Question

我正在执行视平截头剔除并在计算着色器中的GPU上生成绘制命令，我想在SSBO中传递边界体积。目前，我仅使用大型统一阵列，但我想扩大尺寸，因此需要移至SSBO。

我要完成的工作类似于使用三重缓冲的AZDO方法，以便在更新SSBO时仅通过更新三分之一的缓冲区，同时用围栏保护其余缓冲区来避免同步问题。

这是否可以与计算着色器调度结合使用？还是应该只创建三个不同的SSBO，然后分别绑定它们？

我目前看到的解决方案是以某种方式告诉下面的调用仅从某个偏移量（0 * buffer_size，1 * buffer_size等）中获取SSBO中的数据。这有可能吗？

渲染循环

  /* Fence creation omitted for clarity */

  // Cycle round updating different parts of the buffer
  const uint32_t buffer_idx = (frame % gl_state.bvb_num_partitions);
  uint8_t* ptr = (uint8_t*)gl_state.bvbp + buffer_idx * gl_state.bvb_buffer_size;
  std::memcpy(ptr, bounding_volumes.data(), gl_state.bvb_buffer_size);
  const uint32_t gl_bv_binding_point = 3; // Shader hard coded
  const uint32_t offset = buffer_idx * gl_state.bvb_buffer_size;
  glBindBufferRange(GL_SHADER_STORAGE_BUFFER, gl_bv_binding_point, gl_state.bvb, offset, gl_state.bvb_buffer_size);

  // OLD WAY: glUniform4fv(glGetUniformLocation(gl_state.cull_shader.gl_program, "spheres"), NUM_OBJECTS, &bounding_volumes[0].pos.x);

  glUniform4fv(glGetUniformLocation(gl_state.cull_shader.gl_program, "frustum_planes"), 6, glm::value_ptr(frustum[0]));

  glDispatchCompute(NUM_OBJECTS, 1, 1);

  glMemoryBarrier(GL_COMMAND_BARRIER_BIT | GL_SHADER_STORAGE_BARRIER_BIT); // Buffer objects affected by this bit are derived from the GL_DRAW_INDIRECT_BUFFER binding.

创建大量SSBO

// Bounding volume buffer
glGenBuffers(1, &gl_state.bvb);
glBindBuffer(GL_SHADER_STORAGE_BUFFER, gl_state.bvb);
gl_state.bvb_buffer_size = NUM_OBJECTS * sizeof(BoundingVolume);
gl_state.bvb_num_partitions = 3; // 1 for application, 1 for OpenGL driver, 1 for GPU
GLbitfield flags = GL_MAP_COHERENT_BIT | GL_MAP_WRITE_BIT | GL_MAP_PERSISTENT_BIT;
glBufferStorage(GL_SHADER_STORAGE_BUFFER, gl_state.bvb_num_partitions * gl_state.bvb_buffer_size, nullptr, flags);
gl_state.bvbp = glMapBufferRange(GL_SHADER_STORAGE_BUFFER, 0, gl_state.bvb_buffer_size * gl_state.bvb_num_partitions, flags);

带有计算着色器的环形缓冲SSBO

0 个答案: