/* Mednafen - Multi-system Emulator
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "main.h"

#include <trio/trio.h>

#include "video.h"
#include "opengl.h"
#include "shader.h"

void OpenGL_Blitter::ReadPixels(MDFN_Surface *surface, const MDFN_Rect *rect)
{
 p_glPixelStorei(GL_UNPACK_ROW_LENGTH, surface->pitchinpix);
 p_glReadPixels(rect->x, gl_screen_h - rect->h - rect->y, rect->w, rect->h, PixelFormat, PixelType, surface->pixels);

 for(int y = 0; y < surface->h / 2; y++)
 {
  uint32 tmp_buffer[surface->w];

  memcpy(tmp_buffer, &surface->pixels[y * surface->pitchinpix], surface->pitchinpix * sizeof(uint32));
  memcpy(&surface->pixels[y * surface->pitchinpix], &surface->pixels[(surface->h - 1 - y) * surface->pitchinpix], surface->pitchinpix * sizeof(uint32));
  memcpy(&surface->pixels[(surface->h - 1 - y) * surface->pitchinpix], tmp_buffer, surface->pitchinpix * sizeof(uint32));
 }
}


void OpenGL_Blitter::BlitRaw(const MDFN_Surface *surface, const MDFN_Rect *rect, const MDFN_Rect *dest_rect, const bool source_alpha)
{
 unsigned int tmpwidth;
 unsigned int tmpheight;

 if(SupportNPOT)
 {
  tmpwidth = rect->w;
  tmpheight = rect->h;
 }
 else
 {
  tmpwidth = round_up_pow2(rect->w);
  tmpheight = round_up_pow2(rect->h);
 }

 if(tmpwidth > MaxTextureSize || tmpheight > MaxTextureSize)
 {
  MDFN_Rect neo_rect;
  MDFN_Rect neo_dest_rect;

  for(int32 xseg = 0; xseg < rect->w; xseg += MaxTextureSize)
  {
   for(int32 yseg = 0; yseg < rect->h; yseg += MaxTextureSize)
   {
    neo_rect.x = rect->x + xseg;
    neo_rect.w = rect->w - xseg;

    if(neo_rect.w > MaxTextureSize)
     neo_rect.w = MaxTextureSize;

    neo_rect.y = rect->y + yseg;
    neo_rect.h = rect->h - yseg;

    if(neo_rect.h > MaxTextureSize)
     neo_rect.h = MaxTextureSize;

    neo_dest_rect.x = dest_rect->x + xseg * dest_rect->w / rect->w;
    neo_dest_rect.y = dest_rect->y + yseg * dest_rect->h / rect->h;
    neo_dest_rect.w = neo_rect.w * dest_rect->w / rect->w;
    neo_dest_rect.h = neo_rect.h * dest_rect->h / rect->h;
    BlitRaw(surface, &neo_rect, &neo_dest_rect, source_alpha);
   }
  }
 }
 else
 {
  // Don't move the source_alpha stuff out of this else { }, otherwise it will break the recursion necessary to work around maximum texture size limits.
  if(source_alpha)
  {
   p_glEnable(GL_BLEND);
   p_glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
  }

  p_glBindTexture(GL_TEXTURE_2D, textures[3]);
  p_glPixelStorei(GL_UNPACK_ROW_LENGTH, surface->pitchinpix);

  p_glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, tmpwidth, tmpheight, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
  p_glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, rect->w, rect->h, PixelFormat, PixelType, surface->pixels + rect->x + rect->y * surface->pitchinpix);

  p_glBegin(GL_QUADS);

  p_glTexCoord2f(0.0f, 1.0f * rect->h / tmpheight);  // Bottom left of our picture.
  p_glVertex2f(dest_rect->x, dest_rect->y + dest_rect->h);

  p_glTexCoord2f((float)rect->w / tmpwidth, 1.0f * rect->h / tmpheight); // Bottom right of our picture.
  p_glVertex2f(dest_rect->x + dest_rect->w, dest_rect->y + dest_rect->h);

  p_glTexCoord2f((float)rect->w / tmpwidth, 0.0f);    // Top right of our picture.
  p_glVertex2f(dest_rect->x + dest_rect->w,  dest_rect->y);

  p_glTexCoord2f(0.0f, 0.0f);     // Top left of our picture.
  p_glVertex2f(dest_rect->x, dest_rect->y);

  p_glEnd();

  if(source_alpha)
  {
   p_glDisable(GL_BLEND);
  }
 }
}

static INLINE void MakeSourceCoords(const MDFN_Rect *src_rect, float sc[4][2], const int32 tmpwidth, const int32 tmpheight, const float y_fudge)
{
 // Upper left
 sc[0][0] = (float)src_rect->x / tmpwidth;			// X
 sc[0][1] = (float)(src_rect->y + y_fudge) / tmpheight;		// Y

