Improve quality of transparency effect

Unity Engine
1

I am porting over a project on a different framework, with the desired effect looking like this:

http://s14.directupload.net/file/d/3079/bk3wr54e_jpg.htm

It’s just a 32x32 px picture with transparencies travling along a column model, creating a warp travel effect for a Sci Fi game.

Using the same assets in Unity I get:

http://s7.directupload.net/file/d/3079/eajtydfj_jpg.htm

The clouds, i.e. less transparent pixels, are blended together it seems. You can see some movement or let’s say color chance over time using a UV coordinate setoff via:

void Update () {
		float dt = Time.deltaTime;
		
		float doffset = offspeed * Time.time;
		renderer.material.mainTextureOffset = new Vector2(doffset,0); }

The shader I use is:

Shader "EVShaders/UnlitTranspDiff" {
Properties {
	_Color ("Main Color", Color) = (1,1,1,1)
	_MainTex ("Base (RGB) Trans (A)", 2D) = "white" {}
}

SubShader {
	Tags {"Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Transparent"}
	LOD 200
	Blend SrcAlpha OneMinusSrcAlpha // SrcAlpha OneMinusSrcAlpha
	Cull Off Lighting On ZWrite Off Fog { Color (0,0,0,0) }

CGPROGRAM
#pragma surface surf Lambert alpha

sampler2D _MainTex;
fixed4 _Color;

struct Input {
	float2 uv_MainTex;
};

void surf (Input IN, inout SurfaceOutput o) {
	fixed4 c = tex2D(_MainTex, IN.uv_MainTex) * _Color;
	o.Albedo = c.rgb;
	o.Alpha = c.a;
}
ENDCG
}

Fallback "Transparent/VertexLit"
}

I assume that the transparency blend mode in the shader is the problem. But absolutely not being a shader dude and not planning on becoming one I just tried various combinations for the Blend variables and didn’t get any visible change - besides a pink solid color every now and then.

I vaguely remember having a similar look on early iterations using the other framework, an then doing something like TransparencyMode.MDUAL, .MBINARY or whatever and then it worked.

So I guess my questions is how to achieve my desired target look in Unity?

Thanks

2

I imagine you want additive blending rather than standard alpha blending.

The blend modes are documented here; Unity - Manual: ShaderLab command: Blend

So you’d want to replace your line
Blend SrcAlpha OneMinusSrcAlpha // SrcAlpha OneMinusSrcAlpha
with
Blend One One

3

I’m always impressed to see the intelligent answers in this forum when I don’t even understand the question. (I don’t even know where to look at in the screen shots!)

4

I’m guessing that based purely on the fact the first image (desired) is brighter than the second one (actual) :stuck_out_tongue:

5

Hm no that’s not it. I tried all the elements in that list (“Below are the most common blend types”) in the past, but no visible change. Maybe with One One it get’s a little brighter, but other than that I still don’t get the cloudy structure I’m looking for, just a blue mist. I do see some differentiation however, I assume from moving the UV coords.

6

I share Martin’s confusion over the difference between your two images. There are quite a few subtle differences, and it’s not clear what you’re after.

7

You can see the desired effect in motion here. It’s a texture moving towards the player via UV coordinates manipulation. I can’t film Unity right now, since I don’t have the software installed right now. But it looks like my second screenshot. You can’t differentiate clouds moving, it’s just a blue mist getting darker and brighter. At first I thought the UV movement was too fast, but decreasing it didn’t help.

The texture itself seems to be correctly recognized by Unity: screenshot in the Inspector. It’s a 32x32 px PNG.