Overview
Cook-Torrance shading combines normal distribution, geometry, and Fresnel terms to approximate physically based specular highlights.
CoreSource checked
Cook-Torrance Shading
Models specular reflection using microfacet surface behavior.
Quick Facts
Compact metadata for implementation and discovery.
- Category
- Rendering
- Difficulty
- Advanced
- Family
- Physically Based Shading
- Tier
- Core
- Status
- Verified
- Review
- Source Checked
- Sources
- 2
- Formulas
- 1
- Relationships
- 4
- Code example
- Ready
- Visualization
- Ready
Core Concepts
microfacet modelfresnel termnormal distributiongeometry term
Quick facts
Complexity
Runtime and memory behavior at a glance.
Best
O(1)
Average
O(pixels * lights)
Worst
O(pixels * lights)
Space
O(1)
When to Use
- Use when real-time graphics needs microfacet model.
- Use when the input matches the assumptions behind physically Based Shading.
When Not to Use
- Avoid when the effect costs more than the visual improvement for the target hardware.
- Avoid when a simpler algorithm gives the required result with less setup.
What It Does
- Models specular reflection using microfacet surface behavior
- Uses microfacet model and fresnel term to guide the work.
- Produces rendered image.
Use Cases
- Real-time graphics
- Offline rendering
- Lighting and visibility effects
Inputs
- Scene geometry
- Materials
- Camera and lighting state
Outputs
- Rendered image
- Visibility or shading buffers
Key Formulas (1)
Cook-Torrance BRDF
f = D · F · G / (4 · NdotL · NdotV)
f = D * F * G / (4 * NdotL * NdotV)Combines microfacet distribution, Fresnel, and masking-shadowing terms.
Pseudocode
- 1.Prepare the inputs and state needed for Cook-Torrance Shading.
- 2.Apply the microfacet model step while the stopping condition has not been met.
- 3.Update intermediate state and discard invalid candidates.
- 4.Return rendered image.
Canonical Example
- Input
- surface normal, light direction, view direction, roughness, and metallic value
- Output
- physically based specular lighting contribution
- Explanation
- The model combines microfacet distribution, geometry, and Fresnel terms to estimate reflected light.
Implementation Notes
- Evaluate distribution, geometry, and Fresnel terms consistently.
- Clamp dot products to valid ranges.
- Keep energy conservation and color-space conversion explicit.
Common Pitfalls
- Using unnormalized normal, light, or view vectors.
- Mixing color-space conventions for material parameters.
- Treating roughness and specular terms as independent of the chosen BRDF convention.
Interactive Mechanism Walkthrough
Spatial Primitive & Sweep-Line CanvasShow rays, samples, buffers, or shading terms that contribute to the final pixel.
Step 1 of 4: Prepare the inputs and state needed for Cook-Torrance Shading.
rendering-mechanismNotes
Cook-Torrance shading is a microfacet model; practical results depend on chosen D, F, and G terms.
Sources (2)
What each reference supports for this entry.
Cook-Torrance paper
PaperOriginal ACM Transactions on Graphics paper for the Cook-Torrance reflectance model.
Open sourcePhysically Based Rendering
BookOnline book reference for ray tracing, path tracing, sampling, BRDFs, and rendering implementation.
Open sourceExplore Next
Good next jumps from the relationship graph, ranked for useful discovery.
Relationships
View full relationship pageAlternative toBlinn-Phong Shading
Cook-Torrance is a physically based alternative to classic empirical specular models.
Often paired withImportance Sampling BRDF
Physically based BRDFs are often importance sampled in renderers.
Related Algorithms
Tags
GraphicsBRDFShadingLighting