Polish rendering driver refactor further

Mainly:
- Make `max_descriptors_per_pool` project setting Vulkan-specific.
- Use a common, render driver agnostic magic FourCC for shader binary data.
- Downgrade spirv_reflect to Vulkan-only dependency.
- Add a `RENDER_DRIVER_*` macro to GLSL shader code for per-driver customizations.

6 files changed, 13 insertions, 11 deletions

diff --git a/SConstruct b/SConstruct
index 646f41839d..3a13b03bcc 100644
--- a/SConstruct
+++ b/SConstruct
@@ -182,8 +182,8 @@ opts.Add(BoolVariable("deprecated", "Enable compatibility code for deprecated an
 opts.Add(EnumVariable("float", "Floating-point precision", "32", ("32", "64")))
 opts.Add(BoolVariable("minizip", "Enable ZIP archive support using minizip", True))
 opts.Add(BoolVariable("xaudio2", "Enable the XAudio2 audio driver", False))
-opts.Add(BoolVariable("vulkan", "Enable the vulkan video driver", True))
-opts.Add(BoolVariable("opengl3", "Enable the OpenGL/GLES3 video driver", True))
+opts.Add(BoolVariable("vulkan", "Enable the vulkan rendering driver", True))
+opts.Add(BoolVariable("opengl3", "Enable the OpenGL/GLES3 rendering driver", True))
 opts.Add(BoolVariable("openxr", "Enable the OpenXR driver", True))
 opts.Add(BoolVariable("use_volk", "Use the volk library to load the Vulkan loader dynamically", True))
 opts.Add("custom_modules", "A list of comma-separated directory paths containing custom modules to build.", "")
diff --git a/doc/classes/ProjectSettings.xml b/doc/classes/ProjectSettings.xml
index 85bb9a64a6..3c988fae6e 100644
--- a/doc/classes/ProjectSettings.xml
+++ b/doc/classes/ProjectSettings.xml
@@ -2097,8 +2097,6 @@
 		<member name="rendering/renderer/rendering_method.web" type="String" setter="" getter="" default="&quot;gl_compatibility&quot;">
 			Override for [member rendering/renderer/rendering_method] on web.
 		</member>
-		<member name="rendering/rendering_device/descriptor_pools/max_descriptors_per_pool" type="int" setter="" getter="" default="64">
-		</member>
 		<member name="rendering/rendering_device/driver" type="String" setter="" getter="" default="&quot;vulkan&quot;">
 			Sets the driver to be used by the renderer when using a RenderingDevice-based renderer like the clustered renderer or the mobile renderer. This property can not be edited directly, instead, set the driver using the platform-specific overrides.
 		</member>
@@ -2123,6 +2121,8 @@
 		</member>
 		<member name="rendering/rendering_device/staging_buffer/texture_upload_region_size_px" type="int" setter="" getter="" default="64">
 		</member>
+		<member name="rendering/rendering_device/vulkan/max_descriptors_per_pool" type="int" setter="" getter="" default="64">
+		</member>
 		<member name="rendering/scaling_3d/fsr_sharpness" type="float" setter="" getter="" default="0.2">
 			Determines how sharp the upscaled image will be when using the FSR upscaling mode. Sharpness halves with every whole number. Values go from 0.0 (sharpest) to 2.0. Values above 2.0 won't make a visible difference.
 		</member>
diff --git a/drivers/SCsub b/drivers/SCsub
index dd81fc645c..6cfcb1d18c 100644
--- a/drivers/SCsub
+++ b/drivers/SCsub
@@ -24,6 +24,7 @@ SConscript("winmidi/SCsub")
 
 # Graphics drivers
 if env["vulkan"]:
+    SConscript("spirv-reflect/SCsub")
     SConscript("vulkan/SCsub")
 if env["opengl3"]:
     SConscript("gl_context/SCsub")
@@ -31,7 +32,6 @@ if env["opengl3"]:
 