 // Upper right
 sc[1][0] = (float)(src_rect->x + src_rect->w) / tmpwidth;	// X
 sc[1][1] = (float)(src_rect->y + y_fudge) / tmpheight;		// Y

 // Lower right
 sc[2][0] = (float)(src_rect->x + src_rect->w) / tmpwidth;	// X
 sc[2][1] = (float)(src_rect->y + y_fudge + src_rect->h) / tmpheight;	// Y

 // Lower left
 sc[3][0] = (float)src_rect->x / tmpwidth;			// X
 sc[3][1] = (float)(src_rect->y + y_fudge + src_rect->h) / tmpheight;	// Y
}

static INLINE void MakeDestCoords(const MDFN_Rect *dest_rect, int dest_coords[4][2], const unsigned rotated)
{
  signed dco = 0;

  if(rotated == MDFN_ROTATE90)
   dco = 1;
  else if(rotated == MDFN_ROTATE270)
   dco = 3;
  else if(rotated == MDFN_ROTATE180)
   dco = 2;

  // Upper left
  dest_coords[dco][0] = dest_rect->x;
  dest_coords[dco][1] = dest_rect->y;
  dco = (dco + 1) & 3;

  // Upper Right
  dest_coords[dco][0] = dest_rect->x + dest_rect->w;
  dest_coords[dco][1] = dest_rect->y;
  dco = (dco + 1) & 3;

  // Lower right
  dest_coords[dco][0] = dest_rect->x + dest_rect->w;
  dest_coords[dco][1] = dest_rect->y + dest_rect->h;
  dco = (dco + 1) & 3;

  // Lower left
  dest_coords[dco][0] = dest_rect->x;
  dest_coords[dco][1] = dest_rect->y + dest_rect->h;
  dco = (dco + 1) & 3;

  //printf("%f:%f %f:%f %f:%f %f:%f\n", dest_coords[0][0], dest_coords[0][1], dest_coords[1][0], dest_coords[1][1], dest_coords[2][0], 
  //	dest_coords[2][1], dest_coords[3][0], dest_coords[3][1]);
}

//#define MDFN_TRIANGLE_STRIP_TEST

#ifdef MDFN_TRIANGLE_STRIP_TEST
INLINE void OpenGL_Blitter::DrawQuad(float src_coords[4][2], int dest_coords[4][2])
{
 puts("TRIANGLESSSS");
#if 0
  // Lower left
  p_glTexCoord2f(src_coords[3][0], src_coords[3][1]);
   p_glVertex2f(dest_coords[3][0], dest_coords[3][1]);

  // Upper left
  p_glTexCoord2f(src_coords[0][0], src_coords[0][1]);
   p_glVertex2f(dest_coords[0][0], dest_coords[0][1]);

  // Lower right
  p_glTexCoord2f(src_coords[2][0], src_coords[2][1]);
   p_glVertex2f(dest_coords[2][0], dest_coords[2][1]);

#endif

  // Upper right
  p_glTexCoord2f(src_coords[1][0], src_coords[1][1]);
   p_glVertex2f(dest_coords[1][0], dest_coords[1][1]);

  // Upper left
  p_glTexCoord2f(src_coords[0][0], src_coords[0][1]);
   p_glVertex2f(dest_coords[0][0], dest_coords[0][1]);

  // Lower right
  p_glTexCoord2f(src_coords[2][0], src_coords[2][1]);
   p_glVertex2f(dest_coords[2][0], dest_coords[2][1]);

