Ensure MovieWriter output is in gamma space when using HDR 2D

10 files changed, 61 insertions, 1 deletions

diff --git a/core/io/image.cpp b/core/io/image.cpp
index 5498b448d7..44418fc69e 100644
--- a/core/io/image.cpp
+++ b/core/io/image.cpp
@@ -3475,6 +3475,7 @@ void Image::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("fix_alpha_edges"), &Image::fix_alpha_edges);
 	ClassDB::bind_method(D_METHOD("premultiply_alpha"), &Image::premultiply_alpha);
 	ClassDB::bind_method(D_METHOD("srgb_to_linear"), &Image::srgb_to_linear);
+	ClassDB::bind_method(D_METHOD("linear_to_srgb"), &Image::linear_to_srgb);
 	ClassDB::bind_method(D_METHOD("normal_map_to_xy"), &Image::normal_map_to_xy);
 	ClassDB::bind_method(D_METHOD("rgbe_to_srgb"), &Image::rgbe_to_srgb);
 	ClassDB::bind_method(D_METHOD("bump_map_to_normal_map", "bump_scale"), &Image::bump_map_to_normal_map, DEFVAL(1.0));
@@ -3741,6 +3742,37 @@ void Image::srgb_to_linear() {
 	}
 }
 
+void Image::linear_to_srgb() {
+	if (data.size() == 0) {
+		return;
+	}
+
+	static const uint8_t lin2srgb[256] = { 0, 12, 21, 28, 33, 38, 42, 46, 49, 52, 55, 58, 61, 63, 66, 68, 70, 73, 75, 77, 79, 81, 82, 84, 86, 88, 89, 91, 93, 94, 96, 97, 99, 100, 102, 103, 104, 106, 107, 109, 110, 111, 112, 114, 115, 116, 117, 118, 120, 121, 122, 123, 124, 125, 126, 127, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 151, 152, 153, 154, 155, 156, 157, 157, 158, 159, 160, 161, 161, 162, 163, 164, 165, 165, 166, 167, 168, 168, 169, 170, 171, 171, 172, 173, 174, 174, 175, 176, 176, 177, 178, 179, 179, 180, 181, 181, 182, 183, 183, 184, 185, 185, 186, 187, 187, 188, 189, 189, 190, 191, 191, 192, 193, 193, 194, 194, 195, 196, 196, 197, 197, 198, 199, 199, 200, 201, 201, 202, 202, 203, 204, 204, 205, 205, 206, 206, 207, 208, 208, 209, 209, 210, 210, 211, 212, 212, 213, 213, 214, 214, 215, 215, 216, 217, 217, 218, 218, 219, 219, 220, 220, 221, 221, 222, 222, 223, 223, 224, 224, 225, 226, 226, 227, 227, 228, 228, 229, 229, 230, 230, 231, 231, 232, 232, 233, 233, 234, 234, 235, 235, 236, 236, 237, 237, 237, 238, 238, 239, 239, 240, 240, 241, 241, 242, 242, 243, 243, 244, 244, 245, 245, 245, 246, 246, 247, 247, 248, 248, 249, 249, 250, 250, 251, 251, 251, 252, 252, 253, 253, 254, 254, 255 };
+
+	ERR_FAIL_COND(format != FORMAT_RGB8 && format != FORMAT_RGBA8);
+
+	if (format == FORMAT_RGBA8) {
+		int len = data.size() / 4;
+		uint8_t *data_ptr = data.ptrw();
+
+		for (int i = 0; i < len; i++) {
+			data_ptr[(i << 2) + 0] = lin2srgb[data_ptr[(i << 2) + 0]];
+			data_ptr[(i << 2) + 1] = lin2srgb[data_ptr[(i << 2) + 1]];
+			data_ptr[(i << 2) + 2] = lin2srgb[data_ptr[(i << 2) + 2]];
+		}
+
+	} else if (format == FORMAT_RGB8) {
+		int len = data.size() / 3;
+		uint8_t *data_ptr = data.ptrw();
+
+		for (int i = 0; i < len; i++) {
+			data_ptr[(i * 3) + 0] = lin2srgb[data_ptr[(i * 3) + 0]];
+			data_ptr[(i * 3) + 1] = lin2srgb[data_ptr[(i * 3) + 1]];
+			data_ptr[(i * 3) + 2] = lin2srgb[data_ptr[(i * 3) + 2]];
+		}
+	}
+}
+
 void Image::premultiply_alpha() {
 	if (data.size() == 0) {
 		return;
diff --git a/core/io/image.h b/core/io/image.h
index daddfac59d..6ed042092a 100644
--- a/core/io/image.h
+++ b/core/io/image.h
@@ -381,6 +381,7 @@ public:
 	void fix_alpha_edges();
 	void premultiply_alpha();
 	void srgb_to_linear();
+	void linear_to_srgb();
 	void normal_map_to_xy();
 	Ref<Image> rgbe_to_srgb();
 	Ref<Image> get_image_from_mipmap(int p_mipamp) const;
diff --git a/doc/classes/Image.xml b/doc/classes/Image.xml
