techno game dev forum

The challenge is to make a computer game more fun even than the hardware game I was given as a Christmas present.

In the hardware game the entire big dipper is enclosed in a transparent sphere clasped in our hands.
We shake and gyrate this sphere so that the ball on the rails of this "Funfare Big Dipper" experiences the dynamic forces that we hope (vainly) will keep it on the rails.
Instead of the "seat-of-the-pants" terrifying sensations of the big dipper we have only the VIEW (our external view) of the ball rolling down the slope and soon leaving the rails! This big dipper has no seat belts nor restraining structures. Only two narrow rails whose spacing and incline vary and whose banking is "all wrong".

The FUN lies in creating a game where the computer provides ONLY the visual feedback required for those of skill to be able to win.
We must manipulate the sphere so the ball rolls down the slopes
1. So it is ALWAYS above the rails (in the gravitational sense)
2. NOT so fast it goes off the rails due to centrifugal force on corners (curved sections)
3. Not so SLOW that it fails to traverse straight sections where the two rails are almost touching.

In the code snippet below I have tried to illustrate these ideas:
A. A pitch, roll, yaw headup display for the HANDS that control the SPHERE
B. A "pilot's view" from atop the ball looking down the track the way the ball is rolling

The twists and turns of the descent seen ahead lets the pilot GUESS what motions of the sphere will all-too-soon be required if the ball is to stay on the rails

We will NOT spoil all the fun by giving too much help from the computer - such as displaying the force currently exerted by each rail.
But we may decide to help with a warning flashing red dot when the force on any rail goes to zero.

Assuming consumate skill from the hands that control the sphere (correcting for all incorrectly-banked turns etc annd successfully controlling speed along the rails) there are TWO situations:
1. The ball is stably supported above rails that appear CONCAVE to it. (bottom of a valley)
2. The ball is supported above rails that appear CONVEX to it (top of a hill)

In case 1 the game CAN be paused, for a breathtaking cuppa: the ball "parked" there at rest
But case 2 is UNSTABLE - the ball is about to plunge down the valley!

OK here is my ATTEMPT at showing a portion of the game (towards its end, when "NOT TOO SLOW" is demanded to reach the goal over a SINGLE rail straight section). Run it in any flavor of BASIC


'@ help guiding a ball down a Roller Coaster
SCREEN 12
WINDOW (-1.5, -1)-(1.5, 1)
PRINT
PRINT "                        Lost contact warning lights"
 
PRINT "         Left rail                                           Right rail"
CIRCLE (-1, .78), .031
CIRCLE (1, .78), .031
LOCATE 24, 1: PRINT "View down track from atop ball";
LOCATE 24, 40
PRINT "Headup display Pitch, Roll, Yaw"
PRINT "                                      rate for hands controling Sphere"
LOCATE 7, 28: PRINT "goal"
CIRCLE (-.8, .2), .5, 14, 1.4, 3.34, 1
CIRCLE (-.745, .195), .5, 14, 1.45, 3.6, 1
LINE (-.68, .632)-(-.5, .632), 4
CIRCLE (-.42, .57), .1, 2

LINE (-.68, .6)-(-.75, .5)
LINE (-1.29, .11)-(-1.2, -.5), 14
LINE (-1.2, .014)-(-.8, -.5), 14
LOCATE 5, 1: PRINT "Too fast"
PRINT "here and"
PRINT "Fall off"
LINE (-1.33, .53)-(-1.23, .4)
LOCATE 9, 16
PRINT "Too SLOW here"
LOCATE 10, 16
PRINT "and fall off"
LOCATE 11, 16
PRINT "one rail only!"
LOCATE 14, 40
PRINT "How to show RATE of roll, pitch, yaw"
LOCATE , 40: PRINT "and control in a way understood!"



Here is an example and a challenge game for you.
Using gravity I have set up 4 equal heavenly bodies to rotate about one another sharing one and the same double figure 8 orbit.

