# RENDER

#### SYNOPSIS

Render is the central image-rendering program of the Raster3D molecular graphics package. Render reads an ascii file consisting of several header lines followed by individual object descriptors. The objects are rendered using a fast Z-buffer algorithm. Output is to stdout [or optional file] in the form of a pixel image with 24 bits of color information per pixel. The default output file format is an PNG image sent to stdout. Additional image file types may be optionally included during installation of the Raster3D package.

Usage:

       input from stdin; output mode controlled from command line

         render                        PNG image to stdout
         render -avs  [outfile]        AVS image to outfile (defaults to stdout)
         render -png  [outfile]        PNG image to outfile (defaults to stdout)
         render -jpeg [outfile]        JPEG image to outfile (defaults to stdout)
         render -sgi  [outfile]        output to SGI libimage file (defaults to render.rgb)
         render -tiff [outfile]        output to TIFF file (defaults to render.tif)
         render -out   outfile.xxx     pipe output to ImageMagick for
                                       conversion to image type xxx

Options:

       these over-ride contents of input stream header records

        -aa                   anti-aliasing (SCHEME 4)
        -alpha                alpha channel in output image (SCHEME 0)
        -bg            set background,  is black, white or #RRGGBB
        -debug                verbose output while running
        -draft                no anti-aliasing (SCHEME 1)
        -fontscale FF         multiplier for PostScript label fonts
        -gamma GG             apply gamma correction GG to output image
        -invert               invert y axis
        -labels [outfile.ps]  write labels to PostScript file [default: label3d.ps]
        -quality QQ           0 < QQ < 100   jpeg compression parameter (default 90)
        -[no]shadow	          enable or disable shadowing
        -size HHHxVVV         specify size of output image in pixels
        -transparent          same as -alpha (SCHEME 0)
        -zoom ZZ[%]           rescale image by a factor of ZZ

#### MORE INFORMATION

Examples | Options | Description | Header Records
Sample Header | Object Types | Comments | File Indirection
Sample Data Stream | Error Messages | Increasing Array Sizes
Authors

#### EXAMPLES

Render a simple space-filling model coloured by residue type:

        cat mycolors.pdb protein.pdb | balls | render > mypicture.avs

Display the same picture on an X-windows display directly using ImageMagick:

        cat mycolors.pdb protein.pdb | balls | render | display avs:-

Render and display the same picture using the SGI libimage format:

        cat mycolors.pdb protein.pdb | balls | render -sgi picture.rgb
        ipaste picture.rgb

Render a stick-figure model of a cofactor jointly with a ribbon model of a protein. Note that the header records are generated by the ribbon command in this case; the -h flag suppresses generation of a second set of header records in the rods command. The ImageMagick convert command is used to save the resulting image as a TIFF file.

        ribbon -d4 protein.pdb > ribbon.r3d
        cat colors.pdb cofactor.pdb | rods -bs -h > cofactor.r3d
        cat ribbon.r3d cofactor.r3d | render | convert avs:- picture.tiff

If TIFF support has been built directly into Raster3D, then the previous command can be modified to produce a TIFF file without conversion:

        cat ribbon.r3d cofactor.r3d | render -tiff picture.tiff

#### OPTIONS

-aa
  Force anti-aliasing (SCHEME 4) regardless of the scheme specified in the file header
-alpha
  Force output of transparency information (SCHEME 0) regardless of the scheme specified in the file header. This only works if the output format supports an alpha channel (AVS, TIFF, but not JPEG). Note that this turns off anti-aliasing. This option can be used to produce an image with a transparent background.
-bg white|black|#RRGGBB
  Set background color. #RRGGBB is a hexadecimal representation of the color components.
-draft
  Turn off anti-aliasing (SCHEME 1) to increase rendering speed.
-fontscale XX
  Only meaningful in conjunction with the -labels option. Modifies the interpretation of font sizes during label processing. If -fontscale is not specified, the program next looks for an environmental variable FONTSCALE. If neither a command line value or an environmental variable is found, the program defaults to -fontscale 3.0, which generates PostScript labels that are approximately the nominal font size when printed at 300 dpi.
-help
  Print summary of options.
-gamma GG
  Apply gamma correction to output image. Gamma > 1 makes it lighter; gamma < 1 makes it darker.
-invert
  Invert the image top-to-bottom. This could be necessary if you are using some odd viewing program.
-jpeg
  Only if compiled with -DJPEG_SUPPORT. By default render will produce an AVS-compatible image on stdout. The -jpeg flag will cause it to output a JPEG image stream to stdout instead.
-labels [outfile.ps]
  Process labels (object types 10,11,12) and create a PostScript output file label3d.ps in addition to the rendered image file. If no filename is given, output file defaults to label3d.ps. This option is used by the label3d script.
-out filename.xxx
  Only if compiled with -DIMAGEPIPE. The -out flag will cause render to pipe output to the ImageMagick command convert, with instructions to convert it to an image file whose type is determined by the filename extension xxx.
-quality NN
  Only meaningful in conjunction with the -jpeg option;
-size HHHxVVV
  Override the image size parameters (NTX,NTY,NPX,NPY) in the file header and produce an output image that is exactly HHH pixels in the horizontal and VVV pixels in the vertical.
-sgi [filename.rgb]
  Only if compiled with -DLIBIMAGE_SUPPORT. The -sgi flag will cause render to output an SGI libimage style *.rgb file instead. In this case default output is to the file render.rgb, but specifying a file on the command line will override this default. sets the output image quality parameter. Allowable values range from 1-100 (default = 90).
-tiff filename.tiff
  Only if compiled with -DTIFF_SUPPORT. The -tiff flag will cause render to output a TIFF image to the specified file.
-transparent
  (same as -alpha) Force output of transparency information (SCHEME 0). This only works if the output format supports an alpha channel (AVS, TIFF, but not JPEG).
-zoom ZZ[%]
  Modifies the scale factor TMAT(4,4) in the header records. This does not change the overall dimensions of the image, just the size of the objects within the image. ZZ > 1 will make the objects appear larger, ZZ < 1 will shrink them. If the ZZ is is given as a percentage, then ZZ > 100% enlarges and ZZ < 100% shrinks.

#### DESCRIPTION

The input to render consists of a single text file containing everything necessary to prepare the image of a scene consisting of coloured spheres, cylinders and triangles. The header records contain information global to the scene being rendered. The header records are followed by individual object records containing coordinate and color specification for the objects in the scene. The surface shading of primitive objects (spheres, cylinders, and simple triangles) is calculated analytically. Sequential triangles forming a ribbon-like chain are rendered by a more complex algorithm which produces the appearance of a a smoothly-shaded surface rather than a faceted one [ref: Merritt & Murphy].

#### HEADER RECORDS

The required header records of a render input file are described below. Except where noted, each item is on a line by itself in free format. The names are of variables in the program source code.

