/**

 * $Id$

 *

 * Generic GL vertex buffer/vertex array support

 *

 * Copyright (c) 2011 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.

 */

#define GL_GLEXT_PROTOTYPES 1

#include <assert.h>

#include <stdlib.h>

#include <sys/mman.h>

#include "lxdream.h"

#include "display.h"

#include "drivers/video_gl.h"

#include "pvr2/glutil.h"

#define MIN_VERTEX_ARRAY_SIZE (1024*1024)

vertex_buffer_t vertex_buffer_new( vertex_buffer_t vtable )

{

    vertex_buffer_t buf = g_malloc(sizeof(struct vertex_buffer));

    memcpy( buf, vtable, sizeof(struct vertex_buffer));

    buf->data = 0;

    buf->id = 0;

    buf->mapped_size = buf->capacity = 0;

    buf->fence = 0;

    return buf;

}

/******************************* Default ***********************************/

static void *def_map( vertex_buffer_t buf, uint32_t size )

{

    buf->mapped_size = size;

    if( size < MIN_VERTEX_ARRAY_SIZE )

        size = MIN_VERTEX_ARRAY_SIZE;

    if( size > buf->capacity ) {

        g_free(buf->data);

        buf->data = g_malloc(size);

        buf->capacity = size;

    }

    return buf->data;

}

static void *def_unmap( vertex_buffer_t buf )

{

    return buf->data;

}

static void def_finished( vertex_buffer_t buf )

{

}

static void def_destroy( vertex_buffer_t buf )

{

    g_free(buf->data);

    buf->data = NULL;

    g_free(buf);

}

static struct vertex_buffer def_vtable = { def_map, def_unmap, def_finished, def_destroy };

static vertex_buffer_t def_create_buffer( )

{

    return vertex_buffer_new( &def_vtable );

}

/************************** vertex_array_range *****************************/

/**

 * VAR extensions like the buffer to be allocated on page boundaries.

 */

static void var_alloc_pages( vertex_buffer_t buf, uint32_t size )

{

    if( size < MIN_VERTEX_ARRAY_SIZE )

        size = MIN_VERTEX_ARRAY_SIZE;

    if( size > buf->capacity ) {

        size = (size + 4096-1) & (~(4096-1));

        if( buf->data != NULL ) {

            munmap( buf->data, buf->capacity );

        }

        buf->data = mmap( NULL, size, PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, -1, 0 );

        assert( buf->data != MAP_FAILED );

        buf->capacity = size;

    }

}

#ifdef APPLE_BUILD

static void *apple_map( vertex_buffer_t buf, uint32_t size )

{

    glFinishFenceAPPLE(buf->fence);

    var_alloc_pages( buf, size );

    glVertexArrayRangeAPPLE(size, buf->data);

    buf->mapped_size = size;

    return buf->data;

}

static void *apple_unmap( vertex_buffer_t buf )

{

    glFlushVertexArrayRangeAPPLE(buf->mapped_size, buf->data);

    return buf->data;

}

static void apple_finished( vertex_buffer_t buf )

{

    glSetFenceAPPLE(buf->fence);

}

static void apple_destroy( vertex_buffer_t buf )

{

    glVertexArrayRangeAPPLE(0,0);

    glDeleteFencesAPPLE(1, &buf->fence);

    munmap( buf->data, buf->capacity );

    g_free(buf);

}

static struct vertex_buffer apple_vtable = { apple_map, apple_unmap, apple_finished, apple_destroy };

static vertex_buffer_t apple_create_buffer( uint32_t size )

{

    vertex_buffer_t buf = vertex_buffer_new( &apple_vtable );

    glGenFencesAPPLE(1, &buf->fence);

    return buf;

}

#endif

#ifdef GL_VERTEX_ARRAY_RANGE_NV

static void *nv_map( vertex_buffer_t buf, uint32_t size )

{

    glFinishFenceNV(buf->fence);

    var_alloc_pages( buf, size );

    glVertexArrayRangeNV(size, buf->data);

    buf->mapped_size = size;

    return buf->data;

}

static void *nv_unmap( vertex_buffer_t buf )

