ext/gl/gstglfilterreflectedscreen.c - imx-gst-plugins-bad - Git at Google

 /*
  * GStreamer
  * Copyright (C) 2010 Pierre Pouzol<pierre.pouzol@hotmail.fr>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public
  * License along with this library; if not, write to the
  * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  */

 /**
  * SECTION:element-glfilterreflectedscreen
  * @title: glfilterreflectedscreen
  *
  * Map Video Texture upon a screen, on a reflecting surface
  *
  * ## Examples
  * |[
  * gst-launch-1.0 videotestsrc ! glupload ! glfilterreflectedscreen ! glimagesink
  * ]|
  *
  */

 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif

 #include <math.h>
 #include "gstglfilterreflectedscreen.h"

 #define GST_CAT_DEFAULT gst_gl_filter_reflected_screen_debug
 GST_DEBUG_CATEGORY_STATIC (GST_CAT_DEFAULT);

 enum
 {
   PROP_0,
   PROP_ACTIVE_GRAPHIC_MODE,
   PROP_SEPARATED_SCREEN,
   PROP_SHOW_FLOOR,
   PROP_FOVY,
   PROP_ASPECT,
   PROP_ZNEAR,
   PROP_ZFAR
 };

 #define DEBUG_INIT \
   GST_DEBUG_CATEGORY_INIT (gst_gl_filter_reflected_screen_debug, "glfilterreflectedscreen", 0, "glfilterreflectedscreen element");

 G_DEFINE_TYPE_WITH_CODE (GstGLFilterReflectedScreen,
     gst_gl_filter_reflected_screen, GST_TYPE_GL_FILTER, DEBUG_INIT);

 static void gst_gl_filter_reflected_screen_set_property (GObject * object,
     guint prop_id, const GValue * value, GParamSpec * pspec);
 static void gst_gl_filter_reflected_screen_get_property (GObject * object,
     guint prop_id, GValue * value, GParamSpec * pspec);

 static gboolean gst_gl_filter_reflected_screen_filter_texture (GstGLFilter *
     filter, guint in_tex, guint out_tex);

 static void gst_gl_filter_reflected_screen_draw_background ();
 static void gst_gl_filter_reflected_screen_draw_floor ();
 static void gst_gl_filter_reflected_screen_draw_screen (GstGLFilter * filter,
     gint width, gint height, guint texture);
 static void gst_gl_filter_reflected_screen_draw_separated_screen (GstGLFilter *
     filter, gint width, gint height, guint texture, gfloat alphs, gfloat alphe);

 static void gst_gl_filter_reflected_screen_callback (gint width, gint height,
     guint texture, gpointer stuff);

 static const GLfloat LightPos[] = { 4.0f, -4.0f, 6.0f, 1.0f };  // Light Position
 static const GLfloat LightAmb[] = { 4.0f, 4.0f, 4.0f, 1.0f };   // Ambient Light
 static const GLfloat LightDif[] = { 1.0f, 1.0f, 1.0f, 1.0f };   // Diffuse Light

 static void
 gst_gl_filter_reflected_screen_class_init (GstGLFilterReflectedScreenClass *
     klass)
 {
   GObjectClass *gobject_class;
   GstElementClass *element_class;

   gobject_class = (GObjectClass *) klass;
   element_class = GST_ELEMENT_CLASS (klass);

   gst_gl_filter_add_rgba_pad_templates (GST_GL_FILTER_CLASS (klass));

   gobject_class->set_property = gst_gl_filter_reflected_screen_set_property;
   gobject_class->get_property = gst_gl_filter_reflected_screen_get_property;

   GST_GL_FILTER_CLASS (klass)->filter_texture =
       gst_gl_filter_reflected_screen_filter_texture;

   g_object_class_install_property (gobject_class, PROP_ACTIVE_GRAPHIC_MODE,
       g_param_spec_boolean ("active-graphic-mode",
           "Activate graphic mode",
           "Allow user to activate stencil buffer and blending.",
           TRUE, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));

   g_object_class_install_property (gobject_class, PROP_SEPARATED_SCREEN,
       g_param_spec_boolean ("separated-screen",
           "Create a separation space",
           "Allow to insert a space between the two screen. Will cancel 'show floor' if active. Value are TRUE or FALSE(default)",
           FALSE, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));

   g_object_class_install_property (gobject_class, PROP_SHOW_FLOOR,
       g_param_spec_boolean ("show-floor",
           "Show the support",
           "Allow the user to show the supportive floor. Will cancel 'separated screen' if active. Value are TRUE(default) or FALSE",
           TRUE, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));

   g_object_class_install_property (gobject_class, PROP_FOVY,
       g_param_spec_double ("fovy", "Fovy", "Field of view angle in degrees",
           0.0, 180.0, 60, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));

   g_object_class_install_property (gobject_class, PROP_ASPECT,
       g_param_spec_double ("aspect", "Aspect",
           "Field of view in the x direction", 1.0, 100, 1.0,
           G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));

   g_object_class_install_property (gobject_class, PROP_ZNEAR,
       g_param_spec_double ("znear", "Znear",
           "Specifies the distance from the viewer to the near clipping plane",
           0.0000000001, 100.0, 0.1,
           G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));

   g_object_class_install_property (gobject_class, PROP_ZFAR,
       g_param_spec_double ("zfar", "Zfar",
           "Specifies the distance from the viewer to the far clipping plane",
           0.0, 1000.0, 100.0, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));

   gst_element_class_set_metadata (element_class,
       "OpenGL Reflected Screen filter", "Filter/Effect/Video",
       "Reflected Screen Filter", "Pierre POUZOL <pierre.pouzol@hotmail.fr>");

