/**

 * $Id$

 *

 * Manage the internal vertex/polygon buffers and scene data structure. 

 * Where possible this uses VBOs for the vertex + index data.

 *

 * 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 <assert.h>

#include <string.h>

#include "lxdream.h"

#include "display.h"

#include "pvr2/pvr2.h"

#include "pvr2/glutil.h"

#include "pvr2/scene.h"

#define VBO_EXT_STRING "GL_ARB_vertex_buffer_object"

#define PBO_EXT_STRING "GL_ARB_pixel_buffer_object"

struct pvr2_scene_struct pvr2_scene;

static gboolean vbo_init = FALSE;

static gboolean vbo_supported = FALSE;

/**

 * Test for VBO support, and allocate all the system memory needed for the

 * temporary structures. GL context must have been initialized before this

 * point.

 */

void pvr2_scene_init()

{

    if( !vbo_init ) {

	if( isGLExtensionSupported(VBO_EXT_STRING) ) {

	    vbo_supported = TRUE;

	    pvr2_scene.vbo_id = 1;

	}

	pvr2_scene.vertex_array = NULL;

	pvr2_scene.vertex_array_size = 0;

	pvr2_scene.poly_array = g_malloc( MAX_POLY_BUFFER_SIZE );

	pvr2_scene.buf_to_poly_map = g_malloc0( BUF_POLY_MAP_SIZE );

	vbo_init = TRUE;

    }

}

void pvr2_scene_shutdown()

{

    if( vbo_supported ) {

	glBindBufferARB( GL_ARRAY_BUFFER_ARB, 0 );

	glDeleteBuffersARB( 1, &pvr2_scene.vbo_id );

	pvr2_scene.vbo_id = 0;

    } else {

	g_free( pvr2_scene.vertex_array );

	pvr2_scene.vertex_array = NULL;

    }

    g_free( pvr2_scene.poly_array );

    g_free( pvr2_scene.buf_to_poly_map );

    vbo_init = FALSE;

}

void *vertex_buffer_map()

{

    uint32_t size = pvr2_scene.vertex_count * sizeof(struct vertex_struct);

    if( vbo_supported ) {

	glBindBufferARB( GL_ARRAY_BUFFER_ARB, pvr2_scene.vbo_id );

	if( size > pvr2_scene.vertex_array_size ) {

	    glBufferDataARB( GL_ARRAY_BUFFER_ARB, size, NULL, GL_DYNAMIC_DRAW_ARB );

	    assert( glGetError() == 0 );

	}

	pvr2_scene.vertex_array = glMapBufferARB( GL_ARRAY_BUFFER_ARB, GL_WRITE_ONLY_ARB );

	assert(pvr2_scene.vertex_array != NULL );

    } else {

	if( size > pvr2_scene.vertex_array_size ) {

	    pvr2_scene.vertex_array = g_realloc( pvr2_scene.vertex_array, size );

	}

    }

    return pvr2_scene.vertex_array;

}

gboolean vertex_buffer_unmap()

{

    if( vbo_supported ) {

	pvr2_scene.vertex_array = NULL;

	return glUnmapBufferARB( GL_ARRAY_BUFFER_ARB );

    } else {

	return TRUE;

    }

}

static struct polygon_struct *vertex_buffer_add_polygon( pvraddr_t poly_idx, int vertex_count,

							 gboolean is_modified ) 

{

    int vert_mul = is_modified ? 2 : 1;

    if( pvr2_scene.buf_to_poly_map[poly_idx] != NULL ) {

	if( vertex_count > pvr2_scene.buf_to_poly_map[poly_idx]->vertex_count ) {

	    pvr2_scene.vertex_count += (vertex_count - pvr2_scene.buf_to_poly_map[poly_idx]->vertex_count) * vert_mul;

	    pvr2_scene.buf_to_poly_map[poly_idx]->vertex_count = vertex_count;

	}

	return pvr2_scene.buf_to_poly_map[poly_idx];