TITLE
  Anything you like, up to 80 characters.
NTX,NTY
  Number of ``tiles'' in each direction. (The output display is considered to be divided up into an array of identical rectangular tiles.) The maximum is 192 unless you have increased MAXNTX and MAXNTY in render.f.
NPX,NPY
  Number of computing pixels per tile in each direction. Maximum = 36 (MAXNPX, MAXNPY in render.f)
SCHEME
  Pixel averaging (anti-aliasing) scheme. Anti-aliasing reduces the jaggedness of edges at the cost of additional computation. If you are going to matte your images against an externally generated background, use scheme 0 (matting and anti-aliasing do not mix well).
  Scheme 0
    no anti-aliasing, include alpha blend (matte) channel in output image
  Scheme 1
    no anti-aliasing, no matted channel
  Scheme 2
    anti-alias by averaging 2x2 computing pixels for each output pixel
  Scheme 3
    anti-alias by averaging 3x3 computing pixels for each 2x2 output pixels (obsolete - use scheme 4 instead)
  Scheme 4
    anti-alias as in scheme 3, but header specifies final raster size rather than computing raster size
  (i.e. schemes 0, 1, and 4 produce a NTX*NPX by NTY*NPY pixel image; scheme 3 produces a (2/3)NTX*NPX by (2/3)NTY*NPY image). Scheme 3 requires that NPX and NPY be divisible by 3. Schemes 2 and 4 require that NPX and NPY be divisible by 2.
  Images can be previewed using scheme 1 for greater speed, and re-rendered with anti-aliasing scheme 4 with no change in the output image size. No changes to NTX, NTY, NPX, NPY are required in this case.
BKGND
  Background colour (red, green, and blue components, each in the range 0 to 1).
SHADOW
  T to calculate shadowing within the scene, F to omit shadows
IPHONG
  Phong power (e.g., 25) for specular highlights. A smaller value results in a larger spot.
  IPHONG = 0 disables specular highlighting and all processing of ribbon triangles
STRAIT
  Straight-on (secondary) light source contribution (e.g., 0.15). The primary light source contribution (see also SOURCE below) is given by PRIMAR = 1 - STRAIT.
AMBIEN
  Ambient illumination contribution (e.g., 0.05). Increasing the ambient light will reduce the contrast between shadowed and non-shadowed regions.
SPECLR
  Specular reflection contribution (e.g., 0.25).
  The diffuse reflection quantity is given by DIFFUS = 1 - (AMBIEN+SPECLR). Ambient and diffuse reflections are chromatic, taking on the specified colour of each object, whereas specular reflections are white.
EYEPOS
  You can think of the image produced by render as corresponding to a photograph taken by a camera placed a certain distance away from the objects making up the scene. This distance is controlled by the EYEPOS parameter. EYEPOS = 4 describes a perspective corresponding to a viewing distance 4 times the narrow dimension of the described scene. EYEPOS = 0 disables perspective.
SOURCE
  Primary light source position (e.g., 1 1 1). This is a white light point source at infinite distance in the direction of the vector given (see note on co-ordinate convention below). The secondary light source is always head-on. Only the primary light source casts shadows.
TMAT
  Homogeneous global transformation for input objects, given as a 4x4 matrix on 4 lines just as you would write it if you intended it to be a postfix (suffix) operator. The upper left 3x3 submatrix expresses a pure rotation, the lower left 1x3 submatrix gives a translation, the upper right 3x1 submatrix should be zero (otherwise extra perspective is introduced), and the lower right scalar (h) produces global scaling. Note that the scale factor h ends up being applied as an inverse; i.e. a larger value of h will result in shrinking the objects in the picture. Input coordinate vectors [x y z] are extended with a 1 to make them homogeneous, and then post-multiplied by the entire matrix; i.e. [x' y' z' h'] = [x y z 1][TMAT], then the ultimate co-ordinates are [x'' y'' z''] = (1/h')[x' y' z'].
INMODE
  Object input mode (1, 2, or 3), where mode 1 means that all objects are triangles, mode 2 means that all objects are spheres, and mode 3 means that each object will be preceded by a record containing a single number indicating its type. The Raster3D programs use only mode 3.
INFMT or INFMTS
  Object input format specifier(s). For object input modes 1 and 2, there is just one format specifier INFMT for the corresponding object type, while for mode 3, there are three format specifiers INFMTS on three lines. The first describes the format for a triangle, the second for a sphere, and the third for a cylinder. Each format specifier is either a Fortran format enclosed in parentheses, or a single asterisk to indicate free-format input.

