Improvements to VRS/Foveated rendering

4 files changed, 225 insertions, 89 deletions

diff --git a/servers/xr/xr_interface.cpp b/servers/xr/xr_interface.cpp
index 9ced28fd52..26f315a454 100644
--- a/servers/xr/xr_interface.cpp
+++ b/servers/xr/xr_interface.cpp
@@ -132,13 +132,7 @@ void XRInterface::set_primary(bool p_primary) {
 
 XRInterface::XRInterface() {}
 
-XRInterface::~XRInterface() {
-	if (vrs.vrs_texture.is_valid()) {
-		ERR_FAIL_NULL(RenderingServer::get_singleton());
-		RS::get_singleton()->free(vrs.vrs_texture);
-		vrs.vrs_texture = RID();
-	}
-}
+XRInterface::~XRInterface() {}
 
 // query if this interface supports this play area mode
 bool XRInterface::supports_play_area_mode(XRInterface::PlayAreaMode p_mode) {
@@ -176,80 +170,7 @@ int XRInterface::get_camera_feed_id() {
 }
 
 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.
-
-	int32_t texel_width = RD::get_singleton()->limit_get(RD::LIMIT_VRS_TEXEL_WIDTH);
-	int32_t texel_height = RD::get_singleton()->limit_get(RD::LIMIT_VRS_TEXEL_HEIGHT);
-	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_width), round(0.5 + target_size.y / texel_height));
-	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
-			// 2, // 1x4 - not supported
-			// 3, // 1x8 - not supported
-			// 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...
-			Projection 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;
-				}
-			}
-			images.push_back(Image::create_from_data(vrs_sizei.x, vrs_sizei.y, false, Image::FORMAT_R8, data));
-		}
-
-		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;
+	return RID();
 }
 
 /** these are optional, so we want dummies **/
diff --git a/servers/xr/xr_interface.h b/servers/xr/xr_interface.h
index 809800d8b9..7beec219bb 100644
--- a/servers/xr/xr_interface.h
+++ b/servers/xr/xr_interface.h
@@ -34,6 +34,7 @@
 #include "core/math/projection.h"
 #include "core/os/thread_safe.h"
 #include "servers/xr_server.h"
+#include "xr_vrs.h"
 
 // forward declaration
 struct BlitToScreen;
@@ -133,7 +134,6 @@ public:
 	// These methods are called from the rendering thread.
 	virtual Transform3D get_transform_for_view(uint32_t p_view, const Transform3D &p_cam_transform) = 0; /* get each views transform */
 	virtual Projection 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 */
 	virtual RID get_color_texture(); /* obtain color output texture (if applicable) */
 	virtual RID get_depth_texture(); /* obtain depth output texture (if applicable, used for reprojection) */
 	virtual RID get_velocity_texture(); /* obtain velocity output texture (if applicable, used for spacewarp) */
@@ -149,19 +149,16 @@ public:
 	virtual bool start_passthrough() { return false; }
 	virtual void stop_passthrough() {}
 
-	/** environment blend mode. */
+	/** environment blend mode **/
 	virtual Array get_supported_environment_blend_modes();
 	virtual XRInterface::EnvironmentBlendMode get_environment_blend_mode() const { return XR_ENV_BLEND_MODE_OPAQUE; }
 	virtual bool set_environment_blend_mode(EnvironmentBlendMode mode) { return false; }
 
+	/** VRS **/
+	virtual RID get_vrs_texture(); /* obtain VRS texture */
+
 	XRInterface();
 	~XRInterface();
-
-private:
-	struct VRSData {
-		RID vrs_texture;
-		Size2i size;
-	} vrs;
 };
 
