Ray Tracing Assignment Goal is to reproduce the following Whitted, - - PDF document

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So You Want to Write a Ray Tracer

Checkpoint 4 – Procedural Shading

Ray Tracing Assignment

 Goal is to reproduce the following Whitted, 1980

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Ray Tracing Assignment

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Seven checkpoints

  Setting the Scene  Camera Modeling  Basic Shading   Procedural Shading  Recursive Ray Tracing – Reflection  Recursive Ray Tracing – Transmission   Tone Reproduction

Ray Tracing Assignment

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Seven checkpoints

  Setting the Scene  Camera Modeling  Basic Shading   Procedural Shading  Recursive Ray Tracing – Reflection  Recursive Ray Tracing – Transmission   Tone Reproduction

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Procedural Shading

 Use procedural texture to create a

checkerboard floor

 On floor intersection

 Rather than using Phong model  Compute color based on checkerboard

Texture Mapping

Will need point of intersection in object / world space Convert to (u,v) based

• n floor specs

Red or yellow based on which check Just return color (if not in shadow) or supply as diffuse / ambient color in Phong

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Texture Mapping

 At intersection point of floor

 Must obtain the “texture coordinates” to

map to u,v on texture.

 Use these u,v, values as a means to

determine color.

Procedural Shading

Point of intersection “origin” of floor Checksize

x / u y / v

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Procedural Shading

 Algorithm

 Given text coordinates (u,v) for point of

intersection

 Find row and col in which intersection point lies

color Col Row Red Odd Odd Yellow Even Odd Yellow Odd Even Red Even Even

Extra, Extra

 For 5 points each

 Implement another procedural shader or

texture (your choice)

 Implement texture map from image.

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Object oriented hints Procedual Shading

 Due date:

 Must be posted to Web site by Monday, January

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 Recall:

 10% penalty per day

 Having trouble?

 Let me know EARLY.

 Questions?