| More 3-D transormations [message #15821] |
Fri, 11 June 1999 00:00 |
philaldis
Messages: 32
Registered: March 1999
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Member |
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Well I thought while a few people are talking about 3-d
transformations, I thought I'd try and get in and ask a question that
I really can't work out.
For starters I don't understand how !p.t really works. I'm only 18 and
my double maths A-Level certainly did not stretch to 4-d
transformation matrixes. So, I really do know nothing about them,
which is why I'm finding this problem a very difficult one to solve.
In this object/direct graphics thing that I'm doing (which by the way
anyone going to the RSI England user seminar will hear about because
I'm doing a talk on it) positions are always a 4 element vector [x, y,
x, y]. The system is not at all 3-d and so that made sense.
However I have also written surface objects (which use direct graphics
to display). I want these also to have a 4 element position vector
[x,y,x,y], which is the same as for a plot.
i.e. It would be as if you displayed the surface in the z
graphics buffer then displayed the image at the right position using
tvimage.
So what I want to know is how can I set up all the x, y, z, scaling
factors and !p.t, and whatever, based on the xz and xy rotations so
that the surface WILL appear within a specified 4 element position
vector.
I hope I've made what I would really like clear. If anyone can help, I
would be SO SO grateful.
Cheers,
Phil Aldis
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