 VARIANT_ENUM_CAST(XRInterface::Capabilities);
diff --git a/servers/xr/xr_vrs.cpp b/servers/xr/xr_vrs.cpp
new file mode 100644
index 0000000000..9d1e2f2068
--- /dev/null
+++ b/servers/xr/xr_vrs.cpp
@@ -0,0 +1,151 @@
+/**************************************************************************/
+/*  xr_vrs.cpp                                                            */
+/**************************************************************************/
+/*                         This file is part of:                          */
+/*                             GODOT ENGINE                               */
+/*                        https://godotengine.org                         */
+/**************************************************************************/
+/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
+/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
+/*                                                                        */
+/* Permission is hereby granted, free of charge, to any person obtaining  */
+/* a copy of this software and associated documentation files (the        */
+/* "Software"), to deal in the Software without restriction, including    */
+/* without limitation the rights to use, copy, modify, merge, publish,    */
+/* distribute, sublicense, and/or sell copies of the Software, and to     */
+/* permit persons to whom the Software is furnished to do so, subject to  */
+/* the following conditions:                                              */
+/*                                                                        */
+/* The above copyright notice and this permission notice shall be         */
+/* included in all copies or substantial portions of the Software.        */
+/*                                                                        */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,        */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF     */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. */
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY   */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,   */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE      */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                 */
+/**************************************************************************/
+
+#include "xr_vrs.h"
+
+#include "servers/rendering/renderer_scene_render.h"
+#include "servers/rendering_server.h"
+
+void XRVRS::_bind_methods() {
+	ClassDB::bind_method(D_METHOD("get_vrs_min_radius"), &XRVRS::get_vrs_min_radius);
+	ClassDB::bind_method(D_METHOD("set_vrs_min_radius", "radius"), &XRVRS::set_vrs_min_radius);
+
+	ClassDB::bind_method(D_METHOD("get_vrs_strength"), &XRVRS::get_vrs_strength);
+	ClassDB::bind_method(D_METHOD("set_vrs_strength", "strength"), &XRVRS::set_vrs_strength);
+
+	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "vrs_min_radius", PROPERTY_HINT_RANGE, "1.0,100.0,1.0"), "set_vrs_min_radius", "get_vrs_min_radius");
+	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "vrs_strength", PROPERTY_HINT_RANGE, "0.1,10.0,0.1"), "set_vrs_strength", "get_vrs_strength");
+
+	ClassDB::bind_method(D_METHOD("make_vrs_texture", "target_size", "eye_foci"), &XRVRS::make_vrs_texture);
+}
+
+XRVRS::~XRVRS() {
+	if (vrs_texture.is_valid()) {
+		ERR_FAIL_NULL(RS::get_singleton());
+		RS::get_singleton()->free(vrs_texture);
+		vrs_texture = RID();
+	}
+}
+
+float XRVRS::get_vrs_min_radius() const {
+	return vrs_min_radius;
+}
+
+void XRVRS::set_vrs_min_radius(float p_vrs_min_radius) {
+	if (p_vrs_min_radius < 1.0) {
+		WARN_PRINT_ONCE("VRS minimum radius can not be set below 1.0");
+		vrs_min_radius = 1.0;
+	} else if (p_vrs_min_radius > 100.0) {
+		WARN_PRINT_ONCE("VRS minimum radius can not be set above 100.0");
+		vrs_min_radius = 100.0;
+	} else {
+		vrs_min_radius = p_vrs_min_radius;
+		vrs_dirty = true;
+	}
+}
+
+float XRVRS::get_vrs_strength() const {
+	return vrs_strength;
+}
+
+void XRVRS::set_vrs_strength(float p_vrs_strength) {
+	if (p_vrs_strength < 0.1) {
+		WARN_PRINT_ONCE("VRS strength can not be set below 0.1");
+		vrs_strength = 0.1;
+	} else if (p_vrs_strength > 10.0) {
+		WARN_PRINT_ONCE("VRS strength can not be set above 10.0");
+		vrs_strength = 10.0;
+	} else {
+		vrs_strength = p_vrs_strength;
+		vrs_dirty = true;
+	}
+}
+
+RID XRVRS::make_vrs_texture(const Size2 &p_target_size, const PackedVector2Array &p_eye_foci) {
+	ERR_FAIL_COND_V(p_eye_foci.is_empty(), RID());
+
+	int32_t texel_width = RD::get_singleton()->limit_get(RD::LIMIT_VRS_TEXEL_WIDTH);
+	int32_t texel_height = RD::get_singleton()->limit_get(RD::LIMIT_VRS_TEXEL_HEIGHT);
+
+	Size2 vrs_size = Size2(0.5 + p_target_size.x / texel_width, 0.5 + p_target_size.y / texel_height).round();
+	float max_radius = 0.5 * MIN(vrs_size.x, vrs_size.y); // Maximum radius that fits inside of our image
+	float min_radius = vrs_min_radius * max_radius / 100.0; // Minimum radius as a percentage of our size
