Geom Format

The "geom" format contains low level geometric primitives, points, lines, facets, etc. The "geom" file consists of a number of lines of printable ascii characters, the first string in each line is the primitive ID. The rest of the line (or lines) contain the data that is different for each primitive. The arguments on each line are separated by any "white" space (fscanf() is my parser). After the last of the required arguments the rest of the current line is considered a comment. At the time of writing the primitives ID's and their required arguments are a follows.

ID	Description	Arguments	Comments
#	Comment		Comments must start with a '#' in the first columns, they extend to the end of the line.
s	Sphere	center(x,y,z), radius, colour(r,g,b)	Spheres should be used sparingly unless the rendering engine explicitly supports them. For example, OpenGL does not and so each sphere becomes a large number of polygons.
st	Textured Sphere	center(x,y,z), radius, colour(r,g,b), texturefilename (tga)
d	Disk	vertex(x,y,z), normal(x,y,z), inner radius, outer radius, colour(r,g,b)
c	Cone	vertex1(x,y,z), vertex2(x,y,z), radius1, radius2, colour(r,g,b)
t	Text	position(x,y,z), right(x,y,z), up(x,y,z), colour(r,g,b), textstring	The text is drawn from a start position, along the right vector, and in the plane of the right-up vector. The size is determined by the right and up vector lengths.
p	Point	vertex(x,y,z), colour(r,g,b)
P	Thick Point	vertex(x,y,z), colour(r,g,b), size	The size is in pixel coordinates, not world coordinates.
i	Illumination (Point light source)	vertex(x,y,z), colour(r,g,b)	There may be limitations on the number of light sources allowed, for example, a maximum of 8 for OpenGL based systems.
l	Line	vertex1(x,y,z), vertex2(x,y,z), colour(r,g,b)
L	Thick Line	vertex1(x,y,z), vertex2(x,y,z), colour(r,g,b), width
lc	Coolour Line	vertex1(x,y,z), vertex2(x,y,z), colour1(r,g,b) colour2(r,g,b)	Colour at each end of the line, blended along the line.
f3	3 vertex facet	vertices[3], colour(r,g,b)	The normal for each vertex is created from the cross product of the three given vertices.
f3n	3 vertex facet With normals	vertices[3], normals[3], colour(r,g,b)
f3c	3 vertex facet With and colours	vertices[3], colour[3]
f3nc	3 vertex facet With normals and colours	vertices[3], normals[3], colour[3]	Each vertex has a normal and colour, this is the general primitive for representing "smooth" objects.
f4	4 vertex facet	vertices[4], colour(r,g,b)	The normal for each vertex is calculated from the cross product of the first 3 vertices. Note that the vertices need not be coplanar but the effects that might occur in such circumstances is undefined. Non planar 4 vertex facets are not recommended.
f4n	4 vertex facet With normals	vertices[4], normals[4], colour(r,g,b)
f4c	4 vertex facet With colours	vertices[4], colour[4]
f4nc	4 vertex facet With normals and colours	vertices[4], normals[4], colour[4]	This is the most general 4 vertex facet for representing smooth objects.
f4t	4 vertex facet With texture	vertices[4], colour, texturefilename (tga), scale, transparency [o,t]	The colour is only used when the object is displayed in a draft or non texture mode (or if the viewer doesn't support texture). The texture scale is between 0 and 1. 1 is for a clamped textures over the whole plane, otherwise the texture will be scaled and tiled over the polygon. The last argument is a flag for transparent or opaque in which case the colour is used internally to create an opaque mask.
m	Marker	type size vertex colour	A non oriented symbol. The size is in world coordinates. The current types are: 0 - tetrahedron 1 - 3D plus 2 - cube 3 - octahedron

Example

# Example geom file, this is a comment
l 0 0 0 1 0 0 1 0 0 red x axis
l 0 0 0 0 1 0 0 0.5 0 green y axis
l 0 0 0 0 0 1 0 0 1 blue z axis
s 0 0 0 0.5 1.0 0.5 0.5 ball
f4 -1 -1 -1   1 -1 -1   1 -1  1   -1 -1  1   0.5 0.5 0.5  bottom face of cube
f4 -1  1 -1   1  1 -1   1  1  1   -1  1  1   0.5 0.5 0.5  top face
f4 -1 -1  1  -1 -1 -1  -1  1 -1   -1  1  1   0.5 0.5 0.5  left face
f4  1 -1  1   1 -1 -1   1  1 -1    1  1  1   0.5 0.5 0.5  right face
f4 -1 -1  1   1 -1  1   1  1  1   -1  1  1   0.5 0.5 0.5  front face
f4 -1 -1 -1   1 -1 -1   1  1 -1   -1  1 -1   0.5 0.5 0.5  back face
f4nc -0 -1.3 1.3 -0 -1.2 1.4 0 -1.3 1.3 0 -1.4 1.2 -1 0 0 -1 0 0 -1 -0.03 0.04 -1 -0.03 0.03 1 0 0 1 0.11 0 1 0.11 0 1 0 0 
f3 -67 27 -53 -67 27 -53 -67 27 -53 1 0 0
f3n -67 27 -53 -67 27 -53 -67 27 -53 0.02 -0.9 -0.2 0.9 -0.3 -0.3 0.5 -0.3 -0.8 1 0 0
p 0 0 0 1 0 0