  // Lower left
  p_glTexCoord2f(src_coords[3][0], src_coords[3][1]);
   p_glVertex2f(dest_coords[3][0], dest_coords[3][1]);
}
#else
INLINE void OpenGL_Blitter::DrawQuad(float src_coords[4][2], int dest_coords[4][2])
{
  // Lower left
  p_glTexCoord2f(src_coords[3][0], src_coords[3][1]);
   p_glVertex2f(dest_coords[3][0], dest_coords[3][1]);

  // Lower right
  p_glTexCoord2f(src_coords[2][0], src_coords[2][1]);
   p_glVertex2f(dest_coords[2][0], dest_coords[2][1]);

  // Upper right
  p_glTexCoord2f(src_coords[1][0], src_coords[1][1]);
   p_glVertex2f(dest_coords[1][0], dest_coords[1][1]);

  // Upper left
  p_glTexCoord2f(src_coords[0][0], src_coords[0][1]);
   p_glVertex2f(dest_coords[0][0], dest_coords[0][1]);
}
#endif

void OpenGL_Blitter::DrawLinearIP(const unsigned UsingIP, const unsigned rotated, const MDFN_Rect *tex_src_rect, const MDFN_Rect *dest_rect, const uint32 tmpwidth, const uint32 tmpheight)
{
 MDFN_Rect tmp_sr = *tex_src_rect;
 MDFN_Rect tmp_dr = *dest_rect;
 float tmp_sc[4][2];
 int tmp_dc[4][2];

 int32 start_pos;
 int32 bound_pos;
 bool rotate_side = (rotated == MDFN_ROTATE90 || rotated == MDFN_ROTATE270);
 bool reversi;
 bool dr_y;
 bool sr_y;

 if((UsingIP == VIDEOIP_LINEAR_Y) ^ rotate_side)
 {
  start_pos = dest_rect->x;
  bound_pos = dest_rect->x + dest_rect->w;
  dr_y = false;
  sr_y = rotate_side;
 }
 else
 {
  start_pos = dest_rect->y;
  bound_pos = dest_rect->y + dest_rect->h;
  dr_y = true;
  sr_y = !rotate_side;
 }

 //printf("Start: %4d, Bound: %4d sr_y=%d, reversi=%d\n", start_pos, bound_pos, sr_y, reversi);

 reversi = (rotated == MDFN_ROTATE270 && UsingIP == VIDEOIP_LINEAR_X) || (rotated == MDFN_ROTATE90 && UsingIP == VIDEOIP_LINEAR_Y);

 for(int i = start_pos; i < bound_pos; i++)
 {
  int sr_goon = i - start_pos;

  if(dr_y)
  {
   tmp_dr.y = i;
   tmp_dr.h = 1;
  }
  else
  {
   tmp_dr.x = i;
   tmp_dr.w = 1;
  }

  if(reversi)
   sr_goon = (bound_pos - start_pos) - 1 - sr_goon;

  if(sr_y)
  {
   tmp_sr.y = sr_goon * tex_src_rect->h / (rotate_side ? dest_rect->w : dest_rect->h);
   tmp_sr.h = 1;
  }
  else
  {
   tmp_sr.x = sr_goon * tex_src_rect->w / (rotate_side ? dest_rect->h : dest_rect->w);
   tmp_sr.w = 1;
  }

  MakeSourceCoords(&tmp_sr, tmp_sc, tmpwidth, tmpheight, 0);
  MakeDestCoords(&tmp_dr, tmp_dc, rotated);

  DrawQuad(tmp_sc, tmp_dc);
 }
}

void OpenGL_Blitter::Blit(const MDFN_Surface *src_surface, const MDFN_Rect *src_rect, const MDFN_Rect *dest_rect, const MDFN_Rect *original_src_rect, int InterlaceField, int UsingIP, int rotated)
{
 MDFN_Rect tex_src_rect = *src_rect;
 float src_coords[4][2];
 int dest_coords[4][2];
 unsigned int tmpwidth;
 unsigned int tmpheight;
 uint32 *src_pixies;
 const bool ShaderIlace = (InterlaceField >= 0) && shader && shader->ShaderNeedsProperIlace();

 if(shader)
 {
  if(shader->ShaderNeedsBTIP())
   UsingIP = VIDEOIP_BILINEAR;
  else
   UsingIP = VIDEOIP_OFF;
 }

