Disclosed herein is a spray coating process for a robotic spray gun assembly comprising importing a discretized model of an object geometry to be coated; importing a numerically characterized spray pattern file; importing a robot motion file comprising a plurality of motion positions, dwell times and orientations defining a spray direction of the robotic spray gun; reading each motion position within the motion file; determining which portions of the object geometry are visible at each motion position; computing a void volume fraction at each visible portion of the object geometry based on the core compression, the incident angle of the robotic spray gun and the ricocheting of the spray for each motion position; and calculating total coating thickness on portions of the object geometry for the complete motion step.