Drive a tank around the screen

[TBMan]

I've been playing around with rotating points and rectangles. I wanted to try rotating a bitmap and I succeeded this morning. I even managed to get the background to redraw. Here's the code. I don't know what I will do with this, but maybe combining with some sort of acceleration factor would be interesting.

Code: Pascal  [Select][+][-]

1. program rotatetank3;
2. {
3.  version 3
4.  
5.  Rotates a 32x32 tile with 0 as the transparent color
6.  
7.  Press Q or q or esc to quit.
8.  
9.  Keypad controls rotation and movement
10.  + = clockwise rotation
11.  - = counterclockwise rotation
12.  
13.       7 8 9
14.       4 5 6
15.       1 2 3
16.  The tank will rotate to direction prior to movement
17.  if not already in that orientation
18.  
19.  There isn't any screen range checking done. PTCgraph clips by default
20. }
21.  
22.  
23. uses
24.   ptccrt,
25.   ptcgraph,
26.   Math;
27.  
28. const
29.   MaxCol = 31;
30.  
31. type
32.   MapIconType = array[0..maxcol, 0..maxcol] of byte;
33.  
34. const
35.  
36.  
37.  
38.   desert01: MapIconType = ((2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
39.     2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2),
40.     (2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2),
41.     (2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2),
42.     (2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 26, 2, 2, 2, 2, 26, 2, 2, 2, 2, 2, 2, 22, 2, 22, 2, 2, 2, 2, 2),
43.     (2, 2, 2, 2, 2, 2, 2, 29, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2),
44.     (2, 2, 2, 2, 2, 26, 29, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 22, 2, 2, 2, 2),
45.     (2, 2, 2, 2, 2, 112, 23, 23, 23, 2, 2, 2, 2, 2, 2, 2, 2, 29, 2, 26, 29, 29, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2),
46.     (2, 2, 2, 2, 26, 29, 26, 2, 2, 2, 2, 2, 2, 2, 2, 29, 29, 29, 24, 2, 2, 29, 29, 112, 29, 2, 2, 2, 2, 2, 2, 2),
47.     (2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 24, 26, 24, 24, 24, 2, 2, 26, 24, 24, 2, 2, 2, 2, 2, 2, 2),
48.     (2, 2, 2, 2, 23, 26, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 24, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2),
49.     (2, 2, 2, 2, 23, 2, 2, 2, 2, 2, 22, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2),
50.     (2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2),
51.     (2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2),
52.     (2, 2, 2, 2, 2, 2, 2, 22, 2, 2, 2, 2, 26, 2, 2, 2, 2, 2, 2, 2, 2, 2, 29, 29, 29, 2, 2, 2, 2, 2, 2, 2),
53.     (2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 26, 111, 2, 2, 112, 29, 2, 2, 2, 2, 2),
54.     (2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 26, 2, 2, 2, 2, 111, 29, 2, 2, 22, 22, 29, 2, 2, 2, 2, 2),
55.     (2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 22, 2, 2, 19, 2, 2, 2, 2, 22, 29, 112, 29, 2, 2, 2),
56.     (2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 26, 22, 22, 22, 2, 2, 2),
57.     (2, 2, 2, 2, 2, 2, 2, 2, 2, 23, 23, 2, 2, 29, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2),
58.     (2, 2, 2, 2, 2, 2, 2, 23, 2, 2, 2, 2, 2, 29, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 26),
59.     (2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 19, 19, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2),
60.     (2, 2, 2, 2, 2, 2, 26, 2, 2, 2, 2, 2, 2, 19, 26, 22, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2),
61.     (2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 22, 2, 2, 2, 2, 2, 2, 2, 2, 2),
62.     (2, 2, 2, 26, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2),
63.     (2, 2, 2, 2, 2, 2, 2, 2, 2, 29, 22, 26, 22, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 22, 2, 2, 26, 2, 2),
64.     (2, 2, 2, 2, 29, 29, 2, 2, 2, 112, 19, 26, 29, 22, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2),
