A vertex / fragment shader permitting to display vertex color and change its size (OpenGL).

VertexColorSize.shader

Shader "VertexColorSize" {
  SubShader {
     Pass {
        GLSLPROGRAM

        #ifdef VERTEX
        varying vec4 v_color;
        void main()
        {   
           gl_PointSize = 10.0;
           gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
           v_color = gl_Color;
        }
        #endif

        #ifdef FRAGMENT
        varying vec4 v_color;
        void main()
        {
           gl_FragColor = v_color;
        }
        #endif

        ENDGLSL
     }
  }
}