Why wait for TV pictures of the next Space Shuttle mission? Kevin Boyd's program for the BBC Model B micro simulates it so realistically that you'll think it's the real thing
Sit back and watch as the U.S. Space Shuttle takes off in a cloud of smoke and launches a satellite into orbit. Then you have a pilot's eye view of the spacecraft coming in to land on a runway etched into salt flats.
My simulation uses 6.5K and runs in Mode 1 on the BBC Model B computer for 117 seconds.
The drawings of the shuttle and booster rockets are as accurate as I could make them. Ceratin things were deliberately left out for the sake of clarity.
The program is split into five sections and each uses three main graphics routines which draw triangles (PROCtri, 1090-1130), rectangles (PROCrect, 1140-1190) and circles (PROCcircle, 1200-1280).
These routines are used a lot, so here is a description of each of them:
PROCtri ... has seven parameters. The first six are three sets of two co-ordinates to define the three points of the triangle and the seventh parameter is a flag. If set to 1 the triangle is filled in, if zero it is not.
PROCrect ... works in the same way to draw a rectangle, starting bottom left.
PROCcircle ... begins with two parameters for the centre of the circle. The next two are the radius and a flag, used as above. The routine uses two arrays, set up in lines 130-140. They hold the SIN and COS values to calculate the circle - much faster than calculating the values each time you call the routine.
How It Works
| 110-140 | produce title page while circle arrays are calculated |
| 150 | set graphics mode (resolution is 320 by 256 in hi-res with four colours, 40 by 32 text) |
| 160-170 | set up sound envelopes |
| 180 | change colour 2 (yellow) to colour 6 (cyan) |
| 190 | cursor off |
| 200-240 | call PROCedures |
| 270-600 | draw fuel tank, booster rockets |
| 610-1080 | draw shuttle |
| 1090-1130 | triangle |
| 1140-1190 | rectangle |
| 1200-1280 | circle |
| 1290-1340 | initial blast of smoke |
| 1350-1430 | ever-widening tower of smoke, move shuttle |
| 1720-1730 | over payload doors |
| 1740-1820 | draw satellite inside payload area, define text window from shuttle to top of screen then scroll satellite to top of screen then scroll satellite to top |
| 1830-1970 | launch satellite out of sight of shuttle, then out of your view |
| 1990 | invert: black to white, white to black |
| 2000-2050 | view of shuttle approaching runway |
| 2060-2140 | shuttle touches down |
This demo was originally published in Home Computing Weekly #39.