    } else {

	struct polygon_struct *poly = &pvr2_scene.poly_array[pvr2_scene.poly_count++];

	poly->context = (uint32_t *)(video_base + MMIO_READ(PVR2,RENDER_POLYBASE) + (poly_idx<<2));

	poly->vertex_count = vertex_count;

	poly->vertex_index = -1;

	pvr2_scene.buf_to_poly_map[poly_idx] = poly;

	pvr2_scene.vertex_count += (vertex_count * vert_mul);

	return poly;

    }

}

/**

 * Decode a single PVR2 renderable vertex (opaque/trans/punch-out, but not shadow

 * volume)

 * @param vert Pointer to output vertex structure

 * @param poly1 First word of polygon context (needed to understand vertex)

 * @param pvr2_data Pointer to raw pvr2 vertex data (in VRAM)

 * @param modify_offset Offset in 32-bit words to the tex/color data. 0 for

 *        the normal vertex, half the vertex length for the modified vertex.

 */

static void pvr2_decode_render_vertex( struct vertex_struct *vert, uint32_t poly1, 

				       uint32_t *pvr2_data, int modify_offset )

{

    union pvr2_data_type {

	uint32_t *ival;

	float *fval;

    } data;

    data.ival = pvr2_data;

    vert->x = *data.fval++;

    vert->y = *data.fval++;

    float z = *data.fval++;

    if( z > pvr2_scene.bounds[5] ) {

	pvr2_scene.bounds[5] = z;

    } else if( z < pvr2_scene.bounds[4] && z != 0 ) {

	pvr2_scene.bounds[4] = z;

    }

    vert->z = z;

    data.ival += modify_offset;

    if( POLY1_TEXTURED(poly1) ) {

	if( POLY1_UV16(poly1) ) {

	    vert->u = halftofloat( *data.ival>>16 );

	    vert->v = halftofloat( *data.ival );

	    data.ival++;

	} else {

	    vert->u = *data.fval++;

	    vert->v = *data.fval++;

	}

    }

    vert->rgba = *data.ival++;

    if( POLY1_SPECULAR(poly1) ) {

	vert->offset_rgba = *data.ival++;

    }

}

/**

 * Compute texture, colour, and z values for a result point by interpolating from

 * a set of 3 input points. The result point must define its x,y.

 */

static void vertex_buffer_compute_vertex( struct vertex_struct *result, 

					  struct vertex_struct *input,

					  gboolean is_solid_shaded )

{

    int i;

    float sx = input[2].x - input[1].x;

    float sy = input[2].y - input[1].y;

    float tx = input[0].x - input[1].x;

    float ty = input[0].y - input[1].y;

    float detxy = ((sy) * (tx)) - ((ty) * (sx));

    if( detxy == 0 ) {

	result->z = input[2].z;

	result->u = input[2].u;

	result->v = input[2].v;

	result->rgba = input[2].rgba;

	result->offset_rgba = input[2].offset_rgba;

	return;

    }

    float t = ((result->x - input[1].x) * sy -

	       (result->y - input[1].y) * sx) / detxy;

    float s = ((result->y - input[1].y) * tx -

	       (result->x - input[1].x) * ty) / detxy;

    float sz = input[2].z - input[1].z;

    float tz = input[0].z - input[1].z;

    float su = input[2].u - input[1].u;

    float tu = input[0].u - input[1].u;

    float sv = input[2].v - input[1].v;

    float tv = input[0].v - input[1].v;

    float rz = input[1].z + (t*tz) + (s*sz);

    if( rz > pvr2_scene.bounds[5] ) {

	pvr2_scene.bounds[5] = rz;

    } else if( rz < pvr2_scene.bounds[4] ) {

	pvr2_scene.bounds[4] = rz; 

    }

    result->z = rz;

    result->u = input[1].u + (t*tu) + (s*su);

    result->v = input[1].v + (t*tv) + (s*sv);

    if( is_solid_shaded ) {

	result->rgba = input[2].rgba;

	result->offset_rgba = input[2].offset_rgba;

