Technical Q&A QD3D05

Interactive Renderer Not Drawing Flat Surfaces

Q: The Interactive renderer does not draw flat surfaces that are parallel to the camera-view direction with the Orthographic camera, but the wire-frame renderer does. We put in a "floor" of polygons, and when we look along the edge of the floor with the Orthographic camera, it totally disappears. With the wire-frame renderer, we see a line where the floor is, which is as expected.

A: Filled primitives have no thickness, so when you look at them edge-on, they do not appear. Lines, however, are a mathematical abstraction, so they always appear to be 1 pixel thick (when you "zoom in" on a line, its thickness does not increase). While this may seem somewhat odd, it is the way that many libraries work. To achieve the effect you want, make the "floor" a thin box, and texture-shade the top surface. If the depth of the box is small, it appears to be a slab-like structure, and it won't disappear.