 if(tex_src_rect.w == 0 || tex_src_rect.h == 0 || dest_rect->w == 0 || dest_rect->h == 0 || original_src_rect->w == 0 || original_src_rect->h == 0)
 {
  printf("[BUG] OpenGL blitting nothing? --- %d:%d %d:%d %d:%d\n", tex_src_rect.w, tex_src_rect.h, dest_rect->w, dest_rect->h, original_src_rect->w, original_src_rect->h);
  return;
 }


 src_pixies = src_surface->pixels + tex_src_rect.x + (tex_src_rect.y + (InterlaceField & ShaderIlace)) * src_surface->pitchinpix;
 tex_src_rect.x = 0;
 tex_src_rect.y = 0;
 tex_src_rect.h >>= ShaderIlace;

 MakeDestCoords(dest_rect, dest_coords, rotated);

 p_glBindTexture(GL_TEXTURE_2D, textures[0]);
 p_glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, UsingIP ? GL_LINEAR : GL_NEAREST);
 p_glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, UsingIP ? GL_LINEAR : GL_NEAREST);

 if(SupportNPOT)
 {
  tmpwidth = tex_src_rect.w;
  tmpheight = tex_src_rect.h;

  if(tmpwidth != last_w || tmpheight != last_h)
  {
   p_glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, tmpwidth, tmpheight, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
   last_w = tmpwidth;
   last_h = tmpheight;
  }
 }
 else
 {
  bool ImageSizeChange = FALSE;

  tmpwidth = round_up_pow2(tex_src_rect.w);
  tmpheight = round_up_pow2(tex_src_rect.h);

  // If the required GL texture size has changed, resize the texture! :b
  if(tmpwidth != round_up_pow2(last_w) || tmpheight != round_up_pow2(last_h))
  {
   p_glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, tmpwidth, tmpheight, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
   ImageSizeChange = TRUE;
  }
 
  // If the dimensions of our image stored in the texture have changed...
  if(tex_src_rect.w != last_w || tex_src_rect.h != last_h)
   ImageSizeChange = TRUE;

  // Only clean up if we're using pixel shaders and/or bilinear interpolation
  if(ImageSizeChange && (shader || UsingIP))
  {
   uint32 neo_dbs = DummyBlackSize;

   if(tex_src_rect.w != tmpwidth && neo_dbs < tex_src_rect.h)
    neo_dbs = tex_src_rect.h;

   if(tex_src_rect.h != tmpheight && neo_dbs < tex_src_rect.w)
    neo_dbs = tex_src_rect.w;

   if(neo_dbs != DummyBlackSize)
   {
    //printf("Realloc: %d\n", neo_dbs);
    if(DummyBlack)
    {
     delete[] DummyBlack;
     DummyBlack = NULL;
     DummyBlackSize = 0;
    }

    try
    {
     DummyBlack = new uint32[neo_dbs];
     memset(DummyBlack, 0, sizeof(uint32) * neo_dbs);
     DummyBlackSize = neo_dbs;
    }
    catch(...)
    {
    }
   }

   //printf("Cleanup: %d %d, %d %d\n", tex_src_rect.w, tex_src_rect.h, tmpwidth, tmpheight);

   if(DummyBlack) // If memory allocation failed for some reason, don't clean the texture. :(
   {
    if(tex_src_rect.w < tmpwidth)
    {
     //puts("X");
     p_glPixelStorei(GL_UNPACK_ROW_LENGTH, 1);
     p_glTexSubImage2D(GL_TEXTURE_2D, 0, tex_src_rect.w, 0, 1, tex_src_rect.h, GL_RGBA, GL_UNSIGNED_BYTE, DummyBlack);
    }
    if(tex_src_rect.h < tmpheight)
    {
     //puts("Y");
     p_glPixelStorei(GL_UNPACK_ROW_LENGTH, tex_src_rect.w);
     p_glTexSubImage2D(GL_TEXTURE_2D, 0, 0, tex_src_rect.h, tex_src_rect.w, 1, GL_RGBA, GL_UNSIGNED_BYTE, DummyBlack);
    }
   } // end if(DummyBlack)

