Legacy Shaders

Legacy shaders are 'basic' shaders that do not that into account the Unity material system.

These will be much more familiar to anyone who has used shader systems in the past, and consist of a vertex and fragment program.

Shader "Shaders/Simple/BasicFlat" {
    SubShader {
        Pass {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #pragma target 3.0

            #include "UnityCG.cginc"

            float4 vert(appdata_base v) : POSITION {
                return mul (UNITY_MATRIX_MVP, v.vertex);
            }

            fixed4 frag(float4 sp:WPOS) : COLOR {
                return float4(
                  sp.x/_ScreenParams.x,
                  sp.y/_ScreenParams.y,
                  0.0,
                  1.0
                );
            }
            ENDCG
        }
    }
}

This sort of basic shader shouldn't be used for anything other than extremely specific custom content.