65.     (2, 2, 29, 112, 22, 19, 19, 2, 29, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2),
66.     (2, 2, 19, 2, 2, 2, 2, 2, 2, 2, 2, 111, 2, 2, 2, 2, 2, 2, 2, 2, 2, 22, 2, 112, 29, 112, 29, 2, 2, 2, 2, 2),
67.     (2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 113, 29, 2, 2, 2, 2, 29, 2, 2, 2, 2),
68.     (2, 2, 2, 2, 22, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 22, 22, 2, 29, 2, 2, 2),
69.     (2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 22, 2, 2, 2, 2, 2, 29, 22, 22, 2, 2, 22, 2, 112, 2, 2, 2),
70.     (2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2));
71.  
72.  
73.  
74.   TheTank: MapIconType = ((0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
75.     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0),
76.     (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
77.     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0),
78.     (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 41, 41, 0, 0, 0,
79.     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0),
80.     (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 26, 26, 0, 0, 0,
81.     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0),
82.     (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 26, 26, 0, 0, 0,
83.     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0),
84.     (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 26, 26, 0, 0, 0,
85.     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0),
86.     (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 26, 26, 0, 0, 0,
87.     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0),
88.     (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 20, 20, 20, 20, 26, 26, 20, 20,
89.     20, 20, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0),
90.     (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 20, 20, 190, 190, 190, 26, 26, 190,
91.     190, 190, 20, 20, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0),
92.     (0, 0, 0, 0, 0, 0, 0, 0, 0, 20, 190, 190, 190, 190, 190, 26, 26,
93.     190, 190, 190, 190, 190, 20, 0, 0, 0, 0, 0, 0, 0, 0, 0),
94.     (0, 0, 0, 0, 0, 0, 0, 0, 0, 20, 190, 190, 190, 190, 190, 26, 26,
95.     190, 190, 190, 190, 190, 20, 0, 0, 0, 0, 0, 0, 0, 0, 0),
96.     (0, 0, 0, 0, 0, 0, 0, 0, 0, 20, 190, 190, 190, 190, 190, 26, 26,
97.     190, 190, 190, 190, 190, 20, 0, 0, 0, 0, 0, 0, 0, 0, 0),
98.     (0, 0, 0, 0, 0, 0, 0, 0, 0, 20, 190, 190, 190, 190, 21, 26, 26,
99.     21, 190, 190, 190, 190, 20, 0, 0, 0, 0, 0, 0, 0, 0, 0),
100.     (0, 0, 0, 0, 0, 0, 0, 0, 0, 20, 190, 190, 190, 21, 23, 23, 23,
101.     23, 21, 190, 190, 190, 20, 0, 0, 0, 0, 0, 0, 0, 0, 0),
102.     (0, 0, 0, 0, 0, 0, 0, 0, 0, 20, 190, 190, 21, 23, 23, 23, 23, 23,
103.     23, 21, 190, 190, 20, 0, 0, 0, 0, 0, 0, 0, 0, 0),
104.     (0, 0, 0, 0, 0, 0, 0, 0, 0, 20, 190, 190, 21, 23, 1, 1, 1, 1, 23,
105.     21, 190, 190, 20, 0, 0, 0, 0, 0, 0, 0, 0, 0),
106.     (0, 0, 0, 0, 0, 0, 0, 0, 0, 20, 190, 190, 21, 23, 1, 1, 1, 1, 23,
107.     21, 190, 190, 20, 0, 0, 0, 0, 0, 0, 0, 0, 0),
108.     (0, 0, 0, 0, 0, 0, 0, 0, 0, 20, 190, 190, 21, 23, 1, 1, 1, 1, 23,
109.     21, 190, 190, 20, 0, 0, 0, 0, 0, 0, 0, 0, 0),
110.     (0, 0, 0, 0, 0, 0, 0, 0, 0, 20, 190, 190, 21, 23, 1, 1, 1, 1, 23,
111.     21, 190, 190, 20, 0, 0, 0, 0, 0, 0, 0, 0, 0),
112.     (0, 0, 0, 0, 0, 0, 0, 0, 0, 20, 190, 190, 21, 23, 23, 23, 23, 23,
113.     23, 21, 190, 190, 20, 0, 0, 0, 0, 0, 0, 0, 0, 0),
114.     (0, 0, 0, 0, 0, 0, 0, 0, 0, 20, 190, 190, 190, 21, 21, 21, 21,
115.     21, 21, 190, 190, 190, 20, 0, 0, 0, 0, 0, 0, 0, 0, 0),
116.     (0, 0, 0, 0, 0, 0, 0, 0, 0, 20, 190, 190, 190, 190, 190, 190, 190,
117.     190, 190, 190, 190, 190, 20, 0, 0, 0, 0, 0, 0, 0, 0, 0),
118.     (0, 0, 0, 0, 0, 0, 0, 0, 0, 20, 190, 190, 190, 190, 190, 190, 190,
119.     190, 190, 190, 190, 190, 20, 0, 0, 0, 0, 0, 0, 0, 0, 0),
120.     (0, 0, 0, 0, 0, 0, 0, 0, 0, 20, 190, 190, 190, 190, 190, 190, 190,