#### SAMPLE HEADER

    My picture. (describes a 1280 x 1024 pixel anti-aliased image)
    80 64 	  tiles in x,y
    16 16     pixels (x,y) per tile
    4 	  anti-aliasing level 4; 3x3->2x2
    0 0 0 	  black background
    F 	  no shadows cast
    25 	  Phong power
    0.25 	  secondary light contribution
    0.05 	  ambient light contribution
    0.25 	  specular reflection component
    4.0 	  eye position
    1 1 1 	  main light source position (from over right shoulder)
    1 0 0 0   view matrix describing input coordinate transformation
    0 1 0 0
    0 0 1 0
    0 0 0 0.6 no translation; enlarge objects in picture by 66% (1/.6)
    3 	  mixed objects
    * 	 (free format triangle and plane descriptors)
    * 	 (free format sphere descriptors)
    * 	 (free format cylinder descriptors)

#### OBJECT TYPES

cylinder (flat) | cylinder (round) | global properties | glow light
isolation | labels | material properties | plane
quadric surface | sphere | surface normals | terminate properties
triangle | vertex colors | vertex transparency |

Object type 1
triangle
  x1, y1, z1, x2, y2, z2, x3, y3, z3, red, green, blue

Object type 2
sphere
  x, y, z, radius, red, green, blue

Object type 3
round-ended cylinder
  x1, y1, z1, R1, x2, y2, z2, R2, red, green, blue
  (R1 is the cylinder radius, R2 is currently ignored).

Object type 4
not used

Object type 5
flat-ended cylinder
  x1, y1, z1, R1, x2, y2, z2, R2, red, green, blue
  (R1 is the cylinder radius, R2 is currently ignored).

Object type 6
plane
  x1, y1, z1, x2, y2, z2, x3, y3, z3, red, green, blue

Object type 7
explicit surface normals at vertices of preceding triangle
  u1, v1, w1, u2, v2, w2, u3, v3, w3
  Explicit vertex normals for preceding triangle object. This object must directly follow the triangle object (see also object type 17). The intended use of this object type is to allow description of arbitrary molecular surfaces in terms of a triangular mesh.

Object type 8
material properties
  These values override the specification of lighting and specular highlighting in the header records, allowing some objects to have different surface properties from the rest. The specified values will apply to all subsequent objects until an object of type 9 is encountered. The parameters are read in free format from the next line of the input stream:
  MPHONG
    override global Phong parameter for specular highlighting
  MSPEC
    override global specular scattering contribution
  SR,SG,SB
    RGB triple specifying color of reflected light (by default all reflections are white), a negative value for any component will default to the base colour component of the object being rendered
  CLRITY
    (floating point value between 0.0 and 1.0) The degree of transparency for this material; 0.0 indicates an opaque surface and 1.0 indicates a purely transparent one.
  OPTS(4)
    four additional fields are reserved for future expansion of the material properties list; these must be present. The first field controls alternative algorithms for rendering transparent objects:
      OPT(1) = 0 render self-occluding portions of a transparent material separately
      OPT(1) = 1 render only the ``top'' surface of transparent material
      OPT(1) = 2 render rear surface of transparent spheres and cylinders
    The last field is non-zero to signal that additional modifier records will follow immediately. Each modifier record must constitute a single line, and OPT(4) states how many of these there will be. For example
      OPT(4) = 2 means that the next two lines contain additional material modifiers
  Object type 8 modifiers
    Additional modifiers to MATERIAL descriptors (type 8) are now supported. Each modifier record must constitute a single line of input, and the total number of such modifier lines must be specified in the final parameter of the MATERIAL record. Modifiers currently supported include SOLID and BACKFACE records, as shown in the following example of a 2- sided material that is solid red on one side and solid blue on the other side:

        # Here is an example of specifying a double sided material
        # The MATERIAL record itself specifies an opaque material with PHONG
        # value to 25 and specular parameters taken from the header records,
        # and says that there are two following modifer lines.
        # The SOLID modifier gives an RGB color triple that over-rides colors on
        # subsequent objects.
        # The BACKFACE modifier specifies a separate RGB color for the other side
        # of this material, and sets the Phong control parameter and specular
        # component of this surface to zero (i.e. it's a matte blue surface).
        8
        20. -1.   1. 1. 1.   0.0    0 0 0 2
        SOLID     1.0 0.0 0.0
        BACKFACE  0.3 0.3 1.0   0 0

