Custom Shader Layering.

Hi guys

I am very new to this shader business and need help fixing/understanding a shader.

i am using TK2D Toolkit in my project and would like to draw on screen using my fingers (mobile development) I've got the drawing to work fine but it is always in front of all the assets on screen. I modified the PremulVertexColor shader and got the line to go behind the asset but then if the asset has any transparency it acts like a mask as shown below..



The NewPremulVertexColor shader:

//unlit, vertexcolour, premultipliedalphablend

Shader"tk2d/NewPremulVertexColor"
{
Properties
{
_MainTex ("Base (RGB) Trans (A)", 2D) = "white" {}
}

SubShader
{
Tags {"Queue"="Overlay""IgnoreProjector"="True""RenderType"="Transparent"}
LightingOffCullOffFog { ModeOff } AlphaTestGreater0.5
LOD110
Pass
{
CGPROGRAM
#pragmavertexvert_vct
#pragmafragmentfrag_mult
#pragmafragmentoptionARB_precision_hint_fastest
#include "UnityCG.cginc"

sampler2D_MainTex;
float4_MainTex_ST;

structvin_vct
{
float4vertex : POSITION;
float4color : COLOR;
float2texcoord : TEXCOORD0;
};

structv2f_vct
{
float4vertex : POSITION;
fixed4color : COLOR;
float2texcoord : TEXCOORD0;
};

v2f_vctvert_vct(vin_vctv)
{
v2f_vcto;
o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);
o.color = v.color;
o.texcoord = v.texcoord;
returno;
}

fixed4frag_mult(v2f_vcti) : COLOR
{
fixed4col = tex2D(_MainTex, i.texcoord) * i.color;
returncol;
}
ENDCG
}
}

SubShader
{
Tags {"Queue"="Transparent""IgnoreProjector"="True""RenderType"="Transparent"}
ZWriteOffBlendOneOneMinusSrcAlphaCullOffFog { ModeOff }
LOD150

BindChannels
{
Bind"Vertex", vertex
Bind"TexCoord", texcoord
Bind"Color", color
}

Pass
{
LightingOff
SetTexture [_MainTex] { combinetexture * primary }
}
}

}

The shader for the line:

Shader "LineShader" {
Properties {
_Color ("Base (RGB)", Color) = (1, 1, 1, 1)
}
SubShader {
Tags {"Queue"="Transparent""IgnoreProjector"="True"}
LightingOff
CullOff

BindChannels {
Bind"Color", color
}
Pass {
Color [_Color]
}
}
}

Thanks
Abdullah Awan

 

nice, i didnt entirely understand the technical nature of the question from that explanation.

I've got the drawing to work fine but it is always in front of all the assets on screen. I modified the PremulVertexColor shader and got the line to go behind the asset but then if the asset has any transparency it acts like a mask as shown below.

you have to figure out transparency of the different objects on screen (in unity asset is more like a loadable file, textured gameobject is what we call thigns on screen, with a renderer, and it has alpha values, it has this page for controlling blending, and there is Z buffer, which is distance essentially to say where the distance of textures are on z axis from camera.

thanks