+/* tube, Copyright (c) 2001 Jamie Zawinski <jwz@jwz.org>
+ * Utility functions to create tubes and cones in GL.
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and its
+ * documentation for any purpose is hereby granted without fee, provided that
+ * the above copyright notice appear in all copies and that both that
+ * copyright notice and this permission notice appear in supporting
+ * documentation. No representations are made about the suitability of this
+ * software for any purpose. It is provided "as is" without express or
+ * implied warranty.
+ */
+
+#include "config.h"
+#include <stdlib.h>
+#include <math.h>
+#include <GL/glx.h>
+#include "tube.h"
+
+static void
+unit_tube (int faces, Bool smooth, Bool wire)
+{
+ int i;
+ GLfloat step = M_PI * 2 / faces;
+ GLfloat s2 = step/2;
+ GLfloat th;
+ GLfloat x, y, x0, y0;
+ int z = 0;
+
+ /* side walls
+ */
+ glFrontFace(GL_CCW);
+ glBegin (wire ? GL_LINES : (smooth ? GL_QUAD_STRIP : GL_QUADS));
+
+ th = 0;
+ x = 1;
+ y = 0;
+
+ if (!smooth)
+ {
+ x0 = cos (s2);
+ y0 = sin (s2);
+ }
+
+ if (smooth) faces++;
+
+ for (i = 0; i < faces; i++)
+ {
+ if (smooth)
+ glNormal3f(x, 0, y);
+ else
+ glNormal3f(x0, 0, y0);
+
+ glVertex3f(x, 0, y);
+ glVertex3f(x, 1, y);
+
+ th += step;
+ x = cos (th);
+ y = sin (th);
+
+ if (!smooth)
+ {
+ x0 = cos (th + s2);
+ y0 = sin (th + s2);
+
+ glVertex3f(x, 1, y);
+ glVertex3f(x, 0, y);
+ }
+ }
+ glEnd();
+
+ /* End caps
+ */
+ for (z = 0; z <= 1; z++)
+ {
+ glFrontFace(z == 0 ? GL_CCW : GL_CW);
+ glNormal3f(0, (z == 0 ? -1 : 1), 0);
+ glBegin(wire ? GL_LINE_LOOP : GL_TRIANGLE_FAN);
+ if (! wire) glVertex3f(0, z, 0);
+ for (i = 0, th = 0; i <= faces; i++)
+ {
+ GLfloat x = cos (th);
+ GLfloat y = sin (th);
+ glVertex3f(x, z, y);
+ th += step;
+ }
+ glEnd();
+ }
+}
+
+
+static void
+unit_cone (int faces, Bool smooth, Bool wire)
+{
+ int i;
+ GLfloat step = M_PI * 2 / faces;
+ GLfloat s2 = step/2;
+ GLfloat th;
+ GLfloat x, y, x0, y0;
+
+ /* side walls
+ */
+ glFrontFace(GL_CW);
+ glBegin(wire ? GL_LINES : GL_TRIANGLES);
+
+ th = 0;
+ x = 1;
+ y = 0;
+ x0 = cos (s2);
+ y0 = sin (s2);
+
+ for (i = 0; i < faces; i++)
+ {
+ glNormal3f(x0, 0, y0);
+ glVertex3f(0, 1, 0);
+
+ if (smooth) glNormal3f(x, 0, y);
+ glVertex3f(x, 0, y);
+
+ th += step;
+ x0 = cos (th + s2);
+ y0 = sin (th + s2);
+ x = cos (th);
+ y = sin (th);
+
+ if (smooth) glNormal3f(x, 0, y);
+ glVertex3f(x, 0, y);
+ }
+ glEnd();
+
+ /* End cap
+ */
+ glFrontFace(GL_CCW);
+ glNormal3f(0, -1, 0);
+ glBegin(wire ? GL_LINE_LOOP : GL_TRIANGLE_FAN);
+ if (! wire) glVertex3f(0, 0, 0);
+ for (i = 0, th = 0; i <= faces; i++)
+ {
+ GLfloat x = cos (th);
+ GLfloat y = sin (th);
+ glVertex3f(x, 0, y);
+ th += step;
+ }
+ glEnd();
+}
+
+
+static void
+tube_1 (GLfloat x1, GLfloat y1, GLfloat z1,
+ GLfloat x2, GLfloat y2, GLfloat z2,
+ GLfloat diameter, GLfloat cap_size,
+ int faces, Bool smooth, Bool wire,
+ Bool cone_p)
+{
+ GLfloat length, angle, a, b, c;
+
+ if (diameter <= 0) abort();
+
+ a = (x2 - x1);
+ b = (y2 - y1);
+ c = (z2 - z1);
+
+ length = sqrt (a*a + b*b + c*c);
+ angle = acos (a / length);
+
+ glPushMatrix();
+ glTranslatef(x1, y1, z1);
+ glScalef (length, length, length);
+
+ if (c == 0 && b == 0)
+ glRotatef (angle / (M_PI / 180), 0, 1, 0);
+ else
+ glRotatef (angle / (M_PI / 180), 0, -c, b);
+
+ glRotatef (-90, 0, 0, 1);
+ glScalef (diameter/length, 1, diameter/length);
+
+ /* extend the endpoints of the tube by the cap size in both directions */
+ if (cap_size != 0)
+ {
+ GLfloat c = cap_size/length;
+ glTranslatef (0, -c, 0);
+ glScalef (1, 1+c+c, 1);
+ }
+
+ if (cone_p)
+ unit_cone (faces, smooth, wire);
+ else
+ unit_tube (faces, smooth, wire);
+ glPopMatrix();
+}
+
+
+void
+tube (GLfloat x1, GLfloat y1, GLfloat z1,
+ GLfloat x2, GLfloat y2, GLfloat z2,
+ GLfloat diameter, GLfloat cap_size,
+ int faces, Bool smooth, Bool wire)
+{
+ tube_1 (x1, y1, z1, x2, y2, z2, diameter, cap_size, faces, smooth, wire,
+ False);
+}
+
+
+void
+cone (GLfloat x1, GLfloat y1, GLfloat z1,
+ GLfloat x2, GLfloat y2, GLfloat z2,
+ GLfloat diameter, GLfloat cap_size,
+ int faces, Bool smooth, Bool wire)
+{
+ tube_1 (x1, y1, z1, x2, y2, z2, diameter, cap_size, faces, smooth, wire,
+ True);
+}