  }

  last_w = tex_src_rect.w;
  last_h = tex_src_rect.h;
 }

 MakeSourceCoords(&tex_src_rect, src_coords, tmpwidth, tmpheight, (ShaderIlace & InterlaceField) * -0.5);

 if(shader)
  shader->ShaderBegin(gl_screen_w, gl_screen_h, src_rect, dest_rect, tmpwidth, tmpheight, round((double)tmpwidth * original_src_rect->w / tex_src_rect.w), round((double)tmpheight * (original_src_rect->h >> ShaderIlace) / tex_src_rect.h), rotated);

 p_glPixelStorei(GL_UNPACK_ROW_LENGTH, src_surface->pitchinpix << ShaderIlace);

 p_glTexSubImage2D(GL_TEXTURE_2D, 0, tex_src_rect.x, tex_src_rect.y, tex_src_rect.w, tex_src_rect.h, PixelFormat, PixelType, src_pixies);

 //
 // Draw texture
 //
#ifdef MDFN_TRIANGLE_STRIP_TEST
 p_glBegin(GL_TRIANGLE_STRIP);
#else
 p_glBegin(GL_QUADS);
#endif

 if(UsingIP == VIDEOIP_LINEAR_X || UsingIP == VIDEOIP_LINEAR_Y)	// Linear interpolation, on one axis
 {
  DrawLinearIP(UsingIP, rotated, &tex_src_rect, dest_rect, tmpwidth, tmpheight);
 }
 else	// Regular bilinear or no interpolation.
 {
  DrawQuad(src_coords, dest_coords);
 }

 p_glEnd();

 if(shader)
  shader->ShaderEnd();

 if(using_scanlines && (dest_rect->h + (InterlaceField >= 0)) > original_src_rect->h)
 {
  float yif_offset = 0;
  int yh_shift = 0;

  if((using_scanlines < 0 || (dest_rect->h == original_src_rect->h)) && InterlaceField >= 0)
  {
   yif_offset = (float)InterlaceField / 512;
   yh_shift = 1;
  }


  p_glEnable(GL_BLEND);

  p_glBindTexture(GL_TEXTURE_2D, textures[1]);
  p_glBlendFunc(GL_DST_COLOR, GL_SRC_ALPHA);

  p_glBegin(GL_QUADS);

  p_glTexCoord2f(0.0f, yif_offset + (original_src_rect->h >> yh_shift) / 256.0f);  // Bottom left of our picture.
  p_glVertex2f((signed)dest_coords[3][0], (signed)dest_coords[3][1]);

  p_glTexCoord2f(1.0f, yif_offset + (original_src_rect->h >> yh_shift) / 256.0f); // Bottom right of our picture.
  p_glVertex2f((signed)dest_coords[2][0], (signed)dest_coords[2][1]);

  p_glTexCoord2f(1.0f, yif_offset);    // Top right of our picture.
  p_glVertex2f((signed)dest_coords[1][0], (signed)dest_coords[1][1]);

  p_glTexCoord2f(0.0f, yif_offset);     // Top left of our picture.
  p_glVertex2f((signed)dest_coords[0][0], (signed)dest_coords[0][1]);

  p_glEnd();
  p_glDisable(GL_BLEND);
 }
}


#if 0
void OpenGL_Blitter::HardSync(uint64 timeout)
{
 GLsync s;

 if(SupportARBSync)
 {
  if((s = p_glFenceSync(GL_SYNC_GPU_COMMANDS_COMPLETE, 0)) != NULL)
  {
   p_glBegin(GL_POINTS);
   p_glVertex2f(0.0, 0.0);
   p_glEnd();

   uint64 before = Time::MonoUS();

   p_glClientWaitSync(s, 0, timeout); //50ULL * 1000 * 1000);	// 50 milliseconds.

   printf("Waited: %llu\n", (unsigned long long)(Time::MonoUS() - before));

   p_glDeleteSync(s);
  }
 }
}
#endif

void OpenGL_Blitter::Cleanup(void)
{
 if(textures[0])
  p_glDeleteTextures(4, &textures[0]);

 textures[0] = textures[1] = textures[2] = textures[3] = 0;

 if(DummyBlack)
 {
  delete[] DummyBlack;
  DummyBlack = NULL;
 }
 DummyBlackSize = 0;

 if(shader)
 {
  delete shader;
  shader = NULL;
 }
}

OpenGL_Blitter::~OpenGL_Blitter()
{
 Cleanup();
}

static bool CheckExtension(const char *extensions, const char *testval)
{
 const char *extparse = extensions;
 const size_t testval_len = strlen(testval);