index 68d4deaffd..cae525fce9 100644
--- a/doc/classes/Image.xml
+++ b/doc/classes/Image.xml
@@ -305,6 +305,12 @@
 				Returns [code]true[/code] if all the image's pixels have an alpha value of 0. Returns [code]false[/code] if any pixel has an alpha value higher than 0.
 			</description>
 		</method>
+		<method name="linear_to_srgb">
+			<return type="void" />
+			<description>
+				Converts the entire image from the linear colorspace to the sRGB colorspace. Only works on images with [constant FORMAT_RGB8] or [constant FORMAT_RGBA8] formats.
+			</description>
+		</method>
 		<method name="load">
 			<return type="int" enum="Error" />
 			<param index="0" name="path" type="String" />
@@ -574,7 +580,7 @@
 		<method name="srgb_to_linear">
 			<return type="void" />
 			<description>
-				Converts the raw data from the sRGB colorspace to a linear scale.
+				Converts the raw data from the sRGB colorspace to a linear scale. Only works on images with [constant FORMAT_RGB8] or [constant FORMAT_RGBA8] formats.
 			</description>
 		</method>
 	</methods>
diff --git a/doc/classes/Viewport.xml b/doc/classes/Viewport.xml
index b288ee7ff6..edfb140346 100644
--- a/doc/classes/Viewport.xml
+++ b/doc/classes/Viewport.xml
@@ -102,6 +102,7 @@
 				    await RenderingServer.frame_post_draw
 				    $Viewport.get_texture().get_image().save_png("user://Screenshot.png")
 				[/codeblock]
+				[b]Note:[/b] When [member use_hdr_2d] is [code]true[/code] the returned texture will be an HDR image encoded in linear space.
 			</description>
 		</method>
 		<method name="get_viewport_rid" qualifiers="const">
diff --git a/doc/classes/ViewportTexture.xml b/doc/classes/ViewportTexture.xml
index ba2352ab61..f6840d6b09 100644
--- a/doc/classes/ViewportTexture.xml
+++ b/doc/classes/ViewportTexture.xml
@@ -8,6 +8,11 @@
 		To get a [ViewportTexture] in code, use the [method Viewport.get_texture] method on the target viewport.
 		[b]Note:[/b] A [ViewportTexture] is always local to its scene (see [member Resource.resource_local_to_scene]). If the scene root is not ready, it may return incorrect data (see [signal Node.ready]).
 		[b]Note:[/b] Instantiating scenes containing a high-resolution [ViewportTexture] may cause noticeable stutter.
+		[b]Note:[/b] When using a [Viewport] with [member Viewport.use_hdr_2d] set to [code]true[/code] the returned texture will be an HDR image encoded in linear space. This may look darker than normal when displayed directly on screen. To convert to gamma space, you can do the following:
+		[codeblock]
+		img.convert(Image.FORMAT_RGBA8)
+		imb.linear_to_srgb()
+		[/codeblock]
 	</description>
 	<tutorials>
 		<link title="GUI in 3D Viewport Demo">https://godotengine.org/asset-library/asset/2807</link>
diff --git a/servers/movie_writer/movie_writer.cpp b/servers/movie_writer/movie_writer.cpp
index 9df05ba94a..aebed4b432 100644
--- a/servers/movie_writer/movie_writer.cpp
+++ b/servers/movie_writer/movie_writer.cpp
@@ -185,6 +185,10 @@ void MovieWriter::add_frame() {
 	RID main_vp_rid = RenderingServer::get_singleton()->viewport_find_from_screen_attachment(DisplayServer::MAIN_WINDOW_ID);
 	RID main_vp_texture = RenderingServer::get_singleton()->viewport_get_texture(main_vp_rid);
 	Ref<Image> vp_tex = RenderingServer::get_singleton()->texture_2d_get(main_vp_texture);
+	if (RenderingServer::get_singleton()->viewport_is_using_hdr_2d(main_vp_rid)) {
+		vp_tex->convert(Image::FORMAT_RGBA8);
+		vp_tex->linear_to_srgb();
+	}
 
