Purpose:

Read a GRASP surface file (.srf) and create a modified mesh object with colors at each vertex. This object replaces the need of using a conversion utility to import a GRASP surface into POV-Ray. It's also faster and usually requires much less memory when using huge surfaces. Any of the surface properties contained in the GRASP file might be selected for display. Several properties can be shown on copies of the same surface ("template") with reduced memory requirements. * Examples and benchmarks * See also the tutorial section

Syntax:

grasp_surface
{
  "FILENAME.srf"                 // GRASP surface file, e.g. "surface.srf"
  [ with OBJECT_IDENTIFIER ]     // template (another grasp_surface object)
  [ colored_by PROPERTY_NAME ]   // see below for syntax
  [ gradient <COLOR1>,<COLOR2>,<COLOR3> ] // color gradient
  [ colors_file "FILENAME.dat" ] // GRASP colors file, e.g. "defcol.dat"
  [ filter FLOAT ]               // filtering transparency
  [ transmit FLOAT ]             // transmitting transparency
  [ range <VECTOR> ]             // for color gradient
  [ precision INTEGER ]          // for decimal numbers (default = 0 = full)
  [ verbose [BOOL] ]             // verbose mode (default = off)
  [ smooth [BOOL] ]              // smooth surface (default = on)
  [ preview [LEVEL] ]            // preview mode, level in 1..4 range
  [ persistent [BOOL] ]          // parse surface data only once (animation)
  [ ... ]                        // any valid mesh object option
}

  potentials     potential
  curvatures     curvature
  distances      distance
  gproperty1     property1
  gproperty2     property2
  discretecolors discretecolours discretecolor discretecolour vertexcolor

  colored_by  coloured_by
  gradient    with
  color_file  colors_file colour_file colours_file with
  persistent  persist

Notes:
* Options which are not relevant to the specified property are simply ignored, and thus won't generate an error.
* For any of the properties, the defaults for color range or vertex colors are those that GRASP uses (e.g red,white,blue for potentials).

Limitations:
* Reads only GRASP file format=2 (the newest)
* Reads only the first surface of merged GRASP files, i.e. that contains several headers.
* Persistent objects are not supported in CSG or when defined as variables.

Purpose:

Define a pattern texture allowing for color interpolation within any triangle (in a mesh or not). This object can be used when a grasp_surface is not adequate. It normally requires less memory than using a POV-Ray macro, such as Chris Colefax's Trimap macro fileweb . * Example and comparison

Syntax:

triangle
{
  <0,0,0>,  // point A, will be Red
  <1,2,0>,  // point B, will be Green
  <2,0,0>   // point C, will be Blue
  texture{ pigment{ vertexcolor Red, Green, Blue } }
}

Limitations:
* Only works with triangle and smooth_triangle defined in or out of a mesh.
* The texture must be declared outside of the mesh (POV-Ray limitation).

Purpose:

Allows to define a starting boundary for constant fog and ground fog. Fogs can be used to setup a depth-cueing effect since the visibility decreases with the distance. With a standard fog it is usually necessary to put the camera very close to the objects so that their front part is fully visible. To avoid strong deformations due to the perspective, an orthographic camera must be used; but this is somewhat limitating. Using fog_start in the fog object definition allows to use distant perspective camera with the fog effect starting near the objects. * Examples and comparisons

Syntax:

fog
{
  fog_type    1  // Constant fog
  fog_start  35  // Starting offset from the camera [Pov4Grasp addition]
  distance   20  // Distance starting from fog_start (here it's 55 units from
                 // the camera) where 36.8% of the background is still visible
}

Limitations:
* Fog density decreases faster than in normal fog.

Syntax:

camera
{
  [...]                       // camera specifications
  move_factor     FLOAT       // in 0..1 range, 0 disables motion blur
  blur_samples    INTEGER     // used also for focal blur
  [ location_prev <VECTOR> ]  // previous camera location
  [ look_at_prev  <VECTOR> ]  // previous camera look_at
  [ confidence    FLOAT ]     // same as focal blur
  [ variance      FLOAT ]
  [ aperture      FLOAT ]     // to add focal blur
}

Please refer to the text document to get details on this feature.