CS488 - Introduction to Computer Graphics - Lecture 7

Comments and Questions


  1. Transformation Matrices
  2. Rotation
  3. Transposition

Non-rigid Transformations


Three interpretations

  1. Change of units
  2. Movement of point
  3. Change of frame


Device Transformations


On the view plane


On the device

Normalized Device Coordinates

For the device, obviously


What is it?

Representations of Lines

  1. Parametric
  2. Implicit

Clip a Point against a Half-space.

Representation of a Half-space.

Calculate ( R - P ) . n

Clip a Line Segment to a Half-space.

The line segment

Test if each of R and S are inside. Calculate

  1. ( R - P ) . n
  2. ( S - P ) . n

There are three cases

  1. Both inside: keep the segment as is.
  2. Both outside: discard the segment.
  3. One inside, one outside: the segment crosses the boundary of the half-space.

Clip a Line Segment to a Rectangle

Straightforward, BUT what if the line segment crosses a corner?

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