© Richard Ashbery


Section # Contents
1 Website Purpose
Hardware/Software Requirements
Important Hardware Note
Screen Mode
2 Getting Started with Graphics
3 Creating Geometric Shapes With PLOT Command
4 Shapes and Patterns
5 Other Graphic Designs
6 Animated Patterns
7 3D Patterns
8 Appendix
9 Acknowledgements


  • Use contents table to navigate the relevant links.
  • Section 1 contains short paragraphs covering hardware and software details.
  • Section 2 and 3 (italics) explain how the various geometric shapes are created. Read these if you are unfamiliar with RISC OS BASIC graphic keywords.
  • Section 4-7 implement ideas outlined in the two previous sections to create some interesting shapes.
  • Sections greyed out are being written.
  • The appendix contains all PLOT commands including offsets.
  • Some sections contain links which return you to the contents table.

5-Point Deltoid

Simple Colour Animation Applied to a Segment Routine

1. Introduction

Website Purpose

The website is intended for any user who is interested in creating geometric art by programming. RISC OS BASIC is fast and rendering quality good with current ARM based hardware. Inspiration for these graphic programs comes from the excellent collection of 55 BBC Micro books from the Drag 'N Drop editor, Chris Dewhurst ( http://www.dragdrop.co.uk ). Much of the material is still relevant to current versions of RISC OS. Changes to the original programs were necessary to ensure compatibility with Raspberry Pi/Hi Def monitors. All programs are single tasking running outside the desktop.

Hardware/Software Requirements

Important Hardware Note

The graphics processor in the Raspberry Pi switches from the desktop to running a BASIC program instantly. Delays can occur with other hardware like R-Comp Interactive's ARMX6 but will still run.

Screen Mode

All program examples use a screen resolution of 1920 x 1080. This equates to a full HD widescreen monitor commonly available and giving the best graphic performance for the price. The MODE command commonly used is: MODE 1920,1080,32. The last parameter being the pixel resolution. Monitors with larger resolutions can be used but MODE and co-ordinates would have to be altered in the program examples.


The screen co-ordinates are specified in OS units. The co-ordinates are referenced from the bottom left corner of the screen (x = 0, y = 0). Where the keyword, ORIGIN is used to set the screen centre to 1920,1080 the screen co-ordinates are specified from the screen centre.

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