Worm Screw

[Peter]

Deleted

[JRS]

Peter,

I tried to convert your example to SB/SDL and the SB RAD() function errors when getting a value range of -254. (first iteration value for a - i) I'm surprised that O2 allows a negative value for RAD().

[Charles Pegge]

This is what you may dream of, after eating too much plum pudding.  


Yes, negative degs and rads are okay with the FPU trig, but should of course, be modulated to avoid building up huge values.

[JRS]

Using your Radians() function. The SB SDL Draw_FillCircle() function is seg faulting on the call.    I changed the radius (i) to a hard coded 30 and it drew a filled circle. The value of 255 causes the seg. fault. Maybe the SDL_draw library doesn't like drawing off the screen surface.

Note: *super (screen surface) is handled internally as a global variable.

Draw a filled circle with center x0,y0 and radius r.

void Draw_FillCircle(SDL_Surface *super,
                     Sint16 x0, Sint16 y0, Uint16 r,
                     Uint32 color);

Code: [Select]

DECLARE SUB Window ALIAS "SB_Window" LIB "sdl"
DECLARE SUB CLS ALIAS "SB_CLS" LIB "sdl"
DECLARE SUB RGB ALIAS "SB_RGB" LIB "sdl"
DECLARE SUB WaitKey ALIAS "SB_WaitKey" LIB "sdl"
DECLARE SUB Draw_FillCircle ALIAS "SB_Draw_FillCircle" LIB "sdl"
DECLARE SUB UpdateRect ALIAS "SB_UpdateRect" LIB "sdl"

Function Radians(radius)
    Radians = radius*pi/180
End Function

Window 640,480, "Worm Screw"

FOR a = 1 TO 360 STEP 5
  CLS(RGB(0,0,255))
  FOR i = 255 TO 1 STEP -1
PRINT Radians(a-i),"\n"
    Draw_FillCircle(200+SIN(Radians(a-i))*40, 120+COS(Radians(a-i))*40, i, RGB(i, i, i))
    Draw_FillCircle(200+COS(Radians(a-i))*40, 120+SIN(Radians(-a-i))*40, i, RGB(i, i, i))
    Draw_FillCircle(200+SIN(Radians(a-i))*40, 120+COS(Radians(a-i))*40, i, RGB(i, i, i))
  NEXT
  UpdateRect
NEXT
WaitKey

jrs@laptop:~/sb/sb22/sdl$ scriba wormscrew.sb
-4.433136e+00
Segmentation fault (core dumped)
jrs@laptop:~/sb/sb22/sdl$

If I wrap the X,Y positions with an INT(), it still seg faults.

Code: [Select]

 FOR i = 255 TO 1 STEP -1
PRINT INT(200+SIN(Radians(a-i))*40),"\n"
PRINT INT(120+COS(Radians(a-i))*40),"\n"
    Draw_FillCircle(INT(200+SIN(Radians(a-i))*40), INT(120+COS(Radians(a-i))*40), i, RGB(i, i, i))
    Draw_FillCircle(INT(200+COS(Radians(a-i))*40), INT(120+SIN(Radians(-a-i))*40), i, RGB(i, i, i))
    Draw_FillCircle(INT(200+SIN(Radians(a-i))*40), INT(120+COS(Radians(a-i))*40), i, RGB(i, i, i))
  NEXT

jrs@laptop:~/sb/sb22/sdl$ scriba wormscrew.sb
238
108
Segmentation fault (core dumped)
jrs@laptop:~/sb/sb22/sdl$

[JRS]

I just ran your example under O2 to see what it is suppose to look like and the X,Y positions I'm getting aren't even close. It could be the COS/SIN functions. With negative values being used I don't know where to start. Anyways I have waste too much time on this already and attached the screen shot of it running under O2 under Wine.



.

[Charles Pegge]

Adjusting negative angles to positive:

Code: [Select]

include "sw.inc"
Window 640,480,1
sys a1,a2


while Key(27)=0

For a=1 to 360 step 5
Cls sw_blue

For i=255 to 1 step -1
    a1=a-i
    a2=-a-i
    while a1<0 : a1+=360 : wend
    while a2<0 : a2+=360 : wend
    FillCircle 200+sin(Rad(a1))*40,120+cos(Rad(a1))*40,i, RGB i, i, i
    FillCircle 200+cos(Rad(a1))*40,120+sin(Rad(a2))*40,i,RGB i, i, i
    FillCircle 200+sin(Rad(a1))*40,120+cos(Rad(a1))*40,i, RGB i, i, i
Next

DoEvents
Sync
Next

Wend
CloseWindow


[JRS]

Still can't get it to work. (seg. fault on Draw_FillCircle)