Additive Light Blobs with Shaders

Target Platforms Mobile
1

I’m new to editing/creating shaders and I’m attempting to create a shader for a material to be used in an additive projector(Blob Lights instead of Blob Shadows). This cant use pixels shading techniques because its on the iPhone platform.
Here is what I attempted to modify from the blob multiply shader.

Shader "FX/Projector Add" { 
	Properties {
		_ShadowTex ("Cookie", 2D) = "gray" { TexGen ObjectLinear }
		_FalloffTex ("FallOff", 2D) = "white" { TexGen ObjectLinear	}
	}

	Subshader {
		Tags { "RenderType"="Transparent" }
		Pass {
			ZWrite Off
			Offset -1, -1

			Fog { Color (1, 1, 1) }
			AlphaTest Greater 0
			ColorMask RGB
			Blend DstColor One
			SetTexture [_ShadowTex] {
				combine texture, ONE - texture
				Matrix [_Projector]
			}
			SetTexture [_FalloffTex] {
				constantColor (1,1,1,0)
				combine previous lerp (texture) constant
				Matrix [_ProjectorClip]
			}
		}
	}
}

It seems to work but becomes glitchy when out of the clipping ranges and is not the effect I was looking for(See ugly pixels and not smooth like it should be in the cookie).

Thanks,

Dragonos[/code]

2

  1. ugly looking: perhaps I’m blind but the cookie is smooth, as smooth as it can be with compression and on a phone without higher class texture filtering.
    Its your ground below thats “ugly” and that blends through

  2. glitchy : what do you mean by that.

3

1 It’s Ugly because it gets distorted even if I use the highest filtering in the regular unity.

2 Its glitchy because it does not work with any textures except one (The normal shadow blob).

Edit: This was actually caused by a messed up alpha channel.
If you try the shader on a projector and use an image like this,
http://dl.getdropbox.com/u/1752614/Light.psd
You can get effects on the iPhone that are similar looking yo a pixel based spotlight.

(Mip Maps cause strange artifacts)

4

  1. The iphone has no anisotropic filtering (-> disortion etc within texture) and also no antialiasing (steppy edges).
    Its a phone, not a pc and at 480x320 and the iphones performance you definitely have more important things to worry especially if you use blob projectors, like “having more than a dia show”

  2. check the import settings. I would guess that yours are wrong, the blob projector is pretty picky

5

1 I know.
2…
Yes it turns out to be an import settings problem.
This actually is a very good technique to make a flash light.
Use the code and the image above (With no mip maps or compression and full 32bit RGBA)

This scene(I can’t show all of it due to NDA) Has two animated meshes at ~700 tris
two blob shadows, a scene of 7.1K tris, and the modified light “Blob” with a directional light and four pointlights. It runs at about 32 fps in unity 1.5 iPhone.

BTW I disagree. I think faking shadows and pixel lights on the iPhone is important and I do not know what a “dia show” is.

6

What device is that on?
First generation itouch / old iphones or 2nd gen itouch or even a iPhone 3GS? (the differences between the 3 is in the range of 300 - 400% performance wise)

A “dia show” means that it runs that fast that you can nearly watch picture per picture as it is rendered. Don’t know if the term in english exists too or what the english term is actually.

And that faking is required on the iPhone is clear :slight_smile:
Really using such techs (if they were even available) would not work out acceptable performance wise, its all about pretending to have the tech and still have performance and its always great to hear what people achieved on that end :smile:

7

I’m using a 3g. I think that the 1.5 update is helping alot.
Thanks for the input Dremora! :smile: It is really all about tricking people isn’t it. lol

8

Indeed, 1.5 must have done real wonders to that end then :slight_smile:

Thanks for sharing that knowledge.

And yes. Game dev on such restricted devices is all about illusions and about programmers who are able to program it (thank you UT, without you many would have ideas for illusions and no tech to pull it off :smile: )

9

Hey guys, i wonder if you have already tried the Additive-Projector?
Mines do not work on the iPhone/iPod Touch device, only in the editor… :shock:
Also, i have tried the moddified blob-shadow posted by dragonos, this one is visible on the device but have lots of uncorrect UV problems.
Do this have something to do with the main camera field of view?
Btw, i changed the projector field of view to 160, but again i dont think this is the cause of UVs problems…
Are this kind of shaders an advance feature?

10

Turns out to be a bug. It will be fixed on the next 1.5.1 version. :smile: