400 |
However, the tearout shape can rotate, requiring surfaces |
However, the tearout shape can rotate, requiring surfaces |
401 |
for all tearing directions in the paper. |
for all tearing directions in the paper. |
402 |
We compute the outer surfaces for a small number of different |
We compute the outer surfaces for a small number of different |
403 |
tearing directions (45 or 60 degress apart) and store them |
tearing directions and store them |
404 |
in the components of a texture. |
in the components of a texture. |
405 |
The surface corresponding to a a tearing direction between |
The surface corresponding to a a tearing direction between |
406 |
two stored angles is computed |
two stored angles is computed |
410 |
The interpolation works better for non-vertical cutting planes. |
The interpolation works better for non-vertical cutting planes. |
411 |
For a vertical cutting plane, the circle may fit in a narrow valley |
For a vertical cutting plane, the circle may fit in a narrow valley |
412 |
only in a certain angle, making large changes in the outer surface |
only in a certain angle, making large changes in the outer surface |
413 |
over small changes of angle. On the other hand, when the cutting |
over small changes of angle. |
414 |
plane is closer to horizontal, there can be no such gaps, |
When the cutting plane is closer to horizontal, there can be no such gaps, |
415 |
because the surface is defined as a displacement from a horizontal plane. |
because the surface is defined as a displacement from a horizontal plane. |
416 |
|
On the other hand, it suffices to store only half of the tearing angles |
417 |
|
of a vertical cutting plane, because 180 degree rotation of the plane |
418 |
|
has no effect. |
419 |
|
A four-component texture can store angles 45 degress apart for a vertical |
420 |
|
cutting plane and 90 degrees apart for a non-vertical plane. |
421 |
|
|
422 |
Non-photorealistic line-width through mip-mapping. |
Non-photorealistic line-width through mip-mapping. |
423 |
%Pyramidal parametrics, Lance Williams (mipmap) ref. |
%Pyramidal parametrics, Lance Williams (mipmap) ref. |