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blender-archive/source/blender/gpu/metal/mtl_index_buffer.mm

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/* SPDX-License-Identifier: GPL-2.0-or-later */
/** \file
* \ingroup gpu
*/
#include "mtl_index_buffer.hh"
#include "mtl_context.hh"
#include "mtl_debug.hh"
#include "BLI_span.hh"
namespace blender::gpu {
/* -------------------------------------------------------------------- */
/** \name Core MTLIndexBuf implementation.
* \{ */
MTLIndexBuf::~MTLIndexBuf()
{
if (ibo_ != nullptr && !this->is_subrange_) {
ibo_->free();
}
this->free_optimized_buffer();
}
void MTLIndexBuf::free_optimized_buffer()
{
if (optimized_ibo_) {
optimized_ibo_->free();
optimized_ibo_ = nullptr;
}
}
void MTLIndexBuf::bind_as_ssbo(uint32_t binding)
{
/* Flag buffer as incompatible with optimized/patched buffers as contents
* can now have partial modifications from the GPU. */
this->flag_can_optimize(false);
this->free_optimized_buffer();
/* Ensure we have a valid IBO. */
BLI_assert(this->ibo_);
/* TODO(Metal): Support index buffer SSBO's. Dependent on compute implementation. */
MTL_LOG_WARNING("MTLIndexBuf::bind_as_ssbo not yet implemented!\n");
}
const uint32_t *MTLIndexBuf::read() const
{
if (ibo_ != nullptr) {
/* Return host pointer. */
void *data = ibo_->get_host_ptr();
return static_cast<uint32_t *>(data);
}
BLI_assert(false && "Index buffer not ready to be read.");
return nullptr;
}
void MTLIndexBuf::upload_data()
{
/* Handle sub-range upload. */
if (is_subrange_) {
MTLIndexBuf *mtlsrc = static_cast<MTLIndexBuf *>(src_);
mtlsrc->upload_data();
#ifndef NDEBUG
BLI_assert_msg(!mtlsrc->point_restarts_stripped_,
"Cannot use sub-range on stripped point buffer.");
#endif
/* If parent sub-range allocation has changed,
* update our index buffer. */
if (alloc_size_ != mtlsrc->alloc_size_ || ibo_ != mtlsrc->ibo_) {
/* Update index buffer and allocation from source. */
alloc_size_ = mtlsrc->alloc_size_;
ibo_ = mtlsrc->ibo_;
/* Reset any allocated patched or optimized index buffers. */
this->free_optimized_buffer();
}
return;
}
/* If new data ready, and index buffer already exists, release current. */
if ((ibo_ != nullptr) && (this->data_ != nullptr)) {
MTL_LOG_INFO("Re-creating index buffer with new data. IndexBuf %p\n", this);
ibo_->free();
ibo_ = nullptr;
}
/* Prepare Buffer and Upload Data. */
if (ibo_ == nullptr && data_ != nullptr) {
alloc_size_ = this->size_get();
if (alloc_size_ == 0) {
MTL_LOG_WARNING("[Metal] Warning! Trying to allocate index buffer with size=0 bytes\n");
}
else {
ibo_ = MTLContext::get_global_memory_manager().allocate_with_data(alloc_size_, true, data_);
BLI_assert(ibo_);
ibo_->set_label(@"Index Buffer");
}
/* No need to keep copy of data_ in system memory. */
MEM_SAFE_FREE(data_);
}
}
void MTLIndexBuf::update_sub(uint32_t start, uint32_t len, const void *data)
{
BLI_assert(!is_subrange_);
/* If host-side data still exists, modify and upload as normal */
if (data_ != nullptr) {
/* Free index buffer if one exists. */
if (ibo_ != nullptr && !this->is_subrange_) {
ibo_->free();
ibo_ = nullptr;
}
BLI_assert(start + len < this->size_get());
/* Apply start byte offset to data pointer. */
void *modified_base_ptr = data_;
uint8_t *ptr = static_cast<uint8_t *>(modified_base_ptr);
ptr += start;
modified_base_ptr = static_cast<void *>(ptr);
/* Modify host-side data. */
memcpy(modified_base_ptr, data, len);
return;
}
/* Verify buffer. */
BLI_assert(ibo_ != nullptr);
/* Otherwise, we will inject a data update, using staged data, into the command stream.