Can you get them to maintain that double-8 orbit?

It should be very easy! - There are only 4 numbers to adjust:
xc(1) = .1306 x-position start
xc(6) = -.0153 y-position start
xc(10) = -6.0005 x-speed start
xc(13) = 1.9245 y=speed start

Adjust these EVER-so-slightly and you may find what I am missing!

I always find the computation errors are too big - the orbit falls apart (beginning in ever-growing fashion)
To begin with all seems fine - but soon your hopes are dashed!

But the SINGLE figure-8 shared orbit (3 stars or planets sharing one orbit) is DIFFERENT - for the laws of gravity forgive and correct the computation errors!
Similarly if you provide a large central "sun" to rotate around, everything works fine.

DEFDBL A-H, K-M, O-Z: DEFINT I-J, N
n = 16: OPTION BASE 1
DIM x(n), xc(n), f(n), c1(n), c2(n), c3(n), c4(n)
GOSUB graphics
m1 = 1#: m2 = 1#: m3 = 1#: m4 = 1
t = 0#
' ** initial positions **
xc(1) = .1306: xc(2) = 0: xc(3) = -xc(1): xc(4) = 0 'x coords
xc(5) = 0#: xc(6) = -.0153#: xc(7) = 0: xc(8) = -xc(6) 'y coords
' ** initial speeds **
xc(9) = 0: xc(10) = -6.0005: xc(11) = 0: xc(12) = -xc(10) 'x vel
xc(13) = 1.9245: xc(15) = -xc(13): xc(16) = 0 'y vel

h = .0000015#

agn:
GOSUB Runge
PSET (xc(1), xc(5)), 12
PSET (xc(2), xc(6)), 9
PSET (xc(3), xc(7)), 15
PSET (xc(4), xc(8)), 13

t = t + h
'IF j = 30000 THEN CLS : j = 0: GOSUB energy
GOTO agn
END


Equations:
d21 = x(2) - x(1): d32 = x(3) - x(2): d43 = x(4) - x(3): d14 = x(1) - x(4)
d13 = x(3) - x(1): d24 = x(4) - x(2)
d65 = x(6) - x(5): d76 = x(7) - x(6): d87 = x(8) - x(7): d58 = x(5) - x(8)
d75 = x(7) - x(5): d86 = x(8) - x(6)
r12 = (d21 ^ 2# + d65 ^ 2#) ^ .5#
r23 = (d32 ^ 2# + d76 ^ 2#) ^ .5#
r34 = (d43 ^ 2# + d87 ^ 2#) ^ .5#
r41 = (d14 ^ 2# + d58 ^ 2#) ^ .5#
r13 = (d13 ^ 2# + d75 ^ 2#) ^ .5#
r24 = (d24 ^ 2# + d86 ^ 2#) ^ .5#
 
p12 = r12 ^ 3#: p23 = r23 ^ 3#: p34 = r34 ^ 3: p41 = r41 ^ 3#
p31 = r13 ^ 3: p24 = r24 ^ 3
f(1) = x(9): f(2) = x(10): f(3) = x(11): f(4) = x(12)
f(5) = x(13): f(6) = x(14): f(7) = x(15): f(8) = x(16)
f(9) = m2 * d21 / p12 + m3 * d13 / p31 - m4 * d14 / p41 'x accn of m1
f(10) = m3 * d32 / p23 + m4 * d24 / p24 - m1 * d21 / p12 '          m2
f(11) = m4 * d43 / p34 - m1 * d13 / p31 - m2 * d32 / p23 '          m3
f(12) = m1 * d14 / p41 - m2 * d24 / p24 - m3 * d43 / p34 '          m4
f(13) = m2 * d65 / p12 + m3 * d75 / p31 - m4 * d58 / p41 'y         m1
f(14) = m3 * d76 / p23 + m4 * d86 / p24 - m1 * d65 / p12 '          m2
f(15) = m4 * d87 / p34 - m1 * d75 / p31 - m2 * d76 / p23 '          m3
f(16) = m1 * d58 / p41 - m2 * d86 / p24 - m3 * d87 / p34 '          m4
RETURN

