1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
|
/*
* beam.c
*
* FUNCTION:
* Show how twisting is applied.
*
* HISTORY:
* -- linas Vepstas October 1991
* -- heavily modified to draw corrugated surface, Feb 1993, Linas
* -- modified to demo twistoid March 1993
* -- port to glut Linas Vepstas March 1995
* Copyright (c) 1991, 1993, 1995 Linas Vepstas <linas@linas.org>
*/
/* required include files */
#include <math.h>
#include <stdlib.h>
#include <GL/gl.h>
#include <GL/glut.h>
#include <GL/gle.h>
#include "main.h"
/* =========================================================== */
#define NUM_BEAM_PTS 22
double beam_spine[NUM_BEAM_PTS][3];
double beam_twists [NUM_BEAM_PTS];
#define TSCALE (6.0)
#define TPTS(x,y,z) { \
beam_spine[i][0] = TSCALE * (x); \
beam_spine[i][1] = TSCALE * (y); \
beam_spine[i][2] = TSCALE * (z); \
i++; \
}
#define TXZERO() { \
beam_twists[i] = 0.0; \
}
/* =========================================================== */
#define SCALE 0.1
#define XSECTION(x,y) { \
double ax, ay, alen; \
xsection[i][0] = SCALE * (x); \
xsection[i][1] = SCALE * (y); \
if (i!=0) { \
ax = xsection[i][0] - xsection[i-1][0]; \
ay = xsection[i][1] - xsection[i-1][1]; \
alen = 1.0 / sqrt (ax*ax + ay*ay); \
ax *= alen; ay *= alen; \
xnormal [i-1][0] = - ay; \
xnormal [i-1][1] = ax; \
} \
i++; \
}
#define NUM_XSECTION_PTS (12)
double xsection [NUM_XSECTION_PTS][2];
double xnormal [NUM_XSECTION_PTS][2];
/* =========================================================== */
void InitStuff (void)
{
int i;
i=0;
while (i<22) {
TXZERO ();
TPTS (-1.1 +((float) i)/10.0, 0.0, 0.0);
}
i=0;
XSECTION (-6.0, 6.0);
XSECTION (6.0, 6.0);
XSECTION (6.0, 5.0);
XSECTION (1.0, 5.0);
XSECTION (1.0, -5.0);
XSECTION (6.0, -5.0);
XSECTION (6.0, -6.0);
XSECTION (-6.0, -6.0);
XSECTION (-6.0, -5.0);
XSECTION (-1.0, -5.0);
XSECTION (-1.0, 5.0);
XSECTION (-6.0, 5.0);
}
static void TwistBeam (double howmuch) {
int i;
double z;
for (i=0; i<22; i++) {
z = ((double) (i-14)) / 10.0;
beam_twists[i] = howmuch * exp (-3.0 * z*z);
}
}
/* =========================================================== */
void DrawStuff (void) {
TwistBeam ((double) (lastx -121) / 8.0);
glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
/* set up some matrices so that the object spins with the mouse */
glPushMatrix ();
glTranslatef (0.0, 0.0, -80.0);
glRotated (43.0, 1.0, 0.0, 0.0);
glRotated (43.0, 0.0, 1.0, 0.0);
glScaled (1.8, 1.8, 1.8);
gleTwistExtrusion (NUM_XSECTION_PTS, xsection, xnormal,
NULL, NUM_BEAM_PTS, beam_spine, NULL, beam_twists);
glPopMatrix ();
glutSwapBuffers ();
}
/* ------------------ end of file -------------------- */
|
