Appendix A
Implementation Notes

wire4	4D Wireframe Display Program	wire4-101.tar.gz wire4-101.zip wire4data.tar.gz wire4data.zip
ray4	4D Raytracer	ray4-131.tar.gz ray4-131.zip
r4toiff	Ray4 to Interchange File Format (IFF) Image	Included in Ray4 Package
r4tosgi	Ray4 to SGI Display	Included in Ray4 Package

The wire4 Program

The wire4 program runs on the Silicon Graphics Iris 3130 workstation and uses the Silicon Graphics GL display language. The input file specifies the following data:

• 3D Viewing Parameters: From, To, Up, View-Angle
• 4D Viewing Parameters: From, To, Up, Over, View-Angle
• Vertex List
• Edge List
• Edge Color Palette
• Depthcue Parameters: Minimum & Maximum Distance
• Depthcue Parameters: Near & Far Colors, Depthcue Levels

wire4 reads the input file and displays the wireframe with the initial viewing parameters. Since only the viewpoints are rotated, the 4D and 3D distances from the from-point to the to-point are constant. The user has interactive control over the following:

• Rotation in 3D (3 Planes)
• Rotation in 4D (6 Planes)
• 4D Projection Type (Parallel or Perspective)
• 3D Projection Type (Parallel or Perspective)
• Depthcue On/Off
• 3D Projection Cube Display On/Off

The ray4 Program

ray4 runs on both the Commodore Amiga and most Unix platforms. Since the output is sent to a file, this program is device independent.

The input file contains the following information:

• Global Ambient Light
• Background Color
• Maximum Raytrace Depth
• 4D Viewing Parameters:
  • From Point,
  • To Point,
  • Up Vector,
  • Over Vector,
  • Viewing-Angle
• Light Sources:
  • Point,
  • Directional
• Attribute Descriptions
  • Ambient Color,
  • Diffuse Color,
  • Specular Color,
  • Transparent Color,
  • Phong Specular Exponent,
  • Index of Refraction,
  • Reflection
• Object Definitions
  • Hyperspheres,
  • Tetrahedrons,
  • Parallelepipeds

In addition to the scene description, ray4 takes the following command-line arguments which govern the resolution of the output image:

• Aspect Ratios (X:Y:Z)
• Image Resolution (X:Y:Z)
• Scan Range (Xmin-Xmax:Ymin-Ymax:Zmin-Zmax)
• Scene Description Filename
• Output Image Filename