121.     190, 190, 190, 190, 190, 20, 0, 0, 0, 0, 0, 0, 0, 0, 0),
122.     (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 20, 20, 20, 20, 20, 20, 20, 20,
123.     20, 20, 20, 20, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0),
124.     (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 20, 20, 20, 20, 20, 20, 20, 20,
125.     20, 20, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0),
126.     (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 20, 20, 20, 20, 20, 20, 20, 20,
127.     20, 20, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0),
128.     (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
129.     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0),
130.     (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
131.     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0),
132.     (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
133.     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0),
134.     (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
135.     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0),
136.     (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
137.     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0));
138.  
139.  
140.  
141. type
142.  
143.   TSinglePoint = record
144.     x, y: single;
145.   end;
146.  
147.   linedata = record
148.     P: Tsinglepoint;
149.     color: byte;
150.   end;
151.  
152.   matrixType = array[0..maxcol, 0..maxcol] of linedata;
153.  
154. var
155.   I: integer;
156.   ch: char;
157.   lastdegree: integer;
158.  
159.   cx, cy: integer;     // center x and center y
160.   b: MatrixType;
161.   gmode, gdriver: smallint;
162.  
163.  
164.   procedure SetUpTank(x, y: integer);
165.   var
166.     rr, cc: integer;
167.   begin
168.     // setup initial tank coord matrix
169.     for rr := 0 to maxcol do
170.     begin
171.       for cc := 0 to maxcol do
172.       begin
173.         b[rr, cc].color := TheTank[rr, cc];
174.         b[rr, cc].p.x := x + cc;
175.         b[rr, cc].p.y := y + rr;
176.       end;
177.     end;
178.  
179.     cx := X + 16;   // x + 1/2 matrix width
180.     cy := y + 16;   // y + 1/2 matrix depth
181.  
182.   end;
183.  
184.   procedure drawcell(xx, yy: integer);
185.   var
186.     startx, rr, cc: integer;
187.   begin
188.     startx := xx;
189.     for rr := 0 to maxcol do
190.     begin
191.       xx := startX;
192.       for cc := 0 to maxcol do
193.       begin
194.         putpixel(xx, yy, desert01[rr, cc]);
195.         Inc(xx);
196.       end;
197.       Inc(yy);
198.     end;
199.   end;
200.  
201.  
202.   procedure rotatepoint(var P: Tsinglepoint; degrees, centerx, centerY: float);
203.   var
204.     newx, newy, angle: float;
205.     cx, cy, y, x: single;
206.   begin
207.     angle := degTorad(degrees);
208.     cx := centerx;
209.     cy := centery;
210.     x := p.x;
211.     y := p.y;
212.     x := x - cx;
213.     Y := y - cy;
214.     newx := (x * cos(angle)) - (y * sin(angle));
215.     newy := (x * sin(angle)) + (y * cos(angle));
216.     newx := newx + cx;
217.     newy := newy + cy;
218.     p.x := newx;
219.     p.y := newy;
220.   end;
221.  
222.   procedure moveobject(var M: MatrixType; Xc, Yc: integer);
223.   var
224.     r, c: integer;
225.   begin
226.     for r := 0 to maxcol do
227.       for c := 0 to maxcol do
228.       begin
229.         M[r, c].p.x := M[r, c].p.x + Xc;
230.         M[r, c].p.Y := M[r, c].p.Y + Yc;
231.       end;
232.   end;
233.  
234.   procedure rotateobject(var M: Matrixtype; Degrees, CenterX, CenterY: integer);
235.   var
236.  
237.     r, c: integer;
238.     Row, Column: integer;
239.   begin
240.     for r := 0 to maxcol do
241.       for c := 0 to maxcol do
242.       begin
243.         rotatepoint(M[r, c].p, degrees, centerx, centery);
244.         Column := round(M[r, c].p.x) mod (maxcol + 1);  // map x,y to background tile pixel
