render: don't infer luminance multipliers from color TF

Make scene pass them explicitly instead. Ref #3995

include/render/vulkan.h

@@ -372,7 +372,6 @@ struct wlr_vk_frag_texture_pcr_data {
 
 struct wlr_vk_frag_output_pcr_data {
 	float matrix[4][4]; // only a 3x3 subset is used
-	float luminance_multiplier;
 	float lut_3d_offset;
 	float lut_3d_scale;
 };

include/wlr/render/pass.h

@@ -109,6 +109,8 @@ struct wlr_render_texture_options {
 	enum wlr_color_encoding color_encoding;
 	/* Color range of the source texture */
 	enum wlr_color_range color_range;
+	/* Default: 1.0 */
+	const float *luminance_multiplier;
 
 	/* Wait for a timeline synchronization point before texturing.
 	 *

render/vulkan/pass.c

@@ -146,11 +146,6 @@ static VkSemaphore render_pass_wait_sync_file(struct wlr_vk_render_pass *pass,
 	return *sem_ptr;
 }
 
-static float get_luminance_multiplier(const struct wlr_color_luminances *src_lum,
-		const struct wlr_color_luminances *dst_lum) {
-	return (dst_lum->reference / src_lum->reference) * (src_lum->max / dst_lum->max);
-}
-
 static bool unwrap_color_transform(struct wlr_color_transform *transform,
 		float matrix[static 9], enum wlr_color_transfer_function *tf) {
 	if (transform == NULL) {
@@ -248,7 +243,6 @@ static bool render_pass_submit(struct wlr_render_pass *wlr_pass) {
 		}
 
 		struct wlr_vk_frag_output_pcr_data frag_pcr_data = {
-			.luminance_multiplier = 1,
 			.lut_3d_offset = 0.5f / dim,
 			.lut_3d_scale = (float)(dim - 1) / dim,
 		};
@@ -276,12 +270,6 @@ static bool render_pass_submit(struct wlr_render_pass *wlr_pass) {
 				pipeline = render_buffer->two_pass.render_setup->output_pipe_bt1886;
 				break;
 			}
-
-			struct wlr_color_luminances srgb_lum, dst_lum;
-			wlr_color_transfer_function_get_default_luminance(
-				WLR_COLOR_TRANSFER_FUNCTION_SRGB, &srgb_lum);
-			wlr_color_transfer_function_get_default_luminance(tf, &dst_lum);
-			frag_pcr_data.luminance_multiplier = get_luminance_multiplier(&srgb_lum, &dst_lum);
 		}
 		bind_pipeline(pass, pipeline);
 		vkCmdPushConstants(render_cb->vk, renderer->output_pipe_layout,
@@ -883,13 +871,8 @@ static void render_pass_add_texture(struct wlr_render_pass *wlr_pass,
 	}
 
 	float luminance_multiplier = 1;
-	if (tf != WLR_COLOR_TRANSFER_FUNCTION_SRGB
+	if (options->luminance_multiplier != NULL) {
-			&& tf != WLR_COLOR_TRANSFER_FUNCTION_GAMMA22) {
+		luminance_multiplier = *options->luminance_multiplier;
-		struct wlr_color_luminances src_lum, srgb_lum;
-		wlr_color_transfer_function_get_default_luminance(tf, &src_lum);
-		wlr_color_transfer_function_get_default_luminance(
-			WLR_COLOR_TRANSFER_FUNCTION_SRGB, &srgb_lum);
-		luminance_multiplier = get_luminance_multiplier(&src_lum, &srgb_lum);
 	}
 
 	struct wlr_vk_frag_texture_pcr_data frag_pcr_data = {

render/vulkan/shaders/output.frag

@@ -10,7 +10,6 @@ layout(location = 0) out vec4 out_color;
 /* struct wlr_vk_frag_output_pcr_data */
 layout(push_constant, row_major) uniform UBO {
 	layout(offset = 80) mat4 matrix;
-	float luminance_multiplier;
 	float lut_3d_offset;
 	float lut_3d_scale;
 } data;
@@ -71,8 +70,6 @@ void main() {
 		rgb = in_color.rgb / alpha;
 	}
 
