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
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
|
/*
* taper.c
*
* FUNCTION:
* Draws a tapered screw shape.
*
* HISTORY:
* -- created by Linas Vepstas October 1991
* -- heavily modified to draw more texas shapes, Feb 1993, Linas
* -- converted to use GLUT -- December 1995, Linas
*
*/
#include "extrusion.h"
#include <math.h>
#include <stdlib.h>
#ifndef NULL
#define NULL ((void *) 0x0)
#endif /* NULL */
/* Some <math.h> files do not define M_PI... */
#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif
/* =========================================================== */
#define SCALE 3.33333
#define CONTOUR(x,y) { \
double ax, ay, alen; \
contour[i][0] = SCALE * (x); \
contour[i][1] = SCALE * (y); \
if (i!=0) { \
ax = contour[i][0] - contour[i-1][0]; \
ay = contour[i][1] - contour[i-1][1]; \
alen = 1.0 / sqrt (ax*ax + ay*ay); \
ax *= alen; ay *= alen; \
norms [i-1][0] = ay; \
norms [i-1][1] = -ax; \
} \
i++; \
}
#define NUM_PTS (25)
static double contour [NUM_PTS][2];
static double norms [NUM_PTS][2];
static void init_contour (void)
{
int i;
/* outline of extrusion */
i=0;
CONTOUR (1.0, 1.0);
CONTOUR (1.0, 2.9);
CONTOUR (0.9, 3.0);
CONTOUR (-0.9, 3.0);
CONTOUR (-1.0, 2.9);
CONTOUR (-1.0, 1.0);
CONTOUR (-2.9, 1.0);
CONTOUR (-3.0, 0.9);
CONTOUR (-3.0, -0.9);
CONTOUR (-2.9, -1.0);
CONTOUR (-1.0, -1.0);
CONTOUR (-1.0, -2.9);
CONTOUR (-0.9, -3.0);
CONTOUR (0.9, -3.0);
CONTOUR (1.0, -2.9);
CONTOUR (1.0, -1.0);
CONTOUR (2.9, -1.0);
CONTOUR (3.0, -0.9);
CONTOUR (3.0, 0.9);
CONTOUR (2.9, 1.0);
CONTOUR (1.0, 1.0); /* repeat so that last normal is computed */
}
/* =========================================================== */
#define PSIZE 40
static double path[PSIZE][3];
static double twist[PSIZE];
static double taper[PSIZE];
static void init_taper (void) {
int j;
double z, deltaz;
double ang, dang;
z = -10.0;
deltaz = 0.5;
ang = 0.0;
dang = 20.0;
for (j=0; j<40; j++) {
path[j][0] = 0x0;
path[j][1] = 0x0;
path[j][2] = z;
twist[j] = ang;
ang += dang;
taper[j] = 0.1 * sqrt (9.51*9.51 - z*z);
z += deltaz;
}
taper[0] = taper[1];
taper[39] = taper[38];
}
/* =========================================================== */
/* controls shape of object */
extern float lastx;
extern float lasty;
void InitStuff_taper (void)
{
int style;
/* configure the pipeline */
style = TUBE_JN_CAP;
style |= TUBE_CONTOUR_CLOSED;
style |= TUBE_NORM_FACET;
style |= TUBE_JN_ANGLE;
gleSetJoinStyle (style);
init_contour();
init_taper();
}
/* =========================================================== */
static void gleTaper (int ncp,
gleDouble contour[][2],
gleDouble cont_normal[][2],
gleDouble up[3],
int npoints,
gleDouble point_array[][3],
float color_array[][3],
gleDouble taper[],
gleDouble twist[])
{
int j;
gleAffine *xforms;
double co, si, angle;
/* malloc the extrusion array and the twist array */
xforms = (gleAffine *) malloc (npoints * sizeof(gleAffine));
for (j=0; j<npoints; j++) {
angle = (M_PI/180.0) * twist[j];
si = sin (angle);
co = cos (angle);
xforms[j][0][0] = taper[j] * co;
xforms[j][0][1] = - taper[j] * si;
xforms[j][0][2] = 0.0;
xforms[j][1][0] = taper[j] * si;
xforms[j][1][1] = taper[j] * co;
xforms[j][1][2] = 0.0;
}
gleSuperExtrusion (ncp, /* number of contour points */
contour, /* 2D contour */
cont_normal, /* 2D contour normals */
up, /* up vector for contour */
npoints, /* numpoints in poly-line */
point_array, /* polyline */
color_array, /* color of polyline */
xforms);
free (xforms);
}
/* =========================================================== */
void DrawStuff_taper (void) {
int j;
double ang, dang;
double z, deltaz;
double ponent;
z=-1.0;
deltaz = 1.999/38;
ang = 0.0;
dang = lasty/40.0;
ponent = fabs (lastx/540.0);
for (j=1; j<39; j++) {
twist[j] = ang;
ang += dang;
taper[j] = pow ((1.0 - pow (fabs(z), 1.0/ponent)), ponent);
z += deltaz;
}
glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glColor3f (0.5, 0.6, 0.6);
/* set up some matrices so that the object spins with the mouse */
glPushMatrix ();
/* glTranslatef (0.0, 0.0, -80.0); */
/* glRotatef (130.0, 0.0, 1.0, 0.0); */
/* glRotatef (65.0, 1.0, 0.0, 0.0); */
/* draw the brand and the handle */
gleTaper (20, contour, norms, NULL, 40, path, NULL, taper, twist);
glPopMatrix ();
}
/* ===================== END OF FILE ================== */
|
