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1993-03-13
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Changes in version 3.0 vs. version 2.1
- Pure z-buffer replaced with a more powerful "pixel-buffer" which
allow transparent surfaces to be rendered. Transparency is controlled
in the shaders which allow interesing effects, like
"transparency-mapping"
- Shadow casting supported through depth-maps.
- A more general lightsource concept which make it possible to have
colored lightsources of different kind, turn these on and off and
manipulate them in various other ways.
- It is possible to create several virtual cameras and then use
any of them as viewpoint in a rendering.
- Viewing vectors sent to the shaders are no longer an approximation.
- Shaders can be more powerful since more information is sent to them,
and a more flexibel shader-lightsource interface is used.
- A background color can be specified.
- Texture coordinate interpolation is finally done right (I hope...)
- Bezier patches and surfaces of revoultion can be created with a
simple function call instead of reading them from a file in our
weird format.
- All object primitives can now be created with one of a few different
texture coordinate mappings.
- A new shader: The familiar Phong illumination model.
- A complete user manual in texinfo format.
Changes in version 2.1 vs. version 2.0.*
- Support for more rendering modes: Phong, Gouraud, flat and line.
Only Phong mode can do real texture mapping though.
- Support for rendering into other places than files. We have chosen
to call this rendering into pixmaps, but there is no restriction on
what is really used. This is accomplished through a callback function
similar to the shader interface. A basic implementation of pixmaps
and bitmaps that could be used are supplied in the library.
- Oversampling for antialiasing can now be arbitrarily large.
- It is possible to turn off backface culling. This is useful if you
have a database of objects that are inconsequent in the ordering
of its vertices (clockwize/counterclockwize).
- Two new object primitives, cone and prism.
Thanks to David Jones (djones@awesome.berkeley.edu) for these.
- Two new shaders.
1. strauss_shader() - This is an implementation of the shading
model designed by Paul S. Strauss at Silicon Graphics Inc.
and described in IEEE CG&A November 1990.
2. wood_shader() - A shader that simulates wood texture using
noise and turbulence.
- Matrix and vector handling functions and macros are now "public".
- Correct interpolation of texture coordinates. Previously there
were disturbing "rubberband" effects on objects spanning large
depths in the picture.
- A full polygon clipper is now used instead of the previous, rather
strange approach. Objects behind the viewpoint are now handled correctly
(I hope), previously they caused strange effects.
- It is possible to get the current transformation matrix from an object
and not only to set it. This makes it a lot easier to do animations.
- Subobjects and surfaces can now be removed from objects.