#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>       
#include <GL/glut.h>

 
GLboolean doubleBuffer = GL_TRUE, iconic = GL_FALSE, keepAspect = GL_FALSE;
int moving, startx, starty;
int useStencil = 1, useClippingPlane = 1; 
GLdouble bodyWidth = 3.0;
float jump = 0.0;
GLuint floor_texture;

// The coordinates (A,B,C,D) for the plane with equation Ax + By + Cz + D = 0
GLdouble mirror_plane[4] = { 0, 1, 0, 0 };

void mouse(int button, int state, int x, int y);
void motion(int x, int y);
void controlLights(int value);
void idle(void);
void visible(int vis);
GLuint loadTheTexture( void );
void makeDisplayLists(void);
void drawBouncingTeapot(void);
void drawFloor(void);

void InitializeViewingAndLighting( void );
void SetupEyeViewBasedOnUserInput( void );
void SetLightPostionInCurrentCoordinateFrame( void );
void DrawMirrorIntoStencilBuffer( void );
void SetStencilToRenderOnlyWhenEqualToOne( void );
void MultiplyReflectionMatrixOntoStack( void );
void DrawMirrorBlendedWithReflectedScene( void );


void DrawReflectedScene( void )
{
	glPushMatrix();
	 
	/* figure out new viewing matrix */
	MultiplyReflectionMatrixOntoStack();

	/* if objects (instead of the viewer) are being reflected, you need to move */
	/*   the light to compensate                                                */
	SetLightPostionInCurrentCoordinateFrame();

    /* Deal with flipped facings & scaled normals */
    glEnable(GL_NORMALIZE);
    glCullFace( GL_FRONT );

	/* make sure to clip to the floor */
	glClipPlane( GL_CLIP_PLANE0, mirror_plane );
	if (useClippingPlane)
	    glEnable( GL_CLIP_PLANE0 );

    /* draw the reflected scene. */
    drawBouncingTeapot();

    /* Reset the GL state. */
	glDisable( GL_CLIP_PLANE0 );
    glDisable(GL_NORMALIZE);
	glCullFace( GL_BACK );

    glPopMatrix();
}

void redraw(void)
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT); 
    glPushMatrix();

	/* Do standard per-frame OpenGL setup (for view and lights) */
    SetupEyeViewBasedOnUserInput();
	SetLightPostionInCurrentCoordinateFrame();  // simply calls glLightfv() with a position

	/* draw the mirror into the stencil buffer */
    DrawMirrorIntoStencilBuffer();
	SetStencilToRenderOnlyWhenEqualToOne();  // Note: this enables GL_STENCIL_TEST
    
    /* Draw the scene reflected around the mirror */
	DrawReflectedScene();

    /* Restore light positions to their locations in the non-reflected scene. */
	/*   Note:  Only necessary if lights were moved in DrawReflectedScene()   */
	SetLightPostionInCurrentCoordinateFrame();   

	/* If you want the mirror to have color (only reflect part of the light) */
	/*    then you need to draw it to partially occlude stuff (i.e., with    */
	/*    alpha-blending enabled)                                            */
	DrawMirrorBlendedWithReflectedScene();

	/* time to draw the actual scene, so disable the stencil test */
    glDisable(GL_STENCIL_TEST);

    /* Draw "actual" scene, not its reflection. */
    drawBouncingTeapot();

    glPopMatrix();
    glutSwapBuffers();
}



int main(int argc, char **argv)
{
  glutInit(&argc, argv);
  glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH | GLUT_STENCIL);
  glutInitWindowSize( 512, 512 );
  glutCreateWindow("Basic Planar Reflection Demo");

  glutDisplayFunc(redraw);
  glutMouseFunc(mouse);
  glutMotionFunc(motion);
  glutVisibilityFunc(visible);
  glutCreateMenu(controlLights);
  
  glutAddMenuEntry("Toggle right light", 1);
  glutAddMenuEntry("Toggle left light", 2);
  glutAddMenuEntry("Toggle artifact elimination", 3);
  glutAddMenuEntry("Toggle mirror shape", 4 );
  glutAttachMenu(GLUT_RIGHT_BUTTON);
  
  makeDisplayLists();
  floor_texture = loadTheTexture();
  InitializeViewingAndLighting();

  glEnable(GL_CULL_FACE);
  glEnable(GL_DEPTH_TEST);
  glEnable(GL_LIGHTING);


  glutMainLoop();
  return 0;             
}