/*
 * Exercise LLVM stencil bug # 41787
 * Command extracted from the GL api trace attached to that bug.
 */
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include "glut_wrap.h"

static int Win;
static int WinWidth = 403, WinHeight = 302;
static GLfloat Xrot = -70, Yrot = 0, Zrot = 0;
static GLboolean Anim = GL_FALSE;


static void
Idle(void)
{
   Zrot += .2;
   glutPostRedisplay();
}


static void
draw_floor(void)
{
   float z = -0.22;
   glColor3f(.5, .5, 0);
   glPushMatrix();
   glScalef(2, 2, 2);
   glBegin(GL_TRIANGLE_FAN);
#if 0
   /* irregular floor */
   glColor3f(0, .5, 0);
   glVertex3f(0, 0, 0);
   glColor3f(.5, .5, 0);
   glVertex3f(-1, -1, z);
   glColor3f(0, .5, 0);
   glVertex3f(0, -1, z);
   glColor3f(.5, .5, 0);
   glVertex3f(1, -1, z);
   glColor3f(0, .5, 0);
   glVertex3f(1, 0, z);
   glColor3f(.5, .5, 0);
   glVertex3f(1, 1, z);
   glColor3f(0, .5, 0);
   glVertex3f(0, 1, z);
   glColor3f(.5, .5, 0);
   glVertex3f(-1, 1, z);
   glColor3f(0, .5, 0);
   glVertex3f(-1, 0, z);
   glColor3f(.5, .5, 0);
   glVertex3f(-1, -1, z);
#else
   /* flat floor */
   glVertex3f(-1, -1, z);
   glVertex3f( 1, -1, z);
   glVertex3f( 1,  1, z);
   glVertex3f(-1,  1, z);
#endif
   glEnd();
   glPopMatrix();
}


/*
 * Draw a closed shape to represent a shadow volume.
 */
static void
draw_shadow_volume(void)
{
   glPushMatrix();
   if (0) {
      glScalef(1, 1, 4);
      glutSolidCube(2.0);
   }
   else if (0) {
      glScalef(1, 1, 4);
      glutSolidDodecahedron();
   }
   else if (1) {
      /* XXX more tessellation = more artifacts */
      glutSolidSphere(1.0, 20*3, 10*3);
   }
   else {
      glutSolidTeapot(1.0);
   }
   glPopMatrix();
}


static void
draw_scene(void)
{
   /*130*/ /*glDepthFunc(GL_LEQUAL);*/
   /*220*/ glEnable(GL_DEPTH_TEST);
   /*247*/ /*glFogi(pname = GL_FOG_COORD_SRC, param = GL_FRAGMENT_DEPTH);*/

   /* draw scene */
#if 0
   /*387*/ glClear(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT);
#else
   glClear(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
#endif

#if 0
   /*531*/ glDrawElements(GL_TRIANGLES, 468, GL_UNSIGNED_SHORT, blob(936));
   /*622*/ glDrawElements(GL_TRIANGLES, 9600, GL_UNSIGNED_SHORT, blob(19200));
   /*708*/ glDrawElements(GL_TRIANGLES, 696, GL_UNSIGNED_SHORT, blob(1392));
   /*776*/ glDrawElements(GL_TRIANGLES, 4992, GL_UNSIGNED_SHORT, blob(9984));
#else
   draw_floor();
#endif

   /*786*/ glPushAttrib(GL_POLYGON_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT | GL_ENABLE_BIT | GL_COLOR_BUFFER_BIT);
   /*789*/ /*glDepthFunc(GL_LEQUAL);*/
   /*790*/ glDepthMask(GL_FALSE);
#if 1
   /*791*/ glColorMask(0, 0, 0, 0);
#endif
   /*792*/ glEnable(GL_STENCIL_TEST);
   /*793*/ glEnable(GL_POLYGON_OFFSET_FILL);
   /*794*/ glPolygonOffset(0, 1);
   /*796*/ glStencilMask(~0);
   /*797*/ glStencilFunc(GL_ALWAYS, 0, ~0);
#if 1 /* XXX WE ONLY SEE CORRUPTION WHEN CULLING IS ENABLED */
   /*798*/ glEnable(GL_CULL_FACE);
#endif
   /*799*/ glStencilOp(GL_KEEP, GL_INCR_WRAP, GL_KEEP);
   /*800*/ glCullFace(GL_FRONT);
#if 0
   /*802*/ glDrawArrays(GL_TRIANGLES, 0, 23424);
#else
   draw_shadow_volume();
#endif
   /*803*/ glStencilOp(GL_KEEP, GL_DECR_WRAP, GL_KEEP);
   /*804*/ glCullFace(GL_BACK);
#if 0
   /*806*/ glDrawArrays(GL_TRIANGLES, 0, 23424);
#else
   draw_shadow_volume();
#endif
   /*808*/ glPopAttrib();