   GST_GL_BASE_FILTER_CLASS (klass)->supported_gl_api = GST_GL_API_OPENGL;
 }

 static void
 gst_gl_filter_reflected_screen_init (GstGLFilterReflectedScreen * filter)
 {
   filter->active_graphic_mode = TRUE;
   filter->separated_screen = FALSE;
   filter->show_floor = TRUE;
   filter->fovy = 90;
   filter->aspect = 1.0;
   filter->znear = 0.1;
   filter->zfar = 1000;
 }

 static void
 gst_gl_filter_reflected_screen_set_property (GObject * object, guint prop_id,
     const GValue * value, GParamSpec * pspec)
 {
   GstGLFilterReflectedScreen *filter = GST_GL_FILTER_REFLECTED_SCREEN (object);

   switch (prop_id) {
     case PROP_ACTIVE_GRAPHIC_MODE:
       filter->active_graphic_mode = g_value_get_boolean (value);
       break;
     case PROP_SEPARATED_SCREEN:
       filter->separated_screen = g_value_get_boolean (value);
       break;
     case PROP_SHOW_FLOOR:
       filter->show_floor = g_value_get_boolean (value);
       break;
     case PROP_FOVY:
       filter->fovy = g_value_get_double (value);
       break;
     case PROP_ASPECT:
       filter->aspect = g_value_get_double (value);
       break;
     case PROP_ZNEAR:
       filter->znear = g_value_get_double (value);
       break;
     case PROP_ZFAR:
       filter->zfar = g_value_get_double (value);
       break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
   }
 }

 static void
 gst_gl_filter_reflected_screen_get_property (GObject * object, guint prop_id,
     GValue * value, GParamSpec * pspec)
 {
   GstGLFilterReflectedScreen *filter = GST_GL_FILTER_REFLECTED_SCREEN (object);

   switch (prop_id) {
     case PROP_ACTIVE_GRAPHIC_MODE:
       g_value_set_boolean (value, filter->active_graphic_mode);
       break;
     case PROP_SEPARATED_SCREEN:
       g_value_set_boolean (value, filter->separated_screen);
       break;
     case PROP_SHOW_FLOOR:
       g_value_set_boolean (value, filter->show_floor);
       break;
     case PROP_FOVY:
       g_value_set_double (value, filter->fovy);
       break;
     case PROP_ASPECT:
       g_value_set_double (value, filter->aspect);
       break;
     case PROP_ZNEAR:
       g_value_set_double (value, filter->znear);
       break;
     case PROP_ZFAR:
       g_value_set_double (value, filter->zfar);
       break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
   }
 }

 static gboolean
 gst_gl_filter_reflected_screen_filter_texture (GstGLFilter * filter,
     guint in_tex, guint out_tex)
 {
   GstGLFilterReflectedScreen *reflected_screen_filter =
       GST_GL_FILTER_REFLECTED_SCREEN (filter);

   //blocking call, use a FBO
   gst_gl_context_use_fbo (filter->context,
       GST_VIDEO_INFO_WIDTH (&filter->out_info),
       GST_VIDEO_INFO_HEIGHT (&filter->out_info),
       filter->fbo, filter->depthbuffer, out_tex,
       gst_gl_filter_reflected_screen_callback,
       GST_VIDEO_INFO_WIDTH (&filter->in_info),
       GST_VIDEO_INFO_HEIGHT (&filter->in_info), in_tex,
       reflected_screen_filter->fovy, reflected_screen_filter->aspect,
       reflected_screen_filter->znear, reflected_screen_filter->zfar,
       GST_GL_DISPLAY_PROJECTION_PERSPECTIVE,
       (gpointer) reflected_screen_filter);

   return TRUE;
 }

 static void
 gst_gl_filter_reflected_screen_draw_separated_screen (GstGLFilter * filter,
     gint width, gint height, guint texture, gfloat alphs, gfloat alphe)
 {
   //enable ARB Rectangular texturing
   //that's necessary to have the video displayed on our screen (with gstreamer)
   glEnable (GL_TEXTURE_2D);
   glBindTexture (GL_TEXTURE_2D, texture);
   //configure parameters for the texturing
   //the two first are used to specified how the texturing will be done if the screen is greater than the texture herself
   glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
   glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
   //the next two specified how the texture will comport near the limits
   glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
   glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

   //creating screen and setting the texture (depending on texture's height and width)
   glBegin (GL_QUADS);

