Falloff

**What Falloff does.** Falloff [3Fa] is a 3D material node that blends two material branches according to the angle between the surface normal and camera direction. It is neither a normal 2D mask nor a light source.

**Two independent inputs.** FaceOnMaterial (orange) and GlancingMaterial (green) accept either an existing 3D material or a 2D image, which is adapted to the built-in basic diffuse-texture material. Both inputs are optional.

**Material, not image.** Falloff outputs a material. Connect it to a material socket on Shape3D, ImagePlane3D or another compatible 3D object; do not wire it straight to a 2D Merge or MediaOut.

**You need a scene to observe it.** Connect Falloff.Material → Shape3D.MaterialInput → Merge3D → Renderer3D.Image → MediaOut. Add Camera3D and lighting to compare shaded geometry consistently.

**Two Tone / Gradient.** Two Tone provides Face On and Glancing color groups; Gradient allows intermediate angular colors. The controlling coordinate is view angle, not image X/Y position.

**RGB, Alpha and Opacity are distinct.** RGB changes tint, Alpha provides the color alpha and Opacity scales color and alpha of the corresponding material branch. An external material may also have alpha, so inspect RGB and alpha after Renderer3D separately.

**Falloff is not physically based Fresnel reflection by itself.** It is an artistic gamma-like curve between materials. Realistic glass or metal also needs appropriate reflective shading, environment and lighting.

**Normals matter.** A sphere presents a smooth range of angles. A face-on plane is almost entirely Face On. Imported meshes with invalid or flipped normals will produce misleading blends.

**Camera motion changes the result.** Rotating the camera or object changes angle weighting without changing tint controls. Check the entire animated shot and inspect silhouettes at 100%.

**Screenshot evidence.** falloff-controls.png captures Two Tone, Face On Opacity 0.2, Glancing Opacity 1.0, Falloff 2.0 and Material ID 1. These are not proven factory defaults. Settings is closed; its fields are not photographed.

**Using footage as a material.** MediaIn can feed FaceOnMaterial as a diffuse texture source. MediaIn remains a texture inside the material graph; Falloff still outputs material and must pass through geometry and Renderer3D.

**Material ID is not a matte.** ID may be written into the auxiliary MatID channel only when Renderer3D is configured to generate it. To produce a 2D edge map, first rasterize with Renderer3D and only then process it in image space.

**If the object disappears.** Check both branch opacities, tint, normals, camera direction, mesh position, renderer settings and lighting. A missing 3D render is not necessarily a material fault.

**Compositing over footage.** Renderer3D.Image is ordinary RGBA. Feed it into Merge.Foreground, put MediaIn in Background, and check transparent alpha in empty render pixels before adding Glow.