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coolgirl97

Thu Jun 06, 2013 8:37 am


getting a ball to bounce inside a rotating cube??

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hey... i was given this assignment where i have a box that needs to rotate in all direction when pressing the arrow keys. There needs to be a ball moving inside the box as well... 

i've got the box to rotate, and tried to get the ball to bounce around... but i think there's something wrong with my coding... because it is not working.. 

can u please have a look below, and help?? thank you so much!! 

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%getting the cube 
setscreen ("graphics:1280,1080") 


%Variable for Colour 
var box, background : int 

%Variable for Size 
var S : real 

%Perspective Related Variables 
var theta, phi, psi : real 

%Location Related Variables 
var x_cm, y_cm : real 

%Cube Related Variables 
var cube_x, cube_y, cube_z, vort_x, vort_y, vort_z, p_x, p_y : array 1 .. 8 of real 

%--------------------------------------------------------------------------------------------- 

const DELTA_TIME := 1 
const TIME_DELAY := 10 
const DELTA_THETA := 0.1 
const DELTA_PHI := 0.1 
const DELTA_PSI := 0.1 

background := 0 
box := 7 
S := 200 

const ZV := 1500 

var ch : string (1) 

x_cm := 640 
y_cm := 600 

phi := 0 
psi := 0 
theta := 300 

var t : real 

const L := 75 
const w := 20 
t := 0 

%--------------------------------------------------------------------------------------------- 

cube_x (1) := +S 
cube_y (1) := +S 
cube_z (1) := +S 

cube_x (2) := -S 
cube_y (2) := -S 
cube_z (2) := -S 

cube_x (3) := -S 
cube_y (3) := +S 
cube_z (3) := +S 

cube_x (4) := +S 
cube_y (4) := -S 
cube_z (4) := -S 

cube_x (5) := -S 
cube_y (5) := -S 
cube_z (5) := +S 

cube_x (6) := +S 
cube_y (6) := +S 
cube_z (6) := -S 

cube_x (7) := +S 
cube_y (7) := -S 
cube_z (7) := +S 

cube_x (8) := -S 
cube_y (8) := +S 
cube_z (8) := -S 

%--------------------------------------------------------------------------------------------- 

Draw.FillBox (0, 0, maxx, maxy, background) 

%--------------------------------------------------------------------------------------------- 

%Rotative Formula 
loop 

for i : 1 .. 8 
vort_x (i) := (cos (theta) * cos (phi) * cos (psi) - sin (phi) * sin (psi)) * cube_x (i) - 
(cos (theta) * cos (phi) * sin (psi) + sin (phi) * cos (psi)) * cube_y (i) + 
sin (theta) * cos (phi) * cube_z (i) 
vort_y (i) := (cos (theta) * sin (phi) * cos (psi) + cos (phi) * sin (psi)) * cube_x (i) - 
(cos (theta) * sin (phi) * sin (psi) - cos (phi) * cos (psi)) * cube_y (i) + 
sin (theta) * sin (phi) * cube_z (i) 
vort_z (i) := -sin (theta) * cos (psi) * cube_x (i) + 
sin (theta) * sin (psi) * cube_y (i) + 
cos (theta) * cube_z (i) 
end for 

for i : 1 .. 8 
p_x (i) := vort_x (i) / (1 - vort_z (i) / ZV) 
p_y (i) := vort_y (i) / (1 - vort_z (i) / ZV) 
end for 

%--------------------------------------------------------------------------------------------- 

%Cube Illustration 
drawline (round (x_cm + p_x (1)), round (y_cm + p_y (1)), round (x_cm + p_x (3)), round (y_cm + p_y (3)), box) 
drawline (round (x_cm + p_x (1)), round (y_cm + p_y (1)), round (x_cm + p_x (6)), round (y_cm + p_y (6)), box) 
drawline (round (x_cm + p_x (1)), round (y_cm + p_y (1)), round (x_cm + p_x (7)), round (y_cm + p_y (7)), box) 
drawline (round (x_cm + p_x (2)), round (y_cm + p_y (2)), round (x_cm + p_x (4)), round (y_cm + p_y (4)), box) 
drawline (round (x_cm + p_x (2)), round (y_cm + p_y (2)), round (x_cm + p_x (5)), round (y_cm + p_y (5)), box) 
drawline (round (x_cm + p_x (2)), round (y_cm + p_y (2)), round (x_cm + p_x (8)), round (y_cm + p_y (8)), box) 
drawline (round (x_cm + p_x (3)), round (y_cm + p_y (3)), round (x_cm + p_x (5)), round (y_cm + p_y (5)), box) 
drawline (round (x_cm + p_x (3)), round (y_cm + p_y (3)), round (x_cm + p_x (8)), round (y_cm + p_y (8)), box) 
drawline (round (x_cm + p_x (4)), round (y_cm + p_y (4)), round (x_cm + p_x (6)), round (y_cm + p_y (6)), box) 
drawline (round (x_cm + p_x (4)), round (y_cm + p_y (4)), round (x_cm + p_x (7)), round (y_cm + p_y (7)), box) 
drawline (round (x_cm + p_x (5)), round (y_cm + p_y (5)), round (x_cm + p_x (7)), round (y_cm + p_y (7)), box) 
drawline (round (x_cm + p_x (6)), round (y_cm + p_y (6)), round (x_cm + p_x (8)), round (y_cm + p_y (8)), box) 

delay (TIME_DELAY) 

