/**

 * $Id$

 *

 * Standard OpenGL rendering engine. 

 *

 * 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 "display.h"

#include "pvr2/pvr2.h"

#include "pvr2/scene.h"

/**

 * Clip the tile bounds to the clipping plane. 

 * @return TRUE if the tile was not clipped completely.

 */

static gboolean clip_tile_bounds( uint32_t *tile, float *clip )

{

    if( tile[0] < clip[0] ) tile[0] = clip[0];

    if( tile[1] > clip[1] ) tile[1] = clip[1];

    if( tile[2] < clip[2] ) tile[2] = clip[2];

    if( tile[3] > clip[3] ) tile[3] = clip[3];

    return tile[0] < tile[1] && tile[2] < tile[3];

}

/**

 * Once-off call to setup the OpenGL context.

 */

void pvr2_setup_gl_context()

{

    texcache_gl_init(); // Allocate texture IDs

    glShadeModel(GL_SMOOTH);

    glCullFace( GL_BACK );

    glEnable( GL_BLEND );

    glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);

    glMatrixMode(GL_MODELVIEW);

    glLoadIdentity();

    glEnableClientState( GL_COLOR_ARRAY );

    glEnableClientState( GL_VERTEX_ARRAY );

    glEnableClientState( GL_TEXTURE_COORD_ARRAY );

    glEnableClientState( GL_SECONDARY_COLOR_ARRAY );

    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);

    glClearDepth(0);

    glClearStencil(0);

}

static void gl_render_poly( struct polygon_struct *poly )

{

    render_set_context( poly->context, RENDER_NORMAL );

    glDrawArrays(GL_TRIANGLE_STRIP, poly->vertex_index, poly->vertex_count );

}

static void gl_render_tilelist( pvraddr_t tile_entry )

{

    uint32_t *tile_list = (uint32_t *)(video_base+tile_entry);

    int strip_count;

    struct polygon_struct *poly;

    while(1) {

	uint32_t entry = *tile_list++;

	switch( entry >> 28 ) {

	case 0x0F:

	    return; // End-of-list

	case 0x0E:

	    tile_list = (uint32_t *)(video_base + (entry&0x007FFFFF));

	    break;

	case 0x08:

	case 0x09:

	case 0x0A:

	case 0x0B:

	    strip_count = ((entry >> 25) & 0x0F)+1;

	    poly = pvr2_scene.buf_to_poly_map[entry&0x000FFFFF];

	    while( strip_count > 0 ) {

		gl_render_poly( poly );

		poly = poly->next;

		strip_count--;

	    }

	    break;

	default:

	    poly = pvr2_scene.buf_to_poly_map[entry&0x000FFFFF];

	    gl_render_poly( poly );

	}

    }	    

}

/**

 * Render the currently defined scene in pvr2_scene

 */

void pvr2_scene_render( render_buffer_t buffer )

{

    /* Scene setup */

    display_driver->set_render_target(buffer);

    pvr2_check_palette_changed();

    /* Setup view projection matrix */

    glMatrixMode(GL_PROJECTION);

    glLoadIdentity();

    float nearz = pvr2_scene.bounds[4];

    float farz = pvr2_scene.bounds[5];

    if( nearz == farz ) {

	farz*= 2.0;

    }

    glOrtho( 0, pvr2_scene.buffer_width, pvr2_scene.buffer_height, 0, 

	     -nearz, -farz );

    /* Clear the buffer (FIXME: May not want always want to do this) */

    glDisable( GL_SCISSOR_TEST );

    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT );

    /* Setup vertex array pointers */

    glInterleavedArrays(GL_T2F_C4UB_V3F, sizeof(struct vertex_struct), pvr2_scene.vertex_array);

    glSecondaryColorPointerEXT(4, GL_UNSIGNED_BYTE, sizeof(struct vertex_struct), &pvr2_scene.vertex_array[0].offset_rgba );

    uint32_t bgplane_mode = MMIO_READ(PVR2, RENDER_BGPLANE);

    uint32_t *bgplane = pvr2_scene.pvr2_pbuf + (((bgplane_mode & 0x00FFFFFF)) >> 3) ;

    render_backplane( bgplane, pvr2_scene.buffer_width, pvr2_scene.buffer_height, bgplane_mode );

    glEnable( GL_SCISSOR_TEST );

    /* Process the segment list */

    struct tile_segment *segment = pvr2_scene.segment_list;

    do {

	int tilex = SEGMENT_X(segment->control);

	int tiley = SEGMENT_Y(segment->control);

	int tile_bounds[4] = { tilex << 5, (tilex+1)<<5, tiley<<5, (tiley+1)<<5 };

	if( !clip_tile_bounds(tile_bounds, pvr2_scene.bounds) ) {

	    continue; // fully clipped, skip tile

	}

	/* Clip to the visible part of the tile */

	glScissor( tile_bounds[0], pvr2_scene.buffer_height-tile_bounds[3], 

		   tile_bounds[1]-tile_bounds[0], tile_bounds[3] - tile_bounds[2] );

	if( IS_TILE_PTR(segment->opaque_ptr) ) {

	    gl_render_tilelist(segment->opaque_ptr);

	}

	if( IS_TILE_PTR(segment->trans_ptr) ) {

	    gl_render_tilelist(segment->trans_ptr);

	}

	if( IS_TILE_PTR(segment->punchout_ptr) ) {

	    gl_render_tilelist(segment->punchout_ptr);

	}

    } while( !IS_LAST_SEGMENT(segment++) );

    glDisable( GL_SCISSOR_TEST );

}