 while((extparse = strstr(extparse, testval)))
 {
  if(extparse == extensions || *(extparse - 1) == ' ')
  {
   if(extparse[testval_len] == ' ' || extparse[testval_len] == 0)
   {
    return(TRUE);
   }
  }
  extparse += testval_len;
 }
 return(FALSE);
}

static bool CheckAlternateFormat(const uint32 version_h)
{
 if(version_h >= 0x0102)        // >= 1.2
 {
  #if defined(__amd64__) || defined(__x86_64__) || defined(_M_AMD64) || defined(__386__) || defined(__i386__) || defined(__i386) || defined(_M_IX86) || defined(_M_I386)
  return(true);
  #endif
 }
 return(false);
}

/* Rectangle, left, right(not inclusive), top, bottom(not inclusive). */
OpenGL_Blitter::OpenGL_Blitter(int scanlines, ShaderType pixshader, const ShaderParams& shader_params, const int screen_w, const int screen_h, int *rs, int *gs, int *bs, int *as) : gl_screen_w(screen_w), gl_screen_h(screen_h)
{
 try
 {
 const char *extensions;
 const char *vendor;
 const char *renderer;
 const char *version;
 uint32 version_h;

 MaxTextureSize = 0;
 SupportNPOT = false;
 SupportARBSync = false;
 PixelFormat = 0;
 PixelType = 0;

 for(unsigned i = 0; i < 4; i++)
  textures[i] = 0;

 using_scanlines = 0;
 last_w = 0;
 last_h = 0;

 OSDLastWidth = 0;
 OSDLastHeight = 0;

 shader = NULL;

 DummyBlack = NULL;
 DummyBlackSize = 0;


 #define LFG(x) if(!(p_##x = (x##_Func) SDL_GL_GetProcAddress(#x))) { throw MDFN_Error(0, _("Error getting proc address for: %s\n"), #x); }
 #define LFGN(x) p_##x = (x##_Func) SDL_GL_GetProcAddress(#x)

 LFG(glGetError);
 LFG(glBindTexture);
 LFGN(glColorTableEXT);
 LFG(glTexImage2D);
 LFG(glBegin);
 LFG(glVertex2f);
 LFG(glTexCoord2f);
 LFG(glEnd);
 LFG(glEnable);
 LFG(glBlendFunc);
 LFG(glGetString);
 LFG(glViewport);
 LFG(glGenTextures);
 LFG(glDeleteTextures);
 LFG(glTexParameteri);
 LFG(glClearColor);
 LFG(glLoadIdentity);
 LFG(glClear);
 LFG(glMatrixMode);
 LFG(glDisable);
 LFG(glPixelStorei);
 LFG(glTexSubImage2D);
 LFG(glFinish);
 LFG(glOrtho);
 LFG(glPixelTransferf);
 LFG(glColorMask);
 LFG(glTexEnvf);
 LFG(glGetIntegerv);
 LFG(glTexGend);
 LFG(glRasterPos2i);
 LFG(glDrawPixels);
 LFG(glPixelZoom);
 LFG(glAccum);
 LFG(glClearAccum);
 LFG(glGetTexLevelParameteriv);
 LFG(glPushMatrix);
 LFG(glPopMatrix);
 LFG(glRotated);
 LFG(glScalef);
 LFG(glReadPixels);

 vendor = (const char *)p_glGetString(GL_VENDOR);
 renderer = (const char *)p_glGetString(GL_RENDERER);
 version = (const char *)p_glGetString(GL_VERSION);

 {
  int major = 0, minor = 0;
  trio_sscanf(version, "%d.%d", &major, &minor);
  if(minor < 0) minor = 0;
  if(minor > 255) minor = 255;

  version_h = (major << 8) | minor;
  //printf("%08x\n", version_h);
 }

 MDFN_printf(_("OpenGL Implementation: %s %s %s\n"), vendor, renderer, version);

 extensions = (const char*)p_glGetString(GL_EXTENSIONS);

 MDFN_printf(_("Checking extensions:\n"));
 MDFN_indent(1);

