Initial revision
diff --git a/progs/samples/stencil.c b/progs/samples/stencil.c
new file mode 100644
index 0000000..e00bbb6
--- /dev/null
+++ b/progs/samples/stencil.c
@@ -0,0 +1,143 @@
+/*
+ * Copyright (c) 1991, 1992, 1993 Silicon Graphics, Inc.
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and
+ * its documentation for any purpose is hereby granted without fee, provided
+ * that (i) the above copyright notices and this permission notice appear in
+ * all copies of the software and related documentation, and (ii) the name of
+ * Silicon Graphics may not be used in any advertising or
+ * publicity relating to the software without the specific, prior written
+ * permission of Silicon Graphics.
+ *
+ * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF
+ * ANY KIND,
+ * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
+ * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * IN NO EVENT SHALL SILICON GRAPHICS BE LIABLE FOR
+ * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
+ * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
+ * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
+ * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
+ * OF THIS SOFTWARE.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+#include <GL/glut.h>
+
+
+static void Init(void)
+{
+ glShadeModel(GL_FLAT);
+ glClearColor(0.0, 0.0, 0.0, 0.0);
+
+ glClearStencil(0);
+ glStencilMask(1);
+ glEnable(GL_STENCIL_TEST);
+}
+
+static void Reshape(int width, int height)
+{
+
+ glViewport(0, 0, (GLint)width, (GLint)height);
+
+ glMatrixMode(GL_PROJECTION);
+ glLoadIdentity();
+ glOrtho(-5.0, 5.0, -5.0, 5.0, -5.0, 5.0);
+ glMatrixMode(GL_MODELVIEW);
+}
+
+static void Key(unsigned char key, int x, int y)
+{
+
+ switch (key) {
+ case 27:
+ exit(1);
+ }
+}
+
+static void Draw(void)
+{
+
+ glClear(GL_COLOR_BUFFER_BIT|GL_STENCIL_BUFFER_BIT);
+
+ glStencilFunc(GL_ALWAYS, 1, 1);
+ glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE);
+
+ glColor3ub(200, 0, 0);
+ glBegin(GL_POLYGON);
+ glVertex3i(-4, -4, 0);
+ glVertex3i( 4, -4, 0);
+ glVertex3i( 0, 4, 0);
+ glEnd();
+
+ glStencilFunc(GL_EQUAL, 1, 1);
+ glStencilOp(GL_INCR, GL_KEEP, GL_DECR);
+
+ glColor3ub(0, 200, 0);
+ glBegin(GL_POLYGON);
+ glVertex3i(3, 3, 0);
+ glVertex3i(-3, 3, 0);
+ glVertex3i(-3, -3, 0);
+ glVertex3i(3, -3, 0);
+ glEnd();
+
+ glStencilFunc(GL_EQUAL, 1, 1);
+ glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
+
+ glColor3ub(0, 0, 200);
+ glBegin(GL_POLYGON);
+ glVertex3i(3, 3, 0);
+ glVertex3i(-3, 3, 0);
+ glVertex3i(-3, -3, 0);
+ glVertex3i(3, -3, 0);
+ glEnd();
+
+ glFlush();
+}
+
+static GLenum Args(int argc, char **argv)
+{
+ GLint i;
+
+
+ for (i = 1; i < argc; i++) {
+ if (strcmp(argv[i], "-dr") == 0) {
+ } else {
+ printf("%s (Bad option).\n", argv[i]);
+ return GL_FALSE;
+ }
+ }
+ return GL_TRUE;
+}
+
+int main(int argc, char **argv)
+{
+ GLenum type;
+
+ glutInit(&argc, argv);
+
+ if (Args(argc, argv) == GL_FALSE) {
+ exit(1);
+ }
+
+ glutInitWindowPosition(0, 0); glutInitWindowSize( 300, 300);
+
+ type = GLUT_RGB | GLUT_SINGLE | GLUT_STENCIL;
+ glutInitDisplayMode(type);
+
+ if (glutCreateWindow("Stencil Test") == GL_FALSE) {
+ exit(1);
+ }
+
+ Init();
+
+ glutReshapeFunc(Reshape);
+ glutKeyboardFunc(Key);
+ glutDisplayFunc(Draw);
+ glutMainLoop();
+ return 0;
+}