Homework3
A reminder: you are free to collaborate, but you must understand and write up the final answers by yourself!
Complete the homework as a pdf, doc, or on paper (and scan), then submit it to the homework3 directory in your class repo.
- The Phong shading model does not account for shadows, that is, light sources being occluded (blocked) by other objects. Based on your knowledge of the fragment shading stage, describe the difficulties of supporting shadows.
Rubric
| Requirements for shadow support | No changes to fragment stage : 0 | List of data sources/functions needed for shadow test : 5 |
| Cost analysis | No analysis : 0 | Compute cost analysis : 5 |
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Consider the 16 combinations of: near or far viewer; near or far light source; planar or curved surfaces; and, diffuse or specular material. Label each combination with the lowest cost shading model which will produce correct results. The choices for shading models are 'flat | Gouraud | Phong : and 'other'. Other is a shading model better than Phong.
You should definitely consider the derivative of the reflectance vectors when doing this problem!
| Near light | Near light | Far light | Far light | ||
| Near view | Far view | Near view | Far view | ||
| Diffuse surface | Curved | ||||
| Diffuse surface | Planer | ||||
| Specular surface | Curved | ||||
| Specular surface | Planer |
Rubric
| Correct model used | Incorrect models : 0 | Model selected based on vector derivatives : 16 |
- Explain why the incremental effort to go from flat shading to Gouraud shading is small, but the incremental effort to go from Gouraud shading to Phong shading is large.
Rubric
| Flat-Gouraud analysis | No analysis : 0 | Notes differences in flat to Gouraud : 4 |
| Gouraud-Phong analysis | No analysis : 0 | Notes differences in Gouraud to Phong : 4 |