Adding Variable Rate Shading support to Godot

Improve GI renderer and add VRS support
Implement render device has_feature and move subgroup settings to limit_get

4 files changed, 105 insertions, 2 deletions

diff --git a/servers/xr/xr_interface.cpp b/servers/xr/xr_interface.cpp
index 7ae111b5e7..0808b1fd7b 100644
--- a/servers/xr/xr_interface.cpp
+++ b/servers/xr/xr_interface.cpp
@@ -29,7 +29,7 @@
 /*************************************************************************/
 
 #include "xr_interface.h"
-// #include "servers/rendering/renderer_compositor.h"
+#include "servers/rendering/renderer_compositor.h"
 
 void XRInterface::_bind_methods() {
 	ADD_SIGNAL(MethodInfo("play_area_changed", PropertyInfo(Variant::INT, "mode")));
@@ -114,7 +114,12 @@ void XRInterface::set_primary(bool p_primary) {
 
 XRInterface::XRInterface() {}
 
-XRInterface::~XRInterface() {}
+XRInterface::~XRInterface() {
+	if (vrs.vrs_texture.is_valid()) {
+		RS::get_singleton()->free(vrs.vrs_texture);
+		vrs.vrs_texture = RID();
+	}
+}
 
 // query if this interface supports this play area mode
 bool XRInterface::supports_play_area_mode(XRInterface::PlayAreaMode p_mode) {
@@ -151,6 +156,85 @@ int XRInterface::get_camera_feed_id() {
 	return 0;
 }
 
+RID XRInterface::get_vrs_texture() {
+	// Default logic will return a standard VRS image based on our target size and default projections.
+	// Note that this only gets called if VRS is supported on the hardware.
+
+	Size2 texel_size = Size2(16.0, 16.0); // For now we assume we always use 16x16 texels, seems to be the standard.
+	int view_count = get_view_count();
+	Size2 target_size = get_render_target_size();
+	real_t aspect = target_size.x / target_size.y; // is this y/x ?
+	Size2 vrs_size = Size2(round(0.5 + target_size.x / texel_size.x), round(0.5 + target_size.y / texel_size.y));
+	real_t radius = vrs_size.length() * 0.5;
+	Size2 vrs_sizei = vrs_size;
+
+	if (vrs.size != vrs_sizei) {
+		const uint8_t densities[] = {
+			0, // 1x1
+			1, // 1x2
+			// 4, // 2x1
+			5, // 2x2
+			6, // 2x4
+			// 9, // 4x2
+			10, // 4x4
+		};
+
+		// out with the old
+		if (vrs.vrs_texture.is_valid()) {
+			RS::get_singleton()->free(vrs.vrs_texture);
+			vrs.vrs_texture = RID();
+		}
+
+		// in with the new
+		Vector<Ref<Image>> images;
+		vrs.size = vrs_sizei;
+
+		for (int i = 0; i < view_count && i < 2; i++) {
+			PackedByteArray data;
+			data.resize(vrs_sizei.x * vrs_sizei.y);
+			uint8_t *data_ptr = data.ptrw();
+
+			// Our near and far don't matter much for what we're doing here, but there are some interfaces that will remember this as the near and far and may fail as a result...
+			CameraMatrix cm = get_projection_for_view(i, aspect, 0.1, 1000.0);
+			Vector3 center = cm.xform(Vector3(0.0, 0.0, 999.0));
+
+			Vector2i view_center;
+			view_center.x = int(vrs_size.x * (center.x + 1.0) * 0.5);
+			view_center.y = int(vrs_size.y * (center.y + 1.0) * 0.5);
+
+			int d = 0;
+			for (int y = 0; y < vrs_sizei.y; y++) {
+				for (int x = 0; x < vrs_sizei.x; x++) {
+					Vector2 offset = Vector2(x - view_center.x, y - view_center.y);
+					offset.y *= aspect;
+					real_t distance = offset.length();
+					int idx = round(5.0 * distance / radius);
+					if (idx > 4) {
+						idx = 4;
+					}
+					uint8_t density = densities[idx];
+
+					data_ptr[d++] = density;
+				}
+			}
+
+			Ref<Image> image;
+			image.instantiate();
+			image->create_from_data(vrs_sizei.x, vrs_sizei.y, false, Image::FORMAT_R8, data);
+
+			images.push_back(image);
+		}
+
+		if (images.size() == 1) {
+			vrs.vrs_texture = RS::get_singleton()->texture_2d_create(images[0]);
+		} else {
+			vrs.vrs_texture = RS::get_singleton()->texture_2d_layered_create(images, RS::TEXTURE_LAYERED_2D_ARRAY);
+		}
+	}
+
+	return vrs.vrs_texture;
+}
+
 /** these are optional, so we want dummies **/
 PackedStringArray XRInterface::get_suggested_tracker_names() const {
 	PackedStringArray arr;
diff --git a/servers/xr/xr_interface.h b/servers/xr/xr_interface.h
index 62eba2f00b..b4eb4694f6 100644
--- a/servers/xr/xr_interface.h
+++ b/servers/xr/xr_interface.h
@@ -120,6 +120,7 @@ public:
 	virtual Transform3D get_camera_transform() = 0; /* returns the position of our camera for updating our camera node. For monoscopic this is equal to the views transform, for stereoscopic this should be an average */
 	virtual Transform3D get_transform_for_view(uint32_t p_view, const Transform3D &p_cam_transform) = 0; /* get each views transform */
 	virtual CameraMatrix get_projection_for_view(uint32_t p_view, double p_aspect, double p_z_near, double p_z_far) = 0; /* get each view projection matrix */
+	virtual RID get_vrs_texture(); /* obtain VRS texture */
 