   // right Face
   glColor4f (1.0f, 1.0f, 1.0f, alphs);
   glTexCoord2f (0.5f, 1.0f);
   glVertex3f (-0.75f, 0.0f, -1.0f);
   glColor4f (1.0f, 1.0f, 1.0f, alphe);
   glTexCoord2f (0.5f, 0.0f);
   glVertex3f (-0.75f, 1.25f, -1.0f);
   glTexCoord2f (1.0f, 0.0f);
   glVertex3f (1.25f, 1.25f, -1.0f);
   glColor4f (1.0f, 1.0f, 1.0f, alphs);
   glTexCoord2f (1.0f, 1.0f);
   glVertex3f (1.25f, 0.0f, -1.0f);
   // Left Face
   glColor4f (1.0f, 1.0f, 1.0f, alphs);
   glTexCoord2f (0.5f, 1.0f);
   glVertex3f (-1.0f, 0.0f, -0.75f);
   glTexCoord2f (0.0f, 1.0f);
   glVertex3f (-1.0f, 0.0f, 1.25f);
   glColor4f (1.0f, 1.0f, 1.0f, alphe);
   glTexCoord2f (0.0f, 0.0f);
   glVertex3f (-1.0f, 1.25f, 1.25f);
   glTexCoord2f (0.5f, 0.0f);
   glVertex3f (-1.0f, 1.25f, -0.75f);

   glEnd ();
   glDisable (GL_TEXTURE_2D);
 }

 static void
 gst_gl_filter_reflected_screen_draw_screen (GstGLFilter * filter,
     gint width, gint height, guint texture)
 {
   //enable ARB Rectangular texturing
   //that's necessary to have the video displayed on our screen (with gstreamer)
   glEnable (GL_TEXTURE_2D);
   glBindTexture (GL_TEXTURE_2D, texture);
   //configure parameters for the texturing
   //the two first are used to specified how the texturing will be done if the screen is greater than the texture herself
   glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
   glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
   //the next two specified how the texture will comport near the limits
   glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
   glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

   //creating screen and setting the texture (depending on texture's height and width)
   glBegin (GL_QUADS);

   glTexCoord2f (0.5f, 1.0f);
   glVertex3f (-1.0f, 0.0f, -1.0f);
   glTexCoord2f (0.5f, 0.0f);
   glVertex3f (-1.0f, 1.0f, -1.0f);
   glTexCoord2f (1.0f, 0.0f);
   glVertex3f (1.0f, 1.0f, -1.0f);
   glTexCoord2f (1.0f, 1.0f);
   glVertex3f (1.0f, 0.0f, -1.0f);
   // Left Face
   glTexCoord2f (0.5f, 1.0f);
   glVertex3f (-1.0f, 0.0f, -1.0f);
   glTexCoord2f (0.0f, 1.0f);
   glVertex3f (-1.0f, 0.0f, 1.0f);
   glTexCoord2f (0.0f, 0.0f);
   glVertex3f (-1.0f, 1.0f, 1.0f);
   glTexCoord2f (0.5f, 0.0f);
   glVertex3f (-1.0f, 1.0f, -1.0f);

   glEnd ();

   //disable this kind of texturing (useless for the gluDisk)
   glDisable (GL_TEXTURE_2D);
 }

 static void
 gst_gl_filter_reflected_screen_draw_background (void)
 {
   glBegin (GL_QUADS);

   // right Face

   glColor4f (0.0f, 0.0f, 0.0f, 1.0f);
   glVertex3f (-10.0f, -10.0f, -1.0f);

   glColor4f (0.0f, 0.0f, 0.2f, 1.0f);
   glVertex3f (-10.0f, 10.0f, -1.0f);
   glVertex3f (10.0f, 10.0f, -1.0f);
   glVertex3f (10.0f, -10.0f, -1.0f);

   glEnd ();
 }

 static void
 gst_gl_filter_reflected_screen_draw_floor (void)
 {
   GLUquadricObj *q;
   //create a quadric for the floor's drawing
   q = gluNewQuadric ();
   //configure this quadric's parameter (for lighting and texturing)
   gluQuadricNormals (q, GL_SMOOTH);
   gluQuadricTexture (q, GL_FALSE);

   //drawing the disk. The texture are mapped thanks to the parameter we gave to the GLUquadric q
   gluDisk (q, 0.0, 2.2, 50, 1);
 }

 //opengl scene, params: input texture (not the output filter->texture)
 static void
 gst_gl_filter_reflected_screen_callback (gint width, gint height, guint texture,
     gpointer stuff)
 {
   GstGLFilter *filter = GST_GL_FILTER (stuff);
   GstGLFilterReflectedScreen *reflected_screen_filter =
       GST_GL_FILTER_REFLECTED_SCREEN (stuff);

   glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);

