
 
#declare msize=3.0;
move { original cristal { accuracy 150 original sphere { 0,msize } }
modulation { tt }
move < 0.6,+0.4,0, 0,1,0, 0,-0.2,0.1, 0,0,0 >
pigment { Yellow } 
}

planet

To Do : illustration and explanation.

roll

original mesh_object : the original mesh object whose data are used as source for the new mesh
albinos : do not copy the texture from the original mesh
modulation { texture_description } : the luminosity of the colour from the texture evaluated at the vertex is used to ponder the deformation effect; full black means no transformation, white (<1,1,1>) means 100%.
direction vector : vector of the rotation (as usual) for a unit length along that vector.
maximal float : when rotation's angle is bigger, the transformation is limited to the float.
minimal float : when rotation's angle is smaller, the transformation is limited to the float.
origin vector : vertex used as the origin of the transformation's reference base.

mesh{ ...
  roll {
    original mesh_object
    [albinos] [direction vector] [maximal float] [minimal float] [modulation { texture_description }]
    [origin vector]
    [texture { Tid }]
  }
  ...
}

OR

roll {
    original mesh_object
    [albinos] [direction vector] [maximal float] [minimal float] [modulation { texture_description }]
    [origin vector]

[Object_Mods...]
}

screw

#default { pigment { rgb <1,.8,.6> } finish { specular .5 } }
#declare Objiii = cubicle { original box { <-0.5,-3.5,-0.5>,<0.5,3.5,0.5>  } accuracy <20,120,20> }
#local i=0;
#while (i<15)
screw  { original Objiii origin 0  direction i*20*y
  #if (mod(i,3)=1) minimal -30.0 maximal i*45.0 #end
  #if (mod(i,4)=0) right #end
rotate 30*x*mod(i+1,2)  translate i*2*x } 
#local i=i+1;
#end
camera { location <14.0,0,150> up 8*y right 8*x*image_width/image_height direction -z angle 12 }
light_source { <200,100,-150>, z }
light_source { <00,10,150>, 1 }
light_source { <200,100,100>, x }
light_source { 0, y }

original mesh_object : the original mesh object whose data are used as source for the new mesh
albinos : do not copy the texture from the original mesh
modulation { texture_description } : the luminosity of the colour from the texture evaluated at the vertex is used to ponder the deformation effect; full black means no transformation, white (<1,1,1>) means 100%.
direction vector : vector of the rotation (as usual) for a unit length along that vector.
maximal float : when rotation's angle is bigger, the transformation is limited to the float.
minimal float : when rotation's angle is smaller, the transformation is limited to the float.
origin vector : vertex used as the origin of the transformation's reference base.
right : inverse the handedness of the the screw (on a default left-handed scene, the default screw is the traditional clockwise; right allows to produce the chiral one)

mesh{ ...
  screw {
    original mesh_object
    [albinos] [direction vector] [maximal float] [minimal float] [modulation { texture_description }]
    [origin vector] [right]
    [texture { Tid }]
  }
  ...
}

OR

screw {
    original mesh_object
    [albinos] [direction vector] [maximal float] [minimal float] [modulation { texture_description }]
    [origin vector] [right]

[Object_Mods...]
}

keep

Keep only part(s) of a mesh, relative to a 3D object. Four parts are possible:

inner all 3 vertices of a triangle are inside the 3D object.
inbound only 2 vertices of a triangle are inside.
outbound only 1 vertex of a triangle is inside.
outside all 3 vertices of a triangle are not inside the 3D object.

