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- basic model: rectangular paper, of which a convex region is shown |
- basic model: rectangular paper, of which a convex region is shown |
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\subsection{Why} |
\subsection{Rationale ``Why?''} |
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A smooth rectangular or elliptical frame can make small viewports seem claustrophobic. |
A smooth rectangular or elliptical frame can make small viewports seem claustrophobic. |
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One reason for this is that the frame is often visually too small for its contents |
One reason for this is that the frame is often visually too small for its contents |
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Because of this, it should be readily comprehensible |
Because of this, it should be readily comprehensible |
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to users that we're not tearing the original paper but only a depiction of it. |
to users that we're not tearing the original paper but only a depiction of it. |
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\subsection{What} |
\subsection{Detailed design ``What?''} |
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- distinguishing between edges of paper and the viewport useful |
- distinguishing between edges of paper and the viewport useful |
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- edge of paper = line, edge of viewport = torn |
- edge of paper = line, edge of viewport = torn |
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is visible as the ``rippling speed'' |
is visible as the ``rippling speed'' |
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porthole |
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Knuth \& John Hobby ref. |
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Non-photorealism: easier to understand motion; photorealistic would seem bizarre. |
Non-photorealism: easier to understand motion; photorealistic would seem bizarre. |
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porthole |
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- draw edge |
- draw edge |
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For the edge thickness, scaling it with the scale of the paper is not good |
For the edge thickness, scaling it with the scale of the paper is not good |
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(too photorealistic...), but neither is a constant width, which ... |
(too photorealistic...), but neither is a constant width, which ... |
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Square root |
Square root |
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Edge shapes: attached and sprinkled. |
Edge shapes: attached and sprinkled and intermediates. |
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\subsection{How} |
\subsection{Algorithm ``How?''} |
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Surface defined by $(x, y, f(x,y))$. |
Surface defined by $(x, y, f(x,y))$. |
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The jagged version of an edge in the $z=0$ plane is obtained by first |
The jagged version of an edge in the $z=0$ plane is obtained by first |
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the feature sets of other APIs and manufacturers |
the feature sets of other APIs and manufacturers |
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are quite similar. |
are quite similar. |
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Knuth \& John Hobby ref. |
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\subsection{A shape with the correct type of motion} |
\subsection{A shape with the correct type of motion} |
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stored in a ``displacement map'' texture |
stored in a ``displacement map'' texture |