questions about drawing polygons
Dan Christensen
jdchrist at watcgl.waterloo.edu
Thu May 18 01:25:14 AEST 1989
I have a couple of questions regarding the drawing of filled polygons
on an Iris 4D/120GTX.
1) Using the fastest settings of the lighting model (single light source
at infinity, viewer at infinity), how many shaded polygons can be
drawn per second? (I know that this is a difficult question, but a
rough figure would be useful).
2) I am trying to draw a large mesh of shaded triangles. The GT
Library has routines for drawing triangular meshes. These
routines look like they would speed up drawing significantly because
only one third of the lighting calculations need to be done and one
third of the data needs to be put into the pipeline, compared to
drawing each triangle separately. The problem I found with these
routines is that you have no control over the order in which the
vertices are drawn so that backface removal becomes useless.
Turning off backface removal results in an overall slowing in the
drawing. Is there any way to specify the order in which the
vertices are drawn? It would be a shame if there isn't because
these routines look like they could speed things up greatly. Is
there a way to do the same thing manually? Could the program draw
each vertex and save the colours calculated by the hardware and then
draw the polygons with the lighting model turned off, using the
precalculated colours?
Thanks for any help.
----
Dan Christensen, Computer Graphics Lab, jdchrist at watcgl.uwaterloo.ca
University of Waterloo, Waterloo, Ont. jdchrist at watcgl.waterloo.edu
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