How to achieve this kind of look of a cube in a most efficient way?

Question

It might be a trivial question, but I couldn't come up with a simple solution. I need to create a cube like on the image below in Unity.

As always, I target mobile so it would be nice if it was made on a mobile/diffuse shader.

I was playing with lights a little bit, but in order to achieve this kind of look, I'd need to stack multiple lights because one shadow is not enough. Also, I tried adjusting the angles of the lighting - with no luck.

Do you have any tips, how could I make one in a most efficient way?

Answer 1

I will be giving you two answers, The one for your actuall problem,and another one with a cube that has faces colored based on how much they are facing top:

---

To simply create a Cube like that:

• Create an image, and color it like the left half should be COLOR_X and the other half, COLOR_Y, save it; (paint will do it)
• create a cube inside blender, and go to UV/Unwrapp;
• place the face you want to be COLOR_X in the left, the others in the right;
• Export to Unity;
• Inside Unity create a simple Unlit/Texture Material;
• Set the image you created as the Texture;
• Apply the material to the UV/mapped cube;

---

Faces should have a color depending of the normal angle;

    Shader "Unlit/NormalColored"
    {
        Properties
        {
            _NormalColor ("Color facing TOP", Color) = (1,.5,0,1)
        }
        SubShader
        {
            Pass
            {
                CGPROGRAM
                #pragma vertex vert
                #pragma fragment frag
                // include file that contains UnityObjectToWorldNormal helper function
                #include "UnityCG.cginc"

                struct v2f {
                    // we'll output world space normal as one of regular ("texcoord") interpolators
                    half3 worldNormal : TEXCOORD0;
                    float4 pos : SV_POSITION;
                };

                // vertex shader: takes object space normal as input too
                v2f vert (float4 vertex : POSITION, float3 normal : NORMAL)
                {
                    v2f o;
                    o.pos = UnityObjectToClipPos(vertex);
                    // UnityCG.cginc file contains function to transform
                    // normal from object to world space, use that
                    o.worldNormal = UnityObjectToWorldNormal(normal);
                    return o;
                }

                float4 _NormalColor;
                float _ShadeColor;

                fixed4 frag (v2f i) : SV_Target
                {
                    // The Y component is TOP direction
                    float normal_y = (i.worldNormal).y/2 + .5;
                    float normal_y_2 = (i.worldNormal).y;
                    return (normal_y_2 * _NormalColor);
                }
                ENDCG
            }
        }
    }

• only a face pointing EXACTLY TOP should be colored, change the Frag function to this;

  fixed4 frag (v2f i) : SV_Target
              {
                  // The Y component is TOP direction
                  float normal_y = (i.worldNormal).y/2 + .5;
                  if (normal_y >= .999) // THIS VALUE CAN BE SET AS A PROPERTY SO U CAN PLAY AROUND WITH IT
                      return _NormalColor;
                  return 0;
              }