245.         Row := round(m[r, c].p.y) mod (maxcol + 1);
246.  
247.         // redraw background
248.         putpixel(round(m[r, c].p.x), round(m[r, c].p.y), desert01[Row, Column]);
249.  
250.         //overlay tank on screen
251.         if m[r, c].color <> 0 then
252.           putpixel(round(M[r, c].p.x), round(m[r, c].p.y), m[r, c].color);
253.       end;
254.   end;
255.  
256.  
257.   procedure showobject(M: MatrixType);
258.   var
259.     r, c: integer;
260.   begin
261.     for r := 0 to maxcol do
262.       for c := 0 to maxcol do
263.         if m[r, c].color <> 0 then
264.           putpixel(round(M[r, c].p.x), round(m[r, c].p.y), m[r, c].color);
265.   end;
266.  
267.  
268.   procedure DrawBackground;
269.   var
270.     ScreenX, ScreenY: integer;
271.     r, c: integer;
272.   begin
273.     screenY := 0;
274.     for r := 0 to 5 do
275.     begin
276.       screenx := 0;
277.       for c := 0 to 8 do
278.       begin
279.         drawcell(screenx, screeny);
280.         Inc(screenx, maxcol + 1);
281.       end;
282.       Inc(screeny, maxcol + 1);
283.     end;
284.   end;
285.  
286.  
287. begin
288.  
289.   gdriver := vesa;  // this is for my system - check documentation for use of initgraph
290.  
291.   Gmode := installusermode(320, 200, 256, 1, 8000, 6000);
292.   WindowTitle := 'Tank Rotation';
293.   initgraph(gdriver, gmode, '');
294.  
295.   SetupTank(160, 128);
296.  
297.   DrawBackground;
298.  
299.  
300.   lastdegree := 0;
301.   ShowObject(b);
302.  
303.   repeat
304.     i := 0;
305.     ch := readkey;
306.  
307.  
308.     case ch of
309.       '-': i := -1;      // counter clockwise
310.       '+': i := 1;       // clockwise
311.       '3': begin
312.         if lastdegree <> 135 then
313.         begin
314.           if lastdegree > 135 then i := -1;
315.           if lastdegree < 135 then i := 1;
316.           if lastdegree > 315 then   // 316 to 360
317.           begin
318.             i := 1;
319.             repeat
320.               rotateobject(b, i, cx, cy);
321.               LastDegree := lastDegree + i;
322.               delay(10);
323.             until lastdegree = 360;
324.             lastdegree := 0;
325.           end;
326.           repeat
327.             rotateobject(b, i, cx, cy);
328.             LastDegree := lastDegree + i;
329.             delay(10);
330.           until lastdegree = 135;
331.         end;
332.         Inc(cx);
333.         Inc(cy);
334.         i := 0;
335.         moveobject(b, 1, 1);
336.       end;
337.       '1': begin
338.         if lastdegree <> 225 then
339.         begin
340.           if lastdegree = 0 then lastdegree := 360;
341.           if lastdegree > 225 then i := -1
342.           else
343.             i := 1;
344.           if lastdegree <= 45 then
345.           begin
346.             i := -1;
347.             repeat
348.               rotateobject(b, i, cx, cy);
349.               LastDegree := lastDegree + i;
350.               delay(10);
351.             until lastdegree = 0;
352.             i := -1;
353.             lastdegree := 360;
354.           end;
355.           repeat
356.             rotateobject(b, i, cx, cy);
357.             LastDegree := lastDegree + i;
358.             delay(10);
359.           until lastdegree = 225;
360.         end
361.         else
362.  
363.           i := 0;
364.         Dec(cx);
365.         Inc(cy);
366.         moveobject(b, -1, 1);
367.       end;
368.       '9': begin
369.         if lastdegree <> 45 then
370.         begin
371.           if lastdegree < 45 then i := 1;
372.           if (lastdegree > 45) and (lastdegree <= 225) then
373.             i := -1;
374.           if lastdegree > 225 then
375.           begin
376.             i := 1;
377.             repeat
378.               rotateobject(b, i, cx, cy);
379.               LastDegree := lastDegree + i;
