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pbuffer.cpp

//FILE:     pbuffer.cpp
//AUTHOR:   Andrew Van Pernis <arakel@vr.clemson.edu>

#include "pbuffer.h"

//Static constant definitons
#ifdef GLX_SGIX_fbconfig
const int gl::pixel_buffer::VISUAL_ATTRIBUTES_8BPP[] = {
  GLX_DRAWABLE_TYPE_SGIX, GLX_PBUFFER_BIT_SGIX,
  GLX_RENDER_TYPE_SGIX, GLX_RGBA_BIT_SGIX,
  GLX_DOUBLEBUFFER, GL_FALSE,
  GLX_RED_SIZE, 2,
  GLX_GREEN_SIZE, 2,
  GLX_BLUE_SIZE, 2,
  GLX_ALPHA_SIZE, 2,
  None
};

const int gl::pixel_buffer::VISUAL_ATTRIBUTES_16BPP[] = {
  GLX_DRAWABLE_TYPE_SGIX, GLX_PBUFFER_BIT_SGIX,
  GLX_RENDER_TYPE_SGIX, GLX_RGBA_BIT_SGIX,
  GLX_DOUBLEBUFFER, GL_FALSE,
  GLX_RED_SIZE, 4,
  GLX_GREEN_SIZE, 4,
  GLX_BLUE_SIZE, 4,
  GLX_ALPHA_SIZE, 4,
  None,
};

const int gl::pixel_buffer::VISUAL_ATTRIBUTES_24BPP[] = {
  GLX_DRAWABLE_TYPE_SGIX, GLX_PBUFFER_BIT_SGIX,
  GLX_RENDER_TYPE_SGIX, GLX_RGBA_BIT_SGIX,
  GLX_DOUBLEBUFFER, GL_FALSE,
  GLX_RED_SIZE, 6,
  GLX_GREEN_SIZE, 6,
  GLX_BLUE_SIZE, 6,
  GLX_ALPHA_SIZE, 6,
  None  
};

const int gl::pixel_buffer::VISUAL_ATTRIBUTES_32BPP[] = {
  GLX_DRAWABLE_TYPE_SGIX, GLX_PBUFFER_BIT_SGIX,
  GLX_RENDER_TYPE_SGIX, GLX_RGBA_BIT_SGIX,
  GLX_DOUBLEBUFFER, GL_FALSE,
  GLX_RED_SIZE, 8,
  GLX_GREEN_SIZE, 8,
  GLX_BLUE_SIZE, 8,
  GLX_ALPHA_SIZE, 8,
  None
};

const int gl::pixel_buffer::PIXEL_BUFFER_ATTRIBUTES[] = {
  GLX_PRESERVED_CONTENTS_SGIX,
  None
};
#endif

//Method definitions for pixel_buffer class

bool gl::pixel_buffer::init(unsigned int w, unsigned int h, unsigned int bpp, GLXContext shared){

  //Check to see if init has already been called      
  if (m_initialized){        
    set_error("Pixel buffer has already been initialized.");        
    return false;      
  }

#ifdef GLX_SGIX_fbconfig
#ifdef GLX_SGIX_pbuffer
  int screen;
  
  //Check to see if the arguments are sane
  if (w < 1)
    w = 1;
  if (h < 1)
    h = 1;
  if (bpp < 8)
    bpp = 8;

  //Check to see if the X display gan be grabbed and grab some defaults
  if ((m_display = XOpenDisplay(NULL)) == NULL){
    set_error("Unable to open the X display.");
    return false;
  }
  screen = DefaultScreen(m_display);

  //Get a list of frame buffer configurations
  m_num_available_configs = 0;
  if (bpp < 16)
    m_available_configs = glXChooseFBConfigSGIX(m_display, screen, VISUAL_ATTRIBUTES_8BPP, &m_num_available_configs);
  else if (bpp < 24)
    m_available_configs = glXChooseFBConfigSGIX(m_display, screen, VISUAL_ATTRIBUTES_16BPP, &m_num_available_configs);
  else if (bpp < 32)
    m_available_configs = glXChooseFBConfigSGIX(m_display, screen, VISUAL_ATTRIBUTES_24BPP, &m_num_available_configs);
  else
    m_available_configs = glXChooseFBConfigSGIX(m_display, screen, VISUAL_ATTRIBUTES_32BPP, &m_num_available_configs);
  if (m_num_available_configs == 0){
    set_error("A framebuffer configuration with the chosen bit depth could not be found.");
    return false;
  }

