Modular Renderer

Introduction

The Modular Renderer is a set of C++ classes and functions, which provide a superset of the functionality previously found in the RT raytracer.

This means that now the full C++ language can be at your disposal to help build models for tracing and also for automating the generation of animations. It also opens the door to procedural textures and other advanced features.

Furthermore, MR provides other forms of rendering, such as wire-frame and polygon rendering, in order to provide fast previews etc..

It has the disadvantage that in order to perform raytracing, you have to write a program and compile it. Accordingly MR has a raytracer called RTMR, which is backwardly compatible with RT and implemented using MR.

Features

Raytracing

It provides ray-tracer functionality based on information given in "Computer Graphics, Principles and Practice", by Foley, vanDam, Feiner and Hughes, and Byte magazine. It provides :-

• A class for (x,y,z) vectors, and operations upon them, including addition, subtraction, scalar and vector product, magnitude and rotations around various axes.
• A class representing an (r,g,b) colour triple, including various arithmetic operations.
• Classes supporting 3x3 and 4x4 matrix manipulation.
• A class representing bitmaps loaded from disk and written to from code. Includes a number of methods specifically aimed at providing functionality for 8bpp bitmaps, including line draw, rectangle fill and polygon fill (with or without clipping).
• A class representing 3D textures loaded from disk and written to from code.
• Class representing colours, defined to be a function of a location in space, supporting the use static colours, as well as linear, cylindrical and spherical texture maps.
• A class representing a surface, which includes ambient, diffuse, specular and transmissive colour coefficients, diffuse and specular colours, combined with phong power and refractive index coefficient.
• A CSG shape class which can represent half-planes, bi-planes, spheres, ellipsoids cylinders, elliptical cylinders, cones and elliptical cones and arbitrary quadratics.
• A class representing the viewpoint from which the picture is to be drawn.
• A light class covering the locations and colours of light sources.
• Raytracing functions, supporting various anti-aliasing settings (normal, super-sampled, whitted adaptive super-sampled and unpixelate), various view transformations (normal, wide-angle, tall-angle, fish-eye and user-defined) and various depths of recursion.
• Classes supporting the display of progress during a raytracing operation, including "ignore", display status on stream, and display to Windows window or XWindows window during tracing.

Polygon rendering

Supporting (convex) polygon rendering, there are :-

• Classes for generating polygon operation lists, including the setting of colours, definition of vertexes and definition of polygons constructed from a number of vertexes.
• Methods to render polygon operation lists into 8bpp bitmaps. Exploits functionality of bitmap class mentioned above.
• Helper functions to provide polygon operation lists for common 3D shapes, such as cubiods and elliptical cylinders.

Wire-frame rendering

Supporting wire-frame rendering, there are :-

• Classes for generating wire-frame operation lists, including the setting of colours, definition of vertexes, and definition of edges between vertexes.
• Methods to render wire-frame operation lists into 8bpp bitmaps. Exploits functionality of bitmap class mentioned above.
• Helper functions to provide wire-frame operation lists for common 3D shapes, such as cubiods and elliptical cylinders.

Real time display

To support the real-time display of generated bitmap data are viewer classes which display a bitmap in a Windows window or XWindows window. There are limitations as to the quality of the display on non-24bpp displays. Error-diffusion to a small fixed palette may be employed.

Viewers have a refresh method, that when called make the screen match the contents of the bitmap data.

To help platforms which which a real-time display viewer does not exist, a viewer exists which is given a GBM filename template and an initial value. It will write a bitmap under that name and increment the value. eg: if passed frame%03d.tif,lzw and an initial value of 20, the refresh method will cause frame020.tif, frame021.tif, frame022.tif, .. etc. to be written (with LZW compression).

3D translations and rotations

The classes representing (x,y,z) vector, colours, surfaces, shapes, viewpoints, polygon and wire-frame operations lists, all have methods allowing them to be translated and rotated in 3D space.

Usage

When compiling MR itself :-

• Obtain GBM and if necessary compile it up. Its available from the same place where MR is obtained.
• Copy the platform specific makefile to the main MR directory.
• Edit it so that the GBM variable points to the directory with GBM in it.
• Make any other platform specific modifications (eg: XOPTS may need to be changed on UNIX platforms other than Linux, to reflect where the XWindows libraries are installed).
• Compile up MR if necessary.

When writing a program using MR :-

• #include "mr.h"
• Read and use the headers referred to from mr.h ("use the source Luke"). Look at samples such as RTMR, CUBE and LADYBIRD, available from the same place where MR is obtained.
• Use -Isomedir to ensure the C++ compiler can find mr.h and any nested headers it uses.
• Link with mr.a or mr.lib.
• Use -Isomedir to ensure the C++ compiler can find gbm.h and any nested headers it uses.
• Link with gbm.a or gbm.lib.
• If using the classes which give real-time display of bitmaps, link with gbmerr.a or gbmerr.lib.
• If displaying to Windows, link with user32.lib and gdi32.lib.
• If displaying to XWindows, link with the appropriate XWindows library, typically using -L/usr/X11R6/lib -lX11.

Compilers etc.

I've compiled MR with the IBM xlC++ compiler under AIX, g++ under Linux, and it should compile fine with any ANSI UNIX compiler.

I've also used the IBM VisualAge C/C++ 3.0 compiler for OS/2, with CTC306, CTD302 and CTU304 fixes.

I've used MSVC 6.0 under 32 bit Windows and it works too.

The UNIX makefile relys on GNU make. If you haven't got this, you can use the mpp script on my home page to pre-process the ifdefs and produce a file suitable for your platform.

Public domain declaration

I wrote all this code in my own time on my own equiptment. I hereby place all this code into the public domain. Feel free to do whatever you like with it. No copyright / no royalties / no guarantees / no problem. Caveat Emptor.

Source code

All the source code is folded using Andys Source Code Folding Editor, which should be available from the same place you obtained this package. The source is all highly portable.

The full source to GBM is hopefully available from the same place you obtained this Ray Tracer. GBM is also highly portable.

Obtaining this code

MR, the GBM executables, the GBM source, and Andys Source Code Folding Editor are best obtained via my home page :-

• http://www.nyangau.fsnet.co.uk/.