   //load identity befor tracing
   glLoadIdentity ();
   //camera translation
   glTranslatef (0.0f, 0.1f, -1.3f);
   //camera configuration
   if (reflected_screen_filter->separated_screen)
     gluLookAt (0.1, -0.25, 2.0, 0.025, 0.0, 0.0, 0.0, 1.0, 0.0);
   else
     gluLookAt (0.1, -0.35, 2.0, 0.025, 0.0, 0.0, 0.0, 1.0, 0.0);

   gst_gl_filter_reflected_screen_draw_background ();

   if (reflected_screen_filter->separated_screen) {
     glEnable (GL_BLEND);

     glPushMatrix ();
     glScalef (1.0f, -1.0f, 1.0f);
     glTranslatef (0.0f, 0.0f, 1.2f);
     glRotatef (-45.0f, 0.0, 1.0, 0.0);
     gst_gl_filter_reflected_screen_draw_separated_screen (filter, width, height,
         texture, 1.0f, 1.0f);
     glPopMatrix ();

     if (reflected_screen_filter->active_graphic_mode) {
       //configuration of the transparency function
       glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
       glTranslatef (0.0f, 0.0f, 1.2f);
       glRotatef (-45.0f, 0.0, 1.0, 0.0);
       gst_gl_filter_reflected_screen_draw_separated_screen (filter, width,
           height, texture, 0.5f, 0.0f);
       glDisable (GL_BLEND);
     }
   }
   if (reflected_screen_filter->show_floor) {
     glLightfv (GL_LIGHT0, GL_AMBIENT, LightAmb);
     glLightfv (GL_LIGHT0, GL_DIFFUSE, LightDif);
     glLightfv (GL_LIGHT0, GL_POSITION, LightPos);

     //enable lighting
     glEnable (GL_LIGHT0);
     glEnable (GL_LIGHTING);

     if (reflected_screen_filter->active_graphic_mode) {
       glColorMask (GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE);
       //enable stencil buffer use
       glEnable (GL_STENCIL_TEST);
       //setting the stencil buffer. Each time a pixel will be drawn by now, this pixel value will be set to 1
       glStencilFunc (GL_ALWAYS, 1, 1);
       glStencilOp (GL_KEEP, GL_KEEP, GL_REPLACE);

       //disable the zbuffer
       glDisable (GL_DEPTH_TEST);
       //make a rotation of 90 degree on x axis. By default, gluDisk draw a disk on z axis
       glRotatef (-90.0f, 1.0, 0.0, 0.0);
       //draw the floor. Each pixel representing this floor will now have a value of 1 on stencil buffer
       gst_gl_filter_reflected_screen_draw_floor ();
       //make an anti-rotation of 90 degree to draw the rest of the scene on the right angle
       glRotatef (90.0f, 1.0, 0.0, 0.0);
       //enable zbuffer again
       glEnable (GL_DEPTH_TEST);
       //enable the drawing to be shown
       glColorMask (GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
       //say that the next object have to be drawn ONLY where the stencil buffer's pixel's value is 1
       glStencilFunc (GL_EQUAL, 1, 1);
       glStencilOp (GL_KEEP, GL_KEEP, GL_KEEP);

       //save the actual matrix
       glPushMatrix ();
       glLightfv (GL_LIGHT0, GL_POSITION, LightPos);
       //translate the object on z axis
       glTranslatef (0.0f, 0.0f, 1.4f);
       //rotate it (because the drawing method place the user behind the left part of the screen)
       glRotatef (-45.0f, 0.0, 1.0, 0.0);
       //draw the reflexion
       gst_gl_filter_reflected_screen_draw_screen (filter, width, height,
           texture);
       //return to the saved matrix position
       glPopMatrix ();
       //end of the stencil buffer uses
       glDisable (GL_STENCIL_TEST);

       //enable the blending to mix the floor and reflexion color
       glEnable (GL_BLEND);
       glDisable (GL_LIGHTING);
       //specified a white color (for the floor) with 20% transparency
       glColor4f (1.0f, 1.0f, 1.0f, 0.8f);
       //configuration of the transparency function
       glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
     }
     //draw the floor (which will appear this time)
     glRotatef (-90.0f, 1.0, 0.0, 0.0);
     gst_gl_filter_reflected_screen_draw_floor ();
     glRotatef (90.0f, 1.0, 0.0, 0.0);
     glDisable (GL_BLEND);
     glEnable (GL_LIGHTING);
     //draw the real object
     //scale on y axis. The object must be drawn upside down (to suggest a reflexion)
     glScalef (1.0f, -1.0f, 1.0f);
     glTranslatef (0.0f, 0.0f, 1.4f);
     glRotatef (-45.0f, 0.0, 1.0, 0.0);
     gst_gl_filter_reflected_screen_draw_screen (filter, width, height, texture);
     glDisable (GL_LIGHTING);
   }
 }
	/*
	* GStreamer
	* Copyright (C) 2010 Pierre Pouzol<pierre.pouzol@hotmail.fr>
	*
	* This library is free software; you can redistribute it and/or
	* modify it under the terms of the GNU Library General Public
	* License as published by the Free Software Foundation; either
	* version 2 of the License, or (at your option) any later version.
	*
	* This library is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	* Library General Public License for more details.
	*
	* You should have received a copy of the GNU Library General Public
	* License along with this library; if not, write to the
	* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
	* Boston, MA 02110-1301, USA.
	*/