* Stage update contents in temporary buffer. */
MTLContext *ctx = static_cast<MTLContext *>(unwrap(GPU_context_active_get()));
BLI_assert(ctx);
MTLTemporaryBuffer range = ctx->get_scratchbuffer_manager().scratch_buffer_allocate_range(len);
memcpy(range.data, data, len);
/* Copy updated contents into primary buffer.
* These changes need to be uploaded via blit to ensure the data copies happen in-order. */
id<MTLBuffer> dest_buffer = ibo_->get_metal_buffer();
BLI_assert(dest_buffer != nil);
id<MTLBlitCommandEncoder> enc = ctx->main_command_buffer.ensure_begin_blit_encoder();
[enc copyFromBuffer:range.metal_buffer
sourceOffset:(uint32_t)range.buffer_offset
toBuffer:dest_buffer
destinationOffset:start
size:len];
/* Synchronize changes back to host to ensure CPU-side data is up-to-date for non
* Shared buffers. */
if (dest_buffer.storageMode == MTLStorageModeManaged) {
[enc synchronizeResource:dest_buffer];
}
/* Invalidate patched/optimized buffers. */
this->free_optimized_buffer();
/* Flag buffer as incompatible with optimized/patched buffers as contents
* have partial modifications. */
this->flag_can_optimize(false);
BLI_assert(false);
}
void MTLIndexBuf::flag_can_optimize(bool can_optimize)
{
can_optimize_ = can_optimize;
}
/** \} */
/** \name Index buffer optimization and topology emulation
*
* Index buffer optimization and emulation. Optimize index buffers by
* eliminating restart-indices.
* Emulate unsupported index types e.g. Triangle Fan and Line Loop.
* \{ */
/* Returns total vertices in new buffer. */
template<typename T>
static uint32_t populate_optimized_tri_strip_buf(Span<T> original_data,
MutableSpan<T> output_data,
uint32_t input_index_len)
{
/* Generate #TriangleList from #TriangleStrip. */
uint32_t current_vert_len = 0;
uint32_t current_output_ind = 0;
T indices[3];
for (int c_index = 0; c_index < input_index_len; c_index++) {
T current_index = original_data[c_index];
if (current_index == T(-1)) {
/* Stop current primitive. Move onto next. */
current_vert_len = 0;
}
else {
if (current_vert_len < 3) {
/* Prepare first triangle.
* Cache indices before generating a triangle, in case we have bad primitive-restarts. */
indices[current_vert_len] = current_index;
}
/* Emit triangle once we reach 3 input verts in current strip. */
if (current_vert_len == 3) {
/* First triangle in strip. */
output_data[current_output_ind++] = indices[0];
output_data[current_output_ind++] = indices[1];
output_data[current_output_ind++] = indices[2];
}
else if (current_vert_len > 3) {
/* All other triangles in strip.
* These triangles are populated using data from previous 2 vertices
* and the latest index. */
uint32_t tri_id = current_vert_len - 3;
uint32_t base_output_ind = current_output_ind;
if ((tri_id % 2) == 0) {
output_data[base_output_ind + 0] = output_data[base_output_ind - 2];
output_data[base_output_ind + 1] = current_index;
output_data[base_output_ind + 2] = output_data[base_output_ind - 1];
}
else {
output_data[base_output_ind + 0] = output_data[base_output_ind - 1];
output_data[base_output_ind + 1] = output_data[base_output_ind - 2];
output_data[base_output_ind + 2] = current_index;
}
current_output_ind += 3;
}
/* Increment relative vertex index. */
current_vert_len++;
}
}
return current_output_ind;
}
/* Returns total vertices in new buffer. */
template<typename T>
static uint32_t populate_emulated_tri_fan_buf(Span<T> original_data,
MutableSpan<T> output_data,
uint32_t input_index_len)
{
/* Generate #TriangleList from #TriangleFan. */
T base_prim_ind_val = 0;
uint32_t current_vert_len = 0;
uint32_t current_output_ind = 0;
T indices[3];
for (int c_index = 0; c_index < input_index_len; c_index++) {
T current_index = original_data[c_index];
if (current_index == T(-1)) {
/* Stop current primitive. Move onto next. */
current_vert_len = 0;
}
else {
if (current_vert_len < 3) {
/* Prepare first triangle.
* Cache indices before generating a triangle, in case we have bad primitive-restarts. */
indices[current_vert_len] = current_index;
}
/* emit triangle once we reach 3 input verts in current strip. */
if (current_vert_len == 3) {
/* First triangle in strip. */
output_data[current_output_ind++] = indices[0];
output_data[current_output_ind++] = indices[1];
output_data[current_output_ind++] = indices[2];
base_prim_ind_val = indices[0];
}
else if (current_vert_len > 3) {
/* All other triangles in strip.