    } else {

	uint8_t *rgba0 = (uint8_t *)&input[0].rgba;

	uint8_t *rgba1 = (uint8_t *)&input[1].rgba;

	uint8_t *rgba2 = (uint8_t *)&input[2].rgba;

	uint8_t *rgba3 = (uint8_t *)&result->rgba;

	for( i=0; i<8; i++ ) { // note: depends on rgba & offset_rgba being adjacent

	    float tc = *rgba0++ - *rgba1;

	    float sc = *rgba2++ - *rgba1;

	    float rc = *rgba1++ + (t*tc) + (s*sc);

	    if( rc < 0 ) {

		rc = 0;

	    } else if( rc > 255 ) {

		rc = 255;

	    }

	    *rgba3++ = rc;

	}

    }    

}

static void vertex_buffer_add_vertexes( pvraddr_t poly_idx, int vertex_length,

					gboolean is_modified )

{

    struct polygon_struct *poly = pvr2_scene.buf_to_poly_map[poly_idx];

    uint32_t *ptr = &pvr2_scene.pvr2_pbuf[poly_idx];

    uint32_t *context = ptr;

    unsigned int i;

    assert( poly != NULL );

    if( poly->vertex_index == -1 ) {

	ptr += (is_modified ? 5 : 3 );

	poly->vertex_index = pvr2_scene.vertex_index;

	assert( pvr2_scene.vertex_index + poly->vertex_count <= pvr2_scene.vertex_count );

	for( i=0; i<poly->vertex_count; i++ ) {

	    pvr2_decode_render_vertex( &pvr2_scene.vertex_array[pvr2_scene.vertex_index++], context[0], ptr, 0 );

	    ptr += vertex_length;

	}

	if( is_modified ) {

	    int mod_offset = (vertex_length - 3)>>1;

	    ptr = &pvr2_scene.pvr2_pbuf[poly_idx] + 5;

	    poly->mod_vertex_index = pvr2_scene.vertex_index;

	    for( i=0; i<poly->vertex_count; i++ ) {

		pvr2_decode_render_vertex( &pvr2_scene.vertex_array[pvr2_scene.vertex_index++], context[0], ptr, mod_offset );

		ptr += vertex_length;

	    }

	}

    }

}

static void vertex_buffer_add_quad_vertexes( pvraddr_t poly_idx, int vertex_length, 

					     gboolean is_modified )

{

    struct polygon_struct *poly = pvr2_scene.buf_to_poly_map[poly_idx];

    uint32_t *ptr = &pvr2_scene.pvr2_pbuf[poly_idx];

    uint32_t *context = ptr;

    unsigned int i;

    if( poly->vertex_index == -1 ) {

	// Construct it locally and copy to the vertex buffer, as the VBO is 

	// allowed to be horribly slow for reads (ie it could be direct-mapped

	// vram).

	struct vertex_struct quad[4];

	assert( poly != NULL );

	ptr += (is_modified ? 5 : 3 );

	poly->vertex_index = pvr2_scene.vertex_index;

	for( i=0; i<4; i++ ) {

	    pvr2_decode_render_vertex( &quad[i], context[0], ptr, 0 );

	    ptr += vertex_length;

	}

	vertex_buffer_compute_vertex( &quad[3], &quad[0], !POLY1_GOURAUD_SHADED(context[0]) );

	memcpy( &pvr2_scene.vertex_array[pvr2_scene.vertex_index], quad, sizeof(quad) );

	pvr2_scene.vertex_index += 4;

	if( is_modified ) {

	    int mod_offset = (vertex_length - 3)>>1;

	    ptr = &pvr2_scene.pvr2_pbuf[poly_idx] + 5;

	    poly->mod_vertex_index = pvr2_scene.vertex_index;

	    for( i=0; i<4; i++ ) {

		pvr2_decode_render_vertex( &quad[4], context[0], ptr, mod_offset );

		ptr += vertex_length;

	    }

	    vertex_buffer_compute_vertex( &quad[3], &quad[0], !POLY1_GOURAUD_SHADED(context[0]) );

	    memcpy( &pvr2_scene.vertex_array[pvr2_scene.vertex_index], quad, sizeof(quad) );

	    pvr2_scene.vertex_index += 4;

	}

    }

}

static void vertex_buffer_extract_polygons( pvraddr_t tile_entry )