	/**
	* SECTION:element-glfilterreflectedscreen
	* @title: glfilterreflectedscreen
	*
	* Map Video Texture upon a screen, on a reflecting surface
	*
	* ## Examples
	* \|[
	* gst-launch-1.0 videotestsrc ! glupload ! glfilterreflectedscreen ! glimagesink
	* ]\|
	*
	*/

	#ifdef HAVE_CONFIG_H
	#include "config.h"
	#endif

	#include <math.h>
	#include "gstglfilterreflectedscreen.h"

	#define GST_CAT_DEFAULT gst_gl_filter_reflected_screen_debug
	GST_DEBUG_CATEGORY_STATIC (GST_CAT_DEFAULT);

	enum
	{
	PROP_0,
	PROP_ACTIVE_GRAPHIC_MODE,
	PROP_SEPARATED_SCREEN,
	PROP_SHOW_FLOOR,
	PROP_FOVY,
	PROP_ASPECT,
	PROP_ZNEAR,
	PROP_ZFAR
	};

	#define DEBUG_INIT \
	GST_DEBUG_CATEGORY_INIT (gst_gl_filter_reflected_screen_debug, "glfilterreflectedscreen", 0, "glfilterreflectedscreen element");

	G_DEFINE_TYPE_WITH_CODE (GstGLFilterReflectedScreen,
	gst_gl_filter_reflected_screen, GST_TYPE_GL_FILTER, DEBUG_INIT);

	static void gst_gl_filter_reflected_screen_set_property (GObject * object,
	guint prop_id, const GValue * value, GParamSpec * pspec);
	static void gst_gl_filter_reflected_screen_get_property (GObject * object,
	guint prop_id, GValue * value, GParamSpec * pspec);

	static gboolean gst_gl_filter_reflected_screen_filter_texture (GstGLFilter *
	filter, guint in_tex, guint out_tex);

	static void gst_gl_filter_reflected_screen_draw_background ();
	static void gst_gl_filter_reflected_screen_draw_floor ();
	static void gst_gl_filter_reflected_screen_draw_screen (GstGLFilter * filter,
	gint width, gint height, guint texture);
	static void gst_gl_filter_reflected_screen_draw_separated_screen (GstGLFilter *
	filter, gint width, gint height, guint texture, gfloat alphs, gfloat alphe);

	static void gst_gl_filter_reflected_screen_callback (gint width, gint height,
	guint texture, gpointer stuff);

	static const GLfloat LightPos[] = { 4.0f, -4.0f, 6.0f, 1.0f }; // Light Position
	static const GLfloat LightAmb[] = { 4.0f, 4.0f, 4.0f, 1.0f }; // Ambient Light
	static const GLfloat LightDif[] = { 1.0f, 1.0f, 1.0f, 1.0f }; // Diffuse Light

	static void
	gst_gl_filter_reflected_screen_class_init (GstGLFilterReflectedScreenClass *
	klass)
	{
	GObjectClass *gobject_class;
	GstElementClass *element_class;

	gobject_class = (GObjectClass *) klass;
	element_class = GST_ELEMENT_CLASS (klass);

	gst_gl_filter_add_rgba_pad_templates (GST_GL_FILTER_CLASS (klass));

	gobject_class->set_property = gst_gl_filter_reflected_screen_set_property;
	gobject_class->get_property = gst_gl_filter_reflected_screen_get_property;

	GST_GL_FILTER_CLASS (klass)->filter_texture =
	gst_gl_filter_reflected_screen_filter_texture;

	g_object_class_install_property (gobject_class, PROP_ACTIVE_GRAPHIC_MODE,
	g_param_spec_boolean ("active-graphic-mode",
	"Activate graphic mode",
	"Allow user to activate stencil buffer and blending.",
	TRUE, G_PARAM_READWRITE \| G_PARAM_STATIC_STRINGS));

	g_object_class_install_property (gobject_class, PROP_SEPARATED_SCREEN,
	g_param_spec_boolean ("separated-screen",
	"Create a separation space",
	"Allow to insert a space between the two screen. Will cancel 'show floor' if active. Value are TRUE or FALSE(default)",
	FALSE, G_PARAM_READWRITE \| G_PARAM_STATIC_STRINGS));

	g_object_class_install_property (gobject_class, PROP_SHOW_FLOOR,
	g_param_spec_boolean ("show-floor",
	"Show the support",
	"Allow the user to show the supportive floor. Will cancel 'separated screen' if active. Value are TRUE(default) or FALSE",
	TRUE, G_PARAM_READWRITE \| G_PARAM_STATIC_STRINGS));

	g_object_class_install_property (gobject_class, PROP_FOVY,
	g_param_spec_double ("fovy", "Fovy", "Field of view angle in degrees",
	0.0, 180.0, 60, G_PARAM_READWRITE \| G_PARAM_STATIC_STRINGS));

	g_object_class_install_property (gobject_class, PROP_ASPECT,
	g_param_spec_double ("aspect", "Aspect",
	"Field of view in the x direction", 1.0, 100, 1.0,
	G_PARAM_READWRITE \| G_PARAM_STATIC_STRINGS));

