SLIDE Language Reference

Introduction

SLIDE is a simple ASCII text file language for describing 3D interactive and dynamic environments. SLIDE files normally use the extension .slf for SLIDE format. The SLIDE language employs many of the same conventions as the C programming language. The SLIDE language also uses embedded Tcl code to control the dynamics of scenes.

The following is a reference guide to the SLIDE language. It is useful for getting a quick understanding of the language and for looking up the parameters of SLIDE primitives. For more detail about language constructs consult the SLIDE Language Spec. This document also contains links to the spec on a primitive by primitive basis.

Contents

• SLIDE Basic Syntax
  
  • White Space
  • Comments
  • Data Types
• SLIDE and Tcl/Tk
  
  • SLIDE API
    
• SLIDE Statements
  

  Flag Types	User Annotations	Geometry	Geometry Nodes	Mesh Nodes	CSG Nodes	Non-geometry Nodes	Group Nodes	Rendering
  On/Off LOD Shading Solid Delaunay Voronoi Accuracy Subdivision Projection Light Fog Stencil Ratio	RIB String	surface point controlpoint face	object sphere cylinder cone disk ring torus cyclide bsplinecurve beziercurve polyline crosssection sweep sweepmorph bsplinepatch bezierpatch nurbpatch	mesh convexhull terrain generalface subdivision offset dual	union difference intersection	camera light	arealight group instance scale translate rotate lookat	window viewport fog render

• Tcl Packages
  

SLIDE Basic Syntax

White Space

Spaces, tabs, and new lines are all considered white space in a SLIDE file. One or more white space characters are used to separate tokens in a SLIDE file.

Comments

# This is a line comment

(* This is 
a region
comment *)

(* These (* are (* nested *) *) (* region *) comments *)

(* This will (* cause a nesting ERROR *)

Data Types

SLIDE and Tcl/Tk

Tcl Variables Exported by SLIDE

SLIDE Enumerated Types

• On/Off Type
• LOD Type
• Camera UI Type
• Shading Type
• Solid Type
• Delaunay Type
• Voronoi Type
• Accuracy Type
• Subdivision Type
• Light Type
• Fog Type
• Stencil Type
• Ratio Type

On/Off Type

The On/Off type is the boolean type for SLIDE. This useful for being able to turn on and off different types rendering options and structures. For example, every light path in the render statement can have an On/Off flag which acts as a light switch for that instance of the light. The possible values of the On/Off type are:

The default value for an On/Off flag is normally SLF_ON.

LOD Type

The LOD type defines the quality of the rendering for a subtree. As LOD flags are passed down the scene hierarchy, a node computes the rendering LOD by taking the minimum of its locally defined LOD and the value being passed down by its parent. If a node of the scene hierarchy has an LOD that is less than SLF_FULL then all of its descendants will not be rendered at their full rendering quality. And in the extreme, if a node has LOD SLF_OFF then that entire subtree will not be rendered at all (and the renderer does not need to compute any bounding box information for its descendants). The possible values for the LOD type are:

The default value for a LOD flag is SLF_FULL.

Camera UI Type

The CUI type defines the style of mouse interaction with a render window. Clicking and dragging in windows with different CUI types set performs different modifications to the view. Each style responds differently to clicking and dragging with one of the three mouse buttons; (R)ight, (M)iddle, and (L)eft. The possible values for the CUI type are:

The default value for a CUI flag is SLF_CRYSTAL_BALL.

Shading Type

The Shading type defines how the polygons of a node will be shaded. A node in the scene hierarchy will pass down its local shading value unless that is SLF_INHERIT in which case it will pass along its parent's shading value. The possible values for the Shading type are:

The default value for a Shading flag is SLF_INHERIT.

NOTE: Renders may not support all the shading types in which case they will do the best job possible. The OpenGL SLIDE render does not support Phong shading, so SLF_PHONG gets reduced to SLF_GOURAUD.

Solid Type

The Solid type defines whether to apply back face culling to an atomic node of the scene hierarchy. SLF_SOLID should be used for objects which are closed for rendering efficiency. SLF_HOLLOW should be used for objects which consist of infinitely thin surface pieces which should be visible from both sides. The possible values for the Solid type are:

The default value for a Solid flag is SLF_SOLID.

Delaunay Type

The Delaunay type defines the algorithm which will be used to compute the Delaunay triangulation. The possible values for the Delaunay type are:

The default value for a Delaunay flag is SLF_TERRAIN_DELAUNAY_DIVIDE_AND_CONQUER_ALTERNATING.

Voronoi Type

The Voronoi type defines the algorithm which will be used to compute the Voronoi diagram. The possible values for the Voronoi type are:

The default value for a Voronoi flag is SLF_VORONOI_OFF.

Accuracy Type

The accuracy type defines which technique to use to try to keep numerical accuracy. The possible values for the accuracy type are:

The default value for an accuracy flag is SLF_FLOAT.

Subdivision Type

The subdivision type defines the subdivision algorithm. The possible values for the Subdivision type are:

The default value for a Subdivision flag is SLF_SUBDIVISION_CATMULL_CLARK.

Projection Type

The Projection type defines whether a camera performs a parallel or perspective projection. The possible values for the Projection type are:

The default value for a Projection flag is SLF_PARALLEL.

Light Type

The Light type defines way a SLIDE light works. The possible values for the Light type are:

The default value for a Light flag is SLF_AMBIENT.

Fog Type

The Fog type defines how the fog effect is computed. The possible values for the Fog type are:

The default value for a Fog flag is SLF_LINEAR.

Stencil Type

The Stencil type defines a stencil pattern to be used in the stencil buffer. This is useful for rendering stereo images by interlacing the left and right eye views in the even and odd horizontal scan lines. Some Head Mounted Displays (HMD's) take this format as stereo input. Also red and green images can be rendered interlaced and viewed with 1950's style 3D glasses to create a low cost stereo display. The possible values for the Stencil type are:

The default value for a Stencil flag is SLF_BOTH.

Ratio Type

The Ratio type defines whether the aspect ratio of a window will be preserved under resizing. The aspect ratio of a window is derived from its size field. The possible values of the Ratio type are:

The default value for a Ratio flag is normally SLF_FIXED.

RIB String

surface

point

face

object

sphere

cylinder

cone

torus

cyclide

bsplinepatch

bezierpatch

convexhull

terrain

generalface

subdivision

union

difference

intersection

camera

light

arealight

group

instance

scale

translate

rotate

lookat

window

viewport

fog

render