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Zephyr: Renderer: pack render bundle item ID into draw command buffer
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@fleroviux
fleroviux committed May 11, 2024
1 parent 5a48502 commit 5a59d46
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Showing 2 changed files with 41 additions and 34 deletions.
74 changes: 41 additions & 33 deletions zephyr/renderer/src/backend/opengl/render_backend.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -23,10 +23,7 @@ namespace zephyr {
glNamedBufferStorage(m_gl_render_bundle_ssbo, sizeof(RenderBundleItem) * k_max_draws_per_draw_call, nullptr, GL_DYNAMIC_STORAGE_BIT);

glCreateBuffers(1u, &m_gl_draw_list_command_ssbo);
glNamedBufferStorage(m_gl_draw_list_command_ssbo, sizeof(OpenGLDrawElementsIndirectCommand) * k_max_draws_per_draw_call, nullptr, 0);

glCreateBuffers(1u, &m_gl_draw_list_transform_ssbo);
glNamedBufferStorage(m_gl_draw_list_transform_ssbo, sizeof(Matrix4) * k_max_draws_per_draw_call, nullptr, 0);
glNamedBufferStorage(m_gl_draw_list_command_ssbo, (sizeof(OpenGLDrawElementsIndirectCommand) + sizeof(u32)) * k_max_draws_per_draw_call, nullptr, 0);

glCreateBuffers(1u, &m_gl_camera_ubo);
glNamedBufferStorage(m_gl_camera_ubo, sizeof(RenderCamera), nullptr, GL_DYNAMIC_STORAGE_BIT);
Expand All @@ -48,7 +45,6 @@ namespace zephyr {
glDeleteBuffers(1u, &m_gl_draw_count_out_ac);
glDeleteBuffers(1u, &m_gl_draw_count_ubo);
glDeleteBuffers(1u, &m_gl_camera_ubo);
glDeleteBuffers(1u, &m_gl_draw_list_transform_ssbo);
glDeleteBuffers(1u, &m_gl_draw_list_command_ssbo);
glDeleteBuffers(1u, &m_gl_render_bundle_ssbo);
glDeleteProgram(m_gl_draw_list_builder_program);
Expand Down Expand Up @@ -99,10 +95,9 @@ namespace zephyr {

glNamedBufferSubData(m_gl_camera_ubo, 0, sizeof(RenderCamera), &render_camera);

// TODO(fleroviux): attempt to keep more buffers bound throughout the entire rendering process for minimal number of OpenGL calls.

glBindBufferBase(GL_UNIFORM_BUFFER, 0u, m_gl_camera_ubo);
glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 0u, m_gl_draw_list_transform_ssbo);
glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 0u, m_gl_render_bundle_ssbo);
glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 1u, m_gl_draw_list_command_ssbo);

for(const auto& [key, render_bundle] : render_bundles) {
const size_t render_bundle_size = render_bundle.size();
Expand All @@ -119,19 +114,15 @@ namespace zephyr {
{
glUseProgram(m_gl_draw_list_builder_program);

glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 1u, m_gl_render_bundle_ssbo);
glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 2u, m_render_geometry_manager->GetGeometryRenderDataBuffer());
glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 3u, m_gl_draw_list_command_ssbo);
glBindBufferBase(GL_UNIFORM_BUFFER, 1u, m_gl_draw_count_ubo);
glBindBufferBase(GL_ATOMIC_COUNTER_BUFFER, 0u, m_gl_draw_count_out_ac);

const GLuint workgroup_size = 32u;
const GLuint workgroup_group_count = (number_of_draws + workgroup_size - 1u) / workgroup_size;
glDispatchCompute(workgroup_group_count, 1u, 1u);

glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 1u, 0u);
glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 2u, 0u);
glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 3u, 0u);
glBindBufferBase(GL_UNIFORM_BUFFER, 1u, 0u);
glBindBufferBase(GL_ATOMIC_COUNTER_BUFFER, 0u, 0u);
}
Expand All @@ -144,8 +135,8 @@ namespace zephyr {
glBindBuffer(GL_DRAW_INDIRECT_BUFFER, m_gl_draw_list_command_ssbo);
glBindBuffer(GL_PARAMETER_BUFFER, m_gl_draw_count_out_ac);

glMemoryBarrier(GL_COMMAND_BARRIER_BIT | GL_ATOMIC_COUNTER_BARRIER_BIT);
glMultiDrawElementsIndirectCount(GL_TRIANGLES, GL_UNSIGNED_INT, nullptr, 0u, (GLsizei)number_of_draws, sizeof(OpenGLDrawElementsIndirectCommand));
glMemoryBarrier(GL_COMMAND_BARRIER_BIT | GL_ATOMIC_COUNTER_BARRIER_BIT | GL_SHADER_STORAGE_BARRIER_BIT);
glMultiDrawElementsIndirectCount(GL_TRIANGLES, GL_UNSIGNED_INT, nullptr, 0u, (GLsizei)number_of_draws, sizeof(OpenGLDrawElementsIndirectCommand) + sizeof(u32));

