DrawInfo

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DrawInfo allows clients to render the mesh object more efficiently through LODs (Levels of Detail). Many associate drawinfo with the ability to create moving objects in a map.

Code

The code must be added to the mesh object.

 drawInfo
   dlist		      # display list for all material sets
   decorative		      # older clients with not see this mesh
   angvel <degrees/sec>       # rotation about initial Z axis
   extents <minX> <minY> <minZ> <maxX> <maxY> <maxZ>
   sphere <x> <y> <z> <radiusSquared>
   corner <v> <n> <t>	      (repeatable)
   vertex 0.0 0.0 0.0	      (repeatable)
   normal 0.0 0.0 0.0	      (repeatable)
   texcoord 0.0 0.0	      (repeatable)
   lod			      (repeatable)
     lengthPerPixel <value>
     matref <name>	      (repeatable)
       dlist		      # display list for this material set
       sphere <x> <y> <z> <radiusSquared>
       points	 0	      (repeatable)
       lines	 0 1	      (repeatable)
       lineloop  0 1	      (repeatable)
       linestrip 0 1	      (repeatable)
       tris	 0 1 2	      (repeatable)
       tristrip  0 1 2	      (repeatable)
       trifan	 0 1 2	      (repeatable)
       quads	 0 1 2 3      (repeatable)
       quadstrip 0 1 2 3      (repeatable)
       polygon	 0 1 2	      (repeatable)
     end  # matref
   end	  # lod
 end	  # drawInfo

Valid parameters for drawinfo are:

dlist requests that the client use display lists to render the object (recommended for meshes that are not overly complicated)
decorative disables drawInfo in older clients
angvel causes the mesh object to spin at the given rate in degrees per second
extents the minimum and maximum x, y, and z point of the mesh to be drawn. This helps with rendering efficiency, meshes whose extents are outside of the point of view will not be drawn.
sphere an imaginary sphere that encompasses all x, y, and z coordinates. Similar to extents, this helps increase rendering efficiency.
vertex if defined within the drawInfo section, the vertices, normals, and texcoords will be used instead of those defined in the mesh
corner (required)a point defined by a vertex, normal, and a texcoord
lod (required)sections that determines which faces/points will be rendered from specific distances (lengthPerPixel)
lengthPerPixel (required)distance from which the points will be rendered, 0 is close, .3 is about as far away as is needed
matref (required)material to use for the faces that follow it.
points description
lines description
lineloop description
linestrip description
tris index numbers of corners that create triangles
tristrip series of points that form a chain of triangles.
trifan a series of points that create triangles that fan out from a single point. That point, usually in the center, is placed first in the series. Trifans are used only in pyramid and cone-shaped meshes.
quads points that create 4-sided mesh planes
quadstrip series of points that create a chain of 4-sided planes. Similarly to tristrips, the series zig-zags between the points, starting in the counter-clockwise direction.
polygon same as quads except for planes of more than 4 sides.


Appearance

DrawInfo is only applied to existing mesh objects. These mesh objects will be altered by DrawInfo parameters.

A common example are spinning objects (angvel parameter in DrawInfo).

LODs can improve framerate as it features substitution of complex mesh objects at given lengthPerPixel steps with more simplistic objects. If the substitution is done decent then it'll be unobtrusive. LODs are used in Louman's Mystic Valley for instance: Shrubbery and trees will change in appearance slightly when viewed from about 200 units away.

Editor Support

DrawInfo support has been added to obj to bzw converters: Modeltool (available through Git) and php-dIMachine.

History

DrawInfo was added (by trepan) in BZFlag version 2.0.4 and is rarely used for anything other than experimental and proof-of-concept maps. Notable exceptions to this are trees in Louman's "Mystic Valley" and "Churchyard" maps, and a more recent practical use of moving drawinfo in Planet MoFo's halloween passion map. Following the creation of tools to generate drawinfo from .obj files, it is getting more frequent use by more experienced map makers.