gpu_uniform_buffer.cc

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/* SPDX-FileCopyrightText: 2020 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */

 
#include "MEM_guardedalloc.h"
#include <cstring>
 
#include "BLI_listbase.h"
#include "BLI_math_base.h"
#include "BLI_string.h"
 
#include "BKE_global.hh"
 
#include "gpu_backend.hh"
#include "gpu_node_graph.hh"
 
#include "GPU_context.hh"
#include "GPU_material.hh"
 
#include "GPU_uniform_buffer.hh"
#include "gpu_context_private.hh"
#include "gpu_uniform_buffer_private.hh"
 
/* -------------------------------------------------------------------- */
 
namespace blender::gpu {
 
UniformBuf::UniformBuf(size_t size, const char *name)
{
  /* Make sure that UBO is padded to size of vec4 */
  BLI_assert((size % 16) == 0);
 
  size_in_bytes_ = size;
 
  STRNCPY(name_, name);
}
 
UniformBuf::~UniformBuf()
{
  MEM_SAFE_FREE(data_);
}
 
}  // namespace blender::gpu

 
/* -------------------------------------------------------------------- */

static eGPUType get_padded_gpu_type(LinkData *link)
{
  GPUInput *input = (GPUInput *)link->data;
  eGPUType gputype = input->type;
  /* Metal cannot pack floats after vec3. */
  if (GPU_backend_get_type() == GPU_BACKEND_METAL) {
    return (gputype == GPU_VEC3) ? GPU_VEC4 : gputype;
  }
  /* Unless the vec3 is followed by a float we need to treat it as a vec4. */
  if (gputype == GPU_VEC3 && (link->next != nullptr) &&
      (((GPUInput *)link->next->data)->type != GPU_FLOAT))
  {
    gputype = GPU_VEC4;
  }
  return gputype;
}

static int inputs_cmp(const void *a, const void *b)
{
  const LinkData *link_a = (const LinkData *)a, *link_b = (const LinkData *)b;
  const GPUInput *input_a = (const GPUInput *)link_a->data;
  const GPUInput *input_b = (const GPUInput *)link_b->data;
  return input_a->type < input_b->type ? 1 : 0;
}

static void buffer_from_list_inputs_sort(ListBase *inputs)
{
/* Only support up to this type, if you want to extend it, make sure static void
 * inputs_sobuffer_size_compute *inputs) padding logic is correct for the new types. */
#define MAX_UBO_GPU_TYPE GPU_MAT4
 
  /* Order them as mat4, vec4, vec3, vec2, float. */
  BLI_listbase_sort(inputs, inputs_cmp);
 
  /* Metal cannot pack floats after vec3. */
  if (GPU_backend_get_type() == GPU_BACKEND_METAL) {
    return;
  }
 
  /* Creates a lookup table for the different types. */
  LinkData *inputs_lookup[MAX_UBO_GPU_TYPE + 1] = {nullptr};
  eGPUType cur_type = static_cast<eGPUType>(MAX_UBO_GPU_TYPE + 1);
 
  LISTBASE_FOREACH (LinkData *, link, inputs) {
    GPUInput *input = (GPUInput *)link->data;
 
    if (input->type == GPU_MAT3) {
      /* Alignment for mat3 is not handled currently, so not supported */
      BLI_assert_msg(0, "mat3 not supported in UBO");
      continue;
    }
    if (input->type > MAX_UBO_GPU_TYPE) {
      BLI_assert_msg(0, "GPU type not supported in UBO");
      continue;
    }
 
    if (input->type == cur_type) {
      continue;
    }
 
    inputs_lookup[input->type] = link;
    cur_type = input->type;
  }
 
  /* If there is no GPU_VEC3 there is no need for alignment. */
  if (inputs_lookup[GPU_VEC3] == nullptr) {
    return;
  }
 
  LinkData *link = inputs_lookup[GPU_VEC3];
  while (link != nullptr && ((GPUInput *)link->data)->type == GPU_VEC3) {
    LinkData *link_next = link->next;
 
