If your lines are actually filled primitives in line mode, you can alwaysQuote:> Anyone know of a fairly straight-
> forward way to make lines invisible from the backside? The best I
> can do right now is use thin quads drawn with 'PolygonMode' set
> to (GL_FRONT, GL_LINE). Thanks for your suggestions. mfw.
If not, you will need to cull them yourself. This can be done by
hand-transforming the normals, doing a dot product with a vector to the eye,
and culling the line if the result is negative.
Hidden surface removal of wireframe primitives was a hot area of research in
the 1970s and there are several mechanisms which are very efficient for
specific types of data. You might try hunting down some old SIGGRAPH
proceedings (usually readily available in the libraries of large
Hewlett Packard Workstation Systems Lab
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i want to draw in hidden line mode in an SoXtRenderArea. the manual page for
VIEW_HIDDEN_LINE - Renders the object as wireframe, but only show
the object front faces. This is accomplished using a two pass
rendering. In the first pass, the objects are rendered as FILLED
using the background BASE_COLOR (this sets up the wanted z-buffer
values). The second pass then renders the objects as LINES, while
adjusting the z-buffer range to limit overlapping polygons problems.
i understand that. my problems are:
-) to draw in the background color i have to use a basecolor node (+ a
material node ?) that sets the color to the background color with its override
flag set to keep the color fixed. but how can i change the color again when i
draw the lines?
-) how do i adjust the z-buffer range and how much adjusting is needed to
avoid the known problems?
thanks in advance.