Gradient shader for mobile?

Questions & Answers
1

Where is the mistake in the code? I just want a simple basic gradient shader for mobile. I get only one color, when I use the bottom shader. Or is there a better gradient shader for mobile?

Shader "Custom/BasicGradient"
{
Properties
{
	_TopColor ("Top Color", Color) = (1, 1, 1, 1)
	_BottomColor ("Bottom Color", Color) = (1, 1, 1, 1)
	_RampTex ("Ramp Texture", 2D) = "white" {}
}

SubShader
{
	Pass
	{
		Blend SrcAlpha OneMinusSrcAlpha

		CGPROGRAM
		#pragma vertex vert
		#pragma fragment frag

		struct vertexIn {
			float4 pos : POSITION;
			float2 uv : TEXCOORD0;
		};

		struct v2f {
			float4 pos : SV_POSITION;
			float2 uv : TEXCOORD0;
		};

		v2f vert(vertexIn input)
		{
			v2f output;

			output.pos = mul(UNITY_MATRIX_MVP, input.pos);
			output.uv = input.uv;

			return output;
		}

		fixed4 _TopColor, _BottomColor;
		sampler2D _RampTex;

		fixed4 frag(v2f input) : COLOR
		{
			return lerp(_BottomColor, _TopColor, tex2D(_RampTex, input.uv).a);
		}
		ENDCG
	}
}

}

It should look like this:
Shader

2

OK, your problem is simply at this part:

 return lerp(_BottomColor, _TopColor, tex2D(_RampTex, input.uv).a);

What you are interpolating is from the alpha channel of your texture, not the y - axis you want.
Simply change to

 return lerp(_BottomColor, _TopColor, input.uv.x);

or

 return lerp(_BottomColor, _TopColor, input.uv.y);

Will show what you want.
If you want to keep your texture, simply multiply this part with the texture.
Besides, you can also choose to use a texture already saved with gradient alpha channel, then you no need to change anything.