Make foreground opacity configurable

Author: quantum5

kitty/cell_vertex.glsl

@@ -12,7 +12,7 @@
 
 // Inputs {{{
 layout(std140) uniform CellRenderData {
-    float xstart, ystart, dx, dy, sprite_dx, sprite_dy, background_opacity, cursor_text_uses_bg;
+    float xstart, ystart, dx, dy, sprite_dx, sprite_dy, background_opacity, foreground_opacity, cursor_text_uses_bg;
 
     uint default_fg, default_bg, highlight_fg, highlight_bg, cursor_color, cursor_text_color, url_color, url_style, inverted;
 
@@ -184,7 +184,7 @@ void main() {
     fg_as_uint = has_mark * color_table[NUM_COLORS + MARK_MASK + 1 + mark] + (ONE - has_mark) * fg_as_uint;
     foreground = color_to_vec(fg_as_uint);
     float has_dim = float((text_attrs >> DIM_SHIFT) & ONE);
-    effective_text_alpha = inactive_text_alpha * mix(1.0, dim_opacity, has_dim);
+    effective_text_alpha = foreground_opacity * inactive_text_alpha * mix(1.0, dim_opacity, has_dim);
     float in_url = float((is_selected & TWO) >> 1);
     decoration_fg = choose_color(in_url, color_to_vec(url_color), to_color(colors[2], fg_as_uint));
 #ifdef USE_SELECTION_FG

kitty/config_data.py

@@ -1038,6 +1038,11 @@ def active_tab_title_template(x: str) -> Optional[str]:
 default as it has a performance cost)
 '''))
 
+o('foreground_opacity', 1.0, option_type=unit_float, long_text=_('''
+The opacity of the foreground. A number between 0 and 1, where 1 is opaque and
+0 is fully transparent. This has similar constraints to :opt:`background_opacity`
+'''))
+
 
 def config_or_absolute_path(x: str) -> Optional[str]:
     if x.lower() == 'none':

kitty/shaders.c

@@ -252,7 +252,7 @@ send_graphics_data_to_gpu(size_t image_count, ssize_t gvao_idx, const ImageRende
 static inline void
 cell_update_uniform_block(ssize_t vao_idx, Screen *screen, int uniform_buffer, GLfloat xstart, GLfloat ystart, GLfloat dx, GLfloat dy, CursorRenderInfo *cursor, bool inverted, OSWindow *os_window) {
     struct CellRenderData {
-        GLfloat xstart, ystart, dx, dy, sprite_dx, sprite_dy, background_opacity, cursor_text_uses_bg;
+        GLfloat xstart, ystart, dx, dy, sprite_dx, sprite_dy, background_opacity, foreground_opacity, cursor_text_uses_bg;
 
         GLuint default_fg, default_bg, highlight_fg, highlight_bg, cursor_color, cursor_text_color, url_color, url_style, inverted;
 
@@ -295,6 +295,7 @@ cell_update_uniform_block(ssize_t vao_idx, Screen *screen, int uniform_buffer, G
     rd->sprite_dx = 1.0f / (float)x; rd->sprite_dy = 1.0f / (float)y;
     rd->inverted = inverted ? 1 : 0;
     rd->background_opacity = os_window->is_semi_transparent ? os_window->background_opacity : 1.0f;
+    rd->foreground_opacity = os_window->is_semi_transparent ? OPT(foreground_opacity) : 1.0f;
 
 #define COLOR(name) colorprofile_to_color(screen->color_profile, screen->color_profile->overridden.name, screen->color_profile->configured.name)
     rd->default_fg = COLOR(default_fg); rd->default_bg = COLOR(default_bg); rd->highlight_fg = COLOR(highlight_fg); rd->highlight_bg = COLOR(highlight_bg);

kitty/state.c

@@ -670,6 +670,7 @@ PYWRAP1(set_options) {
     S(background_image_layout, bglayout);
     S(background_tint, PyFloat_AsFloat);
     S(background_image_linear, PyObject_IsTrue);
+    S(foreground_opacity, PyFloat_AsFloat);
     S(dim_opacity, PyFloat_AsFloat);
     S(dynamic_background_opacity, PyObject_IsTrue);
     S(inactive_text_alpha, PyFloat_AsFloat);

kitty/state.h

@@ -44,7 +44,7 @@ typedef struct {
     WindowTitleIn macos_show_window_title_in;
     int adjust_line_height_px, adjust_column_width_px;
     float adjust_line_height_frac, adjust_column_width_frac;
-    float background_opacity, dim_opacity;
+    float background_opacity, foreground_opacity, dim_opacity;
 
     char* background_image;
     BackgroundImageLayout background_image_layout;