/**

  * $Id$

  *

  * Common GL code that doesn't depend on a specific implementation

  *

  * Copyright (c) 2005 Nathan Keynes.

  *

  * 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.

  */

 #include <sys/time.h>

 #include "display.h"

 #include "pvr2/pvr2.h"

 #include "drivers/video_gl.h"

 extern uint32_t video_width, video_height;

 /**

  * Reset the gl state to simple orthographic projection with 

  * texturing, alpha/depth/scissor/cull tests disabled.

  */

 void gl_reset_state()

 {

     glViewport( 0, 0, video_width, video_height );

     glMatrixMode(GL_PROJECTION);

     glLoadIdentity();

     glOrtho( 0, video_width, video_height, 0, 0, 65535 );

     glMatrixMode(GL_MODELVIEW);

     glLoadIdentity();

     glEnable( GL_BLEND );

     glDisable( GL_TEXTURE_2D );

     glDisable( GL_TEXTURE_RECTANGLE_ARB );

     glDisable( GL_ALPHA_TEST );

     glDisable( GL_DEPTH_TEST );

     glDisable( GL_SCISSOR_TEST );

     glDisable( GL_CULL_FACE );

     glDrawBuffer( GL_FRONT );

 }

 void gl_display_render_buffer( render_buffer_t buffer )

 {

     gl_texture_window( buffer->width, buffer->height, buffer->buf_id, buffer->inverted );

 }

 /**

  * Convert window coordinates to dreamcast device coords (640x480) using the 

  * same viewable area as gl_texture_window.

  * If the coordinates are outside the viewable area, the result is -1,-1.

  */ 

 void gl_window_to_system_coords( int *x, int *y )

 {

     int x1=0,y1=0,x2=video_width,y2=video_height;

     int ah = video_width * 0.75;

     if( ah > video_height ) {

         int w = (video_height/0.75);

         x1 = (video_width - w)/2;

         x2 -= x1;

     } else if( ah < video_height ) {

         y1 = (video_height - ah)/2;

         y2 -= y1;

     }

     if( *x < x1 || *x >= x2 || *y < y1 || *y >= y2 ) {

         *x = -1;

         *y = -1;

     } else {

         *x = (*x - x1) * DISPLAY_WIDTH / (x2-x1);

         *y = (*y - y1) * DISPLAY_HEIGHT / (y2-y1);

     }

 }

 void gl_texture_window( int width, int height, int tex_id, gboolean inverted )

 {

     float top, bottom;

     if( inverted ) {

         top = ((float)height);

         bottom = 0;

     } else {

         top = 0;

         bottom = ((float)height);

     }

     /* Reset display parameters */

     gl_reset_state();

     glColor3f( 0,0,0 );    

     int x1=0,y1=0,x2=video_width,y2=video_height;

     int ah = video_width * 0.75;

     if( ah > video_height ) {

         int w = (video_height/0.75);

         x1 = (video_width - w)/2;

         x2 -= x1;

         glBegin( GL_QUADS );

         glVertex2f( 0, 0 );

         glVertex2f( x1, 0 );

         glVertex2f( x1, video_height );

         glVertex2f( 0, video_height);

         glVertex2f( x2, 0 );

         glVertex2f( video_width, 0 );

         glVertex2f( video_width, video_height );

         glVertex2f( x2, video_height);

         glEnd();

     } else if( ah < video_height ) {

         y1 = (video_height - ah)/2;

         y2 -= y1;

         glBegin( GL_QUADS );

         glVertex2f( 0, 0 );

         glVertex2f( video_width, 0 );

         glVertex2f( video_width, y1 );

         glVertex2f( 0, y1 );

         glVertex2f( 0, y2 );

         glVertex2f( video_width, y2 );

         glVertex2f( video_width, video_height );

         glVertex2f( 0, video_height );

         glEnd();

     }

     /* Render the textured rectangle */

     glEnable( GL_TEXTURE_RECTANGLE_ARB );

     glBindTexture( GL_TEXTURE_RECTANGLE_ARB, tex_id );

     glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE );

     glTexParameteri(GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

     glTexParameteri(GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

     glEnable( GL_BLEND );

     glBlendFunc( GL_ONE, GL_ZERO );

     glBegin( GL_QUADS );

     glTexCoord2f( 0, top );

     glVertex2f( x1, y1 );

     glTexCoord2f( ((float)width), top );

     glVertex2f( x2, y1 );

     glTexCoord2f( ((float)width), bottom );

     glVertex2f( x2, y2 );

     glTexCoord2f( 0, bottom );

     glVertex2f( x1, y2 );

     glEnd();

     glDisable( GL_TEXTURE_RECTANGLE_ARB );

     glFlush();

 }

 gboolean gl_load_frame_buffer( frame_buffer_t frame, int tex_id )

 {

     GLenum type = colour_formats[frame->colour_format].type;

     GLenum format = colour_formats[frame->colour_format].format;

     int bpp = colour_formats[frame->colour_format].bpp;

     int rowstride = (frame->rowstride / bpp) - frame->width;

     glPixelStorei( GL_UNPACK_ROW_LENGTH, rowstride );

     glBindTexture( GL_TEXTURE_RECTANGLE_ARB, tex_id );

     glTexSubImage2D( GL_TEXTURE_RECTANGLE_ARB, 0, 0,0,

                      frame->width, frame->height, format, type, frame->data );

     return TRUE;

 }

 void gl_display_blank( uint32_t colour )

 {

     gl_reset_state();

     glColor3ub( (colour >> 16) & 0xFF, (colour >> 8) & 0xFF, colour & 0xFF );

     glRecti(0,0, video_width, video_height );

     glFlush();

 }

 /**

  * Generic GL read_render_buffer. This function assumes that the caller

  * has already set the appropriate glReadBuffer(); in other words, unless

  * there's only one buffer this needs to be wrapped.

  */

 gboolean gl_read_render_buffer( unsigned char *target, render_buffer_t buffer, 

                                 int rowstride, int colour_format ) 

 {

     glFinish();

     GLenum type = colour_formats[colour_format].type;

     GLenum format = colour_formats[colour_format].format;

     // int line_size = buffer->width * colour_formats[colour_format].bpp;

     // int size = line_size * buffer->height;

     int glrowstride = (rowstride / colour_formats[colour_format].bpp) - buffer->width;

     glPixelStorei( GL_PACK_ROW_LENGTH, glrowstride );

     glReadPixels( 0, 0, buffer->width, buffer->height, format, type, target );

     return TRUE;

 }