  //Create the pixel buffer
  m_pixel_buffer = glXCreateGLXPbufferSGIX(m_display, m_available_configs[0], w, h, PIXEL_BUFFER_ATTRIBUTES);
  if (m_pixel_buffer == None){
    set_error("A pixel buffer could not be created.");
    return false;
  }

  //Setup texture object
  GLuint texture_number;
  glGenTextures(1, &texture_number);
  m_texture.set(texture_number, w / h);

  //Create an OpenGL context for the pixel buffer
  m_pixel_buffer_context = glXCreateContextWithConfigSGIX(m_display, m_available_configs[0], GLX_RGBA_TYPE_SGIX,
                                                          shared, GL_TRUE);

  //Copy parameters to internal variables
  m_width = w;
  m_height = h;
  m_bpp = bpp;
  m_initialized = true;
  return true;
#endif
#endif
  set_error("Pixel buffers are not supported on this machine.");
  return false;
}

/*===========================================================================*/

bool gl::pixel_buffer::init(unsigned int w, unsigned int h, unsigned int bpp, const int attributes[], GLXContext shared){

  //Check to see if init has already been called      
  if (m_initialized){        
    set_error("Pixel buffer has already been initialized.");        
    return false;      
  }
  
#ifdef GLX_SGIX_fbconfig
#ifdef GLX_SGIX_pbuffer
  int screen;
  
  //Check to see if the arguments are sane
  if (w < 1)
    w = 1;
  if (h < 1)
    h = 1;
  if (bpp < 8)
    bpp = 8;

  //Check to see if the X display gan be grabbed and grab some defaults
  if ((m_display = XOpenDisplay(NULL)) == NULL){
    set_error("Unable to open the X display.");
    return false;
  }
  screen = DefaultScreen(m_display);

  //Get a list of frame buffer configurations
  m_num_available_configs = 0;
  m_available_configs = glXChooseFBConfigSGIX(m_display, screen, attributes, &m_num_available_configs);
  if (m_num_available_configs == 0){
    set_error("A framebuffer configuration with the chosen attributes could not be found.");
    return false;
  }

  //Create the pixel buffer
  m_pixel_buffer = glXCreateGLXPbufferSGIX(m_display, m_available_configs[0], w, h, PIXEL_BUFFER_ATTRIBUTES);
  if (m_pixel_buffer == None){
    set_error("A pixel buffer could not be created.");
    return false;
  }

  //Setup texture object
  GLuint texture_number;
  glGenTextures(1, &texture_number);
  m_texture.set(texture_number, (float)w/(float)h);

  //Create an OpenGL context for the pixel buffer
  m_pixel_buffer_context = glXCreateContextWithConfigSGIX(m_display, m_available_configs[0], GLX_RGBA_TYPE_SGIX,
                                                          shared, GL_TRUE);

  //Copy parameters to internal variables
  m_width = w;
  m_height = h;
  m_bpp = bpp;
  m_initialized = true;
  return true;
#endif
#endif
  set_error("Pixel buffers are not supported on this machine.");
  return false;
}

/*===========================================================================*/

void gl::pixel_buffer::activate(void){
#ifdef GLX_SGIX_fbconfig
#ifdef GLX_SGIX_pbuffer
  //Switch to drawing in the pixel buffer
  glXMakeContextCurrent(m_display, m_pixel_buffer, m_pixel_buffer, m_pixel_buffer_context);
#endif
#endif
}

/*===========================================================================*/

void gl::pixel_buffer::shutdown(void){
  if (m_initialized){
#ifdef GLX_SGIX_fbconfig
#ifdef GLX_SGIX_pbuffer
    //Destroy the GL context
    glXDestroyContext(m_display, m_pixel_buffer_context);
    m_pixel_buffer_context = NULL;
    
    //Destroy the pixel pbuffer
    glXDestroyGLXPbufferSGIX(m_display, m_pixel_buffer);
#endif
#endif
    //Close the X display
    XCloseDisplay(m_display);
    m_display = NULL;
    m_initialized = false;
  }
}

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