line drawing speed on iris 4D
Dan Christensen
jdchrist at watcgl.waterloo.edu
Wed Nov 9 06:26:06 AEST 1988
I am working on a program that draws many spheres. These spheres are
approximated by a set of polygons. Often I just want to draw a
wireframe image of this sphere, so I construct a set of lines
representing the edges of the polygons. I am interested in drawing
these lines as quickly as possible. My questions are:
1) Will it make a significant difference if I draw the sphere as a
series of connected paths rather than as separate line segments?
In other words, is
move( pos1 ); draw( pos2 ); draw( pos3 ); ... ; draw( posn )
going to be much quicker than
move( pos1 ); draw( pos2 ); move( pos2 ); draw( pos3 ); ...
move( posn-1 ); draw( posn ) ?
2) How much will the length of lines change this?
3) How much will precompiling the lines into an object affect this and
how will removing the extra moves affect the precompiling speed?
4) What is a good way to experimentally check this? I am finding it
difficult to do accurate timings, as timing how long it takes to
perform the moves and draws, doesn't take into account how long
they spend going through the pipeline. The timer stops before
the drawing is actually drawn.
Thanks in advance for any help.
I'll post a summary.
Dan
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