Anti-Aliasing Bezier Curves

Hi!

I've made a program that draws bezier curves and now i was to anti-alias them!

Does anyone know how to do this?

Find an antialiased line drawing function, and use that to draw the curve =).

Z.

were can i find that?

Google.

Z.

ok....i've found alot of things but i dont know how to use it in my app! :(

cant anyone give me a sub routine for anti-aliased lines?

if you find one please let me know. I've had no such luck anti aliasing my bresenham line. There are anti aliasing algorithms out there though. I just haven't seen many written in VB. Most are written in C or another language like that.

Code:

Private Sub AntiAliasedLine(ByVal x1 As Single, ByVal y1 As Single, ByVal x2 As Single, ByVal y2 As Single) Dim spx As Single, epx As Single Dim spy As Single, epy As Single Dim ax As Double, bx As Double, cx As Double, dx As Double Dim ay As Double, by As Double, cy As Double, dy As Double Dim ex As Double, ey As Double Dim mp5 As Single, pp5 As Single Dim rex As Integer, rey As Integer Dim trz As Double, tri As Double Dim lwris As Double, lwrun As Double Dim zsl As Single Dim slope As Double, lsope As Double Dim midx As Double, midy As Double Dim sl2 As Single Dim distanc1 As Double, distanc2 As Double Dim diagonal As Boolean Dim a As Single Dim st As Integer Dim one As Single Static sr(0 To 128) As Single Static firstrun As Boolean Dim w As Byte If Not firstrun Then 'Initialize some things sr(0) = 0: sr(128) = 0.5 For w = 1 To 127 sr(w) = (w / 128) ^ 2 / 2 Next w 'Initialize an array which maps a curve of 256 Single values pow = 1 / (1 + shape / 255) For w = 1 To 254 gs(w) = (w / 255) ^ pow Next w: gs(0) = 0: gs(255) = 1 firstrun = 1: End If If x1 < x2 Then epy = y2: epx = x2 spy = y1: spx = x1 Else spy = y2: spx = x2 epy = y1: epx = x1: End If If epx = spx Or epy = spy Then diagonal = 0 If epy > spy Then st = 1 Else: st = -1: End If Else: slope = (epy - spy) / (epx - spx): lsope = -1 / slope diagonal = 1: End If midx = 0.5 * lsope: midy = 0.5 * slope sl2 = slope * slope: one = 1 / Sqr(1 + sl2) lwris = 1 - (one - Abs(slope) + sl2 * one) lwrun = lwris * Abs(lsope) distanc1 = 0.5 * one distanc2 = slope * distanc1 ax = spx - distanc1 - distanc2 ay = spy + distanc1 - distanc2 bx = epx + distanc1 - distanc2 by = epy + distanc1 + distanc2 cx = epx + distanc1 + distanc2 cy = epy - distanc1 + distanc2 dx = spx - distanc1 + distanc2 dy = spy - distanc1 - distanc2 one = 255 * (1 - 0.5 * lwris * lwrun) If diagonal Then If slope > 0 Then If slope <= 1 Then ey# = slope# * (Round(ax#) + 1.5 - ax#) + ay# rey% = Round(ey#): mp5! = rey% - 0.5: pp5! = mp5! + 1 tri# = pp5! - lwris#: trz = pp5! - slope#: zsl! = mp5! - midy For ex# = Round(ax#) + 1.5 To Round(bx#) - 1.5 Step 1 If ey# > tri# Then Call DrawPixel(Int(ex# + 1), rey%, gs(one!)) Else If ey# > trz Then Call DrawPixel(Int(ex# + 1), rey%, gs(255 * (1 + lsope# * sr(Int((pp5! - ey#) * 128))))) Else: Call DrawPixel(Int(ex# + 1), rey%, gs(255 * (ey# - zsl!))): End If End If If ey# > trz Then pp5! = pp5! + 1: tri# = tri# + 1: trz = trz + 1 zsl! = zsl! + 1: rey% = rey% + 1: End If ey = ey# + slope: Next ex# ey# = cy# - slope# * (cx# - Round(cx#) + 