    Here is the complete list of modifiers currently available, and their parameters

            SOLID       	RED GREEN BLUE
            BACKFACE    	RED GREEN BLUE MPHONG MSPEC
            FRONTCLIP   	ZFRONT
            BACKCLIP		ZBACK
            BOUNDING_COLOR	RED GREEN BLUE
            BOUNDING_PLANE	BPTYPE X Y Z Xnorm Ynorm Znorm

    See elsewhere for more information on clipping planes and bounding planes.
Object type 9
terminate special properties
  Terminates previous set of special material properties (object type 8) or isolation from TMAT transformation (object type 15). The rest of this record is ignored, so object type 9 may also be used as a comment record. It is preferable, however, to begin pure comments with '#' rather than '9'.

Object types 10-12
Label descriptors
  Version 2.3 introduced preliminary support for labels in a render input file. This has been substantially upgraded in version 2.4j. Object types 10, 11, and 12 are used to specify labels. The current implementation of label handling is not done in render, however, but rather in a separate program called r3dtops. The executable shell script label3d will automatically feed an input file containing labels through render, r3dtops, ghostscript and ImageMagick to yield a final image containing both the renderered molecular graphics objects and the specified labels. Here is an example:

              # Force the label coordinates to be interpreted as screen coords
              # (obviously you wouldn't do this if you want the label to get the
              # same translation/rotation/scaling as other objects do)
              15
              # Choose a font
              10
              "Times-Italic" 12. "Center-align"
              # specifiy a label
              11
              0.0 0.45 0.0       1.0 0.0 0.0
              I am a red title centered at the top of the image
              # Terminate isolation from coordinate transformation
              9

  Object type 10

        "Font specifier" size  "alignment"

    Legal fonts specifiers are subject to the details of label processing implementation. In the context of label3d/r3dtops/ghostscript processing,
    fontname is any PostScript font name recogized by ghostscript,
    size is the font size in points (assuming eventual printing at 300 dpi),
    alignment is either "Right-align", "Left-align", "Center-align", or "Offset" (only the first character is checked).
    The default is "Times-Bold" 10 "Left-align".

  Object type 11
    [XYZ] [RGB]
    Label text

    (see r3dtops for details of label text processing and special characters.

  Object type 12
    reserved (single line of text)

  (If you are developing a higher-level application that will pass labels to Raster3D for rendering, please contact me so that we can make sure the protocols are compatible -EAM).

Object type 13
Glow light source
  This is a colored, non-shadowing, light source with finite [x y z] coordinates and a limited range of illumination. Control parameters are read in free format from a single line of input following the line specifying the object type.
  GLOWSRC(3)
    [x y z] coordinates of light source
  GLOWRAD
    limiting radius of light source (see GOPT)
  GLOW
    fractional contribution (0.0 - 1.0) of glow light to total lighting model
  GOPT
    (integer 0/1/2/3/...) - controls functional form in which limiting radius is applied [under development]
  GPHONG
    Phong parameter controlling specular highlights from glow light source
  GLOWCOL(3)
    RGB triple specifying color of glow light source

Object type 14
quadric surface
  x, y, z, limiting_radius, red, green, blue, A, B, C, D, E, F, G, H, I, J
  Quadric surfaces include spheres, cones, ellipsoids, paraboloids, and hyperboloids. The motivation for this code was to allow rendering thermal ellipsoids for atoms, so the other shapes have not been extensively tested. A quadric surface is described by 10 parameters (A ... J). Although these parameters are sufficient to describe a quadric surface located anywhere, for efficiency during rendering it is also useful to know the center and a bounding sphere. So by convention we require that (A...J) describe a surface centered at the origin, and add additional parameters x, y, z to add a translation component. Therefore a quadric surface descriptor to render has the 17 parameters listed above.