drawline (round (x_cm + p_x (1)), round (y_cm + p_y (1)), round (x_cm + p_x (3)), round (y_cm + p_y (3)), white) 
drawline (round (x_cm + p_x (1)), round (y_cm + p_y (1)), round (x_cm + p_x (6)), round (y_cm + p_y (6)), white) 
drawline (round (x_cm + p_x (1)), round (y_cm + p_y (1)), round (x_cm + p_x (7)), round (y_cm + p_y (7)), white) 
drawline (round (x_cm + p_x (2)), round (y_cm + p_y (2)), round (x_cm + p_x (4)), round (y_cm + p_y (4)), white) 
drawline (round (x_cm + p_x (2)), round (y_cm + p_y (2)), round (x_cm + p_x (5)), round (y_cm + p_y (5)), white) 
drawline (round (x_cm + p_x (2)), round (y_cm + p_y (2)), round (x_cm + p_x (8)), round (y_cm + p_y (8)), white) 
drawline (round (x_cm + p_x (3)), round (y_cm + p_y (3)), round (x_cm + p_x (5)), round (y_cm + p_y (5)), white) 
drawline (round (x_cm + p_x (3)), round (y_cm + p_y (3)), round (x_cm + p_x (8)), round (y_cm + p_y (8)), white) 
drawline (round (x_cm + p_x (4)), round (y_cm + p_y (4)), round (x_cm + p_x (6)), round (y_cm + p_y (6)), white) 
drawline (round (x_cm + p_x (4)), round (y_cm + p_y (4)), round (x_cm + p_x (7)), round (y_cm + p_y (7)), white) 
drawline (round (x_cm + p_x (5)), round (y_cm + p_y (5)), round (x_cm + p_x (7)), round (y_cm + p_y (7)), white) 
drawline (round (x_cm + p_x (6)), round (y_cm + p_y (6)), round (x_cm + p_x (8)), round (y_cm + p_y (8)), white) 

%--------------------------------------------------------------------------------------------- 

% Manipulating the Cube 

if hasch then 
getch (ch) 

%Turn Upwards 

if ch = chr (200) then 
psi := psi + DELTA_PSI 

%Turn Downwards 

elsif ch = chr (208) then 
psi := psi - DELTA_PSI 

%Turn Right 

elsif ch = chr (205) then 
theta := theta + DELTA_THETA 

%Turn Left 

elsif ch = chr (203) then 
theta := theta - DELTA_THETA 


end if 

end if 

% ______________________________________________________________________________________________________________________ 

const DELTATIME := 0.10 
const TIMEDELAY := 10 
var x, y, z, x0, y0, z0, v0x, v0y, v0z, T : real 

const x_right_boundary := 1100 
const x_left_boundary := 250 
const y_top_boundary := 1000 
const y_bottom_boundary := 250 

const RADIUS := 0.025 

const DEPTH_SCALE := 0.1 

x0 := 100 
y0 := 100 
z0 := 100 
v0x := 30 
v0y := 10 
v0z := 20 
T := 0 
x := x0 + v0x * T 
y := y0 + v0y * T 
z := z0 + v0z * T 

drawoval (645, 600, 20, 20, black) 

delay (TIME_DELAY) 

drawfilloval (645, 600, 20, 20, white) 
T := T + 1 

if x > x_right_boundary then 
x0 := 2 * x_right_boundary - x 
y0 := y 
v0x := -v0x 
T := 0 
end if 

if x < x_left_boundary then 
x0 := 2 * x_left_boundary - x 
v0x := -v0x 
y0 := y 
T := 0 
end if 

if y > y_top_boundary then 
y0 := 2 * y_top_boundary - y 
v0y := -v0y 
x0 := x 
T := 0 
end if 

if y < y_bottom_boundary then 
y0 := 2 * y_bottom_boundary - y 
v0y := -v0y 
x0 := x 
T := 0 
end if 
end loop


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MihaiG

Thu Jun 06, 2013 8:04 pm


Re: getting a ball to bounce inside a rotating cube??

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Cool program, before we go ahead and address the main issue you're having lets talk about some basic code practices.
In your main loop you have (roughly lines 170) a bunch of variable/constant declaration inside a loop.. does this seem right? We can move those outside the loop.

I usually keep all my parameters at the very top so i can easily adjust them!

Second of all, try to refrain from using getch, it only allows for the detection of one key intut at a time, i like using Input.KeyDown 
In the code below 

[code]
f x > x_right_boundary then 
x0 := 2 * x_right_boundary - x 
y0 := y 
v0x := -v0x 
T := 0 
end if 

if x < x_left_boundary then 
x0 := 2 * x_left_boundary - x 
v0x := -v0x 
y0 := y 
T := 0 
end if 

if y > y_top_boundary then 
y0 := 2 * y_top_boundary - y 
v0y := -v0y 
x0 := x 
T := 0 
end if 

if y < y_bottom_boundary then 
y0 := 2 * y_bottom_boundary - y 
v0y := -v0y 
x0 := x 
T := 0 
end if 
[/code]

You seem to be forgetting what happens if it hits the z boundry!

Your drawing code can be placed in a seperate procedure so your code can be more readable.  

From a quick look. I think you need to read up on planes in R3 (3d space). Your if statements try to assume that even if we rotate the cube each side has a fixed value for x,y,z while in reality, they have a wide range of values. Ie. If the ball hits the bottom of the cube near the front the x could be 5 while if it hits it at the back it could be -10.

This is a tough endeavor, your concept for rotating in 3d is well done. I might suggest trying to bounce the ball of a square rotating in R2 space. Once you understand the concept youll see it's not a matter of if x < a certain value. It's if a point interesects with a plane in R3.

If you can show me an example of a rotating square in 2d and a ball bouncing around i will guide and give you some further tips!


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scii

Tue Aug 13, 2013 12:42 am


Re: getting a ball to bounce inside a rotating cube??

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You can search it in google