Over Painting


   Overpainting is the artistic technique of allowing paintstrokes to blend and overlap. This is very common in traditional art but very uncommon in computer generated images, where objects normally have very well defined boundaries.

   My shader allowed up to five layers of brush strokes to be applied to each object. These layers were simply texture maps with transparent areas allowing the underlying layers to show through. This layering helped to create the impression of overpainting.

Paint Layers

Vangogh Shader: My shader supported multiple paint layers

 

   The shader also allowed objects to have a brush stroke transparency map applied which caused the object to have transparent brush stroke shaped areas. These allowed objects behind to show through. I also included an option to the hide the backs of objects (those surfaces not facing the viewer) which meant that objects behaved essentially like flat entities on a canvas.

Transparency Mapping

Transparency Mapping: Brush Stroke shaped transparent areas on an object

 

   These techniques worked well over the majority of surfaces of objects but were not so effective on edges - as the transparent areas did not always fall on the edges of objects.