Phong

Phong belongs to Fusion's classic 3D material system. It is neither a 2D filter nor a 3D object: the node creates a material that is assigned to Text3D, Shape3D, ImagePlane3D, imported geometry or another compatible 3D geometry node before scene assembly and Renderer3D.

The Phong model describes how surface normals, light direction and view direction produce diffuse and specular response. The Resolve 21 reference describes Phong as a basic illumination material that is commonly useful for shiny or polished plastic surfaces.

Its diffuse result is similar to Blinn, while the most visible difference is in specular behavior. Classic Fusion documentation notes wider highlights at grazing incidence and the ability to produce sharper highlights at high Exponent values.

Phong has five inputs rather than one generic MaterialInput: orange Diffuse Material, green Specular Color Material, magenta Specular Intensity Material, teal Specular Exponent Material and white Bump Map Material.

The first four inputs accept a 2D image or a 3D material. The incoming map does not replace the Inspector value: its pixels multiply the matching parameter. White generally preserves the contribution, black suppresses it locally, and intermediate values scale it.

Diffuse Material uses the incoming image as the base surface texture. RGB multiplies Diffuse Color and map alpha multiplies material Alpha. Geometry UV coordinates determine how a 2D map is placed on the surface.

Diffuse Alpha and Opacity both affect transparency but are not identical. Alpha defines material alpha and affects diffuse/specular; with a diffuse texture it is multiplied by texture alpha. Opacity reduces both color and alpha of diffuse/specular together, fading the whole material.

Specular Color Material controls highlight color. Its RGB multiplies the Inspector Specular Color, allowing the highlight to be colored or spatially suppressed independently of the diffuse texture.

For a 2D Specular Intensity Material input, only alpha is used and RGB is discarded. That alpha multiplies Specular Intensity, so visually contrasty RGB with flat alpha does not create a varying intensity map.

Specular Exponent Material behaves the same way for a 2D image: alpha is used while RGB is ignored. The map scales Exponent over the surface and therefore changes highlight falloff/size locally.

Specular Exponent is not overall highlight brightness. Higher values sharpen falloff and make the highlight smaller/tighter; Specular Intensity controls strength separately.

Bump Map Material is different from the other map inputs: the current Resolve 21 reference describes it as accepting only a 3D material. The normal workflow is 2D texture → Bump Map → Phong.Bump Map Material rather than connecting an ordinary height image directly.

Bump modifies lighting normals, not actual geometry or silhouette. Fine surface texture can become visible in highlights and shading without adding polygons, but silhouette changes require a geometry/displacement approach.

Transmittance is independent from Opacity. Opacity controls the rendered surface transparency, while Transmittance controls how light passes through the material and therefore affects transmitted/shadow light. Fusion can have a fully opaque surface that still transmits light in this calculation.

Attenuation controls the color of transmitted light. White passes all RGB components; colored values filter the transmitted light and can produce stained-glass-like shadows.

Alpha Detail controls how diffuse alpha participates in shadow density: at 0 the alpha is ignored for the shadow shape, while at 1 alpha determines which parts cast the shadow. Software-renderer shadow maps support this behavior more fully than OpenGL.

Color Detail introduces diffuse and texture color into transmitted light/shadow. Saturation then controls how saturated that color contribution remains; at 0 the transmitted shadow color becomes monochrome.

Receives Lighting and Receives Shadows are separate switches. The first controls scene-light response; the second controls whether the surface receives shadows.

Two-Sided Lighting is not simply a back-face visibility switch. It effectively adds another set of normals facing the opposite direction so the reverse side can respond correctly to light, which is useful for planes and open geometry.

Material ID is a numeric material identifier. It reaches the MatID auxiliary channel only when that channel is enabled in Renderer3D; entering an ID in Phong alone does not automatically create a downstream mask.

Phong does not become a visible 2D image by itself. Connect its Material output to geometry, combine geometry with lights/camera in the classic 3D scene, and use Renderer3D to produce the raster/RGBA result.

With five closely spaced inputs, use the Alt/Option or right-drag input menu when wiring a source to the node body. This is safer than guessing the socket by position.

A reliable diagnostic order is: neutral Diffuse and one light, then Specular Intensity, then Exponent, then texture maps, and only then Bump/Transmittance. Changing every component at once makes the cause of a look difficult to identify.