/**

  * $Id: gl_common.c 602 2008-01-15 20:50:23Z nkeynes $

  *

  * 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 );

 }