Accessing object bounds in cg shader

Basically I need to do something like:

half2 localUV = v.vertex * (1.0 / objectWidth);

I need to access the object's width/height, but i can't figure out how to get those values within a cg shader.
Thanks in advance!

SR

 

you can pass variables from a script to the shader using shader.Setfloat, int, vector...etc commands.
Look at Shader class and Material class in the documents.

 

Thanks for the help aubergine!
I was trying to skip having to pass variables from a script, and was hopping there was a way - or built-in value - to do it within the shader without needing external data. Looks like I was wrong
I'm basically trying to project a gradient texture onto my object, in ObjectSpace, regardless of the object's uv's, so that the gradient repeats only once across the object's surface. I've manage to 'sort of' do it using _ScreenParams.x, but this projects the gradient across the whole scene size instead of the object's size, and I would need to use a different multiplier for each object...getting closer every day haha

 

as far as i know, the distance between center and the farthest vertex is 1.0 so you can use the distance function to get what you are trying to do.
i might be wrong though never tried it.

By the way, passing variables doesnt cause a speed loss in your case if you wonder. Just pass the object size value at the awake or start and thats it.

 

For the distance function (in shader correct?):

float dist = distance( ?, ? ); // In shader, what do I use to calculate the distance as you mentioned

Thanks for the clarification on speed loss when passing variables. Although the only reason I'm trying to avoid it is just because I'd like to keep everything shader related to shaders only, but if it can't then it can't

 

hi guys.. i am interested in that question too ....
i made this simple shader that actually gives a kind of "proportion" and tiles the texture according to it,
and it works..
hope that helps

Code (CSharp):

1. Shader "Custom/detections/extends" {
2.  
3.    Properties {
4.         _Color ("Diffuse Color", Color) = (1,1,1,1)
5.         _MainTex ("Base layer (RGB)", 2D) = "white" {}
6.      
7.  
8.     }
9.       SubShader {
10.    
11.         Tags{"Queue"="Transparent" "LightMode" = "ForwardBase" }
12.  
13.         Blend SrcAlpha OneMinusSrcAlpha
14.         Lighting On
15.         ZWrite On
16.      
17.     Pass { //pass1
18.         CGPROGRAM
19.         #pragma vertex vert
20.         #pragma fragment frag
21.         #include "UnityCG.cginc"
22.            
23.          float4 _MainTex_ST;
24.         float4 _Color;
25.         sampler2D _MainTex;
26.      
27.          struct v2f {
28.               float4 pos : SV_POSITION;
29.               fixed4 color : COLOR;
30.               float3 norm : NORMAL;
31.               float2 uv : TEXCOORD0;
32.               float3 extend : TEXCOORD1;
33.         };
34.    
35.           v2f vert (appdata_full v)
36.           {
37.               v2f o;
38.        
39.             o.norm = v.normal.xyz;
40.                o.pos = mul (UNITY_MATRIX_MVP, v.vertex );
41.             o.uv = TRANSFORM_TEX(v.texcoord.xy,_MainTex);
42.  
43.             float4 centerPos = mul ( _Object2World, float4(0,0,0,1) );
44.             float4 cornerPos = mul ( _Object2World, float4(1,1,1,1) );
45.             o.extend = (cornerPos - centerPos);
46.  
47.             //assign color and alpha
48.             o.color.xyz = _Color.xyz;
49.             o.color.w = 1;
50.             return o;
51.         }
52.      
53.         fixed4 frag (v2f i) : COLOR
54.         {
55.             fixed4 o;
56.             fixed4 tex = _Color * tex2D (_MainTex, i.uv*i.extend);
57.  
58.             o = tex;
59.             return o;
60.           }
61.              
62.         ENDCG
63.     }//pass 1
64.   } //subshader
65. }//shader

 

No it's not right . Coordinates in local space are infinite in theory. and sometimes people combined different pieces of meshes into one giant mesh and its local coordinates are wild.