1.5) rey% = Round(ey#): mp5! = rey% - 0.5: pp5! = mp5! + 1: zsl! = pp5! + midy tri# = mp5! + lwris: trz = mp5! + slope For ex# = Round(cx#) - 1.5 To Round(dx#) + 1.5 Step -1 If ey# > tri# Then If ey# > trz Then Call DrawPixel(Int(ex#), rey%, gs(255 * (zsl! - ey#))) Else: Call DrawPixel(Int(ex#), rey%, gs(255 * (1 + lsope# * sr(Int((ey# - mp5!) * 128))))) End If End If If ey# < trz Then mp5! = mp5! - 1: tri# = tri# - 1: trz = trz - 1 zsl! = zsl! - 1: rey% = rey% - 1: End If ey# = ey# - slope: Next ex# ex# = cx# + lsope * (cy# - Round(cy#) + 0.5) For ey# = Round(cy#) - 0.5 To Round(dy#) + 1.5 Step -1 rex% = Round(ex#) Call DrawPixel(rex%, Int(ey#), gs(255 * (slope# * sr(Int((ex# - rex% + 0.5) * 128))))) ex# = ex# + lsope#: Next ey# ex# = ax# - lsope# * (Round(ay#) + 0.5 - ay#) For ey# = Round(ay) + 0.5 To Round(by) - 0.5 Step 1 rex% = Round(ex#) Call DrawPixel(rex%, Int(ey# + 1), gs(255 * (slope# * sr(Int((rex% + 0.5 - ex#) * 128))))) ex# = ex# - lsope#: Next ey# Else ex# = dx# - lsope# * (Round(dy#) + 1.5 - dy#): rex% = Round(ex#): mp5! = rex% - 0.5 pp5! = mp5! + 1: tri# = pp5! - lwrun: trz = pp5! + lsope: zsl! = mp5! + midx For ey# = Round(dy#) + 1.5 To Round(cy#) - 0.5 Step 1 If ex# > tri# Then Call DrawPixel(rex%, Int(ey# + 1), gs(one!)) Else If ex# > trz Then Call DrawPixel(rex%, Int(ey# + 1), gs(255 * (1 - slope * sr(Int((pp5! - ex#) * 128))))) Else: Call DrawPixel(rex%, Int(ey# + 1), gs(255 * (ex# - zsl!))): End If End If If ex# > trz Then tri# = tri# + 1: trz = trz + 1: pp5! = pp5! + 1 zsl! = zsl! + 1: rex% = rex% + 1: End If ex# = ex# - lsope#: Next ey# ex# = bx# + lsope# * (by# - Round(by#) + 0.5): rex% = Round(ex#): mp5! = rex% - 0.5 pp5! = mp5! + 1: tri# = mp5! + lwrun: trz = mp5! - lsope: zsl! = pp5! - midx# For ey# = Round(by#) - 0.5 To Round(ay#) + 1.5 Step -1 If ex# > tri# Then If ex# < trz Then Call DrawPixel(rex%, Int(ey#), gs(255 * (1 - slope# * sr(Int((ex# - mp5!) * 128))))) Else: Call DrawPixel(rex%, Int(ey#), gs(255 * (zsl! - ex#))): End If End If If ex# < trz Then tri# = tri# - 1: trz = trz - 1: mp5! = mp5! - 1 rex% = rex% - 1: zsl! = zsl! - 1: End If ex# = ex# + lsope#: Next ey# ey# = dy# + slope# * (Round(dx#) + 0.5 - dx#) For ex# = Round(dx#) + 0.5 To Round(cx#) - 1.5 Step 1 rey% = Round(ey#) Call DrawPixel(Int(ex# + 1), rey%, gs(255 * (-lsope# * sr(Int((rey% + 0.5 - ey#) * 128))))) ey# = ey# + slope#: Next ex# ey# = ay# + slope# * (Round(ax#) + 1.5 - ax#) For ex# = Round(ax#) + 1.5 To Round(bx#) - 0.5 Step 1 rey% = Round(ey#) Call DrawPixel(Int(ex#), rey%, gs(255 * (-lsope# * sr(Int((ey# - rey% + 0.5) * 128))))) ey# = ey# + slope: Next ex# End If Else If slope > -1 Then ey# = dy# + slope# * (Round(dx#) + 1.5 - dx#) rey% = Round(ey#): mp5! = rey% - 0.5: pp5! = mp5! + 1: zsl! = pp5! - midy# tri# = mp5! + lwris: trz = mp5! - slope# For ex# = Round(dx#) + 1.5 To Round(cx#) - 1.5 Step 1 If ey# < tri# Then Call DrawPixel(Int(ex# + 1), rey%, gs(one!)) Else If ey# < trz Then Call DrawPixel(Int(ex# + 1), rey%, gs(255 * (1 - lsope# * sr(Int((ey# - mp5!) * 128))))) Else: Call DrawPixel(Int(ex# + 1), rey%, gs(255 * (zsl! - ey#))): End If End If If ey# < trz Then mp5! = mp5! - 1: zsl! = zsl! - 1: tri# = tri# - 1 rey% = rey% - 1: trz = trz - 1: End If ey# = ey# + slope#: Next ex# ey# = by# - slope# * (bx# - Round(bx#) + 1.5) rey% = Round(ey#): mp5! = rey% - 0.5: pp5! = mp5! + 1: zsl! = mp5! + midy# tri# = pp5! - lwris: trz = pp5! + slope# For ex# = Round(bx#) - 1.5 To Round(ax#) + 1.5 Step -1 If ey# < tri# Then If ey# < trz Then Call DrawPixel(Int(ex#), rey%, gs(255 * (ey# - zsl!))) Else Call DrawPixel(Int(ex#), rey%, gs(255 * (1 - lsope# * sr(Int((pp5! - ey#) * 128))))) End If End If If ey# > trz Then rey% = rey% + 1: pp5! = pp5! + 1: zsl! = zsl! + 1 tri# = tri# + 1: trz = trz + 1: End If ey# = ey# - slope#: Next ex# ex# = ax# + lsope# * (ay# - Round(ay#) + 1.5) For ey# = Round(ay#) - 1.5 To Round(by#) + 0.5 Step -1 rex% = Round(ex#) Call DrawPixel(rex%, Int(ey# + 1), gs(255 * (-slope * sr(Int((ex# - rex% + 0.5) * 128))))) ex# = ex# + 2 * midx#: Next ey# ex# = cx# - lsope# * (Round(cy#) + 1.5 - cy#) For ey# = Round(cy#) + 1.5 To Round(dy#) - 0.5 rex% = Round(ex#) Call DrawPixel(rex%, Int(ey#), gs(255 * (-slope# * sr(Int((rex% + 0.5 - ex#) * 128))))) ex# = ex# - 2 * midx#: Next ey# Else ex# = ax# + lsope# * (ay# - Round(ay#) + 1.5): rex% = Round(ex#): mp5! = rex% - 0.5 zsl! = mp5! - midx#: pp5! = mp5! + 1: tri# = pp5! - lwrun#: trz = pp5! - lsope# For ey# = Round(ay#) - 1.5 To Round(by#) + 1.5 Step -1 If ex# > tri# Then Call DrawPixel(rex%, Int(ey#), gs(one!)) Else If ex# > trz Then Call DrawPixel(rex%, Int(ey#), gs(255 * (1 + slope# * sr(Int((pp5! - ex#) * 128))))) Else: Call DrawPixel(rex%, Int(ey#), gs(255 * (ex# - zsl!))): End If End If If ex# > trz Then tri# = tri# + 1: trz = trz + 1: pp5! = pp5! + 1 rex% = rex% + 1: zsl! = zsl! + 1: End If ex# = ex# + lsope#: Next ey# ex# = cx# - lsope# * (Round(cy#) + 1.5 - cy#): rex% = Round(ex#): mp5! = rex% - 0.5 tri# = mp5! + lwrun#: trz = mp5! + lsope#: zsl! = mp5! + 1 + midx# For ey# = Round(cy#) + 1.5 To Round(dy#) - 1.5 Step 1 If ex# > tri# Then If ex# < trz Then Call DrawPixel(rex%, Int(ey# + 1), gs(255 * (1 + slope * sr(Int((ex# - mp5!) * 128))))) Else: Call DrawPixel(rex%, Int(ey# + 1), gs(255 * (zsl! - ex#))): End If End If If ex# < trz Then tri# = tri# - 1: trz = trz - 1: zsl! = zsl! - 1 rex% = rex% - 1: mp5! = mp5! - 1: End If ex# = ex# - lsope#: Next ey# ey# = by# - slope# * (bx# - Round(bx#) + 2.5) For ex# = Round(bx#) - 2.5 To Round(ax#) + 0.5 Step -1 rey% = Round(ey#) Call DrawPixel(Int(ex# + 1), rey%, gs(255 * (lsope# * sr(Int((ey# - rey% + 0.5) * 128))))) ey# = ey# - slope#: Next ex# ey# = dy# + slope# * (Round(dx#) + 1.5 - dx#) For ex# = Round(dx#) + 1.5 To Round(cx#) - 0.5 Step 1 rey% = Round(ey#) Call DrawPixel(Int(ex#), rey%, gs(255 * (lsope# * sr(Int((rey% + 0.5 - ey#) * 128))))) ey# = ey# + slope#: Next ex# End If End If Else If epy! = spy! Then rey% = Round(ay#): a! = ay# - rey% + 0.5 For ex# = Round(ax#) + 1.5 To Round(bx#) - 0.5 Call DrawPixel(Int(ex#), rey%, gs(255 * a!)) Call DrawPixel(Int(ex#), rey% - 1, 1 - gs(255 * a!)) Next ex# Else If epx! = spx! Then rex% = Round(ax#): a! = ax# - rex% + 0.5 For ey# = Round(ay#) - 0.5 To Round(by) + 1.5 Step st Call DrawPixel(rex%, Int(ey#), gs(255 * a!)) Call DrawPixel(rex% - 1, Int(ey#), 1 - gs(255 * a!)) Next ey#: End If End If End If End Sub

Z.

And...

Code:

Private Sub DrawPixel(ByVal X As Long, ByVal Y As Long, _ ByVal Alpha As Single) Dim TempColor As Long Dim R2 As Long, G2 As Long, B2 As Long 'Get the color of the original pixel TempColor = GetPixel(picBack.hdc, X, Y) 'Extract each one of the RGB values of the original pixel '(don't waste your time trying to understand it :) ) R2 = TempColor And 255 G2 = (TempColor And 65535) \ 256 B2 = (TempColor And 16777215) \ 65536 'Add the original RGB values to the particle's RGB values R2 = R2 + PixelR * Alpha G2 = G2 + PixelG * Alpha B2 = B2 + PixelB * Alpha 'Check if they're not above 255 If R2 > 255 Then R2 = 255 If G2 > 255 Then G2 = 255 If B2 > 255 Then B2 = 255 'Draw the pixel SetPixelV picBack.hdc, X, Y, RGB(R2, G2, B2) End Sub

Both functions ripped from Jotaf's sparks tutorial, which ripped the line function from somewhere else.

Z.

now that I see it, I understand that calling Drawpixel, while has rendering option advantage, (you can put a select case around like this

Select case PaintMode
Case 1 'normal
'Add the original RGB values to the particle's RGB values
R2 = R2 + PixelR * Alpha
G2 = G2 + PixelG * Alpha
B2 = B2 + PixelB * Alpha

Case 2 'luminescent look .. byte represents line or point intensity
r2 = r2 + (Byte / 255) * Abs(r2& - pixelr) ^ 0.85
g2 ..
)

is not real fast.

cyborg, if you can compute floating points along the curve, find a way to space the points so that single Aa pixels along a trail will look like an Aa curve:

Private Sub AaUnit(x1 As Single, y1 As Single)
Dim ax!, bx!
Dim ay!, by!
Dim RX1&, RY1&
Dim RX2&, RY2&
Dim xp5!
Dim l1!, l2!
Dim l3!, l4!
Dim Alpha As Byte

ax = x1 - 0.5
ay = y1 - 0.5
bx = ax + 1
by = ay + 1
RX1 = ax
RX2 = RX1 + 1
xp5 = RX1 + 0.5
RY1 = ay
RY2 = by
l1 = RY1 + 0.5 - ay
l2 = 256 * (xp5 - ax) - xp5 + ax
l3 = 255 - l2
l4 = by - RY2 + 0.5

Alpha = l1 * l2
PSet (RX1, RY1), RGB(Alpha, Alpha, Alpha)
Alpha = l1 * l3
PSet (RX2, RY1), RGB(Alpha, Alpha, Alpha)
Alpha = l4 * l2
PSet (RX1, RY2), RGB(Alpha, Alpha, Alpha)
Alpha = l4 * l3
PSet (RX2, RY2), RGB(Alpha, Alpha, Alpha)

End Sub

here is a version that will show you alpha-blended result

my browser doesn't space pasted text correctly so I will attach a file

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alpha-blended AaUnit.txt

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ok...
i tried the aaunit thing and it looked really good! :)

theres only one problem!

it uses Pset and Point and i want to change it to setpixelv and getpixel, but then it does not get AA-ed!

i change these lines:
VB Code:
BGR2 = Form1.Picture1.Point(RX1, RY1)
'and
Form1.Picture1.PSet (RX1, RY1), RGB(Red, Green, Blue)
 
'to
 
GetPixel Form1.Picture1.hdc, RX1, RY1
'and
SetPixelV Form1.Picture1.hdc, RX1, RY1, RGB(Red, Green, Blue)
What wrong?

Heres two pics that shows how it looks.

Here's the one with Pset and Point:

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and here's the one with set/getpixel

i think i know whats wrong now :p

for got bgr2 = before getpixel
lol

but there are still some strange things!

if i change some things in the aaunit code and then change them back, it doesnt look the same as before!

but if i copy the original code back again, it looks good again!

and im 100% sure i changed everything back again!

thats really strange!

oooooh! im an idiot!!!
forget the last things i said!
i found out whats wrong!

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here's the prog with AA

looks good

i like this program.

regarding thick lines, draw regular, then outline with Aa to improve speed

ok...i'll try that...
thanks for your help :)

im currently making a frame interpolator for the prog...
so it's possible to animate it now!

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here's how it looks animated :)

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WOHOO! :)

i've made a new scroll and a bar that shows animation keys!
looks really nice imo :) :) :)
try it and give me some comments!

btw. the animations are not 100% bug-free
animate it forward....i mean for example: do not animate frame 100 and the go back to animate frame 10.....that doesnt work yet
but otherwise it work good :p

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heres an animation from it!

good stuff

thx