OpenGL flag

[Petr]

Hi. This is the solution of the flag movement through OpenGL. I suppose this can be done better, and any suggestions and remarks are welcome.
Please Odin to consider whether it would be appropriate to post OpenGL contributions to a special thread in the future. Thank you.

Code: QB64: [Select]

1. posuvMx = .12 'X sinus speed
2. posuvbmx = .32 'Y sinus speed
3.  
4. DIM SHARED z AS SINGLE
5. z = 10
6. MoX = .5
7. MoY = .5
8.  
9. my& = _NEWIMAGE(1024, 768, 32): _FULLSCREEN
10. s& = _LOADIMAGE("czv.png", 32)
11. _SOURCE s&
12.  
13. '_DISPLAYORDER _GLRENDER: ' _SCREENMOVE _MIDDLE  'FAILS if is this uncommented, because screen position create _glOrtho in this case!!!!
14.  
15. TYPE points
16.     R AS _FLOAT
17.     G AS _FLOAT
18.     B AS _FLOAT
19. END TYPE
20.  
21.  
22. DIM SHARED points(1024 * 768) AS points
23. H = _HEIGHT(s&)
24. w = _WIDTH(s&)
25.  
26. FOR yp = 0 TO H - 1 STEP 1
27.     FOR xp = w - 1 TO 0 STEP -1
28.         points(pc).R = _RED32(POINT(xp, yp)) / 256 'for correct color to use in opengl muss be values converted to range 0 - 1 for statement _glColor2f
29.         points(pc).G = _GREEN32(POINT(xp, yp)) / 256
30.         points(pc).B = _BLUE32(POINT(xp, yp)) / 256
31.         pc = pc + 1
32. NEXT xp, yp
33.  
34.  
35.  
36. DO
37.     DO WHILE _MOUSEINPUT
38.  
39.         MoX = _MOUSEX / 2
40.         MoY = _MOUSEY / 4
41.     LOOP
42.     i$ = INKEY$
43.     IF i$ = CHR$(27) THEN END
44.     IF i$ = "z" THEN z = z + .1
45.     IF i$ = "x" THEN z = z - .1
46.     _DONTBLEND
47.     _DEST 0
48.     LOCATE 20, 1: PRINT TIME$
49.     LOCATE 23, 1: PRINT "The flag of the Czech Republic. OpenGL demo by Petr. Use mouse, z or x for zoom."
50.     _DEST my&
51.     _DISPLAY
52. LOOP
53.  
54.  
55. SUB _GL () STATIC
56. SHARED posuvMx, posuvbmx, posuvb, x, y, sinus, posuv, H, w, s&, MoX, MoY
57. REM $CHECKING:OFF
58.  
59. _glMatrixMode _GL_PROJECTION
60. _glLoadIdentity
61. _glOrtho (-w / 2) * z, (w / 2) * z * (2 * MoX), (-H / 3) * z, (H / 3) * (2 * MoY) * z, -1, 1
62. _glEnable _GL_DEPTH_TEST
63.  
64.  
65. _glBegin _GL_POINTS
66. posuv = posuv + posuvMx
67. IF posuv > 1.7 OR posuv < -1.7 THEN posuvMx = posuvMx * -1
68. posuvb = posuvb + posuvbmx
69. IF posuvb > 1.7 OR posuvb < -1.7 THEN posuvbmx = posuvbmx * -1
70.  
71.  
72. pc = 0
73.  
74. _glClear _GL_COLOR_BUFFER_BIT
75. FOR y = 1 TO H
76.     bs = bs - .034
77.     FOR x = 1 TO w
78.         sinus = sinus + .024 'sinus + periode
79.         _glColor3f points(pc).R, points(pc).G, points(pc).B
80.         _glVertex2f H - (x - 0) + SIN(bs) * posuvb * 12, w - y - 0 + SIN(sinus) * 22 * posuv '_RGB32(_RED32(bod&), _GREEN32(bod&), _BLUE32(bod&)) '   cislo urcuje vysku oblouku
81.         pc = pc + 1
82.     NEXT x
83.     sinus = 0
84.     _glClear _GL_COLOR_BUFFER_BIT
85.     _glClear _GL_DEPTH_BUFFER_BIT
86. NEXT y
87. bs = 0
88. _glEnd
89. _glFlush
90.  
91. END SUB
92.  
93.  

[Ashish]

Wow! :O Impressive work! I noticed that the flag failed to follow the mouse. :)
Also, it get shrink near the left & become wide at the right.
I suggest you to use _glTranslatef instead of _glOrtho.
By the way, You have good progress in OpenGL :D

[Petr]

Hi Ashish. I wanted to do the flying flag a long time ago, but only now I made it. For more sophisticated graphics, I will try in future to do the next waveform, which varies with the distance from the end of the flag. OpenGL coordinates -1 0 1 and their origin in the lower right corner, and the idea of the Z axis makes me pretty confused in my head. But it's fun. Mouse reaction - i made it better in next time.
  Thank you for the reaction when no one reaction is going, so I say - is that stupid that no one cares or is it too complicated? If is none reactions, is difficult to judge it.

[STxAxTIC]

Heya Petr,

I like the demo so far. I also had a spot of trouble controlling the view at first, but once I got the hang of it, things were fine. I posted this demo on *.net on July 4th right before it went down, and then again on N54, and also like 5 times in the past around this time of year - which is why we need a good Samples/Archives section... But if you want to study waves through a flag, I recommend having a look my non-gl QB45 code:

https://qb64.org/basbin/5CC7.txt

(Note the flag is not technically fabric, but a stretchy membrane.)

[Petr]

Hi STxAxTIC, thank for the link, this long code muss i studying. Your code is big work! I like it.

[Ashish]

@STxAxTIC
That demo is awesome! :)