Making blur effect?

BlitzMax Forums/BlitzMax Programming/Making blur effect?

orgos

(Posted 2009) [#1]

Hello people.

I want to make a blur effect, but the problem is that I need to apply the blur effect to entirely screen without affect some sprites. Having a list of sprites, I draw the sprites that must receive the effect, apply the effect and then draw other sprites that not need the effect. In theory is that. I need to make this and make it really fast. Some one can help me, with code?

Ked	(Posted 2009) [#2]

Nothing in BlitzMax is fast enough. Hopefully, it will be implemented soon because a lot of people (including me) have been wanting buffer commands.

Arowx

(Posted 2009) [#3]

You could use an set of alpha/transparent trail of images to create a kind of motion blur effect?

Even better effects if you preprocessed the sprites in an image editor first to give them a blur!

Come to think of it if you use a reduced scale sprite and then scale it up you get a kind of blurring effect if you use the MIPMAPPED image flag.

The only other way I have heard of is writing a shader that will post process you graphics but you have to delve into GPU Shader coding for that which is outside of my current skill set.

Nate the Great

(Posted 2009) [#4]

I have seen real time blur for bmax in the code arcs I think.. anyway here is a little function I wrote!

Function DrawImageBlur(img:TImage, x1:Int, y1:Int, blur_radius:Float, frame:Int = 0)
Local alph:Float = GetAlpha()
Local x:Int = 0
Local y:Int = 0
Local dist# = 0

For x = -blur_radius To blur_radius
	For y = -blur_radius To blur_radius
		dist = Sqr(x*x+y*y)
		If dist <= blur_radius Then
			dist = blur_radius-dist
			If blur_radius = 0 Then blur_radius = 1
			dist = dist/blur_radius
			SetAlpha dist*alph
			DrawImage img,x1+x,y1+y,frame
		EndIf
	Next
Next

SetAlpha alph

End Function

Nate the Great

(Posted 2009) [#5]

oops the code above is slightly bugged.. it still looks decent though.

orgos

(Posted 2009) [#6]

Thanks for the responses but that can't solve my problem.

I have a lots of stuff rendering like images, sprites, guis and particles making a blur effect of each one goes really slow, so thinking the best way it's to make a post draw effect or some thing with the drawed elements.

So I guess need to get the drawed buffer and apply effect...

I test it making a grabpixmap before clip, but i'ts is really slow.

ImaginaryHuman

(Posted 2009) [#7]

Eeee... code above is a good idea but not in terms of speed, unless you're not drawing too many sprites. Tonnes of overdraw going on there.

nawi	(Posted 2009) [#8]

Make blurred version of each sprite beforehand, or atleast blur them non-real time. You're not telling us if you need a directional blur or just a static one. You can also load the image at half the size, and draw at twice the scale.

smilertoo

(Posted 2009) [#9]

the best blur ive seen in bmax was done using opengl buffers.