/**

 * $Id$

 *

 * 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_ALPHA_TEST );

    glDisable( GL_DEPTH_TEST );

    glDisable( GL_SCISSOR_TEST );

    glDisable( GL_CULL_FACE );

}

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 = 1;

        bottom = 0;

    } else {

        top = 0;

        bottom = 1;

    }

    /* 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_2D );

    glBindTexture( GL_TEXTURE_2D, tex_id );

    glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE );

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

    glEnable( GL_BLEND );

    glBlendFunc( GL_ONE, GL_ZERO );

    glBegin( GL_QUADS );

    glTexCoord2f( 0, top );

    glVertex2f( x1, y1 );

    glTexCoord2f( 1, top );

    glVertex2f( x2, y1 );

    glTexCoord2f( 1, bottom );

    glVertex2f( x2, y2 );

    glTexCoord2f( 0, bottom );

    glVertex2f( x1, y2 );

    glEnd();

    glDisable( GL_TEXTURE_2D );

    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_2D, tex_id );

    glTexSubImage2D( GL_TEXTURE_2D, 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;

}