  The surface itself is the set of points for which Q(x,y,z) = 0 where

  Q(x,y,z) = Ax2 + By2 + Cz2 + 2Dxy + 2Eyz + 2Fzx + 2Gx + 2Hy + 2Iz + J

  Points further from the origin (prior to translation!) than the limiting radius are not rendered.

Object type 15
begin isolation from TMAT transformation
  Objects following this descriptor are interpreted as being in an absolute coordinate system centered at the origin and having unit extent in X, Y, and Z. If the image is square, the coordinates run from -0.5 to +0.5 on both X and Y. If the image is rectangular, coordinates run from -0.5 to +0.5 on the shorter dimension. The rotation and translation described by the TMAT matrix is not applied. This isolation from TMAT applies to subsequent objects until an object of type 9 is encountered.

  The coordinate system used following object type 19 is similar except that the horizontal and vertical scales are treated separately, so the the point [-.5,+.5] is always at the top left corner. In both figures below the blue cross is drawn at coordinates [+0.5,+0.3].

  Coordinate system defined by object 15 | Coordinate system defined by object 19

Object type 16
Global properties
  Object type 16 is always followed by a single record that affects the rendering of the entire scene. The only global properties supported at the moment are listed below. FOG allows depth-cueing using either a linear or an exponential model of fog density. A record simply consisting of the keyword FOG will produce reasonable depth-cueing (linear decrease in intensity front closest object to farthest object). If you need to control the depth-cueing indepently from the specific rendered objects in a scene (i.e. to keep the depth-cueing consistent between frames of an animation) then you should specify explicit values for fogfront, fogback and fogden.

      FOG        fogtype fogfront fogback fogden

  fogtype
    0 = linear multiplier = fogden * (fogfront - Z) / (fogfront - fogback)
    1 = exponential multiplier = 1. - exp( -fogden * (fogfront - Z) / (fogfront - fogback) )
  fogfront
    0 = Z coord of front object, else fraction of front clipping plane
  fogback
    0 = Z coord of back object, else fraction of rear clipping plane
  fogden
    (see equations for linear and exponential models controlled by fogtype); fogden=0.0 will default to some reasonable value

      BACKCLIP   zback

  zback
    Z coord of rear clipping plane for all objects; in original units of original coordinate system, but relative to the center of the transformed coordinate system. That means if you are working in PDB coordinates, then everything more than zback Angstroms behind the center is clipped.

      FRONTCLIP  zfront

  zfront
    Z coord of front clipping plane for all objects; in original units of original coordinate system, but relative to the center of the transformed coordinate system. That means if you are working in PDB coordinates, then everything more than zfront Angstroms in front of the center is clipped.

      ROTATION	Matrix

  Matrix
    3x3 rotation matrix applied by post-multiplication after the coordinate transformation in TMAT. This is the transpose of the equivalent rotation if it were specified in TMAT. It applies to all following coordinates in the input stream.

      TRANSLATION	X Y Z

  X Y Z
    3 element translation applied after the coordinate transformation in TMAT. It applies to all following coordinates in the input stream.

Object type 17
explicit coloring at vertices of preceding triangle or cylinder
  R1 G1 B1 R2 G2 B2 R3 G3 B3
  Normally a triangle is colored uniformly in the color specified by the RGB triple in the TRIANGLE record itself. Using this additional object, however, you can specify a separate color for each vertex of the triangle. Points in the interior of the triangle are colored by interpolation using the vertex colors. This is commonly used in conjunction with explicit vertex normals (object type 7) to describe a smooth surface in terms of a triangular mesh. In this case the component triangles of the surface are described by three successive objects of types 1, 7, and 17. (The ordering 1, 17, 7 is also acceptable).