A keep selection can select as many parts as wanted for the resulting mesh, but will only use a single 3D object.

keep { original Foobar_Mesh 
  with intersection { 
            box { <-1,-1,-1>,<4,haut+1,0.04> } 
            sphere { <1.5,haut/2,0>,haut*2/5 }
       }
   outside
}

mesh{ ...
  keep {
    original mesh_object
    with solid_object
    [albinos] [inbound] [inner] [outbound] [outside]
    [texture { Tid }]
  }
  ...
}

OR

keep {
    original mesh_object
    with solid_object
    [albinos] [inbound] [inner] [outbound] [outside]

[Object_Mods...]
}

smooth

#include "colors.inc"
background { rgb z *.5}
#declare T1= texture { pigment { rgb <1,.8,.6> } finish { specular .5 } };
#declare T2= texture { pigment { rgb <.8,.6,1> } finish { specular .5 } };
#declare T3= texture { pigment { rgb <.6,1,.8> } finish { specular .5 } };
#default { texture { T1 }}
#declare Obj = sphere { 0,1 texture { T3} }
#declare Spacing = 2.1;
#declare Tes= tessel { original Obj accuracy 3 offset 0.1 albinos texture { T2 } }
object { Obj translate x*4*Spacing }

object { Tes translate -x*Spacing }
#for(i,0,3,1)
smooth { original Tes method i translate Spacing*x*i }
#end

camera { orthographic location < 0, 4, -18 > *2.1 up y right image_width/image_height*x
look_at < 0, 0, 0 > angle 37 / 2 translate Spacing*x*1.5 }
light_source { <200, 100, -150 >, 1}
light_source { <-200, 100, -100 >, x * .5}

mesh{...
  smooth {
    original mesh_object
    [albinos] [amount float] [method float] [texture { Tid }]
  } 
...
}

OR

smooth {
    original mesh_object
    [albinos] [amount float] [method float ]

  [Object_Mods...]
}

Perturbate the normal of each triangle. By default the perturbation is toward a smoother surface.

amount float : the amount of displacement of the normals toward the unified normal at that vertex. 1 (=100%) by default.
method index : how to compute the unified normal (default to 0)
- 0 : basic average of all contributing normals
- 1 : weighted average, the weight is the angle at the vertex
- 2 : weighted average, the weight is the product of the lengths of segments at the vertex
- 3 : weighted average, the weight is the surface of the triangle

warp

#version 3.7;
global_settings { assumed_gamma 1.0 }
#include "colors.inc"

camera { location <9.3,1.5/2,-100> up y direction z
right image_width/image_height*x look_at <9.3,1.5/2,0> angle 11 }
#declare T0= texture { pigment { Gold } }

light_source { <-30,100,-100>,1 }
light_source { <0,00,-100>,1 }

#declare Obj1= union {
        box { <0,0,0>,<1,1.5,30> texture { pigment { Blue } } }
        box { <1,0,0>,<2,1.5,30> texture { pigment { White } } }
        box { <2,0,0>,<3,1.5,30> texture { pigment { Red } } }
        box { <1.45,0.3,-0.001>,<1.55,1.2,0> texture { T0 } }
        box { <1.2,0.70,-0.001>, <1.8,0.80,0> texture { T0 } }
        box { <1.325,0.925,-0.001>, <1.675,1.025,0> texture { T0 } }
      }

#declare Vector =  <0.1,0.2,0.3>;

#declare Boring_mesh= keep { original tesselate { original  Obj1 offset 0.1 accuracy <100,50,2> }
		with box { <-1,-1,-1>,<4,1.5+1,0.04> } inner };

object { Boring_mesh  }
#for(i,1,5,1)
warp { original Boring_mesh warp { turbulence Vector octaves i } 
			 translate 3.15*i*x }
#end

mesh{...
  warp {
    original mesh_object warp warp_description
    [albinos] [modulation { texture_description } ] [move <coeff_ot_matrix(12)>] [texture { Tid }]
  } 
...
}

OR
warp {
    original mesh_object warp warp_description
    [albinos] [modulation { texture_description } ] [move <coeff_ot_matrix(12)>]
    
  [Object_Mods...]
}

See move for the details about modulation. The matrix provided with move is applied to the points before evaluating the warp (useful in animation for moving an object in the wind: as the wind progress, the translation of the matrix does also).