{

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

    do {

	uint32_t entry = *tile_list++;

	if( entry >> 28 == 0x0F ) {

	    break;

	} else if( entry >> 28 == 0x0E ) {

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

	} else {

	    pvraddr_t polyaddr = entry&0x000FFFFF;

	    int is_modified = (entry & 0x01000000) && pvr2_scene.full_shadow;

	    int vertex_length = (entry >> 21) & 0x07;

	    int context_length = 3;

	    if( is_modified ) {

		context_length = 5;

		vertex_length <<= 1 ;

	    }

	    vertex_length += 3;

	    if( (entry & 0xE0000000) == 0x80000000 ) {

		/* Triangle(s) */

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

		int polygon_length = 3 * vertex_length + context_length;

		int i;

		struct polygon_struct *last_poly = NULL;

		for( i=0; i<strip_count; i++ ) {

		    struct polygon_struct *poly = vertex_buffer_add_polygon( polyaddr, 3, is_modified );

		    polyaddr += polygon_length;

		    if( last_poly != NULL && last_poly->next == NULL ) {

			last_poly->next = poly;

		    }

		    last_poly = poly;

		}

	    } else if( (entry & 0xE0000000) == 0xA0000000 ) {

		/* Sprite(s) */

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

		int polygon_length = 4 * vertex_length + context_length;

		int i;

		struct polygon_struct *last_poly = NULL;

		for( i=0; i<strip_count; i++ ) {

		    struct polygon_struct *poly = vertex_buffer_add_polygon( polyaddr, 4, is_modified );

		    polyaddr += polygon_length;

		    if( last_poly != NULL && last_poly->next == NULL ) {

			last_poly->next = poly;

		    }

		    last_poly = poly;

		}

	    } else {

		/* Polygon */

		int i, last = -1;

		for( i=5; i>=0; i-- ) {

		    if( entry & (0x40000000>>i) ) {

			last = i;

			break;

		    }

		}

		if( last != -1 ) {

		    vertex_buffer_add_polygon( polyaddr, last+3, is_modified );

		}

	    }

	}

    } while( 1 );

}

static void vertex_buffer_extract_vertexes( pvraddr_t tile_entry )

{

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

    do {

	uint32_t entry = *tile_list++;

	if( entry >> 28 == 0x0F ) {

	    break;

	} else if( entry >> 28 == 0x0E ) {

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

	} else {

	    pvraddr_t polyaddr = entry&0x000FFFFF;

	    int is_modified = (entry & 0x01000000) && pvr2_scene.full_shadow;

	    int vertex_length = (entry >> 21) & 0x07;

	    int context_length = 3;

	    if( is_modified ) {

		context_length = 5;

		vertex_length <<=1 ;

	    }

	    vertex_length += 3;

	    if( (entry & 0xE0000000) == 0x80000000 ) {

		/* Triangle(s) */

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

		int polygon_length = 3 * vertex_length + context_length;

		int i;

		for( i=0; i<strip_count; i++ ) {

		    vertex_buffer_add_vertexes( polyaddr, vertex_length, is_modified );

		    polyaddr += polygon_length;

		}

	    } else if( (entry & 0xE0000000) == 0xA0000000 ) {

		/* Sprite(s) */

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

		int polygon_length = 4 * vertex_length + context_length;

		int i;

		for( i=0; i<strip_count; i++ ) {

		    vertex_buffer_add_quad_vertexes( polyaddr, vertex_length, is_modified );

		    polyaddr += polygon_length;

		}

	    } else {

		/* Polygon */

		int i, last = -1;

		for( i=5; i>=0; i-- ) {

		    if( entry & (0x40000000>>i) ) {

			last = i;

			break;

		    }

		}

		if( last != -1 ) {

		    vertex_buffer_add_vertexes( polyaddr, vertex_length, is_modified );

		}

	    }

	}

    } while( 1 );    

}

/**

 * Extract the current scene into the rendering structures. We run two passes

 * - first pass extracts the polygons into pvr2_scene.poly_array (finding vertex counts), 

 * second pass extracts the vertex data into the VBO/vertex array.

