/**

  * $Id$

  *

  * 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;

 }