 	// note, external color/depth/vrs texture support will be added here soon.
 
@@ -133,6 +134,12 @@ public:
 
 	XRInterface();
 	~XRInterface();
+
+private:
+	struct VRSData {
+		RID vrs_texture;
+		Size2i size;
+	} vrs;
 };
 
 VARIANT_ENUM_CAST(XRInterface::Capabilities);
diff --git a/servers/xr/xr_interface_extension.cpp b/servers/xr/xr_interface_extension.cpp
index 1f3d07c357..94953c69a9 100644
--- a/servers/xr/xr_interface_extension.cpp
+++ b/servers/xr/xr_interface_extension.cpp
@@ -50,6 +50,7 @@ void XRInterfaceExtension::_bind_methods() {
 	GDVIRTUAL_BIND(_get_camera_transform);
 	GDVIRTUAL_BIND(_get_transform_for_view, "view", "cam_transform");
 	GDVIRTUAL_BIND(_get_projection_for_view, "view", "aspect", "z_near", "z_far");
+	GDVIRTUAL_BIND(_get_vrs_texture);
 
 	GDVIRTUAL_BIND(_process);
 	GDVIRTUAL_BIND(_pre_render);
@@ -273,6 +274,15 @@ CameraMatrix XRInterfaceExtension::get_projection_for_view(uint32_t p_view, doub
 	return CameraMatrix();
 }
 
+RID XRInterfaceExtension::get_vrs_texture() {
+	RID vrs_texture;
+	if (GDVIRTUAL_CALL(_get_vrs_texture, vrs_texture)) {
+		return vrs_texture;
+	} else {
+		return XRInterface::get_vrs_texture();
+	}
+}
+
 void XRInterfaceExtension::add_blit(RID p_render_target, Rect2 p_src_rect, Rect2i p_dst_rect, bool p_use_layer, uint32_t p_layer, bool p_apply_lens_distortion, Vector2 p_eye_center, double p_k1, double p_k2, double p_upscale, double p_aspect_ratio) {
 	BlitToScreen blit;
 
diff --git a/servers/xr/xr_interface_extension.h b/servers/xr/xr_interface_extension.h
index 5a436b9fd0..7174b412c5 100644
--- a/servers/xr/xr_interface_extension.h
+++ b/servers/xr/xr_interface_extension.h
@@ -101,12 +101,14 @@ public:
 	virtual Transform3D get_camera_transform() override;
 	virtual Transform3D get_transform_for_view(uint32_t p_view, const Transform3D &p_cam_transform) override;
 	virtual CameraMatrix get_projection_for_view(uint32_t p_view, double p_aspect, double p_z_near, double p_z_far) override;
+	virtual RID get_vrs_texture() override;
 
 	GDVIRTUAL0R(Size2, _get_render_target_size);
 	GDVIRTUAL0R(uint32_t, _get_view_count);
 	GDVIRTUAL0R(Transform3D, _get_camera_transform);
 	GDVIRTUAL2R(Transform3D, _get_transform_for_view, uint32_t, const Transform3D &);
 	GDVIRTUAL4R(PackedFloat64Array, _get_projection_for_view, uint32_t, double, double, double);
+	GDVIRTUAL0R(RID, _get_vrs_texture);
 
 	void add_blit(RID p_render_target, Rect2 p_src_rect, Rect2i p_dst_rect, bool p_use_layer = false, uint32_t p_layer = 0, bool p_apply_lens_distortion = false, Vector2 p_eye_center = Vector2(), double p_k1 = 0.0, double p_k2 = 0.0, double p_upscale = 1.0, double p_aspect_ratio = 1.0);