getVertexShader(args) {
    if (this.compiledVertexShader !== null) {
      return this.compiledVertexShader;
    }
    return this.compiledVertexShader = this.replaceArtifacts(this.constructor.vertexShader, this._getVertShaderArtifactMap(args));
  }
@desc Get the vertical shader String
@param {Array|IArguments} args - The actual parameters sent to the Kernel
@returns {string} Vertical Shader string