Runge:
FOR i = 1 TO n: x(i) = xc(i): NEXT
GOSUB Equations
FOR i = 1 TO n: c1(i) = h * f(i): NEXT
FOR i = 1 TO n: x(i) = xc(i) + c1(i) / 2#: NEXT
GOSUB Equations
FOR i = 1 TO n: c2(i) = h * f(i): NEXT
FOR i = 1 TO n: x(i) = xc(i) + c2(i) / 2#: NEXT
GOSUB Equations
FOR i = 1 TO n: c3(i) = h * f(i): NEXT
FOR i = 1 TO n: x(i) = xc(i) + c3(i): NEXT
GOSUB Equations
FOR i = 1 TO n: c4(i) = h * f(i): NEXT
FOR i = 1 TO n
    xc(i) = xc(i) + (c1(i) + 2# * c2(i) + 2# * c3(i) + c4(i)) / 6#
NEXT
RETURN

graphics:
SCREEN 12
PAINT (1, 1), 9
xm = .15: ym = .15
VIEW (180, 17)-(595, 460), 0, 13
WINDOW (-xm, -ym)-(xm, ym)
xg = .134
FOR xi = -xg TO xg + .001 STEP xg / 20
    LINE (-xm, xi)-(xm, xi), 8: LINE (xi, -ym)-(xi, ym), 8
NEXT xi
LINE (-xm, 0)-(xm, 0), 9: LINE (0, -ym)-(0, ym), 9

RETURN

energy:
' ** Is energy conserved? **
kin1 = .5# * m1 * (xc(7) ^ 2# + xc(10) ^ 2#)
kin2 = .5# * m2 * (xc(8) ^ 2# + xc(11) ^ 2#)
kin3 = .5# * m3 * (xc(9) ^ 2# + xc(12) ^ 2#)
pot = -(m1 * m2 / r12 + m2 * m3 / r23 + m3 * m1 / r13)
energy = kin1 + kin2 + kin3 + pot
LOCATE 21, 1: PRINT "Energy"
LOCATE 22, 1: PRINT energy
LOCATE 17, 7: PRINT "             "
LOCATE 17, 1: PRINT "Time ="; CSNG(t)
RETURN


I just joined, in relation to qb64, the best resources are at
 http://www.qb64.net
and
http://qb64.net/wiki/index.php?title=Main_Page
Some tutorials are available at the same wiki,
http://qb64.net/wiki/index.php?title=QB64_Tutorials 
 Well anyway good luck with your forum.
from a qb64user

QB64user, Welcome, good to have your help!
Please tell us more of your ideas on tutorials.

I am not sure "Tutorials" is the best word to use - newbies are easily discxouraged if they suffered from "not the best teachig"!

We can call them "Getting Started" or "How I wrote my first xxxx program"

Put yourself in their shoes - remember how you felt about things when you first began and explain in simple English (keeping away from jargon and technical terms if you can!). Take everything by example and in SIMPLE steps.

Yes qb64 is excellent (and a free download).
Especially it is excellent (fast and powerful with GREAT music via _SNDRAW) - eventually.
That is AFTER you get your program working!
But QB64 has no way to warn you AT ONCE of all the errors you make!
On the other hand QBASIC lets you ASK wht values all the numbers have reached EVERY TIME it stops working. You just type ? and the name like this for example
? N
and it tells you.

This makes QBAS far easier to lean on - and your finished program then runs seamlessly and much faster on qb64
So start with QBAS (Quickbasic) and switch to QB64 once you get it working!
BIll Gates tried to "torpedo" QBAS in his bodge fix SP2.
On many computers he succeeded - but not on mine. So perhaps not on yours.
So give QBAS a try and see if it works on your computer.