 SupportNPOT = FALSE;
 SupportARBSync = false;

 if(CheckExtension(extensions, "GL_ARB_texture_non_power_of_two"))
 {
  MDFN_printf(_("GL_ARB_texture_non_power_of_two found.\n"));
  SupportNPOT = TRUE;
 }

 if(CheckExtension(extensions, "GL_ARB_sync"))
 {
  MDFN_printf(_("GL_ARB_sync found.\n"));
  LFG(glFenceSync);
  LFG(glIsSync);
  LFG(glDeleteSync);
  LFG(glClientWaitSync);
  LFG(glWaitSync);
  LFG(glGetInteger64v);
  LFG(glGetSynciv);
  SupportARBSync = true;
 }

 MDFN_indent(-1);

 // x,y specify LOWER left corner of the viewport.
 p_glViewport(0, 0, gl_screen_w, gl_screen_h);

 p_glGenTextures(4, &textures[0]);
 using_scanlines = 0;

 shader = NULL;

 if(pixshader != SHADER_NONE)
 {
  LFG(glCreateShaderObjectARB);
  LFG(glShaderSourceARB);
  LFG(glCompileShaderARB);
  LFG(glCreateProgramObjectARB);
  LFG(glAttachObjectARB);
  LFG(glLinkProgramARB);
  LFG(glUseProgramObjectARB);
  LFG(glUniform1fARB);
  LFG(glUniform2fARB);
  LFG(glUniform3fARB);
  LFG(glUniform1iARB);
  LFG(glUniform2iARB);
  LFG(glUniform3iARB);
  LFG(glUniformMatrix2fvARB);
  LFG(glUniform1fvARB);
  LFG(glUniform2fvARB);
  LFG(glUniform3fvARB);
  LFG(glUniform4fvARB);
  LFG(glActiveTextureARB);
  LFG(glGetInfoLogARB);
  LFG(glGetUniformLocationARB);
  LFG(glDeleteObjectARB);
  LFG(glDetachObjectARB);

  LFG(glGetObjectParameterivARB);

  shader = new OpenGL_Blitter_Shader(this, pixshader, shader_params);
  SupportNPOT = 0; 	 // Our pixel shaders don't work right with NPOT textures(for them to do so would probably necessitate rewriting them to use texelFetch)
  p_glActiveTextureARB(GL_TEXTURE0_ARB);

  if(pixshader == SHADER_GOAT && shader_params.goat_slen)
   scanlines = 0;
 }

 // printf here because pixel shader code will set SupportNPOT to 0

 if(SupportNPOT)
  MDFN_printf(_("Using non-power-of-2 sized textures.\n"));
 else
  MDFN_printf(_("Using power-of-2 sized textures.\n"));

 if(scanlines)
 {
  int slcount;

  using_scanlines = scanlines;

  p_glBindTexture(GL_TEXTURE_2D, textures[1]);
  p_glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_NEAREST);
  p_glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_NEAREST);

  std::unique_ptr<uint8[]> buf(new uint8[64 * (256 * 2) * 4]);

  slcount = 0;
  for(int y=0;y<(256 * 2);y++)
  {
   for(int x=0;x<64;x++)
   {
    int sl_alpha;

    if(slcount)
     sl_alpha = 0xFF - (0xFF * abs(scanlines) / 100);
    else
     sl_alpha = 0xFF;

    buf[y*64*4+x*4]=0;
    buf[y*64*4+x*4+1]=0;
    buf[y*64*4+x*4+2]=0;
    buf[y*64*4+x*4+3] = sl_alpha;
    //buf[y*256+x]=(y&1)?0x00:0xFF;
   }
   slcount ^= 1;
  }
  p_glPixelStorei(GL_UNPACK_ROW_LENGTH, 64);
  p_glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, 64, 256 * 2, 0, GL_RGBA, GL_UNSIGNED_BYTE, buf.get());
 }
 p_glBindTexture(GL_TEXTURE_2D, textures[3]);
 p_glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_NEAREST);
 p_glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_NEAREST);
 p_glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S,GL_CLAMP);
 p_glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T,GL_CLAMP);


 p_glBindTexture(GL_TEXTURE_2D, textures[0]);
     
 p_glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
 p_glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);

 p_glBindTexture(GL_TEXTURE_2D, textures[2]);

 p_glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S,GL_CLAMP);
 p_glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T,GL_CLAMP);