* These triangles are populated using data from previous 2 vertices
* and the latest index. */
uint32_t base_output_ind = current_output_ind;
output_data[base_output_ind + 0] = base_prim_ind_val;
output_data[base_output_ind + 1] = output_data[base_output_ind - 1];
output_data[base_output_ind + 2] = current_index;
current_output_ind += 3;
}
/* Increment relative vertex index. */
current_vert_len++;
}
}
return current_output_ind;
}
id<MTLBuffer> MTLIndexBuf::get_index_buffer(GPUPrimType &in_out_primitive_type,
uint32_t &in_out_v_count)
{
/* Determine whether to return the original index buffer, or whether we
* should emulate an unsupported primitive type, or optimize a restart-
* compatible type for faster performance. */
bool should_optimize_or_emulate = (in_out_primitive_type == GPU_PRIM_TRI_FAN) ||
(in_out_primitive_type == GPU_PRIM_TRI_STRIP);
if (!should_optimize_or_emulate || is_subrange_ || !can_optimize_) {
/* Ensure we are not optimized. */
BLI_assert(this->optimized_ibo_ == nullptr);
/* Return regular index buffer. */
BLI_assert(this->ibo_ && this->ibo_->get_metal_buffer());
return this->ibo_->get_metal_buffer();
}
/* Perform optimization on type. */
GPUPrimType input_prim_type = in_out_primitive_type;
this->upload_data();
if (!ibo_ && optimized_ibo_ == nullptr) {
/* Cannot optimize buffer if no source IBO exists. */
return nil;
}
/* Verify whether existing index buffer is valid. */
if (optimized_ibo_ != nullptr && optimized_primitive_type_ != input_prim_type) {
BLI_assert_msg(false,
"Cannot change the optimized primitive format after generation, as source "
"index buffer data is discarded.");
return nil;
}
/* Generate optimized index buffer. */
if (optimized_ibo_ == nullptr) {
/* Generate unwrapped index buffer. */
switch (input_prim_type) {
case GPU_PRIM_TRI_FAN: {
/* Calculate maximum size. */
uint32_t max_possible_verts = (this->index_len_ - 2) * 3;
BLI_assert(max_possible_verts > 0);
/* Allocate new buffer. */
optimized_ibo_ = MTLContext::get_global_memory_manager().allocate(
max_possible_verts *
((index_type_ == GPU_INDEX_U16) ? sizeof(uint16_t) : sizeof(uint32_t)),
true);
/* Populate new index buffer. */
if (index_type_ == GPU_INDEX_U16) {
Span<uint16_t> orig_data(static_cast<const uint16_t *>(ibo_->get_host_ptr()),
this->index_len_);
MutableSpan<uint16_t> output_data(
static_cast<uint16_t *>(optimized_ibo_->get_host_ptr()), this->index_len_);
emulated_v_count = populate_emulated_tri_fan_buf<uint16_t>(
orig_data, output_data, this->index_len_);
}
else {
Span<uint32_t> orig_data(static_cast<const uint32_t *>(ibo_->get_host_ptr()),
this->index_len_);
MutableSpan<uint32_t> output_data(
static_cast<uint32_t *>(optimized_ibo_->get_host_ptr()), this->index_len_);
emulated_v_count = populate_emulated_tri_fan_buf<uint32_t>(
orig_data, output_data, this->index_len_);
}
BLI_assert(emulated_v_count <= max_possible_verts);
/* Flush buffer and output. */
optimized_ibo_->flush();
optimized_primitive_type_ = input_prim_type;
in_out_v_count = emulated_v_count;
in_out_primitive_type = GPU_PRIM_TRIS;
}
case GPU_PRIM_TRI_STRIP: {
/* Calculate maximum size. */
uint32_t max_possible_verts = (this->index_len_ - 2) * 3;
BLI_assert(max_possible_verts > 0);
/* Allocate new buffer. */
optimized_ibo_ = MTLContext::get_global_memory_manager().allocate(
max_possible_verts *
((index_type_ == GPU_INDEX_U16) ? sizeof(uint16_t) : sizeof(uint32_t)),
true);
/* Populate new index buffer. */
if (index_type_ == GPU_INDEX_U16) {
Span<uint16_t> orig_data(static_cast<const uint16_t *>(ibo_->get_host_ptr()),
this->index_len_);
MutableSpan<uint16_t> output_data(
static_cast<uint16_t *>(optimized_ibo_->get_host_ptr()), this->index_len_);
emulated_v_count = populate_optimized_tri_strip_buf<uint16_t>(
orig_data, output_data, this->index_len_);
