Metablob shader testing

An article by mgear

10 Comments

Metablob shader testing.

2D metablobs..hmm..could this be used for (2D) fluids somehow?

Instructions:

– New scene
– Add plane, Location: 0,0,0 Rotation: 0,0,0
– Add camera, Location: 0,10,0 Rotation: 90,0,0 (its looking down the plane)
– Add material using this shader to the plane, you should see some blobs (its using screenposition, so you might not see blobs in editor, depending on your view pos)

Download source:
blobshader.unityPackage

Shader source: (v1.0)

// ORIGINAL GLSL SHADER: 'Metablob' by Adrian Boeing (2011)
Shader "mShaders/mblob1"
{
Properties
{
}
SubShader
{
Tags {Queue = Geometry}
Pass
{
CGPROGRAM
#pragma target 3.0
#pragma vertex vert
#pragma fragment frag
#include "UnityCG.cginc"

struct v2f {
float4 pos : POSITION;
float4 color : COLOR0;
float4 fragPos : COLOR1;
};

v2f vert (appdata_base v)
{
v2f o;
o.pos = mul (UNITY_MATRIX_MVP, v.vertex);
o.fragPos = o.pos;
o.color = float4 (1.0, 1.0, 1.0, 1);
return o;
}

half4 frag (v2f i) : COLOR
{
float animtime = _Time*10.0;
//the centre point for each blob
float2 move1;
move1.x = cos(animtime)*0.4;
move1.y = sin(animtime*1.5)*0.4;
float2 move2;
move2.x = cos(animtime*2.0)*0.4;
move2.y = sin(animtime*3.0)*0.4;
//screen coordinates
float2 p = -1.0 + 2.0 * i.fragPos.xy / float2 (7,7);
//radius for each blob
float r1 =(dot(p-move1,p-move1))*8.0;
float r2 =(dot(p+move2,p+move2))*16.0;
//sum the meatballs // uh..typo maybe Oo?
float metaball =(1.0/r1+1.0/r2);
//alter the cut-off power
float col = pow(metaball,8.0);
//set the output color
return float4(col,col,col,1.0);
}
ENDCG
}
}
FallBack "VertexLit"
}

Tags: metaball, metablob, shader

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10 Comments + Add Comment

Neke 25/03/2012 at 20:01

How can I make it work?
All I see is a black sphere 🙁

Thanks!!

Reply
- mgear 25/03/2012 at 22:42
  
  added some instructions, havent tested it on a sphere..but on a plane it seems to work.
  
  Reply
  - Neke 28/03/2012 at 09:18
    
    Thanks for the info and for the blog.
    I thought it was a material to use in several near spheres in order to achive the 2D metablob effect ^_^U
    
    Reply
RevenantX 17/07/2012 at 17:26

how i can remove screen position dependency?

Reply
- mgear 23/07/2012 at 01:27
  
  replace line:
  float4 fragPos : COLOR1;
  with:
  float4 uv : TEXCOORD0;
  
  replace line:
  o.fragPos = o.pos;
  with:
  o.uv = float4( v.texcoord.xy, 0, 0 );
  
  replace line:
  float2 p = -1.0 + 2.0 * i.fragPos.xy / float2 (7,7);
  with:
  float2 p = i.uv.xy-float2(0.5,0.5);
  
  (you might have to adjust those 0.5 values, but for the same scene, it should display the blobs on middle of the plane then)
  
  Reply
fireb4ll 12/10/2012 at 00:17

Hi, just a quick question – does this shader require Unity Pro? 🙁 Can’t get it to work so i guess it does, but want to be shure. Thanks

Reply
- mgear 12/10/2012 at 07:53
  
  Doesn’t need pro, if you set the scene plane & camera to those locations, it should work..
  
  Does it show just black or that pink/magenta color?
  
  Reply
fireb4ll 12/10/2012 at 21:19

Only black plane (everything was done as written above, no idea what could be wrong). Could you maybe upload a project folder where it works for you?
// also tried the modifications written above (screen position dependency), everythings still the same

Reply
- fireb4ll 12/10/2012 at 21:20
  
  /* sorry, forgot to click Reply :-X */
  
  Reply
- mgear 14/10/2012 at 13:57
  
  ^ Added example scene download.
  
  Reply