	g_object_class_install_property (gobject_class, PROP_ZNEAR,
	g_param_spec_double ("znear", "Znear",
	"Specifies the distance from the viewer to the near clipping plane",
	0.0000000001, 100.0, 0.1,
	G_PARAM_READWRITE \| G_PARAM_STATIC_STRINGS));

	g_object_class_install_property (gobject_class, PROP_ZFAR,
	g_param_spec_double ("zfar", "Zfar",
	"Specifies the distance from the viewer to the far clipping plane",
	0.0, 1000.0, 100.0, G_PARAM_READWRITE \| G_PARAM_STATIC_STRINGS));

	gst_element_class_set_metadata (element_class,
	"OpenGL Reflected Screen filter", "Filter/Effect/Video",
	"Reflected Screen Filter", "Pierre POUZOL <pierre.pouzol@hotmail.fr>");

	GST_GL_BASE_FILTER_CLASS (klass)->supported_gl_api = GST_GL_API_OPENGL;
	}

	static void
	gst_gl_filter_reflected_screen_init (GstGLFilterReflectedScreen * filter)
	{
	filter->active_graphic_mode = TRUE;
	filter->separated_screen = FALSE;
	filter->show_floor = TRUE;
	filter->fovy = 90;
	filter->aspect = 1.0;
	filter->znear = 0.1;
	filter->zfar = 1000;
	}

	static void
	gst_gl_filter_reflected_screen_set_property (GObject * object, guint prop_id,
	const GValue * value, GParamSpec * pspec)
	{
	GstGLFilterReflectedScreen *filter = GST_GL_FILTER_REFLECTED_SCREEN (object);

	switch (prop_id) {
	case PROP_ACTIVE_GRAPHIC_MODE:
	filter->active_graphic_mode = g_value_get_boolean (value);
	break;
	case PROP_SEPARATED_SCREEN:
	filter->separated_screen = g_value_get_boolean (value);
	break;
	case PROP_SHOW_FLOOR:
	filter->show_floor = g_value_get_boolean (value);
	break;
	case PROP_FOVY:
	filter->fovy = g_value_get_double (value);
	break;
	case PROP_ASPECT:
	filter->aspect = g_value_get_double (value);
	break;
	case PROP_ZNEAR:
	filter->znear = g_value_get_double (value);
	break;
	case PROP_ZFAR:
	filter->zfar = g_value_get_double (value);
	break;
	default:
	G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
	break;
	}
	}

	static void
	gst_gl_filter_reflected_screen_get_property (GObject * object, guint prop_id,
	GValue * value, GParamSpec * pspec)
	{
	GstGLFilterReflectedScreen *filter = GST_GL_FILTER_REFLECTED_SCREEN (object);

	switch (prop_id) {
	case PROP_ACTIVE_GRAPHIC_MODE:
	g_value_set_boolean (value, filter->active_graphic_mode);
	break;
	case PROP_SEPARATED_SCREEN:
	g_value_set_boolean (value, filter->separated_screen);
	break;
	case PROP_SHOW_FLOOR:
	g_value_set_boolean (value, filter->show_floor);
	break;
	case PROP_FOVY:
	g_value_set_double (value, filter->fovy);
	break;
	case PROP_ASPECT:
	g_value_set_double (value, filter->aspect);
	break;
	case PROP_ZNEAR:
	g_value_set_double (value, filter->znear);
	break;
	case PROP_ZFAR:
	g_value_set_double (value, filter->zfar);
	break;
	default:
	G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
	break;
	}
	}

	static gboolean
	gst_gl_filter_reflected_screen_filter_texture (GstGLFilter * filter,
	guint in_tex, guint out_tex)
	{
	GstGLFilterReflectedScreen *reflected_screen_filter =
	GST_GL_FILTER_REFLECTED_SCREEN (filter);

	//blocking call, use a FBO
	gst_gl_context_use_fbo (filter->context,
	GST_VIDEO_INFO_WIDTH (&filter->out_info),
	GST_VIDEO_INFO_HEIGHT (&filter->out_info),
	filter->fbo, filter->depthbuffer, out_tex,
	gst_gl_filter_reflected_screen_callback,
	GST_VIDEO_INFO_WIDTH (&filter->in_info),
	GST_VIDEO_INFO_HEIGHT (&filter->in_info), in_tex,
	reflected_screen_filter->fovy, reflected_screen_filter->aspect,
	reflected_screen_filter->znear, reflected_screen_filter->zfar,
	GST_GL_DISPLAY_PROJECTION_PERSPECTIVE,
	(gpointer) reflected_screen_filter);

	return TRUE;
	}

	static void
	gst_gl_filter_reflected_screen_draw_separated_screen (GstGLFilter * filter,
	gint width, gint height, guint texture, gfloat alphs, gfloat alphe)
	{
	//enable ARB Rectangular texturing
	//that's necessary to have the video displayed on our screen (with gstreamer)
	glEnable (GL_TEXTURE_2D);
	glBindTexture (GL_TEXTURE_2D, texture);
	//configure parameters for the texturing
	//the two first are used to specified how the texturing will be done if the screen is greater than the texture herself
	glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	//the next two specified how the texture will comport near the limits
	glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

