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SS_COMMAND: A Member of Printf-Family
ss_command is a member of the printf family of functions. It uses formatting descriptors such as %d and %s in the same manner as printf. In additon to the descriptors supported by printf, ss_command also supports one additional descriptor, %z. This descriptor allows for easy formatting of variables of the type SS_XYZ.
The SS_XYZ structure is used to store three-dimensional coordinates. The structure has three components:
C / C++ Code
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struct SS_XYZ
{
double x;
double y;
double z;
};
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The %z descriptor requires a pointer to a variable of type SS_XYZ. Let us assume that p1, p2, and p3 contain the coordinates of three points. Then ss_command can be used to draw a triangle as follows:
C / C++ Code
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SS_XYZ p1,p2,p3;
. . .
ss_command (“begin polygon”);
ss_command (“point %z”,&p1);
ss_command (“point %z”,&p2);
ss_command (“point %z”,&p3);
ss_command (“end polygon”);
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The use of the %z descriptor is equivalent to the use of three comma-separated %.15g descriptors. Without using %z, the above statements can be rewritten as
C / C++ Code
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ss_command (“point %.15g,%.15g,%.15g”,p1.x,p1.y,p1.z);
ss_command (“point %.15g,%.15g,%.15g”,p2.x,p2.y,p2.z);
ss_command (“point %.15g,%.15g,%.15g”,p3.x,p3.y,p3.z);
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A Short Example
The following program begins by opening a drawing with the name machine. The viewing mode is set to perspective, and the drawing is zoomed so that it appears at the center of the screen. The horizonal angle of view is then altered 12 times, each time by 30 degrees. With each change in view, the drawing is rendered and a BMP image is exported.
After unloading the drawing, the 12 BMP images are successively displayed on the screen.
C / C++ Code
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int i;
// Load the drawing
ss_command (“load drawing machine”);
// Set up window view
ss_command (“cursor disable”);
ss_command (“view project perspective”);
ss_command (“zoom drawing”);
// Loop 12 times: hide, save an image, then move view
for ( i = 1 ; i <= 12 ; ++i )
{
ss_command (“hide drawing fill edged gray”);
ss_command (“export picture file vw%d.bmp format bmp24 screen”, i);
ss_command (“view modify h-angle absolute %d”,i*30);
}
ss_command (“unload”);
for ( i = 1 ; i <= 12 ; ++i )
ss_command (“import picture file vw%d.bmp screen best-fit”,i);
ss_command (“cursor enable”);
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