 # Core dependencies
 SConscript("png/SCsub")
-SConscript("spirv-reflect/SCsub")
 
 env.add_source_files(env.drivers_sources, "*.cpp")
 
diff --git a/drivers/vulkan/rendering_device_vulkan.cpp b/drivers/vulkan/rendering_device_vulkan.cpp
index f0f70b62e0..7da6b5480d 100644
--- a/drivers/vulkan/rendering_device_vulkan.cpp
+++ b/drivers/vulkan/rendering_device_vulkan.cpp
@@ -5172,9 +5172,9 @@ Vector<uint8_t> RenderingDeviceVulkan::shader_compile_binary_from_spirv(const Ve
 		uint32_t offset = 0;
 		uint8_t *binptr = ret.ptrw();
 		binptr[0] = 'G';
-		binptr[1] = 'V';
+		binptr[1] = 'S';
 		binptr[2] = 'B';
-		binptr[3] = 'D'; // Godot vulkan binary data.
+		binptr[3] = 'D'; // Godot Shader Binary Data.
 		offset += 4;
 		encode_uint32(SHADER_BINARY_VERSION, binptr + offset);
 		offset += sizeof(uint32_t);
@@ -5235,7 +5235,7 @@ RID RenderingDeviceVulkan::shader_create_from_bytecode(const Vector<uint8_t> &p_
 	uint32_t read_offset = 0;
 	// Consistency check.
 	ERR_FAIL_COND_V(binsize < sizeof(uint32_t) * 3 + sizeof(RenderingDeviceVulkanShaderBinaryData), RID());
-	ERR_FAIL_COND_V(binptr[0] != 'G' || binptr[1] != 'V' || binptr[2] != 'B' || binptr[3] != 'D', RID());
+	ERR_FAIL_COND_V(binptr[0] != 'G' || binptr[1] != 'S' || binptr[2] != 'B' || binptr[3] != 'D', RID());
 
 	uint32_t bin_version = decode_uint32(binptr + 4);
 	ERR_FAIL_COND_V(bin_version != SHADER_BINARY_VERSION, RID());
@@ -9393,7 +9393,7 @@ void RenderingDeviceVulkan::initialize(VulkanContext *p_context, bool p_local_de
 		ERR_CONTINUE(err != OK);
 	}
 
-	max_descriptors_per_pool = GLOBAL_DEF("rendering/rendering_device/descriptor_pools/max_descriptors_per_pool", 64);
+	max_descriptors_per_pool = GLOBAL_DEF("rendering/rendering_device/vulkan/max_descriptors_per_pool", 64);
 
 	// Check to make sure DescriptorPoolKey is good.
 	static_assert(sizeof(uint64_t) * 3 >= UNIFORM_TYPE_MAX * sizeof(uint16_t));
diff --git a/servers/rendering/renderer_rd/shader_rd.cpp b/servers/rendering/renderer_rd/shader_rd.cpp
index 0f2dea6fe9..5e9eadadd9 100644
--- a/servers/rendering/renderer_rd/shader_rd.cpp
+++ b/servers/rendering/renderer_rd/shader_rd.cpp
@@ -180,6 +180,7 @@ void ShaderRD::_build_variant_code(StringBuilder &builder, uint32_t p_variant, c
 #if defined(MACOS_ENABLED) || defined(IOS_ENABLED)
 				builder.append("#define MOLTENVK_USED\n");
 #endif
+				builder.append(String("#define RENDER_DRIVER_") + OS::get_singleton()->get_current_rendering_driver_name().to_upper() + "\n");
 			} break;
 			case StageTemplate::Chunk::TYPE_MATERIAL_UNIFORMS: {
 				builder.append(p_version->uniforms.get_data()); //uniforms (same for vertex and fragment)
diff --git a/servers/rendering_server.cpp b/servers/rendering_server.cpp
index 750121719f..5bd4bae4cb 100644
--- a/servers/rendering_server.cpp
+++ b/servers/rendering_server.cpp
@@ -2868,12 +2868,13 @@ void RenderingServer::init() {
 
 	GLOBAL_DEF("rendering/2d/shadow_atlas/size", 2048);
 
-	// Already defined in RenderingDeviceVulkan::initialize which runs before this code.
+	// Already defined in some RenderingDevice*::initialize, which run before this code.
 	// We re-define them here just for doctool's sake. Make sure to keep default values in sync.
 	GLOBAL_DEF("rendering/rendering_device/staging_buffer/block_size_kb", 256);
 	GLOBAL_DEF("rendering/rendering_device/staging_buffer/max_size_mb", 128);
 	GLOBAL_DEF("rendering/rendering_device/staging_buffer/texture_upload_region_size_px", 64);
-	GLOBAL_DEF("rendering/rendering_device/descriptor_pools/max_descriptors_per_pool", 64);
+	// Vulkan-specific.
+	GLOBAL_DEF("rendering/rendering_device/vulkan/max_descriptors_per_pool", 64);
 
 	GLOBAL_DEF("rendering/shader_compiler/shader_cache/enabled", true);
 	GLOBAL_DEF("rendering/shader_compiler/shader_cache/compress", true);