	//creating screen and setting the texture (depending on texture's height and width)
	glBegin (GL_QUADS);

	// right Face
	glColor4f (1.0f, 1.0f, 1.0f, alphs);
	glTexCoord2f (0.5f, 1.0f);
	glVertex3f (-0.75f, 0.0f, -1.0f);
	glColor4f (1.0f, 1.0f, 1.0f, alphe);
	glTexCoord2f (0.5f, 0.0f);
	glVertex3f (-0.75f, 1.25f, -1.0f);
	glTexCoord2f (1.0f, 0.0f);
	glVertex3f (1.25f, 1.25f, -1.0f);
	glColor4f (1.0f, 1.0f, 1.0f, alphs);
	glTexCoord2f (1.0f, 1.0f);
	glVertex3f (1.25f, 0.0f, -1.0f);
	// Left Face
	glColor4f (1.0f, 1.0f, 1.0f, alphs);
	glTexCoord2f (0.5f, 1.0f);
	glVertex3f (-1.0f, 0.0f, -0.75f);
	glTexCoord2f (0.0f, 1.0f);
	glVertex3f (-1.0f, 0.0f, 1.25f);
	glColor4f (1.0f, 1.0f, 1.0f, alphe);
	glTexCoord2f (0.0f, 0.0f);
	glVertex3f (-1.0f, 1.25f, 1.25f);
	glTexCoord2f (0.5f, 0.0f);
	glVertex3f (-1.0f, 1.25f, -0.75f);

	glEnd ();
	glDisable (GL_TEXTURE_2D);
	}

	static void
	gst_gl_filter_reflected_screen_draw_screen (GstGLFilter * filter,
	gint width, gint height, guint texture)
	{
	//enable ARB Rectangular texturing
	//that's necessary to have the video displayed on our screen (with gstreamer)
	glEnable (GL_TEXTURE_2D);
	glBindTexture (GL_TEXTURE_2D, texture);
	//configure parameters for the texturing
	//the two first are used to specified how the texturing will be done if the screen is greater than the texture herself
	glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	//the next two specified how the texture will comport near the limits
	glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

	//creating screen and setting the texture (depending on texture's height and width)
	glBegin (GL_QUADS);

	glTexCoord2f (0.5f, 1.0f);
	glVertex3f (-1.0f, 0.0f, -1.0f);
	glTexCoord2f (0.5f, 0.0f);
	glVertex3f (-1.0f, 1.0f, -1.0f);
	glTexCoord2f (1.0f, 0.0f);
	glVertex3f (1.0f, 1.0f, -1.0f);
	glTexCoord2f (1.0f, 1.0f);
	glVertex3f (1.0f, 0.0f, -1.0f);
	// Left Face
	glTexCoord2f (0.5f, 1.0f);
	glVertex3f (-1.0f, 0.0f, -1.0f);
	glTexCoord2f (0.0f, 1.0f);
	glVertex3f (-1.0f, 0.0f, 1.0f);
	glTexCoord2f (0.0f, 0.0f);
	glVertex3f (-1.0f, 1.0f, 1.0f);
	glTexCoord2f (0.5f, 0.0f);
	glVertex3f (-1.0f, 1.0f, -1.0f);

	glEnd ();

	//disable this kind of texturing (useless for the gluDisk)
	glDisable (GL_TEXTURE_2D);
	}

	static void
	gst_gl_filter_reflected_screen_draw_background (void)
	{
	glBegin (GL_QUADS);

	// right Face

	glColor4f (0.0f, 0.0f, 0.0f, 1.0f);
	glVertex3f (-10.0f, -10.0f, -1.0f);

	glColor4f (0.0f, 0.0f, 0.2f, 1.0f);
	glVertex3f (-10.0f, 10.0f, -1.0f);
	glVertex3f (10.0f, 10.0f, -1.0f);
	glVertex3f (10.0f, -10.0f, -1.0f);

	glEnd ();
	}

	static void
	gst_gl_filter_reflected_screen_draw_floor (void)
	{
	GLUquadricObj *q;
	//create a quadric for the floor's drawing
	q = gluNewQuadric ();
	//configure this quadric's parameter (for lighting and texturing)
	gluQuadricNormals (q, GL_SMOOTH);
	gluQuadricTexture (q, GL_FALSE);

	//drawing the disk. The texture are mapped thanks to the parameter we gave to the GLUquadric q
	gluDisk (q, 0.0, 2.2, 50, 1);
	}

	//opengl scene, params: input texture (not the output filter->texture)
	static void
	gst_gl_filter_reflected_screen_callback (gint width, gint height, guint texture,
	gpointer stuff)
	{
	GstGLFilter *filter = GST_GL_FILTER (stuff);
	GstGLFilterReflectedScreen *reflected_screen_filter =
	GST_GL_FILTER_REFLECTED_SCREEN (stuff);

	glClear (GL_COLOR_BUFFER_BIT \| GL_DEPTH_BUFFER_BIT \| GL_STENCIL_BUFFER_BIT);

