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VIEWS.C
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C/C++ Source or Header
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1994-04-27
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3KB
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155 lines
#include <stdio.h>
#include "vogle.h"
/*
* Shows various combinations of viewing and
* projection transformations.
*/
main()
{
vinit("mswin");
color(BLACK);
clear();
/*
* we want to draw just within the boundaries of the screen
*/
viewport(-0.9, 0.9, -0.9, 0.9);
ortho2(-5.0, 5.0, -5.0, 5.0); /* set the world size */
color(RED);
rect(-5.0, -5.0, 5.0, 5.0); /* draw a boundary frame */
/*
* set up a perspective projection with a field of view of
* 40.0 degrees, aspect ratio of 1.0, near clipping plane 0.1,
* and the far clipping plane at 1000.0.
*/
perspective(40.0, 1.0, 0.1, 1000.0);
/*
* we want the drawing to be done with our eye point at (5.0, 8.0, 5.0)
* looking towards (0.0, 0.0, 0.0). The last parameter gives a twist
* in degrees around the line of sight, in this case zero.
*/
lookat(5.0, 8.0, 5.0, 0.0, 0.0, 0.0, 0.0);
drawtetra();
move2(-4.5, -4.5);
textsize(0.6, 0.9); /* set the text size */
drawstr("perspective/lookat");
getkey();
/*
* window can also be used to give a perspective projection. Its
* arguments are 6 clipping planes, left, right, bottom, top, near,
* and far.
*/
window(-5.0, 5.0, -5.0, 5.0, -5.0, 5.0);
/*
* as window replaces the current transformation matrix we must
* specify our viewpoint again.
*/
lookat(5.0, 8.0, 5.0, 0.0, 0.0, 0.0, 0.0);
color(BLACK);
clear();
color(GREEN);
rect(-5.0, -5.0, 5.0, 5.0);
drawtetra();
move2(-4.5,-4.5);
textsize(0.6, 0.9); /* set the text size */
drawstr("window/lookat");
getkey();
/*
* set up our original perspective projection again.
*/
perspective(40.0, 1.0, 0.1, 1000.0);
/*
* polarview also specifies our viewpoint, but, unlike lookat, in polar
* coordinates. Its arguments are the distance from the world origin, an
* azimuthal angle in the x-y plane measured from the y axis, an
* incidence angle in the y-z plane measured from the z axis, and a
* twist around the line of sight.
*/
polarview(15.0, 30.0, 30.0, 30.0);
color(BLACK);
clear();
color(MAGENTA);
rect(-5.0, -5.0, 5.0, 5.0);
drawtetra();
move2(-4.5,-4.5);
textsize(0.6, 0.9); /* set the text size */
drawstr("perspective/polarview");
getkey();
/*
* once more with window for comparison
*/
window(-4.0, 4.0, -4.0, 4.0, -4.0, 4.0);
polarview(6.0, 20.0, -30.0, 70.0);
color(BLACK);
clear();
color(YELLOW);
rect(-5.0, -5.0, 5.0, 5.0);
drawtetra();
move2(-4.5,-4.5);
textsize(0.6, 0.9); /* set the text size */
drawstr("window/polarview");
getkey();
vexit();
}
/*
* drawtetra
*
* generate a tetraedron as a series of move draws
*/
drawtetra()
{
move(-0.5, 0.866, -0.5);
draw(-0.5, -0.866, -0.5);
draw( 1.0, 0.0, -0.5);
draw(-0.5, 0.866, -0.5);
draw( 0.0, 0.0, 1.5);
draw(-0.5, -0.866, -0.5);
move( 1.0, 0.0, -0.5);
draw( 0.0, 0.0, 1.5);
/*
* Label the vertices.
*/
color(WHITE);
textsize(0.3, 0.5); /* set the text size */
move(-0.5, 0.866, -0.5);
drawchar('a');
move(-0.5, -0.866, -0.5);
drawchar('b');
move( 1.0, 0.0, -0.5);
drawchar('c');
move( 0.0, 0.0, 1.5);
drawchar('d');
}