   /*
    * draw blended shadow where stencil != 0
    */
   /*811*/ glPushAttrib(GL_POLYGON_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT | GL_ENABLE_BIT | GL_COLOR_BUFFER_BIT);
   /*814*/ glDepthMask(GL_FALSE);
   /*815*/ glShadeModel(GL_FLAT);
   /*816*/ glColorMask(1, 1, 1, 1);
   /*817*/ glEnable(GL_BLEND);
   /*818*/ glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
   /*819*/ glEnable(GL_STENCIL_TEST);
   /*820*/ glStencilFunc(GL_NOTEQUAL, 0, ~0);
   /*821*/ glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
   /*822*/ glMatrixMode(GL_MODELVIEW);
   /*823*/ glPushMatrix();
   /*824*/ glLoadIdentity();
   /*825*/ glMatrixMode(GL_PROJECTION);
   /*826*/ glPushMatrix();
   /*827*/ glLoadIdentity();

   /*828*/ glBegin(GL_QUADS);
   /*829*/ glColor4ub(0, 0, 0, 150);
   /*830*/ glVertex3f( -1,  -1, -0.9);
   /*831*/ glColor4ub(0, 0, 0, 150);
   /*832*/ glVertex3f( -1,  1, -0.9);
   /*833*/ glColor4ub(0, 0, 0, 150);
   /*834*/ glVertex3f( 1,  1,  -0.9);
   /*835*/ glColor4ub(0, 0, 0, 150);
   /*836*/ glVertex3f( 1,  -1, -0.9);
   /*837*/ glEnd();
   /*838*/ glClear(GL_STENCIL_BUFFER_BIT);
   /*839*/ glPopMatrix();
   /*840*/ glMatrixMode(GL_MODELVIEW);
   /*841*/ glPopMatrix();
   /*842*/ glPopAttrib();

   /*890*/ /*glEnable(GL_DEPTH_TEST);*/
   /*891*/ /*glDepthFunc(GL_LEQUAL);*/
   /*892*/ /*glDepthMask(GL_FALSE);*/

   glDisable(GL_BLEND);
   glDisable(GL_STENCIL_TEST);
   glDisable(GL_CULL_FACE);
   glDepthMask(GL_TRUE);
}


static void
Draw(void)
{
   glPushMatrix();
      glRotatef(Xrot, 1, 0, 0);
      glRotatef(Yrot, 0, 1, 0);
      glRotatef(Zrot, 0, 0, 1);
      draw_scene();
   glPopMatrix();
   glutSwapBuffers();
}


static void
Reshape(int width, int height)
{
   WinWidth = width;
   WinHeight = height;
   glViewport(0, 0, width, height);
   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();
   glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 25.0);
   glMatrixMode(GL_MODELVIEW);
   glLoadIdentity();
   glTranslatef(0.0, 0.0, -15.0);
}


static void
Key(unsigned char key, int x, int y)
{
   const GLfloat step = 3.0;
   (void) x;
   (void) y;
   switch (key) {
   case 'a':
      Anim = !Anim;
      if (Anim)
         glutIdleFunc(Idle);
      else
         glutIdleFunc(NULL);
      break;
   case 'z':
      Zrot -= step;
      break;
   case 'Z':
      Zrot += step;
      break;
   case 27:
      glutDestroyWindow(Win);
      exit(0);
      break;
   }
   glutPostRedisplay();
}


static void
SpecialKey(int key, int x, int y)
{
   const GLfloat step = 3.0;
   (void) x;
   (void) y;
   switch (key) {
   case GLUT_KEY_UP:
      Xrot -= step;
      break;
   case GLUT_KEY_DOWN:
      Xrot += step;
      break;
   case GLUT_KEY_LEFT:
      Yrot -= step;
      break;
   case GLUT_KEY_RIGHT:
      Yrot += step;
      break;
   }
   glutPostRedisplay();
}


static void
Init(void)
{
   glShadeModel(GL_FLAT);
   glClearColor(0, 0.25, 0, 0);
}


int
main(int argc, char *argv[])
{
   glutInit(&argc, argv);
   glutInitWindowSize(WinWidth, WinHeight);
   glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH | GLUT_STENCIL);
   Win = glutCreateWindow(argv[0]);
   glutReshapeFunc(Reshape);
   glutKeyboardFunc(Key);
   glutSpecialFunc(SpecialKey);
   glutDisplayFunc(Draw);
   if (Anim)
      glutIdleFunc(Idle);
   Init();
   glutMainLoop();
   return 0;
}