132 lines
3.4 KiB
Groff
132 lines
3.4 KiB
Groff
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.TH gl_wtriangle 3 "2 Aug 1997" "Svgalib (>= 1.2.11)" "Svgalib User Manual"
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.SH NAME
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gl_wtriangle \- draw a shadowed pixmap mapped on a triangle
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.SH SYNOPSIS
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.B #include <triangle.h>
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.B typedef struct {
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.br
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.BI " unsigned char *" bitmap1 ;
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.br
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.BI " unsigned char *" bitmap2 ;
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.br
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.BI " int " bf ;
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.br
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.BI "} " TD_tridata ;
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.BI "void gl_wtriangle(int " x0 ", int " y0 ", int " xd0 ", int " yd0 ", int " z0
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.BI ", int " x1 ", int " y1 ", int " xd1 ", int " yd1 ", int " z1
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.BI ", int " x2 ", int " y2 ", int " xd2 ", int " yd2 ", int " z2 ", TD_tridata *" tri );
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.SH DESCRIPTION
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Draws a triangle at points 0, 1, 2 by mapping the pixmaps defined
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in the
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.B TD_triangle
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structure into the triangle.
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The
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.IR xd " and " yd
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values represent the triangle on the
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bitmap and the
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.IR x " and " y
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values represent the triangle
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on the screen. The
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.I z
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values represent an additional
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value which will be added to the color that is looked
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up from the pixmap data. Once again, if the
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current context is more than 8 bits then the result
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is interpreted as an index to the same lookup table. See
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.BR gl_triangle (3)
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for more details on shadowing.
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.B gl_wtriangle
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is used to draw wrapped surfaces
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.B with
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shadowing interpolation. The function
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.BR gl_swtriangle (3)
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does it without shadowing.
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.I bitmap1
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defines the back side of the triangle,
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.I bitmap2
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the front.
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The
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.I bf
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value is used to tell the routine to draw the backside
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if it is facing the other way.
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.I bf
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tells
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which way the triangle should be facing to show the front,
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since you will more than likely require both
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combinations.
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.IB bf " = 2"
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defines the back to be drawn when the points are arranged clockwise,
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.IB bf " = 3"
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defines the back to be drawn when the points are arranged counter clockwise,
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.IB bf " = -1"
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will probably always draw the front.
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Beware, these functions are not a direct part of the svgalib library.
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Instead their source is part of svgalib and can be found in the
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.I threeDkit/
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subdirectory of the original svgalib distribution. However, it is not
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installed in the system by default, s.t. it is unclear where you can find it
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if your svgalib was installed by some
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linux distribution.
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In case of any such problem, simply get an svgalib distribution from the net. Yo
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don't need to install it. Just
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.B make
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in the
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.I threeDkit/
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subdirectory. As of this writing,
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.I svgalib-1.2.12.tar.gz
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is the latest version and can be retrieved by ftp from
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.IR "sunsite.unc.edu" " at " "/pub/Linux/libs/graphics"
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and
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.IR "tsx-11.mit.edu" " at " "/pub/linux/sources/libs"
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which will most probably be mirrored by a site close to you.
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The functions are defined in the
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.IR tri.o " and " triangl.o
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files (or their resp. sources) which you must link to your program.
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.SH SEE ALSO
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.BR vgagl (7),
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.BR svgalib (7),
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.BR threedkit (7),
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.BR gl_striangle (3),
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.BR gl_swtriangle (3),
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.BR gl_triangle (3),
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.BR gl_trigetcolorlookup (3),
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.BR gl_trisetcolorlookup (3),
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.BR gl_trisetdrawpoint (3),
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.BR plane (6),
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.BR wrapdemo (6).
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.SH AUTHOR
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This manual page was edited by Michael Weller <eowmob@exp-math.uni-essen.de>. The
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demos, the initial documentation and the whole threedkit stuff was done by
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Paul Sheer <psheer@icon.co.za>.
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Paper mail:
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.RS
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Paul Sheer
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.br
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P O BOX 890507
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.br
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Lyndhurst
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.br
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Johannesburg 2106
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.br
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South Africa
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.RE
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Donations (by check or postal order) will be appreciated and will encourage
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further development of this software. However this is strictly on a voluntary
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basis where this software falls under the GNU LIBRARY GENERAL PUBLIC LICENSE.
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