 p_glEnable(GL_TEXTURE_2D);
 p_glClearColor(0.0f, 0.0f, 0.0f, 0.0f);	// Background color to black.
 p_glMatrixMode(GL_MODELVIEW);

 p_glLoadIdentity();
 p_glFinish();

 p_glDisable(GL_TEXTURE_1D);
 p_glDisable(GL_FOG);
 p_glDisable(GL_LIGHTING);
 p_glDisable(GL_LOGIC_OP);
 p_glDisable(GL_DITHER);
 p_glDisable(GL_COLOR_MATERIAL);
 p_glDisable(GL_NORMALIZE);
 p_glDisable(GL_SCISSOR_TEST);
 p_glDisable(GL_STENCIL_TEST);
 p_glDisable(GL_ALPHA_TEST);
 p_glDisable(GL_DEPTH_TEST);

 p_glPixelTransferf(GL_RED_BIAS, 0);
 p_glPixelTransferf(GL_GREEN_BIAS, 0);
 p_glPixelTransferf(GL_BLUE_BIAS, 0);
 p_glPixelTransferf(GL_ALPHA_BIAS, 0);

 p_glPixelTransferf(GL_RED_SCALE, 1);
 p_glPixelTransferf(GL_GREEN_SCALE, 1);
 p_glPixelTransferf(GL_BLUE_SCALE, 1);
 p_glPixelTransferf(GL_ALPHA_SCALE, 1);

 p_glPixelTransferf(GL_MAP_COLOR, GL_FALSE);

 p_glOrtho(0, gl_screen_w, gl_screen_h, 0, -1.0, 1.0);

 last_w = 0;
 last_h = 0;

 OSDLastWidth = OSDLastHeight = 0;


 MDFN_printf(_("Checking maximum texture size...\n"));
 MDFN_indent(1);
 p_glBindTexture(GL_TEXTURE_2D, textures[0]);
 // Assume maximum texture width is the same as maximum texture height to greatly simplify things
 MaxTextureSize = 32768;
 
 while(MaxTextureSize)
 {
  GLint width_test = 0;

  p_glTexImage2D(GL_PROXY_TEXTURE_2D, 0, GL_RGBA, MaxTextureSize, MaxTextureSize, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
  p_glGetTexLevelParameteriv(GL_PROXY_TEXTURE_2D, 0, GL_TEXTURE_WIDTH, &width_test);

  if((unsigned int)width_test == MaxTextureSize)
   break;

  MaxTextureSize >>= 1;
 }
 MDFN_printf(_("Apparently it is at least: %d x %d\n"), MaxTextureSize, MaxTextureSize);

 if(MaxTextureSize < 256)
 {
  MDFN_printf(_("Warning:  Maximum texture size is reported as being less than 256, but we can't handle that.\n"));
  MaxTextureSize = 256;
 }

 DummyBlack = NULL;
 DummyBlackSize = 0;

 MDFN_indent(-1);

 if(!CheckAlternateFormat(version_h))
 {
  #ifdef LSB_FIRST
  *rs = 0;
  *gs = 8;
  *bs = 16;
  *as = 24;
  #else
  *rs = 24;
  *gs = 16;
  *bs = 8;
  *as = 0;
  #endif
  PixelFormat = GL_RGBA;
  PixelType = GL_UNSIGNED_BYTE;
  MDFN_printf(_("Using GL_RGBA, GL_UNSIGNED_BYTE for texture source data.\n"));
 }
 else
 {
  *as = 24;
  *rs = 16;
  *gs = 8;
  *bs = 0;
  PixelFormat = GL_BGRA;
  PixelType = GL_UNSIGNED_INT_8_8_8_8_REV;
  MDFN_printf(_("Using GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV for texture source data.\n"));
 }
 }
 catch(...)
 {
  Cleanup();
  throw;
 }
}

void OpenGL_Blitter::ClearBackBuffer(void)
{
 //if(1)
 //{
 // p_glClearAccum(0.0, 0.0, 0.0, 1.0);
 // p_glClear(GL_COLOR_BUFFER_BIT | GL_ACCUM_BUFFER_BIT);
 //}
 //else
 //{
  p_glClear(GL_COLOR_BUFFER_BIT);
 //}
}