 *

 * Difficult to do in single pass as we don't generally know the size of a 

 * polygon for certain until we've seen all tiles containing it. It also means we

 * can count the vertexes and allocate the appropriate size VBO.

 *

 * FIXME: accesses into VRAM need to be bounds-checked properly

 */

void pvr2_scene_read( void )

{

    pvr2_scene_init();

    pvr2_scene.poly_count = 0;

    pvr2_scene.vertex_count = 0;

    pvr2_scene.bounds[0] = MMIO_READ( PVR2, RENDER_HCLIP ) & 0x03FF;

    pvr2_scene.bounds[1] = ((MMIO_READ( PVR2, RENDER_HCLIP ) >> 16) & 0x03FF) + 1;

    pvr2_scene.bounds[2] = MMIO_READ( PVR2, RENDER_VCLIP ) & 0x03FF;

    pvr2_scene.bounds[3] = ((MMIO_READ( PVR2, RENDER_VCLIP ) >> 16) & 0x03FF) + 1;

    pvr2_scene.bounds[4] = pvr2_scene.bounds[5] = MMIO_READF( PVR2, RENDER_FARCLIP );

    uint32_t *tilebuffer = (uint32_t *)(video_base + MMIO_READ( PVR2, RENDER_TILEBASE ));

    uint32_t *segment = tilebuffer;

    pvr2_scene.segment_list = (struct tile_segment *)tilebuffer;

    pvr2_scene.pvr2_pbuf = (uint32_t *)(video_base + MMIO_READ(PVR2,RENDER_POLYBASE));

    pvr2_scene.full_shadow = MMIO_READ( PVR2, RENDER_SHADOW ) & 0x100 ? FALSE : TRUE;

    int max_tile_x = 0;

    int max_tile_y = 0;

    int obj_config = MMIO_READ( PVR2, RENDER_OBJCFG );

    int isp_config = MMIO_READ( PVR2, RENDER_ISPCFG );

    if( (obj_config & 0x00200000) == 0 ) {

	if( isp_config & 1 ) {

	    pvr2_scene.sort_mode = SORT_NEVER;

	} else {

	    pvr2_scene.sort_mode = SORT_ALWAYS;

	}

    } else {

	pvr2_scene.sort_mode = SORT_BYFLAG;

    }

    // Pass 1: Extract polygon list 

    uint32_t control;

    int i;

    do {

	control = *segment++;

	int tile_x = SEGMENT_X(control);

	int tile_y = SEGMENT_Y(control);

	if( tile_x > max_tile_x ) {

	    max_tile_x = tile_x;

	} 

	if( tile_y > max_tile_y ) {

	    max_tile_y = tile_y;

	}

	for( i=0; i<5; i++ ) {

	    if( (*segment & NO_POINTER) == 0 ) {

		vertex_buffer_extract_polygons( *segment );

	    }

	    segment++;

	}

    } while( (control & SEGMENT_END) == 0 );

    pvr2_scene.buffer_width = (max_tile_x+1)<<5;

    pvr2_scene.buffer_height = (max_tile_y+1)<<5;

    if( pvr2_scene.vertex_count > 0 ) {

	// Pass 2: Extract vertex data

	vertex_buffer_map();

	pvr2_scene.vertex_index = 0;

	segment = tilebuffer;

	do {

	    control = *segment++;

	    for( i=0; i<5; i++ ) {

		if( (*segment & NO_POINTER) == 0 ) {

		    vertex_buffer_extract_vertexes( *segment );

		}

		segment++;

	    }

	} while( (control & SEGMENT_END) == 0 );

	vertex_buffer_unmap();

    }

}

/**

 * Render the data in the scene structure. The GL target should already be setup.

 * Note: thar be GL code here.

 */

void vertex_buffer_render()

{

    /* Scene setup */

    glEnable( GL_SCISSOR_TEST );

    /* Scene render */

    struct tile_segment *segment = pvr2_scene.segment_list;

    do {

    } while( !IS_LAST_SEGMENT(segment) );

    glDisable( GL_SCISSOR_TEST );

}