380.               delay(10);
381.             until lastdegree = 360;
382.             lastdegree := 0;
383.             // i := 1;
384.           end;
385.  
386.           repeat
387.             rotateobject(b, i, cx, cy);
388.             LastDegree := lastDegree + i;
389.             delay(10);
390.           until lastdegree = 45;
391.           ;
392.         end;
393.         Inc(cx);
394.         Dec(cy);
395.         I := 0;
396.         moveobject(b, 1, -1);
397.       end;
398.  
399.       '7': begin
400.         if lastdegree = 0 then lastdegree := 360;
401.         if lastdegree <= 90 then lastdegree := 360 + lastdegree;
402.         if lastdegree <> 315 then
403.         begin
404.           if (lastdegree > 315) then
405.             i := -1
406.           else
407.             i := 1;
408.           repeat
409.             rotateobject(b, i, cx, cy);
410.             LastDegree := lastDegree + i;
411.             delay(10);
412.           until (lastdegree = 315);
413.         end;
414.         i := 0;
415.         Dec(cx);
416.         Dec(cy);
417.         moveobject(b, -1, -1);
418.       end;
419.       '8': begin
420.         // rotate to face position
421.         if (lastdegree <> 0) and (lastdegree <> 360) then
422.         begin
423.           if lastdegree > 180 then i := 1
424.           else
425.             i := -1;
426.           repeat
427.             rotateobject(b, i, cx, cy);
428.             LastDegree := lastDegree + i;
429.             delay(10);
430.           until (lastdegree = 0) or (lastdegree = 360);
431.         end;
432.         Dec(cy);
433.         moveobject(b, 0, -1);
434.         i := 0;
435.       end;
436.       '2': begin
437.         if (lastdegree <> 180) then
438.         begin
439.           if lastdegree > 180 then i := -1
440.           else
441.             i := 1;
442.           repeat
443.             rotateobject(b, i, cx, cy);
444.             LastDegree := lastDegree + i;
445.             delay(10);
446.           until (lastdegree = 180);
447.         end;
448.         Inc(cy);
449.         moveobject(b, 0, 1);
450.         i := 0;
451.       end;
452.       '4': begin
453.         if lastdegree <> 270 then
454.         begin
455.           if lastdegree < 180 then lastdegree := 360 + lastdegree;
456.           if lastdegree > 270 then i := -1
457.           else
458.             i := 1;
459.  
460.           repeat
461.             rotateobject(b, i, cx, cy);
462.             LastDegree := lastDegree + i;
463.             delay(10);
464.           until (lastdegree = 270);
465.         end;
466.         Dec(cx);
467.         moveobject(b, -1, 0);
468.         i := 0;
469.       end;
470.       '6': begin
471.         if lastdegree <> 90 then
472.         begin
473.           if lastdegree > 90 then i := -1
474.           else
475.             i := 1;
476.           repeat
477.             rotateobject(b, i, cx, cy);
478.             LastDegree := lastDegree + i;
479.             delay(10);
480.           until (lastdegree = 90);
481.         end;
482.         i := 0;
483.         Inc(cx);
484.         moveobject(b, 1, 0);
485.       end;
486.     end;
487.     lastdegree := lastdegree + i;
488.     if LastDegree < 1 then lastdegree := 360;
489.     if lastdegree >= 360 then lastdegree := 0;
490.  
491.     RotateObject(b, i, cx, cy);
492.  
493.     while keypressed do readkey;  // eat up extra keypresses
494.  
495.  
496.   until (ch = 'q') or (ch = 'Q') or (ch = chr(27));
497.  
498.   closegraph;
499. end.
500.  
501.  
502.  

[Boleeman]

Not a Tank but:

Came across a car simulator here: https://github.com/GuvaCode/mini_projects/tree/main/miniprojects/Parken

Demo shows how to implement a chain of "vehicles" that are controlled by a single force.


Also attached are 3 misc opensource Tank Game Sources in Delphi (from github)
Perhaps might be able to get some ideas from these.