+	real_t outer_radius = MAX(1.0, (max_radius - min_radius) / vrs_strength);
+	Size2 vrs_sizei = vrs_size;
+
+	// Our density map is now unified, with a value of (0.0, 0.0) meaning a 1x1 texel size and (1.0, 1.0) an max texel size.
+	// For our standard VRS extension on Vulkan this means a maximum of 8x8.
+	// For the density map extension this scales depending on the max texel size.
+
+	if (target_size != vrs_sizei || eye_foci != p_eye_foci || vrs_dirty) {
+		// Out with the old.
+		if (vrs_texture.is_valid()) {
+			RS::get_singleton()->free(vrs_texture);
+			vrs_texture = RID();
+		}
+
+		// In with the new.
+		Vector<Ref<Image>> images;
+		target_size = vrs_sizei;
+		eye_foci = p_eye_foci;
+
+		for (int i = 0; i < eye_foci.size() && i < RendererSceneRender::MAX_RENDER_VIEWS; i++) {
+			PackedByteArray data;
+			data.resize(vrs_sizei.x * vrs_sizei.y * 2);
+			uint8_t *data_ptr = data.ptrw();
+
+			Vector2i view_center;
+			view_center.x = int(vrs_size.x * (eye_foci[i].x + 1.0) * 0.5);
+			view_center.y = int(vrs_size.y * (eye_foci[i].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);
+					real_t density = 255.0 * MAX(0.0, (Math::abs(offset.x) - min_radius) / outer_radius);
+					data_ptr[d++] = MIN(255, density);
+					density = 255.0 * MAX(0.0, (Math::abs(offset.y) - min_radius) / outer_radius);
+					data_ptr[d++] = MIN(255, density);
+				}
+			}
+			images.push_back(Image::create_from_data(vrs_sizei.x, vrs_sizei.y, false, Image::FORMAT_RG8, data));
+		}
+
+		if (images.size() == 1) {
+			vrs_texture = RS::get_singleton()->texture_2d_create(images[0]);
+		} else {
+			vrs_texture = RS::get_singleton()->texture_2d_layered_create(images, RS::TEXTURE_LAYERED_2D_ARRAY);
+		}
+
+		vrs_dirty = false;
+	}
+
+	return vrs_texture;
+}
diff --git a/servers/xr/xr_vrs.h b/servers/xr/xr_vrs.h
new file mode 100644
index 0000000000..35dfe55620
--- /dev/null
+++ b/servers/xr/xr_vrs.h
@@ -0,0 +1,67 @@
+/**************************************************************************/
+/*  xr_vrs.h                                                              */
+/**************************************************************************/
+/*                         This file is part of:                          */
+/*                             GODOT ENGINE                               */
+/*                        https://godotengine.org                         */
+/**************************************************************************/
+/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
+/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
+/*                                                                        */
+/* Permission is hereby granted, free of charge, to any person obtaining  */
+/* a copy of this software and associated documentation files (the        */
+/* "Software"), to deal in the Software without restriction, including    */
+/* without limitation the rights to use, copy, modify, merge, publish,    */
+/* distribute, sublicense, and/or sell copies of the Software, and to     */
+/* permit persons to whom the Software is furnished to do so, subject to  */
+/* the following conditions:                                              */
+/*                                                                        */
+/* The above copyright notice and this permission notice shall be         */
+/* included in all copies or substantial portions of the Software.        */
+/*                                                                        */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,        */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF     */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. */
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY   */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,   */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE      */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                 */
+/**************************************************************************/
+
+#ifndef XR_VRS_H
+#define XR_VRS_H
+
+#include "core/object/class_db.h"
+#include "core/object/object.h"
+#include "core/templates/rid.h"
+#include "core/variant/variant.h"
+
+/* This is a helper class for generating stereoscopic VRS images */
+
+class XRVRS : public Object {
+	GDCLASS(XRVRS, Object);
+
+private:
+	float vrs_min_radius = 20.0;
+	float vrs_strength = 1.0;
+	bool vrs_dirty = true;
+
+	RID vrs_texture;
+	Size2i target_size;
+	PackedVector2Array eye_foci;
+
+protected:
+	static void _bind_methods();
+
+public:
+	~XRVRS();
+
+	float get_vrs_min_radius() const;
+	void set_vrs_min_radius(float p_vrs_min_radius);
+	float get_vrs_strength() const;
+	void set_vrs_strength(float p_vrs_strength);
+
+	RID make_vrs_texture(const Size2 &p_target_size, const PackedVector2Array &p_eye_foci);
+};
+
+#endif // XR_VRS_H