}
else {
Span<uint32_t> orig_data(static_cast<const uint32_t *>(ibo_->get_host_ptr()),
this->index_len_);
MutableSpan<uint32_t> output_data(
static_cast<uint32_t *>(optimized_ibo_->get_host_ptr()), this->index_len_);
emulated_v_count = populate_optimized_tri_strip_buf<uint32_t>(
orig_data, output_data, this->index_len_);
}
BLI_assert(emulated_v_count <= max_possible_verts);
/* Flush buffer and output. */
optimized_ibo_->flush();
optimized_primitive_type_ = input_prim_type;
in_out_v_count = emulated_v_count;
in_out_primitive_type = GPU_PRIM_TRIS;
} break;
case GPU_PRIM_LINE_STRIP: {
/* TODO(Metal): Line strip topology types would benefit from optimization to remove
* primitive restarts, however, these do not occur frequently, nor with
* significant geometry counts. */
MTL_LOG_INFO("TODO: Primitive topology: Optimize line strip topology types\n");
} break;
case GPU_PRIM_LINE_LOOP: {
/* TODO(Metal): Line Loop primitive type requires use of optimized index buffer for
* emulation, if used with indexed rendering. This path is currently not hit as #LineLoop
* does not currently appear to be used alongside an index buffer. */
MTL_LOG_WARNING(
"TODO: Primitive topology: Line Loop Index buffer optimization required for "
"emulation.\n");
} break;
case GPU_PRIM_TRIS:
case GPU_PRIM_LINES:
case GPU_PRIM_POINTS: {
/* Should not get here - TRIS/LINES/POINTS do not require emulation or optimization. */
BLI_assert_unreachable();
return nil;
}
default:
/* Should not get here - Invalid primitive type. */
BLI_assert_unreachable();
break;
}
}
/* Return optimized buffer. */
if (optimized_ibo_ != nullptr) {
/* Delete original buffer if one still exists, as we do no need it. */
if (ibo_ != nullptr) {
ibo_->free();
ibo_ = nullptr;
}
/* Output params. */
in_out_v_count = emulated_v_count;
in_out_primitive_type = GPU_PRIM_TRIS;
return optimized_ibo_->get_metal_buffer();
}
return nil;
}
void MTLIndexBuf::strip_restart_indices()
{
/* We remove point buffer primitive restart indices by swapping restart indices
* with the first valid index at the end of the index buffer and reducing the
* length. Primitive restarts are invalid in Metal for non-restart-compatible
* primitive types. We also cannot just use zero unlike for Lines and Triangles,
* as we cannot create de-generative point primitives to hide geometry, as each
* point is independent.
* Instead, we must remove these hidden indices from the index buffer.
* NOTE: This happens prior to index squeezing so operate on 32-bit indices. */
MutableSpan<uint32_t> uint_idx(static_cast<uint32_t *>(data_), index_len_);
for (uint i = 0; i < index_len_; i++) {
if (uint_idx[i] == 0xFFFFFFFFu) {
/* Find swap index at end of index buffer. */
int swap_index = -1;
for (uint j = index_len_ - 1; j >= i; j--) {
/* If end index is restart, just reduce length. */
if (uint_idx[j] == 0xFFFFFFFFu) {
index_len_--;
continue;
}
/* Otherwise assign swap index. */
swap_index = j;
break;
}
/* If swap index is not valid, then there were no valid non-restart indices
* to swap with. However, the above loop will have removed these indices by
* reducing the length of indices. Debug assertions verify that the restart
* index is no longer included. */
if (swap_index == -1) {
BLI_assert(index_len_ <= i);
}
else {
/* If we have found an index we can swap with, flip the values.
* We also reduce the length. As per above loop, swap_index should
* now be outside the index length range. */
uint32_t swap_index_value = uint_idx[swap_index];
uint_idx[i] = swap_index_value;
uint_idx[swap_index] = 0xFFFFFFFFu;
index_len_--;
BLI_assert(index_len_ <= swap_index);
}
}
}
#ifndef NDEBUG
/* Flag as having been stripped to ensure invalid usage is tracked. */
point_restarts_stripped_ = true;
#endif
}
/** \} */
} // blender::gpu