From 330133ba101591c065e041ae6d5a67bf2cc1c0cd Mon Sep 17 00:00:00 2001
From: harrand <harrysjh98@gmail.com>
Date: Mon, 20 Feb 2023 01:13:17 +0000
Subject: [PATCH] * Vulkan WIP - Draw Indirect Count

---
 demo/gl/tz_gpu_driven_demo.cpp           |  1 +
 src/tz/gl/api/renderer.hpp               |  2 ++
 src/tz/gl/impl/vulkan/detail/command.cpp | 12 ++++++++++++
 src/tz/gl/impl/vulkan/detail/command.hpp | 20 +++++++++++++++++++-
 4 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/demo/gl/tz_gpu_driven_demo.cpp b/demo/gl/tz_gpu_driven_demo.cpp
index f706cb38cd..1c91921fcf 100644
--- a/demo/gl/tz_gpu_driven_demo.cpp
+++ b/demo/gl/tz_gpu_driven_demo.cpp
@@ -25,6 +25,7 @@ int main()
 		tz::gl::renderer_info rinfo;
 		rinfo.debug_name("Triangle renderer");
 		tz::gl::resource_handle dbufh_ref = rinfo.ref_resource(ch, dbufh);
+		rinfo.set_options({tz::gl::renderer_option::draw_indirect_count});
 		rinfo.state().graphics.draw_buffer = dbufh_ref;
 		rinfo.shader().set_shader(tz::gl::shader_stage::vertex, ImportedShaderSource(tz_gpu_driven_demo_render, vertex));
 		rinfo.shader().set_shader(tz::gl::shader_stage::fragment, ImportedShaderSource(tz_gpu_driven_demo_render, fragment));
diff --git a/src/tz/gl/api/renderer.hpp b/src/tz/gl/api/renderer.hpp
index d76d697444..9bb0d508c7 100644
--- a/src/tz/gl/api/renderer.hpp
+++ b/src/tz/gl/api/renderer.hpp
@@ -42,6 +42,8 @@ namespace tz::gl
 		no_clear_output,
 		/// - When a renderer is invoked, the output image is not presented to the screen. If the output is an image_output, this has no effect.
 		no_present,
+		/// - The renderer's `state().graphics.draw_buffer` is assumed to contain a uint32 representing the draw count at the very start of the buffer, and the draw commands appear after that count in memory.
+		draw_indirect_count,
 		// Final debug ui renderer. Do not use.
 		_internal_final_dbgui_renderer,
 		// Internal renderer. Has no effect aside from hiding it from the dbgui.
diff --git a/src/tz/gl/impl/vulkan/detail/command.cpp b/src/tz/gl/impl/vulkan/detail/command.cpp
index f4485a684f..425002d4ea 100644
--- a/src/tz/gl/impl/vulkan/detail/command.cpp
+++ b/src/tz/gl/impl/vulkan/detail/command.cpp
@@ -142,12 +142,24 @@ namespace tz::gl::vk2
 		vkCmdDrawIndirect(this->get_command_buffer().native(), command.draw_indirect_buffer->native(), command.offset, command.draw_count, command.stride);
 	}
 
+	void CommandBufferRecording::draw_indirect_count(VulkanCommand::DrawIndirectCount command)
+	{
+		this->register_command(command);
+		vkCmdDrawIndirectCount(this->get_command_buffer().native(), command.draw_indirect_buffer->native(), command.offset, command.draw_indirect_buffer->native(), 0, command.max_draw_count, command.stride);
+	}
+
 	void CommandBufferRecording::draw_indexed_indirect(VulkanCommand::DrawIndexedIndirect command)
 	{
 		this->register_command(command);
 		vkCmdDrawIndexedIndirect(this->get_command_buffer().native(), command.draw_indirect_buffer->native(), command.offset, command.draw_count, command.stride);
 	}
 
+	void CommandBufferRecording::draw_indexed_indirect_count(VulkanCommand::DrawIndexedIndirectCount command)
+	{
+		this->register_command(command);
+		vkCmdDrawIndexedIndirectCount(this->get_command_buffer().native(), command.draw_indirect_buffer->native(), command.offset, command.draw_indirect_buffer->native(), 0, command.max_draw_count, command.stride);
+	}
+
 	void CommandBufferRecording::bind_index_buffer(VulkanCommand::BindIndexBuffer command)
 	{
 		this->register_command(command);
diff --git a/src/tz/gl/impl/vulkan/detail/command.hpp b/src/tz/gl/impl/vulkan/detail/command.hpp
index 1375ae1a53..f159842799 100644
--- a/src/tz/gl/impl/vulkan/detail/command.hpp
+++ b/src/tz/gl/impl/vulkan/detail/command.hpp
@@ -61,6 +61,14 @@ namespace tz::gl::vk2
 			VkDeviceSize offset = 0;
 		};
 
+		struct DrawIndirectCount
+		{
+			const Buffer* draw_indirect_buffer;
+			std::uint32_t max_draw_count;
+			std::uint32_t stride;
+			VkDeviceSize offset = sizeof(std::uint32_t);
+		};
+
 		/**
 		 * Record an indexed indirect draw.
 		 * See @ref COmmandBufferRecording::draw_indexed_indirect for usage.
@@ -73,6 +81,14 @@ namespace tz::gl::vk2
 			VkDeviceSize offset = 0;
 		};
 
+		struct DrawIndexedIndirectCount
+		{
+			const Buffer* draw_indirect_buffer;
+			std::uint32_t max_draw_count;
+			std::uint32_t stride;
+			VkDeviceSize offset = sizeof(std::uint32_t);
+		};
+
 		/**
 		 * Bind an index buffer.
 		 * See @ref CommandBufferRecording::bind_index_buffer for usage.
@@ -230,7 +246,7 @@ namespace tz::gl::vk2
 		struct DebugEndLabel{};
 
 		/// variant type which has alternatives for every single possible recordable command type.
-		using variant = std::variant<Dispatch, Draw, DrawIndexed, DrawIndirect, DrawIndexedIndirect, BindIndexBuffer, BindPipeline, BindDescriptorSets, BeginRenderPass, EndRenderPass, BufferCopyBuffer, BufferCopyImage, ImageCopyImage, BindBuffer, TransitionImageLayout, SetScissorDynamic, DebugBeginLabel, DebugEndLabel>;
+		using variant = std::variant<Dispatch, Draw, DrawIndexed, DrawIndirect, DrawIndirectCount, DrawIndexedIndirect, DrawIndexedIndirectCount, BindIndexBuffer, BindPipeline, BindDescriptorSets, BeginRenderPass, EndRenderPass, BufferCopyBuffer, BufferCopyImage, ImageCopyImage, BindBuffer, TransitionImageLayout, SetScissorDynamic, DebugBeginLabel, DebugEndLabel>;
 	};
 
 	enum class CommandPoolFlag
@@ -317,11 +333,13 @@ namespace tz::gl::vk2
 		 * See @ref VulkanCommand::DrawIndirect for details.
 		 */
 		void draw_indirect(VulkanCommand::DrawIndirect draw);
+		void draw_indirect_count(VulkanCommand::DrawIndirectCount draw);
 		/**
 		 * Perform some indirect, indexed draws.
 		 * See @ref VulkanCommand::DrawIndexedIndirect for details.
 		 */
 		void draw_indexed_indirect(VulkanCommand::DrawIndexedIndirect draw);
+		void draw_indexed_indirect_count(VulkanCommand::DrawIndexedIndirectCount draw);
 		void bind_index_buffer(VulkanCommand::BindIndexBuffer bind);
 		/**
 		 * Bind a list of @ref DescriptorSet.