I am looking for some good way to make convincing shadows.
I know you’ll have to take the Mask and blur and lighten it, then use it as the mask of a solid-black picture, which you draw with the desired offset.
Blurring seems to be difficult to do.
I know it can be done with CG but I need a cross platform way.
Anyone has luck with this?
[quote=79368:@Christoph De Vocht]I am looking for some good way to make convincing shadows.
I know you’ll have to take the Mask and blur and lighten it, then use it as the mask of a solid-black picture, which you draw with the desired offset.
Blurring seems to be difficult to do.
I know it can be done with CG but I need a cross platform way.
Anyone has luck with this?[/quote]
Could you use the ImagePlayEffects library for blurring? From what I can remember, it slow but it works. http://sourceforge.net/projects/imageplay/
Thanks … I think I can use the blur class.
Not sure how the blur speed compares with the ImagePlayEffects one, but I remember doing some test for the tilt shift effect and that one came out pretty fast. https://alwaysbusycorner.wordpress.com/2012/08/14/lets-shrink-the-world-a-tilt-shift-effect/
EDIT: Just see it’s based on the one from ImagePlayEffects 
Well, it seems there ImagePlayEffects blurring does not support alpha channels. So no use to me.
This method (from Alain) works kinda fast but it does not support alpha. I need the shadow to be a alpha channel.
dim p,t as Picture
dim L,w,h as Integer
w=pic.Width
h=pic.Height
p=NewPicture(w,h,32)
p.Graphics.UseOldRenderer=true
p.Graphics.DrawPicture pic,0,0
t=NewPicture(w,h,32)
t.Graphics.UseOldRenderer=true
t.Mask.Graphics.UseOldRenderer=true
t.Mask.Graphics.ForeColor=&c7F7F7F
t.Mask.Graphics.FillRect 0,0,t.Width,t.Height
for L=abs(Level) DownTo 1
t.Graphics.DrawPicture p,0,0
p.Graphics.DrawPicture t,-L,-L 'upper left
t.Graphics.DrawPicture p,0,0
p.Graphics.DrawPicture t,-L,L 'lower left
t.Graphics.DrawPicture p,0,0
p.Graphics.DrawPicture t,L,L 'lower right
t.Graphics.DrawPicture p,0,0
p.Graphics.DrawPicture t,L,-L 'upper right
next
Return p
[quote=79410:@Alain Bailleul]Not sure how the blur speed compares with the ImagePlayEffects one, but I remember doing some test for the tilt shift effect and that one came out pretty fast. https://alwaysbusycorner.wordpress.com/2012/08/14/lets-shrink-the-world-a-tilt-shift-effect/
EDIT: Just see it’s based on the one from ImagePlayEffects :-)[/quote]
Alien’s solution looks better.
He says it is pretty fast and I am not convinced the ImagePlay effects library is ‘pretty fast’.
Yes it is ‘fast’ but I need the blurring to have an alpha channel. In otter words: the shadows needs to be transparent.
Fair enough.
I’ve been messing around with a blur method… it essentially creates a matrix of scaled down images from the original and then creates a new image by iterating through the matrix pixel by pixel. Works pretty well, but get a little funky above a 30x30 matrix… but I think that depends on the size of the original too… see what you think. (might be a little hard to decipher, just ask if you need clarification…)
[code]Private Function scalePicByMatrix(p As Picture,MatrixSize As integer) As Picture
#Pragma DisableBoundsChecking
#pragma NilObjectChecking false
#Pragma DisableBackgroundTasks
dim workpic As new Picture(p.width+MatrixSize4,p.height+MatrixSize4)
dim buffers as new Picture(workpic.Width+MatrixSize-(workpic.Width mod MatrixSize),workpic.Height+MatrixSize-(workpic.Height mod MatrixSize))
dim buffergraphics As Graphics=buffers.Graphics
dim res As new Picture(workpic.Width,workpic.Height)
dim xmult As double=buffers.width/MatrixSize
dim ymult As double=buffers.height/MatrixSize
workpic.graphics.drawpicture p,MatrixSize2,MatrixSize2
for x as integer=0 to MatrixSize-1
for y as integer=0 to MatrixSize-1
buffergraphics.DrawPicture(workpic,(xmultx),(ymulty),xmult,ymult,x,y,workpic.Width-MatrixSize,workpic.Height-MatrixSize)
next
next
dim surfaces as RGBSurface=buffers.RGBSurface
dim s As RGBSurface=res.RGBSurface
for x as integer=0 to res.Width-1
for y as integer=0 to res.Height-1
s.Pixel(x,y)=surfaces.pixel( (x/MatrixSize)+(xmult*(x mod MatrixSize)) , (y/MatrixSize)+(ymult*(y mod MatrixSize) ))
next
next
workpic=new Picture(p.width,p.height)
workpic.graphics.drawpicture res,0,0,p.width,p.height,MatrixSize2,MatrixSize2
Return workpic
End Function
[/code]
probably should have called it BlurByMatrix() eh late night coding…
There was a solution posted on the Xippets website, not sure if this will help you
Yes, that is a solution for OS X but I want something that is cross platform.
Have you thought about drawing the blur on the MASK, and a solid color on the Image?
Here’s a companion to the code I posted above.
This will draw an image with a dropshadow to a graphics object. Keep in mind that blur>10 will be sloooow.
(the above method was called scaleByMatrix. You’ll need to change it to BlurByMatrix)
[code]Private Sub DrawWithShadow(g As Graphics,p As Picture,picx As integer,picy As integer, shadXoff As integer,shadYoff as integer, blur As integer, fill as color=&c00000000)
dim m As new picture(p.Width,p.Height)
dim shadow As new picture(p.Width,p.Height,32)
m.Graphics.ForeColor=hsv(0,0,fill.Value)
m.Graphics.FillRect(0,0,m.Width,m.Height)
m.ApplyMask p.copymask
shadow.Graphics.ForeColor=fill
shadow.graphics.fillrect(0,0,shadow.Width,shadow.Height)
shadow.ApplyMask m
shadow=BlurPicByMatrix(shadow,blur)
g.DrawPicture shadow,picx+shadXoff,picy+shadYoff
g.DrawPicture p,picx,picy
End Sub
[/code]
Another option would be to use the BlurMBS method (it’s VERY fast) applied to the mask (picture.copymask and picture.applymask are handy for this)
I must admit, with my budget I have not YET bought the MBS plugins but I have tried it out a little and it is really cool because it is massively powerful because it has such a wide-range of functions for just about anything you would expect from a library of this sort. The developer of it might add new things to the plugin on high enough request. He is a nice guy. 
which part of the codes i need to replace on Jim Mckay’s DrawWithShadow if i want to use the BlurMBS??
http://einhugur.com/Html/Libs.html Björn’s Picture Effects plugin is x-plat and has some really highly optimized effects. I think version 9.0.2 is the latest.