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// Gawain vertex buffer
//
// This code is part of the Gawain library, with modifications
// specific to integration with Blender.
//
// Copyright 2016 Mike Erwin
//
// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0. If a copy of
// the MPL was not distributed with this file, You can obtain one at https://mozilla.org/MPL/2.0/.
#include "vertex_buffer.h"
#include "buffer_id.h"
#include "vertex_format_private.h"
#include <stdlib.h>
#include <string.h>
#define KEEP_SINGLE_COPY 1
static unsigned vbo_memory_usage;
VertexBuffer* VertexBuffer_create(void)
{
VertexBuffer* verts = malloc(sizeof(VertexBuffer));
VertexBuffer_init(verts);
return verts;
}
VertexBuffer* VertexBuffer_create_with_format(const VertexFormat* format)
{
VertexBuffer* verts = VertexBuffer_create();
VertexFormat_copy(&verts->format, format);
if (!format->packed)
VertexFormat_pack(&verts->format);
return verts;
// this function might seem redundant, but there is potential for memory savings here...
// TODO: implement those memory savings
}
void VertexBuffer_init(VertexBuffer* verts)
{
memset(verts, 0, sizeof(VertexBuffer));
}
void VertexBuffer_init_with_format(VertexBuffer* verts, const VertexFormat* format)
{
VertexBuffer_init(verts);
VertexFormat_copy(&verts->format, format);
if (!format->packed)
VertexFormat_pack(&verts->format);
}
void VertexBuffer_discard(VertexBuffer* verts)
{
if (verts->vbo_id) {
buffer_id_free(verts->vbo_id);
vbo_memory_usage -= VertexBuffer_size(verts);
}
#if KEEP_SINGLE_COPY
else
#endif
if (verts->data)
free(verts->data);
free(verts);
}
unsigned VertexBuffer_size(const VertexBuffer* verts)
{
return vertex_buffer_size(&verts->format, verts->vertex_ct);
}
void VertexBuffer_allocate_data(VertexBuffer* verts, unsigned v_ct)
{
VertexFormat* format = &verts->format;
if (!format->packed)
VertexFormat_pack(format);
verts->vertex_ct = v_ct;
// Data initially lives in main memory. Will be transferred to VRAM when we "prime" it.
verts->data = malloc(VertexBuffer_size(verts));
}
void VertexBuffer_resize_data(VertexBuffer* verts, unsigned v_ct)
{
#if TRUST_NO_ONE
assert(verts->vertex_ct != v_ct); // allow this?
assert(verts->data != NULL); // has already been allocated
assert(verts->vbo_id == 0); // has not been sent to VRAM
#endif
verts->vertex_ct = v_ct;
verts->data = realloc(verts->data, VertexBuffer_size(verts));
// TODO: skip realloc if v_ct < existing vertex count
// extra space will be reclaimed, and never sent to VRAM (see VertexBuffer_prime)
}
void VertexBuffer_set_attrib(VertexBuffer* verts, unsigned a_idx, unsigned v_idx, const void* data)
{
const VertexFormat* format = &verts->format;
const Attrib* a = format->attribs + a_idx;
#if TRUST_NO_ONE
assert(a_idx < format->attrib_ct);
assert(v_idx < verts->vertex_ct);
assert(verts->data != NULL); // data must be in main mem
#endif
memcpy((GLubyte*)verts->data + a->offset + v_idx * format->stride, data, a->sz);
}
void VertexBuffer_fill_attrib(VertexBuffer* verts, unsigned a_idx, const void* data)
{
const VertexFormat* format = &verts->format;
const Attrib* a = format->attribs + a_idx;
#if TRUST_NO_ONE
assert(a_idx < format->attrib_ct);
#endif
const unsigned stride = a->sz; // tightly packed input data
VertexBuffer_fill_attrib_stride(verts, a_idx, stride, data);
}
void VertexBuffer_fill_attrib_stride(VertexBuffer* verts, unsigned a_idx, unsigned stride, const void* data)
{
const VertexFormat* format = &verts->format;
const Attrib* a = format->attribs + a_idx;
#if TRUST_NO_ONE
assert(a_idx < format->attrib_ct);
assert(verts->data != NULL); // data must be in main mem
#endif
const unsigned vertex_ct = verts->vertex_ct;
if (format->attrib_ct == 1 && stride == format->stride)
{
// we can copy it all at once
memcpy(verts->data, data, vertex_ct * a->sz);
}
else
{
// we must copy it per vertex
for (unsigned v = 0; v < vertex_ct; ++v)
memcpy((GLubyte*)verts->data + a->offset + v * format->stride, (const GLubyte*)data + v * stride, a->sz);
}
}
static void VertexBuffer_prime(VertexBuffer* verts)
{
const unsigned buffer_sz = VertexBuffer_size(verts);
verts->vbo_id = buffer_id_alloc();
glBindBuffer(GL_ARRAY_BUFFER, verts->vbo_id);
// fill with delicious data & send to GPU the first time only
glBufferData(GL_ARRAY_BUFFER, buffer_sz, verts->data, GL_STATIC_DRAW);
vbo_memory_usage += buffer_sz;
#if KEEP_SINGLE_COPY
// now that GL has a copy, discard original
free(verts->data);
verts->data = NULL;
#endif
}
void VertexBuffer_use(VertexBuffer* verts)
{
if (verts->vbo_id)
glBindBuffer(GL_ARRAY_BUFFER, verts->vbo_id);
else
VertexBuffer_prime(verts);
}
unsigned VertexBuffer_get_memory_usage(void)
{
return vbo_memory_usage;
}
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