 	RenderingServer::get_singleton()->viewport_set_measure_render_time(main_vp_rid, true);
 	cpu_time += RenderingServer::get_singleton()->viewport_get_measured_render_time_cpu(main_vp_rid);
diff --git a/servers/rendering/renderer_viewport.cpp b/servers/rendering/renderer_viewport.cpp
index 884f8adb8c..4af89b218e 100644
--- a/servers/rendering/renderer_viewport.cpp
+++ b/servers/rendering/renderer_viewport.cpp
@@ -1270,6 +1270,13 @@ void RendererViewport::viewport_set_use_hdr_2d(RID p_viewport, bool p_use_hdr_2d
 	RSG::texture_storage->render_target_set_use_hdr(viewport->render_target, p_use_hdr_2d);
 }
 
+bool RendererViewport::viewport_is_using_hdr_2d(RID p_viewport) const {
+	Viewport *viewport = viewport_owner.get_or_null(p_viewport);
+	ERR_FAIL_NULL_V(viewport, false);
+
+	return viewport->use_hdr_2d;
+}
+
 void RendererViewport::viewport_set_screen_space_aa(RID p_viewport, RS::ViewportScreenSpaceAA p_mode) {
 	Viewport *viewport = viewport_owner.get_or_null(p_viewport);
 	ERR_FAIL_NULL(viewport);
diff --git a/servers/rendering/renderer_viewport.h b/servers/rendering/renderer_viewport.h
index b36fc7f57f..bf97905f86 100644
--- a/servers/rendering/renderer_viewport.h
+++ b/servers/rendering/renderer_viewport.h
@@ -262,6 +262,8 @@ public:
 	void viewport_set_transparent_background(RID p_viewport, bool p_enabled);
 	void viewport_set_use_hdr_2d(RID p_viewport, bool p_use_hdr_2d);
 
+	bool viewport_is_using_hdr_2d(RID p_viewport) const;
+
 	void viewport_set_global_canvas_transform(RID p_viewport, const Transform2D &p_transform);
 	void viewport_set_canvas_stacking(RID p_viewport, RID p_canvas, int p_layer, int p_sublayer);
 
diff --git a/servers/rendering/rendering_server_default.h b/servers/rendering/rendering_server_default.h
index 164ec3cc09..b0a68fbe35 100644
--- a/servers/rendering/rendering_server_default.h
+++ b/servers/rendering/rendering_server_default.h
@@ -639,6 +639,7 @@ public:
 	FUNC3(viewport_set_canvas_transform, RID, RID, const Transform2D &)
 	FUNC2(viewport_set_transparent_background, RID, bool)
 	FUNC2(viewport_set_use_hdr_2d, RID, bool)
+	FUNC1RC(bool, viewport_is_using_hdr_2d, RID)
 	FUNC2(viewport_set_snap_2d_transforms_to_pixel, RID, bool)
 	FUNC2(viewport_set_snap_2d_vertices_to_pixel, RID, bool)
 
diff --git a/servers/rendering_server.h b/servers/rendering_server.h
index e15dba4353..3324327921 100644
--- a/servers/rendering_server.h
+++ b/servers/rendering_server.h
@@ -934,6 +934,7 @@ public:
 	virtual void viewport_set_canvas_transform(RID p_viewport, RID p_canvas, const Transform2D &p_offset) = 0;
 	virtual void viewport_set_transparent_background(RID p_viewport, bool p_enabled) = 0;
 	virtual void viewport_set_use_hdr_2d(RID p_viewport, bool p_use_hdr) = 0;
+	virtual bool viewport_is_using_hdr_2d(RID p_viewport) const = 0;
 	virtual void viewport_set_snap_2d_transforms_to_pixel(RID p_viewport, bool p_enabled) = 0;
 	virtual void viewport_set_snap_2d_vertices_to_pixel(RID p_viewport, bool p_enabled) = 0;