-	rgb *= data.luminance_multiplier;
-
 	rgb = mat3(data.matrix) * rgb;
 
 	if (OUTPUT_TRANSFORM != OUTPUT_TRANSFORM_IDENTITY) {

types/output/cursor.c

@@ -512,6 +512,15 @@ bool output_cursor_refresh_color_transform(struct wlr_output_cursor *output_curs
 	wlr_color_primaries_from_named(&primaries, img_desc->primaries);
 	float matrix[9];
 	wlr_color_primaries_transform_absolute_colorimetric(&primaries_srgb, &primaries, matrix);
+
+	// Source is sRGB, which has reference == max
+	struct wlr_color_luminances dst_lum;
+	wlr_color_transfer_function_get_default_luminance(img_desc->transfer_function, &dst_lum);
+	float luminance_multiplier = dst_lum.reference / dst_lum.max;
+	for (int i = 0; i < 9; ++i) {
+		matrix[i] *= luminance_multiplier;
+	}
+
 	struct wlr_color_transform *transforms[] = {
 		wlr_color_transform_init_matrix(matrix),
 		wlr_color_transform_init_linear_to_inverse_eotf(img_desc->transfer_function),

types/scene/wlr_scene.c

@@ -1435,6 +1435,11 @@ struct render_list_entry {
 	int x, y;
 };
 
+static float get_luminance_multiplier(const struct wlr_color_luminances *src_lum,
+		const struct wlr_color_luminances *dst_lum) {
+	return (dst_lum->reference / src_lum->reference) * (src_lum->max / dst_lum->max);
+}
+
 static void scene_entry_render(struct render_list_entry *entry, const struct render_data *data) {
 	struct wlr_scene_node *node = entry->node;
 
@@ -1518,6 +1523,13 @@ static void scene_entry_render(struct render_list_entry *entry, const struct ren
 			wlr_color_primaries_from_named(&primaries, scene_buffer->primaries);
 		}
 
+		struct wlr_color_luminances src_lum, srgb_lum;
+		wlr_color_transfer_function_get_default_luminance(
+			scene_buffer->transfer_function, &src_lum);
+		wlr_color_transfer_function_get_default_luminance(
+			WLR_COLOR_TRANSFER_FUNCTION_SRGB, &srgb_lum);
+		float luminance_multiplier = get_luminance_multiplier(&src_lum, &srgb_lum);
+
 		wlr_render_pass_add_texture(data->render_pass, &(struct wlr_render_texture_options) {
 			.texture = texture,
 			.src_box = scene_buffer->src_box,
@@ -1533,6 +1545,7 @@ static void scene_entry_render(struct render_list_entry *entry, const struct ren
 			.primaries = scene_buffer->primaries != 0 ? &primaries : NULL,
 			.color_encoding = scene_buffer->color_encoding,
 			.color_range = scene_buffer->color_range,
+			.luminance_multiplier = &luminance_multiplier,
 			.wait_timeline = scene_buffer->wait_timeline,
 			.wait_point = scene_buffer->wait_point,
 		});
@@ -2208,6 +2221,16 @@ static bool scene_output_combine_color_transforms(
 		wlr_color_primaries_from_named(&primaries, img_desc->primaries);
 		float matrix[9];
 		wlr_color_primaries_transform_absolute_colorimetric(&primaries_srgb, &primaries, matrix);
+
+		struct wlr_color_luminances srgb_lum, dst_lum;
+		wlr_color_transfer_function_get_default_luminance(
+			WLR_COLOR_TRANSFER_FUNCTION_SRGB, &srgb_lum);
+		wlr_color_transfer_function_get_default_luminance(img_desc->transfer_function, &dst_lum);
+		float luminance_multiplier = get_luminance_multiplier(&srgb_lum, &dst_lum);
+		for (int i = 0; i < 9; ++i) {
+			matrix[i] *= luminance_multiplier;
+		}
+
 		color_matrix = wlr_color_transform_init_matrix(matrix);
 		inv_eotf = wlr_color_transform_init_linear_to_inverse_eotf(img_desc->transfer_function);
 		if (color_matrix == NULL || inv_eotf == NULL) {