    /* If GPU_VEC3 is followed by nothing or a GPU_FLOAT, no need for alignment. */
    if ((link_next == nullptr) || ((GPUInput *)link_next->data)->type == GPU_FLOAT) {
      break;
    }
 
    /* If there is a float, move it next to current vec3. */
    if (inputs_lookup[GPU_FLOAT] != nullptr) {
      LinkData *float_input = inputs_lookup[GPU_FLOAT];
      inputs_lookup[GPU_FLOAT] = float_input->next;
 
      BLI_remlink(inputs, float_input);
      BLI_insertlinkafter(inputs, link, float_input);
    }
 
    link = link_next;
  }
#undef MAX_UBO_GPU_TYPE
}
 
static inline size_t buffer_size_from_list(ListBase *inputs)
{
  size_t buffer_size = 0;
  LISTBASE_FOREACH (LinkData *, link, inputs) {
    const eGPUType gputype = get_padded_gpu_type(link);
    buffer_size += gputype * sizeof(float);
  }
  /* Round up to size of vec4. (Opengl Requirement) */
  size_t alignment = sizeof(float[4]);
  buffer_size = divide_ceil_u(buffer_size, alignment) * alignment;
 
  return buffer_size;
}
 
static inline void buffer_fill_from_list(void *data, ListBase *inputs)
{
  /* Now that we know the total ubo size we can start populating it. */
  float *offset = (float *)data;
  LISTBASE_FOREACH (LinkData *, link, inputs) {
    GPUInput *input = (GPUInput *)link->data;
    memcpy(offset, input->vec, input->type * sizeof(float));
    offset += get_padded_gpu_type(link);
  }
}

 
/* -------------------------------------------------------------------- */
 
using namespace blender::gpu;
 
GPUUniformBuf *GPU_uniformbuf_create_ex(size_t size, const void *data, const char *name)
{
  UniformBuf *ubo = GPUBackend::get()->uniformbuf_alloc(size, name);
  /* Direct init. */
  if (data != nullptr) {
    ubo->update(data);
  }
  else if (G.debug & G_DEBUG_GPU) {
    /* Fill the buffer with poison values.
     * (NaN for floats, -1 for `int` and "max value" for `uint`). */
    blender::Vector<uchar> uninitialized_data(size, 0xFF);
    ubo->update(uninitialized_data.data());
  }
  return wrap(ubo);
}
 
GPUUniformBuf *GPU_uniformbuf_create_from_list(ListBase *inputs, const char *name)
{
  /* There is no point on creating an UBO if there is no arguments. */
  if (BLI_listbase_is_empty(inputs)) {
    return nullptr;
  }
 
  buffer_from_list_inputs_sort(inputs);
  size_t buffer_size = buffer_size_from_list(inputs);
  void *data = MEM_mallocN(buffer_size, __func__);
  buffer_fill_from_list(data, inputs);
 
  UniformBuf *ubo = GPUBackend::get()->uniformbuf_alloc(buffer_size, name);
  /* Defer data upload. */
  ubo->attach_data(data);
  return wrap(ubo);
}
 
void GPU_uniformbuf_free(GPUUniformBuf *ubo)
{
  delete unwrap(ubo);
}
 
void GPU_uniformbuf_update(GPUUniformBuf *ubo, const void *data)
{
  unwrap(ubo)->update(data);
}
 
void GPU_uniformbuf_bind(GPUUniformBuf *ubo, int slot)
{
  unwrap(ubo)->bind(slot);
}
 
void GPU_uniformbuf_bind_as_ssbo(GPUUniformBuf *ubo, int slot)
{
  unwrap(ubo)->bind_as_ssbo(slot);
}
 
void GPU_uniformbuf_unbind(GPUUniformBuf *ubo)
{
  unwrap(ubo)->unbind();
}
 
void GPU_uniformbuf_debug_unbind_all()
{
  Context::get()->debug_unbind_all_ubo();
}
 
void GPU_uniformbuf_clear_to_zero(GPUUniformBuf *ubo)
{
  unwrap(ubo)->clear_to_zero();
}