/*
 * 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 <string.h>
#include <math.h>
#include <GL/gltk.h>

GLenum directRender;

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 GLenum Key(int key, GLenum mask)
{

  switch (key) {
    case TK_ESCAPE:
      tkQuit();
  }
  return GL_FALSE;
}

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;

  directRender = GL_TRUE;

  for (i = 1; i < argc; i++) {
    if (strcmp(argv[i], "-dr") == 0) {
      directRender = GL_TRUE;
    }
    else if (strcmp(argv[i], "-ir") == 0) {
      directRender = GL_FALSE;
    }
    else {
      printf("%s (Bad option).\n", argv[i]);
      return GL_FALSE;
    }
  }
  return GL_TRUE;
}

void main(int argc, char **argv)
{
  GLenum type;

  if (Args(argc, argv) == GL_FALSE) {
    tkQuit();
  }

  tkInitPosition(0, 0, 300, 300);

  type = TK_RGB | TK_SINGLE | TK_STENCIL;
  type |= (directRender) ? TK_DIRECT : TK_INDIRECT;
  tkInitDisplayMode(type);

  if (tkInitWindow("Stencil Test") == GL_FALSE) {
    tkQuit();
  }

  Init();

  tkExposeFunc(Reshape);
  tkReshapeFunc(Reshape);
  tkKeyDownFunc(Key);
  tkDisplayFunc(Draw);
  tkExec();
}