  As of version 2.4j this mechanism may also be used to interpolate colors along the length of a cylinder. In this case the third RGB triple is ignored.

Object type 18
explicit transparency at vertices of preceding object
  Trans1 Trans2 Trans3
  Normally an object is transparent only if it belongs to a trasparent material. Using this additional object, however, you can specify a separate degree of transparency at each vertex of an object. The transparency at points in the interior of the object are then determined by interpolation. All three values (Trans1 Trans2 Trans3) are required; Trans3 is ignored for a cylinder, Trans2 and Trans3 are both ignored for a sphere.

Object type 19
begin isolation from TMAT transformation
  Similar to Object type 15, except that the coordinate scale along both x and y always runs from -0.5 to +0.5, regardless of the aspect ratio of the rendered image.

Object type 0
force end of input stream (optional)
  Further records in input file will not be read.

#### COMMENTS

At any point in the input stream to render where an object descriptor would be legal, it is also legal to insert a line beginning with the `#' character. In this case the line is ignored, and may be used as a comment. Earlier versions of the program recommended using object type 9 as a comment delimiter, but this has the potential disadvantage of prematurely terminating the scope of a special material.

#### FILE INDIRECTION

At any point in the input stream to render where an object descriptor would be legal, it is also legal to insert a line beginning with `@'. In this case the remainder of the line is interpreted as the name of a file from which further input is taken. This mechanism makes it possible to re-use standard objects in multiple rendered scenes, e.g. a set of bounding planes or standard definitions of material properties. When input from this level of file indirection is terminated by encountering an object descriptor of type 0, control returns to the previous input stream. Multiple levels of file indirection are possible.

The requested file is first searched for relative to the current directory. If this search fails, the file is searched for relative to the directory specified by the environmental variable R3D_LIB. Typically this would be set via a command such as

    csh/tcsh:    setenv R3D_LIB /usr/local/src/raster3d/materials
    sh/ksh:      R3D_LIB=/usr/local/src/raster3d/materials; export R3D_LIB

#### SAMPLE INPUT DATA FOLLOWING HEADER

The following records describe a single red triangle and a single blue sphere. The blue sphere is affected by whatever material descriptor is in the file material1.r3d

    1
    -.1 0. 0.     .1 0. 0.     0. -.2 0.5         1.0 0.0 0.0
    @material1.r3d
    2
    0.3 0.3 0.0         0.1                       0.0 0.0 1.0
    9 End material1
    0

#### ERROR MESSAGES

Possible shadowing error NSXMAX = xxx
  This is usually caused by an object which extends far out of the field of view, for example a plane surface. In most cases the shadowing "error" refers to a shadow which lies outside of the image entirely. However, if your image does in fact contain missing or truncated shadows you can overcome this problem by re-compiling the render program with larger values of NSX and NSY as indicated by the error message.

#### INCREASING THE ARRAY SIZES IN RENDER:

If you are creating images of very large proteins, or if you are rendering surfaces with many facets, then you may fill the storage arrays in render. If so you will get an error message something like

    	STOP 1234 **** too many objects - increase MAXOBJ and recompile

The parameters which you may need to increase are contained in the file parameters.incl:

    *     Maximum number of objects (was 7500)
          PARAMETER (MAXOBJ = 25000)
    *
    *     Array elements available for object details
          PARAMETER (MAXDET = 250 000, MAXSDT = 250 000)
    *
    *     Array elements available for sorted lists ("short" lists)
          PARAMETER (MAXSHR = 150 000, MAXSSL = 150 000)

You can use the normal3d utility to calculate how many objects and object details are needed for your picture. The sorted list sizes are harder to calculate in advance, but the render program itself should indicate how much space would be required to complete a picture which it cannot currently handle.

Increase the appropriate PARAMETER values by editing paramters.incl, and recompile the render and normal3d programs by typing "make all".

#### AUTHORS

Originally written by David J. Bacon. Extensions, revisions, and modifications by Ethan A Merritt.

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