glBindVertexArray(0u);
glBindBuffer(GL_DRAW_INDIRECT_BUFFER, 0u);
Expand All @@ -156,6 +147,7 @@ namespace zephyr {

glBindBufferBase(GL_UNIFORM_BUFFER, 0u, 0u);
glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 0u, 0u);
glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 1u, 0u);
}

void OpenGLRenderBackend::SwapBuffers() {
Expand All @@ -166,8 +158,22 @@ namespace zephyr {
GLuint vert_shader = CreateShader(R"(
#version 460 core
layout(std430, binding = 0) readonly buffer DrawListTransformBuffer {
mat4 rb_draw_list_transform[];
struct RenderBundleItem {
mat4 local_to_world;
uint geometry_id;
};
struct DrawCommandWithRenderBundleItemID {
uint command[5];
uint render_bundle_item_id;
};
layout(std430, binding = 0) readonly buffer RenderBundleBuffer {
RenderBundleItem rb_render_bundle_items[];
};
layout(std430, binding = 1) readonly buffer CommandBuffer {
DrawCommandWithRenderBundleItemID rb_command_buffer[];
};
layout(std140, binding = 0) uniform Camera {
Expand All @@ -184,9 +190,11 @@ namespace zephyr {
out vec3 v_color;
void main() {
uint render_bundle_item_id = rb_command_buffer[gl_DrawID].render_bundle_item_id;
v_normal = a_normal;
v_color = a_color;
gl_Position = u_projection * u_view * rb_draw_list_transform[gl_DrawID] * vec4(a_position, 1.0);
gl_Position = u_projection * u_view * rb_render_bundle_items[render_bundle_item_id].local_to_world * vec4(a_position, 1.0);
}
)", GL_VERTEX_SHADER);

Expand Down Expand Up @@ -214,38 +222,39 @@ namespace zephyr {
layout(local_size_x = 32) in;
struct DrawIndirectCommand {
struct DrawCommand {
uint data[5];
};
struct DrawCommandWithRenderBundleItemID {
DrawCommand command;
uint render_bundle_item_id;
};
struct RenderGeometryRenderData {
// TODO(fleroviux): evaluate whether the packing can be tighter or not.
vec4 aabb_min;
vec4 aabb_max;
DrawIndirectCommand draw_command;
DrawCommand draw_command;
};
struct RenderBundleItem {
mat4 local_to_world;
uint geometry_id;
};
layout(std430, binding = 0) buffer DrawListTransformBuffer {
mat4 b_draw_list_transform[];
layout(std430, binding = 0) readonly buffer RenderBundleBuffer {
RenderBundleItem rb_render_bundle_items[];
};
layout(std430, binding = 1) readonly buffer RenderBundleBuffer {
RenderBundleItem rb_render_bundle_items[];
layout(std430, binding = 1) buffer CommandBuffer {
DrawCommandWithRenderBundleItemID b_command_buffer[];
};
layout(std430, binding = 2) readonly buffer GeometryBuffer {
RenderGeometryRenderData rb_render_geometry_render_data[];
};
layout(std430, binding = 3) buffer CommandBuffer {
DrawIndirectCommand b_command_buffer[];
};
layout(std140, binding = 0) uniform Camera {
mat4 u_projection;
mat4 u_view;
Expand All @@ -259,15 +268,15 @@ namespace zephyr {
layout(binding = 0) uniform atomic_uint u_draw_count_out;
void main() {
const uint draw_index = gl_GlobalInvocationID.x;
const uint render_bundle_item_id = gl_GlobalInvocationID.x;
if(draw_index == 0u) {
if(render_bundle_item_id == 0u) {
atomicCounterExchange(u_draw_count_out, 0u);
}
barrier();
if(draw_index < u_draw_count) {
RenderBundleItem render_bundle_item = rb_render_bundle_items[draw_index];
if(render_bundle_item_id < u_draw_count) {
RenderBundleItem render_bundle_item = rb_render_bundle_items[render_bundle_item_id];
RenderGeometryRenderData render_data = rb_render_geometry_render_data[render_bundle_item.geometry_id];
bool inside_frustum = true;
Expand Down Expand Up @@ -306,8 +315,7 @@ namespace zephyr {
if(inside_frustum) {
uint draw_id = atomicCounterIncrement(u_draw_count_out);
b_draw_list_transform[draw_id] = render_bundle_item.local_to_world;
b_command_buffer[draw_id] = render_data.draw_command;
b_command_buffer[draw_id] = DrawCommandWithRenderBundleItemID(render_data.draw_command, render_bundle_item_id);
}
}
}
Expand Down
1 change: 0 additions & 1 deletion zephyr/renderer/src/backend/opengl/render_backend.hpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -52,7 +52,6 @@ namespace zephyr {
GLuint m_gl_draw_list_builder_program{};
GLuint m_gl_render_bundle_ssbo{};
GLuint m_gl_draw_list_command_ssbo{};
GLuint m_gl_draw_list_transform_ssbo{};
GLuint m_gl_camera_ubo{};
GLuint m_gl_draw_count_ubo{};
GLuint m_gl_draw_count_out_ac{};
Expand Down

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