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+---- Thread: Accretion Disk (/showthread.php?tid=4530)
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RE: Accretion Disk - Unseen Machine - 03-13-2026
Quote:Nice, ive got a 2004 xp IBM i still use too and happily advocate using old tech for new purposes! However i dont agree that for this program PSet "is good enough" heck when i get my gl 3.3 iteration of this done it'll handle 10 MILLION objects just as fast as Qb64 handles 10 thousand and as such allow for much more detail, realism and in NO way will detract from or impact the original code that has inspired it. Heck i made a version already that had a sun in orbit of the black hole that got eaten and added to the mass and angular momentum...Heck even making this _GL sub and using a 1*1 texture and scaling would not only add the Perspective view it lacks but also allow for vastly more particles and realism such as culling etc...Quote:pset might be slow. but this program is quite good enough! i have a 15-year-old laptop which originally came with windows8. running this under linux/debian.
I dont try to be offensive but have a internal "It can be better" thing that i cannot ignore. Declare Library is there for this very reason, to allow people like ME to still contribute without feeling that we/I am hacking the language I grew up on so please dont criticise me for taking an admittedly AMAZING bit of code and trying to do my best to improve it.
John
Final Pset version : Now with basically everything i know about gravity, local clusters, the blackhole grows and gains angular momentum etc...only thing i havent added is Hawking Radiation
Code: (Select All)
' QB64 - 45-DEGREE ISOMETRIC GALAXY (3D CINEMATIC)
' ---------------------------------------------------------------------------
wd = 1024
ht = 768
SCREEN _NEWIMAGE(wd, ht, 32)
_TITLE "Sagittarius A* - 45 Degree Isometric Projection"
' --- CONSTANTS ---
G = 4.0: M_SagA = 9000: RS = 40
tilt = 0.707 ' Sine of 45 degrees for the isometric tilt
vecs = 22000
DIM Px(vecs), Py(vecs), Pz(vecs), Vx(vecs), Vy(vecs), Vz(vecs), PType(vecs)
' --- INITIALIZE 3D GALAXY ---
FOR i = 0 TO vecs
GOSUB ResetParticle
NEXT i
DO
' Starfield background persistence
LINE (0, 0)-(wd, ht), _RGBA32(0, 0, 0, 45), BF
FOR i = 0 TO vecs
' --- 3D PHYSICS (X, Y, Z) ---
r_3d = SQR(Px(i) * Px(i) + Py(i) * Py(i) + Pz(i) * Pz(i))
IF r_3d < RS THEN
GOSUB ResetParticle
END IF
' Gravity pull toward 0,0,0
mag = (G * M_SagA) / (r_3d * r_3d)
Vx(i) = Vx(i) - (Px(i) / r_3d) * mag
Vy(i) = Vy(i) - (Py(i) / r_3d) * mag
Vz(i) = Vz(i) - (Pz(i) / r_3d) * mag
Px(i) = Px(i) + Vx(i)
Py(i) = Py(i) + Vy(i)
Pz(i) = Pz(i) + Vz(i)
' --- 45 DEGREE ISOMETRIC PROJECTION ---
' We project X and Y, but use Z and Tilt to create the 3D look
sX = (wd / 2) + Px(i)
sY = (ht / 2) + (Py(i) * tilt) - (Pz(i) * tilt)
' --- DEPTH COLORING ---
' Farther stars (negative Py) are dimmer, Closer stars are brighter
depth_fade = 150 + (Py(i) / 4)
IF depth_fade > 255 THEN depth_fade = 255
IF depth_fade < 50 THEN depth_fade = 50
IF sX > 0 AND sX < wd AND sY > 0 AND sY < ht THEN
IF PType(i) = 1 THEN ' Core Stars
PSET (sX, sY), _RGBA32(255, 220, 150, depth_fade)
ELSE ' Spiral Arm Dust
PSET (sX, sY), _RGBA32(100, 150, 255, depth_fade / 2)
END IF
END IF
NEXT i
' --- RENDER THE CORE (SAGITTARIUS A*) ---
' Tilt the event horizon to match the galaxy
FOR r_l = RS TO 0 STEP -2
' Ellipse instead of Circle to simulate the 45-degree tilt
FOR a = 0 TO 6.28 STEP 0.2
ex = (wd / 2) + COS(a) * r_l
ey = (ht / 2) + SIN(a) * r_l * tilt
PSET (ex, ey), _RGB32(0, 0, 0)
NEXT a
NEXT r_l
_DISPLAY
_LIMIT 60
LOOP UNTIL _KEYDOWN(27)
END
ResetParticle:
' Spiral Math with 3D "Bulge"
angle = RND * 6.283
dist = RS + 40 + (RND * 450)
spiral = dist * 0.04
Px(i) = COS(angle + spiral) * dist
Py(i) = SIN(angle + spiral) * dist
' Pz creates the "vertical" thickness of the galaxy (thicker in middle)
Pz(i) = (RND - 0.5) * (RS * 4) * (1 - dist / 500)
v_orb = SQR((G * M_SagA) / dist)
Vx(i) = -SIN(angle + spiral) * v_orb
Vy(i) = COS(angle + spiral) * v_orb
Vz(i) = (RND - 0.5) * 0.1 ' Slight vertical drift
IF dist < RS * 3 THEN PType(i) = 1 ELSE PType(i) = 0
RETURNRE: Accretion Disk - bplus - 03-13-2026
Yes John's is good too! +1
I think I heard awhile back that Line (x,y)-step(0,0) is faster than PSet.
Update: more has been posted I was replying to John's first and what hsiangch_ong said about Pset being slow.
Oh the 2nd post looks like a bad day in Ohio! LOL