	//load identity befor tracing
	glLoadIdentity ();
	//camera translation
	glTranslatef (0.0f, 0.1f, -1.3f);
	//camera configuration
	if (reflected_screen_filter->separated_screen)
	gluLookAt (0.1, -0.25, 2.0, 0.025, 0.0, 0.0, 0.0, 1.0, 0.0);
	else
	gluLookAt (0.1, -0.35, 2.0, 0.025, 0.0, 0.0, 0.0, 1.0, 0.0);

	gst_gl_filter_reflected_screen_draw_background ();

	if (reflected_screen_filter->separated_screen) {
	glEnable (GL_BLEND);

	glPushMatrix ();
	glScalef (1.0f, -1.0f, 1.0f);
	glTranslatef (0.0f, 0.0f, 1.2f);
	glRotatef (-45.0f, 0.0, 1.0, 0.0);
	gst_gl_filter_reflected_screen_draw_separated_screen (filter, width, height,
	texture, 1.0f, 1.0f);
	glPopMatrix ();

	if (reflected_screen_filter->active_graphic_mode) {
	//configuration of the transparency function
	glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
	glTranslatef (0.0f, 0.0f, 1.2f);
	glRotatef (-45.0f, 0.0, 1.0, 0.0);
	gst_gl_filter_reflected_screen_draw_separated_screen (filter, width,
	height, texture, 0.5f, 0.0f);
	glDisable (GL_BLEND);
	}
	}
	if (reflected_screen_filter->show_floor) {
	glLightfv (GL_LIGHT0, GL_AMBIENT, LightAmb);
	glLightfv (GL_LIGHT0, GL_DIFFUSE, LightDif);
	glLightfv (GL_LIGHT0, GL_POSITION, LightPos);

	//enable lighting
	glEnable (GL_LIGHT0);
	glEnable (GL_LIGHTING);

	if (reflected_screen_filter->active_graphic_mode) {
	glColorMask (GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE);
	//enable stencil buffer use
	glEnable (GL_STENCIL_TEST);
	//setting the stencil buffer. Each time a pixel will be drawn by now, this pixel value will be set to 1
	glStencilFunc (GL_ALWAYS, 1, 1);
	glStencilOp (GL_KEEP, GL_KEEP, GL_REPLACE);

	//disable the zbuffer
	glDisable (GL_DEPTH_TEST);
	//make a rotation of 90 degree on x axis. By default, gluDisk draw a disk on z axis
	glRotatef (-90.0f, 1.0, 0.0, 0.0);
	//draw the floor. Each pixel representing this floor will now have a value of 1 on stencil buffer
	gst_gl_filter_reflected_screen_draw_floor ();
	//make an anti-rotation of 90 degree to draw the rest of the scene on the right angle
	glRotatef (90.0f, 1.0, 0.0, 0.0);
	//enable zbuffer again
	glEnable (GL_DEPTH_TEST);
	//enable the drawing to be shown
	glColorMask (GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
	//say that the next object have to be drawn ONLY where the stencil buffer's pixel's value is 1
	glStencilFunc (GL_EQUAL, 1, 1);
	glStencilOp (GL_KEEP, GL_KEEP, GL_KEEP);

	//save the actual matrix
	glPushMatrix ();
	glLightfv (GL_LIGHT0, GL_POSITION, LightPos);
	//translate the object on z axis
	glTranslatef (0.0f, 0.0f, 1.4f);
	//rotate it (because the drawing method place the user behind the left part of the screen)
	glRotatef (-45.0f, 0.0, 1.0, 0.0);
	//draw the reflexion
	gst_gl_filter_reflected_screen_draw_screen (filter, width, height,
	texture);
	//return to the saved matrix position
	glPopMatrix ();
	//end of the stencil buffer uses
	glDisable (GL_STENCIL_TEST);

	//enable the blending to mix the floor and reflexion color
	glEnable (GL_BLEND);
	glDisable (GL_LIGHTING);
	//specified a white color (for the floor) with 20% transparency
	glColor4f (1.0f, 1.0f, 1.0f, 0.8f);
	//configuration of the transparency function
	glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
	}
	//draw the floor (which will appear this time)
	glRotatef (-90.0f, 1.0, 0.0, 0.0);
	gst_gl_filter_reflected_screen_draw_floor ();
	glRotatef (90.0f, 1.0, 0.0, 0.0);
	glDisable (GL_BLEND);
	glEnable (GL_LIGHTING);
	//draw the real object
	//scale on y axis. The object must be drawn upside down (to suggest a reflexion)
	glScalef (1.0f, -1.0f, 1.0f);
	glTranslatef (0.0f, 0.0f, 1.4f);
	glRotatef (-45.0f, 0.0, 1.0, 0.0);
	gst_gl_filter_reflected_screen_draw_screen (filter, width, height, texture);
	glDisable (GL_LIGHTING);
	}
	}