{

    glFlushVertexArrayRangeNV();

    return buf->data;

}

static void nv_finished( vertex_buffer_t buf )

{

    glSetFenceNV(buf->fence, GL_ALL_COMPLETED_NV);

}

static void nv_destroy( vertex_buffer_t buf )

{

    glVertexArrayRangeNV(0,0);

    glDeleteFencesNV(1, &buf->fence);

    munmap( buf->data, buf->capacity );

    g_free(buf);

}

static struct vertex_buffer nv_vtable = { nv_map, nv_unmap, nv_finished, nv_destroy };

static vertex_buffer_t nv_create_buffer( uint32_t size )

{

    vertex_buffer_t buf = vertex_buffer_new( &nv_vtable );

    glGenFencesNV(1, &buf->fence);

    return buf;

}

#endif /* !GL_VERTEX_ARRAY_RANGE_NV */

/************************** vertex_buffer_object *****************************/

#ifdef GL_ARRAY_BUFFER_ARB

static void *vbo_map( vertex_buffer_t buf, uint32_t size )

{

    glBindBufferARB( GL_ARRAY_BUFFER_ARB, buf->id );

     if( size > buf->capacity ) {

         glBufferDataARB( GL_ARRAY_BUFFER_ARB, size, NULL, GL_STREAM_DRAW_ARB );

         assert( gl_check_error("Allocating vbo data") );

         buf->capacity = size;

    }

    buf->data = glMapBufferARB( GL_ARRAY_BUFFER_ARB, GL_WRITE_ONLY_ARB );

    buf->mapped_size = buf->capacity;

    return buf->data;

}

static void *vbo_unmap( vertex_buffer_t buf )

{

    glUnmapBufferARB( GL_ARRAY_BUFFER_ARB );

    return NULL;

}

static void vbo_finished( vertex_buffer_t buf )

{

    glBindBufferARB( GL_ARRAY_BUFFER_ARB, 0 );

}

static void vbo_destroy( vertex_buffer_t buf )

{

    glBindBufferARB( GL_ARRAY_BUFFER_ARB, 0 );

    glDeleteBuffersARB( 1, &buf->id );

}

static struct vertex_buffer vbo_vtable = { vbo_map, vbo_unmap, vbo_finished, vbo_destroy };

static vertex_buffer_t vbo_create_buffer( uint32_t size )

{

    vertex_buffer_t buf = vertex_buffer_new( &vbo_vtable );

    glGenBuffersARB( 1, &buf->id );

    return buf;

}

#endif

/**

 * Auto-detect the supported vertex buffer types, and select between them.

 * Use vertex_buffer_object if available, otherwise vertex_array_range,

 * otherwise just pure host buffers.

 */

void gl_vbo_init( display_driver_t driver ) {

/* VBOs are disabled for now as they won't work with the triangle sorting,

 * plus they seem to be slower than the other options anyway.

 */

#ifdef ENABLE_VBO

#ifdef GL_ARRAY_BUFFER_ARB

    if( isGLVertexBufferSupported() ) {

        driver->create_vertex_buffer = vbo_create_buffer;

        return;

    }

#endif

#endif

#ifdef APPLE_BUILD

    if( isGLExtensionSupported("GL_APPLE_vertex_array_range") &&

            isGLExtensionSupported("GL_APPLE_fence") ) {

        glEnableClientState( GL_VERTEX_ARRAY_RANGE_APPLE );

        driver->create_vertex_buffer = apple_create_buffer;

        return;

    }

#endif

#ifdef GL_VERTEX_ARRAY_RANGE_NV

    if( isGLExtensionSupported("GL_NV_vertex_array_range") &&

            isGLExtensionSupported("GL_NV_fence") ) {

        glEnableClientState( GL_VERTEX_ARRAY_RANGE_NV );

        driver->create_vertex_buffer = nv_create_buffer;

        return;

    }

#endif

    driver->create_vertex_buffer = def_create_buffer;

}

void gl_vbo_fallback_init( display_driver_t driver ) {

    driver->create_vertex_buffer = def_create_buffer;

}