Toon shader + skinned mesh = slow

Unity Engine
1

Hello,

I’m trying to use a toon shader with a skinned mesh and for a single model (53k tris), it makes my framerate goes down from 60 to ~35fps (on iOs, iPad3).

I got 60 fps with the shader when selecting Rig > Animation type > none
I got 60 fps with the animation with a diffuse shader

And here’s my shader code (a simplified version of the toon shader from the Standard Assets) :

Shader "Toon/Basic Outline" {
	Properties {
		_OutlineColor ("Outline Color", Color) = (0,0,0,1)
		_Outline ("Outline width", Range (.002, 0.03)) = .005
		_MainTex ("Base (RGB)", 2D) = "white" { }
	}
	
	CGINCLUDE
	#include "UnityCG.cginc"
	
	struct appdata {
		float4 vertex : POSITION;
		float3 normal : NORMAL;
	};

	struct v2f {
		float4 pos : POSITION;
		float4 color : COLOR;
	};
	
	uniform float _Outline;
	uniform float4 _OutlineColor;
	
	v2f vert(appdata v) {
		v2f o;
		o.pos = mul(UNITY_MATRIX_MVP, v.vertex);

		float3 norm   = mul ((float3x3)UNITY_MATRIX_IT_MV, v.normal);
		float2 offset = TransformViewToProjection(norm.xy);

		o.pos.xy += offset * o.pos.z * _Outline;
		o.color = _OutlineColor;
		return o;
	}
	ENDCG

	SubShader {
		Tags { "RenderType"="Opaque" }
		Pass {
			Name "BASE"
			Cull Off
			SetTexture [_MainTex] 
		}
		Pass {
			Name "OUTLINE"
			Tags { "LightMode" = "Always" }
			Cull Front
			ZWrite On
			ColorMask RGB
			Blend SrcAlpha OneMinusSrcAlpha

			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			half4 frag(v2f i) :COLOR { return i.color; }
			ENDCG
		}
	}
	
	
	
	Fallback "Toon/Basic"
}

Is there something specific in the shader code that could be the reason? Or is it using a vertex shader + skinned meshes in general?

A fallback could be to use a post-processing effect, but I don’t have Unity Pro (yet).

Thanks :slight_smile:

2

I would guess it’s because of the outline. The way it makes the outline is to render it twice, once for the main image, then another time with the model inflated and culling the front. With a skinned mesh, you’re doubling your skinned mesh with the outline. Try a toon shader without the outline and see how it goes. If that does it, I’d recommend maybe trying to see if you can generate the outline just using the inverse dot product of view and normal and see if that can work.

But… I’m pretty much just guessing. Best of luck.