Lighting & rendering · Intermediate

Phong shading

A classic per-pixel lighting method for smooth surfaces and soft highlights

What is Phong shading?

Phong shading is a classic way of lighting a 3D surface that calculates light at every pixel, blending the surface direction smoothly across each polygon. It adds a base light, a matte diffuse layer and a shiny highlight, which made curved models look smooth long before modern physically based shaders.

Think of it like this

It is like airbrushing instead of painting by numbers: color changes gradually across each shape, with no hard steps between patches.

Where it fits in a 3D project

  1. Create
  2. Surface
  3. Rig
  4. Animate
  5. Render
  6. Export

Render: Lighting the scene and turning it into images or video.

How Phong shading works

  1. 01Each vertex stores the direction its surface faces.
  2. 02Those directions are blended smoothly across every pixel of the polygon.
  3. 03At each pixel, ambient, diffuse and specular light are added together.
  4. 04A shininess value sets how small and sharp the highlight is.

Phong shading vs flat shading

PropertyPhong shadingFlat shading
Light calculatedPer pixel, blendedOnce per polygon
LookSmooth curves, soft highlightsFaceted, visible polygons
CostHigherLowest
Typical useSmooth objects, classic real-time 3DLow-poly style, quick previews

Use smooth, Phong-style shading for curved surfaces and flat shading when you want the facets to show, as in low-poly art.

Where Phong shading is used

  • Teaching how lighting models work
  • Simple real-time and web 3D materials
  • Stylized and retro looks

Beginner tip

If a smooth-shaded model shows dark streaks, the problem is usually its normals or topology, not the shading method. Check for flipped or uneven normals first.

Terms related to Phong shading

Phong shading FAQ

Is Phong shading still used?
Mostly in teaching, simple web and mobile 3D, and stylized work. Realistic renderers and modern engines use physically based shading, which handles roughness and energy more accurately, though Phong’s ideas still sit underneath.
What is the Phong reflection model?
It is the lighting formula behind Phong shading: ambient light for a base level, diffuse light for matte brightness, and a specular term for the highlight. Phong shading applies that formula at every pixel.
Is Phong shading the same as smooth shading?
Close. Smooth shading in 3D apps blends normals across faces, which is the core idea of Phong shading. The lighting on top is usually a modern PBR shader.

Updated October 29, 2026 · Browse all 3D terms